Free Pascal :
User’s Guide

Michaël Van Canneyt
Florian Klämpfl

January 2012

Contents

Chapter 1  Introduction

1.1  About this document

This is the user’s guide for Free Pascal . It describes the installation and use of the Free Pascal compiler on the different supported platforms. It does not attempt to give an exhaustive list of all supported commands, nor a definition of the Pascal language. Look at the Reference guide for these things. For a description of the possibilities and the inner workings of the compiler, see the Programmers guide . In the appendices of this document you will find lists of reserved words and compiler error messages (with descriptions).

This document describes the compiler as it is/functions at the time of writing. First consult the README and FAQ files, distributed with the compiler. The README and FAQ files are, in case of conflict with this manual, authoritative.

1.2  About the compiler

Free Pascal is a 32- and 64-bit Pascal compiler. The current version (2.2) can compile code for the following processors:

The compiler and Run-Time Library are available for the following operating systems:

The complete list is at all times available on the Free Pascal website.

Free Pascal is designed to be, as much as possible, source compatible with Turbo Pascal 7.0 and Delphi 7 (although this goal is not yet attained), but it also enhances these languages with elements like operator overloading. And, unlike these ancestors, it supports multiple platforms.

It also differs from them in the sense that you cannot use compiled units from one system for the other, i.e. you cannot use TP compiled units.

Also, there is a text version of an Integrated Development Environment (IDE) available for Free Pascal . Users that prefer a graphical IDE can have a look at the Lazarus or MSIDE projects.

Free Pascal consists of several parts :

  1. The compiler program itself.
  2. The Run-Time Library (RTL).
  3. The packages. This is a collection of many utility units, ranging from the whole Windows 32 API, through native ZIP/BZIP file handling to the whole GTK-2 interface.
  4. The Free Component Library. This is a set of class-based utility units which give a database framework, image support, web support, XML support and many many more.
  5. Utility programs and units.

Of these you only need the first two, in order to be able to use the compiler. In this document, we describe the use of the compiler and utilities. The Pascal Language is described in the Reference guide , and the available routines (units) are described in the RTL and FCL Unit reference guides.

1.3  Getting more information.

If the documentation doesn’t give an answer to your questions, you can obtain more information on the Internet, at the following addresses:

Other than that, some mirrors exist.

Finally, if you think something should be added to this manual (entirely possible), please do not hesitate and contact me at michael@freepascal.org. .

Let’s get on with something useful.

Chapter 2  Installing the compiler

2.1  Before Installation : Requirements

2.1.1  Hardware requirements

The compiler needs at least one of the following processors:

  1. An Intel 80386 or higher processor. A coprocessor is not required, although it will slow down your program’s performance if you do floating point calculations without a coprocessor, since emulation will be used.
  2. An AMD64 or EMT64 processor.
  3. A PowerPC processor.
  4. A SPARC processor
  5. An ARM processor.
  6. Older FPC versions exist for the motorola 68000 processor, but these are no longer maintained.

Memory and disk requirements:

  1. 8 Megabytes of free memory. This is sufficient to allow compilation of small programs.
  2. Large programs (such as the compiler itself) will require at least 64 MB. of memory, but 128MB is recommended. (Note that the compiled programs themselves do not need so much memory.)
  3. At least 80 MB free disk space. When the sources are installed, another 270 MB are needed.

2.1.2  Software requirements

Under DOS

The dos distribution contains all the files you need to run the compiler and compile Pascal programs.

Under UNIX

Under unix systems (such as linux ) you need to have the following programs installed :

  1. gnu as, the gnu assembler.
  2. gnu ld, the gnu linker.
  3. Optionally (but highly recommended) : gnu make. For easy recompiling of the compiler and Run-Time Library, this is needed.

Under Windows

The Windows distributions (both 32 and 64 bit) contain all the files you need to run the compiler and compile Pascal programs. However, it may be a good idea to install the mingw32 tools or the cygwin development tools. Links to both of these tools can be found on http://www.freePascal.org

Under OS/2

While the Free Pascal distribution comes with all necessary tools, it is a good idea to install the EMX extender in order to compile and run programs with the Free Pascal compiler. The EMX extender can be found on:
ftp://hobbes.nmsu.edu/pub/os2/dev/emx/v0.9d

Under Mac OS X

Mac OS X 10.1 or higher is required, and the developer tools or XCode should be installed.

2.2  Installing the compiler.

The installation of Free Pascal is easy, but is platform-dependent. We discuss the process for each platform separately.

2.2.1  Installing under Windows

For Windows , there is a Windows installer, setup.exe. This is a normal installation program, which offers the usual options of selecting a directory, and which parts of the distribution you want to install. It will, optionally, associate the .pp or .pas extensions with the text mode IDE.

It is not recommended to install the compiler in a directory which has spaces in it’s path name. Some of the external tools do not support filenames with spaces in them, and you will have problems creating programs.

2.2.2  Installing under DOS or OS/2

Mandatory installation steps.

First, you must get the latest distribution files of Free Pascal . They come as zip files, which you must unzip first, or you can download the compiler as a series of separate files. This is especially useful if you have a slow connection, but it is also nice if you want to install only some parts of the compiler distribution. The distribution zip files for DOS or OS/2 contain an installation program INSTALL.EXE. You must run this program to install the compiler.

The screen of the DOS or OS/2 installation program looks like figure ??.


Figure ?? The dos install program screen



Figure ??


The program allows you to select:

In order to run Free Pascal from any directory on your system, you must extend your path variable to contain the C:\PP\BIN directory. Usually this is done in the AUTOEXEC.BAT file. It should look something like this :

  SET PATH=%PATH%;C:\PP\2.2\BIN\i386-DOS

for dos or

  SET PATH=%PATH%;C:\PP\2.2\BIN\i386-OS2

for os/2 . (Again, assuming that you installed in the default location).

On os/2 , Free Pascal installs some libraries from the EMX package if they were not yet installed. (The installer will notify you if they should be installed). They are located in the

C:\PP\DLL

directory. The name of this directory should be added to the LIBPATH directive in the config.sys file:

LIBPATH=XXX;C:\PP\DLL

Obviously, any existing directories in the LIBPATH directive (indicated by XXX in the above example) should be preserved.

Optional Installation: The coprocessor emulation

For people who have an older CPU type, without math coprocessor (i387) it is necessary to install a coprocessor emulation, since Free Pascal uses the coprocessor to do all floating point operations.

The installation of the coprocessor emulation is handled by the installation program (INSTALL.EXE) under dos and Windows .

2.2.3  Installing under Linux

Mandatory installation steps.

The linux distribution of Free Pascal comes in three forms:

If you use the .rpm format, installation is limited to

rpm -i fpc-X.Y.Z-N.ARCH.rpm

Where X.Y.Z is the version number of the .rpm file, and ARCH is one of the supported architectures (i386, x86_64 etc.).

If you use Debian, installation is limited to

dpkg -i fpc-XXX.deb

Here again, XXX is the version number of the .deb file.

You need root access to install these packages. The .tar file allows you to do an installation below your home directory if you don’t have root permissions.

When downloading the .tar file, or the separate files, installation is more interactive.

In case you downloaded the .tar file, you should first untar the file, in some directory where you have write permission, using the following command:

tar -xvf fpc.tar

We supposed here that you downloaded the file fpc.tar somewhere from the Internet. (The real filename will have some version number in it, which we omit here for clarity.)

When the file is untarred, you will be left with more archive files, and an install program: an installation shell script.

If you downloaded the files as separate files, you should at least download the install.sh script, and the libraries (in libs.tar.gz).

To install Free Pascal , all that you need to do now is give the following command:

./install.sh

And then you must answer some questions. They’re very simple, they’re mainly concerned with 2 things :

  1. Places where you can install different things.
  2. Deciding if you want to install certain components (such as sources and demo programs).

The script will automatically detect which components are present and can be installed. It will only offer to install what has been found. Because of this feature, you must keep the original names when downloading, since the script expects this.

If you run the installation script as the root user, you can just accept all installation defaults. If you don’t run as root, you must take care to supply the installation program with directory names where you have write permission, as it will attempt to create the directories you specify. In principle, you can install it wherever you want, though.

At the end of installation, the installation program will generate a configuration file (fpc.cfg) for the Free Pascal compiler which reflects the settings that you chose. It will install this file in the /etc directory or in your home directory (with name .fpc.cfg) if you do not have write permission in the /etc directory. It will make a copy in the directory where you installed the libraries.

The compiler will first look for a file .fpc.cfg in your home directory before looking in the /etc directory.

2.3  Optional configuration steps

On any platform, after installing the compiler you may wish to set some environment variables. The Free Pascal compiler recognizes the following variables :

These locations are, however, set in the sample configuration file which is built at the end of the installation process, except for the PPC_CONFIG_PATH variable, which you must set if you didn’t install things in the default places.

2.4  Before compiling

Also distributed in Free Pascal is a README file. It contains the latest instructions for installing Free Pascal , and should always be read first.

Furthermore, platform-specific information and common questions are addressed in the FAQ. It should be read before reporting any bug.

2.5  Testing the compiler

After the installation is completed and the optional environment variables are set as described above, your first program can be compiled.

Included in the Free Pascal distribution are some demonstration programs, showing what the compiler can do. You can test if the compiler functions correctly by trying to compile these programs.

The compiler is called

To compile a program (e.g demo\text\hello.pp), copy the program to your current working directory, and simply type :

  fpc hello

at the command prompt. If you don’t have a configuration file, then you may need to tell the compiler where it can find the units, for instance as follows:

fpc -Fuc:\pp\NNN\units\i386-go32v2\rtl hello

under dos , and under linux you could type

fpc -Fu/usr/lib/fpc/NNN/units/i386-linux/rtl hello

(replace NNN with the version number of Free Pascal that you are using). This is, of course, assuming that you installed under C:\PP or /usr/lib/fpc/NNN, respectively.

If you got no error messages, the compiler has generated an executable called hello.exe under dos , os/2 or Windows , or hello (no extension) under unix and most other operating systems.

To execute the program, simply type :

  hello

or

  ./hello

on Unices (where the current directory usually is not in the PATH).

If all went well, you should see the following friendly greeting:

Hello world

Chapter 3  Compiler usage

Here we describe the essentials to compile a program and a unit. For more advanced uses of the compiler, see the section on configuring the compiler, and the Programmers guide .

The examples in this section suppose that you have an fpc.cfg which is set up correctly, and which contains at least the path setting for the RTL units. In principle this file is generated by the installation program. You may have to check that it is in the correct place. (see section ?? for more information on this.)

3.1  File searching

Before you start compiling a program or a series of units, it is important to know where the compiler looks for its source files and other files. In this section we discuss this, and we indicate how to influence this.

Remark: The use of slashes (/) and backslashes (\) as directory separators is irrelevant, the compiler will convert to whatever character is used on the current operating system. Examples will be given using slashes, since this avoids problems on unix systems (such as linux ).

3.1.1  Command line files

The file that you specify on the command line, such as in

fpc foo.pp

will be looked for ONLY in the current directory. If you specify a directory in the filename, then the compiler will look in that directory:

fpc subdir/foo.pp

will look for foo.pp in the subdirectory subdir of the current directory.

Under case sensitive file systems (such as linux and unix ), the name of this file is case sensitive; under other operating systems (such as dos , Windows NT , os/2 ) this is not the case.

3.1.2  Unit files

When you compile a unit or program that needs other units, the compiler will look for compiled versions of these units in the following way:

  1. It will look in the current directory.
  2. It will look in the directory where the source file resides.
  3. It will look in the directory where the compiler binary is.
  4. It will look in all the directories specified in the unit search path.

You can add a directory to the unit search path with the (-Fu, (see ??) ) option. Every occurrence of one of these options will insert a directory to the unit search path. i.e. the last path on the command line will be searched first.

The compiler adds several paths to the unit search path:

  1. The contents of the environment variable XXUNITS, where XX must be replaced with one of the supported targets: GO32V2, LINUX,WIN32, OS2, BEOS, FREEBSD, NETBSD.
  2. The standard unit directory. This directory is determined from the FPCDIR environment variable. If this variable is not set, then it is defaulted to the following: After this directory is determined , the following paths are added to the search path:
    1. FPCDIR/units/FPCTARGET
    2. FPCDIR/units/FPCTARGET/rtl
    Here target must be replaced by the name of the target you are compiling for: this is a combination of CPU and OS, so for instance
    /usr/local/lib/fpc/2.2/units/i386-linux/
    
    or, when cross-compiling
    /usr/local/lib/fpc/2.2/units/i386-win32/
    

The -Fu option accepts a single * wildcard, which will be replaced by all directories found on that location, but not the location itself. For example, given the directories

rtl/units/i386-linux
fcl/units/i386-linux
packages/base
packages/extra

the command

fpc -Fu"*/units/i386-linux"

will have the same effect as

fpc -Furtl/units/i386-linux -Fufcl/units/i386-linux

since both the rtl and fcl directories contain further units/i386-linux subdirectories. The packages directory will not be added, since it doesn’t contain a units/i386-linux subdirectory.

The following command

fpc -Fu"units/i386-linux/*"

will match any directory below the units/i386-linux directory, but will not match the units/i386-linux directory itself, so you should add it manually if you want the compiler to look for files in this directory as well:

fpc -Fu"units/i386-linux" -Fu"units/i386-linux/*"

Note that (for optimization) the compiler will drop any non-existing paths from the search path, i.e. the existence of the path (after wildcard and environment variable expansion) will be tested.

You can see what paths the compiler will search by giving the compiler the -vu option.

On systems where filenames are case sensitive (such as unix and linux ), the compiler will :

  1. Search for the original file name, i.e. preserves case.
  2. Search for the filename all lowercased.
  3. Search for the filename all uppercased.

This is necessary, since Pascal is case-independent, and the statements Uses Unit1; or uses unit1; should have the same effect.

It will do this first with the extension .ppu (the compiled unit), .pp and then with the extension .pas.

For instance, suppose that the file foo.pp needs the unit bar. Then the command

fpc -Fu.. -Fuunits foo.pp

will tell the compiler to look for the unit bar in the following places:

  1. In the current directory.
  2. In the directory where the compiler binary is (not under linux ).
  3. In the parent directory of the current directory.
  4. In the subdirectory units of the current directory
  5. In the standard unit directory.

Also, unit names that are longer than 8 characters will first be looked for with their full length. If the unit is not found with this name, the name will be truncated to 8 characters, and the compiler will look again in the same directories, but with the truncated name.

If the compiler finds the unit it needs, it will look for the source file of this unit in the same directory where it found the unit. If it finds the source of the unit, then it will compare the file times. If the source file was modified more recent than the unit file, the compiler will attempt to recompile the unit with this source file.

If the compiler doesn’t find a compiled version of the unit, or when the -B option is specified, then the compiler will look in the same manner for the unit source file, and attempt to recompile it.

It is recommended to set the unit search path in the configuration file fpc.cfg. If you do this, you don’t need to specify the unit search path on the command line every time you want to compile something.

3.1.3  Include files

If you include a file in your source with the {$I filename} directive, the compiler will look for it in the following places:

  1. It will look in the path specified in the include file name.
  2. It will look in the directory where the current source file is.
  3. it will look in all directories specified in the include file search path.

You can add files to the include file search path with the -I, (see ??) or -Fi, (see ??) options.

As an example, consider the following include statement in a file units/foo.pp:

{$i ../bar.inc}

Then the following command :

fpc -Iincfiles units/foo.pp

will cause the compiler to look in the following directories for bar.inc:

  1. The parent directory of the current directory.
  2. The units subdirectory of the current directory.
  3. The incfiles subdirectory of the current directory.

3.1.4  Object files

When you link to object files (using the {$L file.o} directive, the compiler will look for this file in the same way as it looks for include files:

  1. It will look in the path specified in the object file name.
  2. It will look in the directory where the current source file is.
  3. It will look in all directories specified in the object file search path.

You can add files to the object file search path with the -Fo, (see ??) option.

3.1.5  Configuration file

Not all options must be given on the compiler command line. The compiler can use a configuration file which can contain the same options as on the command line. There can be only one command-line option on each line in the configuration file.

Unless you specify the -n, (see ??) option, the compiler will look for a configuration file fpc.cfg in the following places:

Versions prior to version 1.0.6 of the compiler used a configuration file ppc386.cfg. This file is still searched, but its usage is considered deprecated. For compatibility, fpc.cfg will be searched first, and if not found, the file ppc386.cfg will be searched and used.

Remark: The searching for ppc386.cfg will be removed from the compiler in version 2.4.0. To indicate this, the compiler gives a warning as of version 2.3.1 if it uses a ppc386.cfg configuration file.

3.1.6  About long filenames

Free Pascal can handle long filenames on all platforms, except DOS. On Windows, it will use support for long filenames if it is available (which is not always the case on older versions of Windows).

If no support for long filenames is present, it will truncate unit names to 8 characters.

It is not recommended to put units in directories that contain spaces in their names, since the external GNU linker doesn’t understand such filenames.

3.2  Compiling a program

Compiling a program is very simple. Assuming that you have a program source in the file prog.pp, you can compile this with the following command:

  fpc [options] prog.pp

The square brackets [ ] indicate that what is between them is optional.

If your program file has the .pp or .pas extension, you can omit this on the command line, e.g. in the previous example you could have typed:

  fpc [options] prog

If all went well, the compiler will produce an executable file. You can execute it straight away; you don’t need to do anything else.

You will notice that there is also another file in your directory, with extension .o. This contains the object file for your program. If you compiled a program, you can delete the object file (.o), but don’t delete it if you compiled a unit. This is because the unit object file contains the code of the unit, and will be linked in any program that uses it.

3.3  Compiling a unit

Compiling a unit is not essentially different from compiling a program. The difference is mainly that the linker isn’t called in this case.

To compile a unit in the file foo.pp, just type :

  fpc  foo

Recall the remark about file extensions in the previous section.

When all went well, you will be left with 2 (two) unit files:

  1. foo.ppu - this is the file describing the unit you just compiled.
  2. foo.o - this file contains the actual code of the unit. This file will eventually end up in the executables.

Both files are needed if you plan to use the unit for some programs. So don’t delete them. If you want to distribute the unit, you must provide both the .ppu and .o file. One is useless without the other.

3.4  Units, libraries and smartlinking

The Free Pascal compiler supports smartlinking and the creation of libraries. However, the default behaviour is to compile each unit into one big object file, which will be linked as a whole into your program. Shared libraries can be created on most platforms, although current level of FPC support may vary (they are e.g. not supported for GO32v2 and OS2 targets).

It is also possible to take existing units and put them together in 1 static or shared library (using the ppumove tool, section ?? ).

3.5  Reducing the size of your program

When you created your program, it is possible to reduce the size of the resulting executable. This is possible, because the compiler leaves a lot of information in the program which, strictly speaking, isn’t required for the execution of the program.

The surplus of information can be removed with a small program called strip.The usage is simple. Just type

strip prog

On the command line, and the strip program will remove all unnecessary information from your program. This can lead to size reductions of up to 30 %.

You can use the -Xs switch to let the compiler do this stripping automatically at program compile time. (The switch has no effect when compiling units.)

Another technique to reduce the size of a program is to use smartlinking. Normally, units (including the system unit) are linked in as a whole. It is however possible to compile units such that they can be smartlinked. This means that only the functions and procedures that are actually used are linked in your program, leaving out any unnecessary code. The compiler will turn on smartlinking with the -XX, (see ??) switch. This technique is described in full in the programmers guide.

Chapter 4  Compiling problems

4.1  General problems

4.2  Problems you may encounter under DOS

Chapter 5  Compiler configuration

The output of the compiler can be controlled in many ways. This can be done essentially in two distinct ways:

The compiler first reads the configuration file. Only then are the command line options checked. This creates the possibility to set some basic options in the configuration file, and at the same time you can still set some specific options when compiling some unit or program. First we list the command line options, and then we explain how to specify the command line options in the configuration file. When reading this, keep in mind that the options are case sensitive.

5.1  Using the command line options

The available options for the current version of the compiler are listed by category. Also, see chapter ?? for a listing as generated by the current compiler.

5.1.1  General options

-h
Print a list of all options and exit.
-?
Same as -h, waiting after each screenfull for the enter key.
-i
Print copyright and other information. You can supply a qualifier, as -ixxx where xxx can be one of the following:
D
: Returns the compiler date.
V
: Returns the short compiler version.
W
: Return full compiler version.
SO
: Returns the compiler OS.
SP
: Returns the compiler processor.
TO
: Returns the target OS.
TP
: Returns the target processor.
-l
Print the Free Pascal logo and version number.
-n
Ignore the default configuration file. You can still pass a configuration file with the @ option.

5.1.2  Options for getting feedback

-vxxx
Be verbose. xxx is a combination of the following :

The difference between an error/fatal error/hint/warning/note is the severity:

Fatal
The compiler encountered an error, and can no longer continue compiling. It will stop at once.
Error
The compiler encountered an error, but can continue to compile (at most till the end of the current unit).
Warning
if there is a warning, it means there is probably an error, i.e. something may be wrong in your code.
Hint
Is issued if the compiler thinks the code could be better, but there is no suspicion of error.
Note
Is some noteworthy information, but again there is no error.

The difference between hints and notes is not really very clear. Both can be ignored without too much risk, but warnings should always be checked.

5.1.3  Options concerning files and directories

-exxx
Specify xxx as the directory containing the executables for the programs as (the assembler) and ld (the linker).
-FaXYZ
load units XYZ after the system unit, but before any other unit is loaded. XYZ is a comma-separated list of unit names. This can only be used for programs, and has the same effect as if XYZ were inserted as the first item in the program’s uses clause.
-FcXXX
Set the input codepage to XXX. Experimental.
-FCxxx
Set the RC compiler (resource compiler) binary name to xxx.
-Fd
Disable the compiler’s internal directory cache. By default, the compiler caches the names all files in a directory as soon as it looks for a single file in said directory. This ensures that the correct case of all file names is used in the debug information and to create compiled files when compiling on a case-preserving file systems under an OS that also support case-sensitive file systems, and it can also increase performance. This feature can however cause severe slowdowns on networked file systems, especially when compiling trivial programs in directories containing many files, and such slowdowns can be addressed by disabling the cache using this switch.
-FD
Same as -e.
-Fexxx
Write errors, etc. to the file named xxx.
-FExxx
Write the executable and units to directory xxx instead of the current directory. If this option is followed by a -o option -o, (see ??) , and this option contains a path component, then the -o path will override the -FE setting.
-Ffxxx
Add xxx to the framework path (only for Darwin).
-Fixxx
Add xxx to the include file search path.
-Flxxx
Add xxx to the library search path. (This is also passed to the linker.)
-FLxxx
(linux only) Use xxx as the dynamic linker. The default is /lib/ld-linux.so.2, or /lib/ld-linux.so.1, depending on which one is found first.
-Fmxxx
Load the unicode conversion table from file x.txt in the directory where the compiler is located. Only used when -Fc is also in effect.
-Foxxx
Add xxx to the object file search path. This path is used when looking for files that need to be linked in.
-Frxxx
Specify xxx as the file which contain the compiler messages. This will override the compiler’s built-in default messages, which are in english.
-FRxxx
set the resource (.res) linker to xxx.
-Fuxxx
Add xxx to the unit search path. Units are first searched in the current directory. If they are not found there then the compiler searches them in the unit path. You must always supply the path to the system unit. The xxx path can contain a single wildcard (*) which will be expanded to all possible directory names found at that location. Note that the location itself is not included in the list. See section ?? for more information about this option.
-FUxxx
Write units to directory xxx instead of the current directory. It overrides the -FE option.
-Ixxx
Add xxx to the include file search path. This option has the same effect as -Fi.
-FWxxx
store generated Whole Program Optimization information in file xxx.
-Fwxxx
Read Whole Program Optimization information from file xxx.

5.1.4  Options controlling the kind of output.

For more information on these options, see Programmers guide .

-a
Do not delete the assembler files (not applicable when using the internal assembler). This also applies to the (possibly) generated batch script.
-al
Include the source code lines in the assembler file as comments.
-an
Write node information in the assember file (nodes are the way the compiler represents statements or parts thereof internally). This is primarily intended for debugging the code generated by the compiler.
-ap
Use pipes instead of creating temporary assembler files. This may speed up the compiler on os/2 and linux . Only with assemblers (such as gnu if the internal assembler is used.
-ar
List register allocation and release info in the assembler file. This is primarily intended for debugging the code generated by the compiler.
-at
List information about temporary allocations and deallocations in the assembler file.
-Axxx
specify what kind of assembler should be generated. Here xxx is one of the following :
default
Use the built-in default.
as
Assemble using gnu as.
nasmcoff
Coff (Go32v2) file using Nasm.
nasmelf
Elf32 (linux ) file using Nasm.
nasmwin32
Windows 32-bit file using Nasm.
nasmwdosx
Windows 32-bit/DOSX file using Nasm.
nasmobj
Object file using Nasm.
masm
Object file using Masm (Microsoft).
tasm
Object file using Tasm (Borland).
elf
Elf32 (linux ) using internal writer.
coff
Coff object file (Go32v2) using the internal binary object writer.
pecoff
PECoff object file (Win32) using the internal binary object writer.
-B
Re-compile all used units, even if the unit sources didn’t change since the last compilation.
-b
Generate browser info. This information can be used by an Integrated Development Environment (IDE) to provide information on classes, objects, procedures, types and variables in a unit.
-bl
The same as -b but also generates information about local variables, types and procedures.
-Caxxx
Set the ABI (Application Binary Interface) to xxx. The -i option gives the possible values for xxx.
-Cb
Generate big-endian code.
-Cc
Set the default calling convention used by the compiler.
-CD
Create a dynamic library. This is used to transform units into dynamically linkable libraries on linux .
-Ce
Emulate floating point operations.
-Cfxxx
Set the used floating point processor to xxx.
-CFNN
Set the minimal floating point precision to NN. Possible values are 32 and 64.
-Cg
Enable generation of PIC code. This should only be necessary when generating libraries on linux or other Unices.
-Chxxx
Reserves xxx bytes heap. xxx should be between 1024 and 67107840.
-Ci
Generate Input/Output checking code. In case some input/output code of your program returns an error status, the program will exit with a run-time error. Which error is generated depends on the I/O error.
-Cn
Omit the linking stage.
-Co
Generate Integer overflow checking code. In case of integer errors, a run-time error will be generated by your program.
-CO
Check for possible overflow of integer operations.
-CpXXX
Set the processor type to XXX.
-CPX=N
Set the packing for X to N. X can be PACKSET, PACKENUM or PACKRECORD, and N can be a value of 1,2,4,8 or one of the keywords DEFAULT or NORMAL.
-Cr
Generate Range checking code. If your program accesses an array element with an invalid index, or if it increases an enumerated type beyond its scope, a run-time error will be generated.
-CR
Generate checks when calling methods to verify if the virtual method table for that object is valid.
-Csxxx
Set stack size to xxx.
-Ct
Generate stack checking code. If your program performs a faulty stack operation, a run-rime error will be generated.
-CX
Create a smartlinked unit when writing a unit. Smartlinking will only link in the code parts that are actually needed by the program. All unused code is left out. This can lead to substantially smaller binaries.
-dxxx
Define the symbol name xxx. This can be used to conditionally compile parts of your code.
-D
Generate a DEF file (for OS/2).
-Dd
Set the description of the executable/library (Windows ).
-Dv
Set the version of the executable/library (Windows ).
-E
Same as -Cn.
-g
Generate debugging information for debugging with gdb.
-gc
Generate checks for pointers. This must be used with the -gh command line option. When this options is enabled, it will verify that all pointer accesses are within the heap.
-gg
Same as -g.
-gh
Use the heaptrc unit (see Unit reference ). (Produces a report about heap usage after the program exits)
-gl
Use the lineinfo unit (see Unit reference ). (Produces file name/line number information if the program exits due to an error.)
-goXXX
set debug information options. One of the options is dwarfsets: It enables dwarf set debug information (this does not work with gdb versions prior to 6.5.
-gp
Preserve case in stabs symbol names. Default is to uppercase all names.
-gs
Write stabs debug information.
-gt
Trash local variables. This writes a random value to local variables at procedure start. This can be used to detect uninitialized variables.
-gv
Emit info for valgrind.
-gw
Emit dwarf debugging info (version 2).
-gw2
Emit dwarf debugging info (version 2).
-gw3
Emit dwarf debugging info (version 3).
-kxxx
Pass xxx to the linker.
-Oxxx
Optimize the compiler’s output; xxx can have one of the following values :
aPARAM=VALUE
Specify alignment of structures and code. PARAM determines what should be aligned; VALUE specifies the alignment boundary. See the Programmer’s Guide for a description of the possible values.
g
Optimize for size, try to generate smaller code.
G
Optimize for time, try to generate faster code (default).
r
Keep certain variables in registers (experimental, use with caution).
u
Uncertain optimizations
1
Level 1 optimizations (quick optimizations).
2
Level 2 optimizations (-O1 plus some slower optimizations).
3
Level 3 optimizations (-O2 plus -Ou).
oxxx
Specify specific optimizations: n can be one of
REGVAR
Use register variables
STACKFRAME
Skip stack frames
LOOPUNROLL
unroll (small) loops
TAILREC
change tail recursion to non-recursive loop.
pxxx
select processor xxx to optimize for. fpc -i lists all available processor instruction sets.
Wxxx
Generate Whole-Program-Optimization information for feature xxx. fpc -i will generate a list of possible values.
wxxx
Perform Whole-Program-Optimization information for feature xxx. fpc -i will generate a list of possible values.
s
Optimize for size rather than speed.
The exact effect of some of these optimizations can be found in the Programmers guide .
-oxxx
Use xxx as the name of the output file (executable). For use only with programs. The output filename can contain a path, and if it does, it will override any previous -FE setting. If the output filename does not contain a path, the -FE setting is observed.
-pg
Generate profiler code for gprof. This will define the symbol FPC_PROFILE, which can be used in conditional defines.
-s
Do not call the assembler and linker. Instead, the compiler writes a script, PPAS.BAT under dos , or ppas.sh under linux , which can then be executed to produce an executable. This can be used to speed up the compiling process or to debug the compiler’s output. This option can take an extra parameter, mainly used for cross-compilation. It can have one of the following values:
h
Generate script to link on host. The generated script can be run on the compilation platform (host platform).
t
Generate script to link on target platform. The generated script can be run on the target platform. (where the binary is intended to be run)
r
Skip register allocation phase (optimizations will be disabled).
-Txxx
Specify the target operating system. xxx can be one of the following: The available list of targets depends on the actual compiler binary. Use fpc -i to get a list of targets supported by the compiler binary.
-uxxx
Undefine the symbol xxx. This is the opposite of the -d option.
-Ur
Generate release unit files. These files will not be recompiled, even when the sources are available. This is useful when making release distributions. This also overrides the -B option for release mode units.
-W
Set some Windows or os/2 attributes of the generated binary. It can be one or more of the following
Bhhh
Set preferred base address to hhh (a hexadecimal address)
C
Generate a console application (+) or a gui application (-).
D
Force use of Def file for exports.
F
Generate a FS application (+) or a console application (-).
G
Generate a GUI application (+) or a console application (-).
N
Do not generate a relocation section.
R
Generate a relocation section.
T
Generate a TOOL application (+) or a console application (-).
-Xx
Specify executable options. This tells the compiler what kind of executable should be generated. The parameter x can be one of the following:

5.1.5  Options concerning the sources (language options)

For more information on these options, see Programmers guide

-Mmode
Set language mode to mode, which can be one of the following:
delphi
Try to be Delphi compatible. This is more strict than the objfpc mode, since some Free Pascal extensions are switched off.
fpc
Free Pascal dialect (default).
macpas
Try to be compatible with Macintosh Pascal dialects.
objfpc
Switch on some Delphi extensions. This is different from Delphi mode, because some Free Pascal constructs are still available.
tp
Try to be TP/BP 7.0 compatible. This means no function overloading etc.
-Mfeature
Select language feature feature. As of FPC version 2.3.1, the -M command line switch can be used to select individual language features. In that case, feature is one of the following keywords:
CLASS
Use object pascal classes.
OBJPAS
Automatically include the ObjPas unit.
RESULT
Enable the Result identifier for function results.
PCHARTOSTRING
Allow automatic conversion of null-terminated strings to strings,
CVAR
Allow the use of the CVAR keyword.
NESTEDCOMMENTS
Allow use of nested comments.
CLASSICPROCVARS
Use classical procedural variables.
MACPROCVARS
Use mac-style procedural variables.
REPEATFORWARD
Implementation and Forward declaration must match completely.
POINTERTOPROCVAR
Allow silent conversion of pointers to procedural variables.
AUTODEREF
Automatic (silent) dereferencing of typed pointers.
INITFINAL
Allow use of Initialization and Finalization
POINTERARITHMETICS
Allow use of pointer arithmetic.
ANSISTRINGS
Allow use of ansistrings.
OUT
Allow use of the out parameter type.
DEFAULTPARAMETERS
Allow use of default parameter values.
HINTDIRECTIVE
Support the hint directives (deprecated, platform etc.)
DUPLICATELOCALS
?
PROPERTIES
Allow use of global properties.
ALLOWINLINE
Allow inline procedures.
EXCEPTIONS
Allow the use of exceptions.
The keyword can be followed by a plus or minus sign to enable or disable the feature.
-Rxxx
Specify what kind of assembler you use in your asm assembler code blocks. Here xxx is one of the following:
att
asm blocks contain AT&T-style assembler. This is the default style.
intel
asm blocks contain Intel-style assembler.
default
Use the default assembler for the specified target.
direct
asm blocks should be copied as is in the assembler, only replacing certain variables.
-S2
Switch on Delphi 2 extensions (objfpc mode). Deprecated, use -Mobjfpc instead.
-Sa
Include assert statements in compiled code. Omitting this option will cause assert statements to be ignored.
-Sc
Support C-style operators, i.e. *=, +=, /= and -=.
-Sd
Try to be Delphi compatible. Deprecated, use -Mdelphi instead.
-SeN
The compiler stops after the N-th error. Normally, the compiler tries to continue compiling after an error, until 50 errors are reached, or a fatal error is reached, and then it stops. With this switch, the compiler will stop after the N-th error (if N is omitted, a default of 1 is assumed). Instead of a number, one of n, h or w can also be specified. In that case the compiler will consider notes, hints or warnings as errors and stop when one is encountered.
-Sg
Support the label and goto commands. By default these are not supported. You must also specify this option if you use labels in assembler statements. (if you use the AT&T style assember)
-Sh
Use ansistrings by default for strings. If this option is specified, the compiler will interpret the string keyword as an ansistring. Otherwise it is supposed to be a shortstring (TP style).
-Si
Support C++ style INLINE.
-SIXXX
Set interfaces style to XXX.
-Sk
Load the Kylix compatibility unit (fpcylix).
-Sm
Support C-style macros.
-So
Try to be Borland TP 7.0 compatible. Deprecated, use -Mtp instead.
-Ss
The name of constructors must be init, and the name of destructors should be done.
-St
Allow the static keyword in objects.
-Sx
Enable exception keywords (default in Delphi/Objfpc mode). This will mark all exception related keywords as keywords, also in Turbo Pascal or FPC mode. This can be used to check for code which should be mode-neutral as much as possible.
-Un
Do not check the unit name. Normally, the unit name is the same as the filename. This option allows them to be different.
-Us
Compile a system unit. This option causes the compiler to define only some very basic types.

5.2  Using the configuration file

Using the configuration file fpc.cfg is an alternative to command line options. When a configuration file is found, it is read, and the lines in it are treated as if you had typed them as options on the command line: Specify one option on each line of the configuration file. They are treated before the options that you type on the command line.

You can specify comments in the configuration file with the # sign. Everything from the # on will be ignored.

The algorithm to determine which file is used as a configuration file is decribed in ?? on page ??.

When the compiler has finished reading the configuration file, it continues to treat the command line options.

One of the command line options allows you to specify a second configuration file: Specifying @foo on the command line will open file foo, and read further options from there. When the compiler has finished reading this file, it continues to process the command line.

The configuration file allows a type of preprocessing. It understands the following directives, which you should place starting on the first column of a line:

#IFDEF
#IFNDEF
#ELSE
#ENDIF
#DEFINE
#UNDEF
#WRITE
#INCLUDE
#SECTION

They work the same way as their {$...} counterparts in Pascal source code. All the default defines used to compile source code are also defined while processing the configuration file. For example, if the target compiler is an intel 80x86 compatible linux platform, both cpu86 and linux will be defined while interpreting the configuration file. For the possible default defines when compiling, consult Appendix G of the Programmers guide .

What follows is a description of the different directives.

5.2.1  #IFDEF

Syntax:

#IFDEF name

Lines following #IFDEF are read only if the keyword name following it is defined.

They are read until the keywords #ELSE or #ENDIF are encountered, after which normal processing is resumed.

Example :

#IFDEF VER2_2_0
-Fu/usr/lib/fpc/2.2.0/linuxunits
#ENDIF

In the above example, /usr/lib/fpc/2.2.0/linuxunits will be added to the path if you’re compiling with version 2.2.0 of the compiler.

5.2.2  #IFNDEF

Syntax:

#IFNDEF name

Lines following #IFNDEF are read only if the keyword name following it is not defined.

They are read until the keywords #ELSE or #ENDIF are encountered, after which normal processing is resumed.

Example :

#IFNDEF VER2_2_0
-Fu/usr/lib/fpc/2.2.0/linuxunits
#ENDIF

In the above example, /usr/lib/fpc/2.2.0/linuxunits will be added to the path if you’re NOT compiling with version 2.2.0 of the compiler.

5.2.3  #ELSE

Syntax:

#ELSE

#ELSE can be specified after a #IFDEF or #IFNDEF directive as an alternative. Lines following #ELSE are read only if the preceding #IFDEF or #IFNDEF was not accepted.

They are skipped until the keyword #ENDIF is encountered, after which normal processing is resumed.

Example :

#IFDEF VER2_2_2
-Fu/usr/lib/fpc/2.2.2/linuxunits
#ELSE
-Fu/usr/lib/fpc/2.2.0/linuxunits
#ENDIF

In the above example, /usr/lib/fpc/2.2.2/linuxunits will be added to the path if you’re compiling with version 2.2.2 of the compiler, otherwise /usr/lib/fpc/2.2.0/linuxunits will be added to the path.

5.2.4  #ENDIF

Syntax:

#ENDIF

#ENDIF marks the end of a block that started with #IF(N)DEF, possibly with an #ELSE between them.

5.2.5  #DEFINE

Syntax:

#DEFINE name

#DEFINE defines a new keyword. This has the same effect as a -dname command line option.

5.2.6  #UNDEF

Syntax:

#UNDEF name

#UNDEF un-defines a keyword if it existed. This has the same effect as a -uname command line option.

5.2.7  #WRITE

Syntax:

#WRITE Message Text

#WRITE writes Message Text to the screen. This can be useful to display warnings if certain options are set.

Example:

#IFDEF DEBUG
#WRITE Setting debugging ON...
-g
#ENDIF

If DEBUG is defined, this will produce a line

Setting debugging ON...

and will then switch on debugging information in the compiler.

5.2.8  #INCLUDE

Syntax:

#INCLUDE filename

#INCLUDE instructs the compiler to read the contents of filename before continuing to process options in the current file.

This can be useful if you want to have a particular configuration file for a project (or, under linux , in your home directory), but still want to have the global options that are set in a global configuration file.

Example:

#IFDEF LINUX
#INCLUDE /etc/fpc.cfg
#ELSE
#IFDEF GO32V2
#INCLUDE c:\pp\bin\fpc.cfg
#ENDIF
#ENDIF

This will include /etc/fpc.cfg if you’re on a linux machine, and will include c:\pp\bin\fpc.cfg on a dos machine.

5.2.9  #SECTION

Syntax:

#SECTION name

The #SECTION directive acts as a #IFDEF directive, only it doesn’t require an #ENDIF directive. The special name COMMON always exists, i.e. lines following #SECTION COMMON are always read.

5.3  Variable substitution in paths

To avoid having to edit your configuration files too often, the compiler allows you to specify the following variables in the paths that you feed to the compiler:

FPCFULLVERSION
is replaced by the compiler’s version string.
FPCVERSION
is replaced by the compiler’s version string.
FPCDATE
is replaced by the compiler’s date.
FPCTARGET
is replaced by the compiler’s target (combination of CPU-OS)
FPCCPU
is replaced by the compiler’s target CPU.
FPCOS
is replaced by the compiler’s target OS.

To have these variables subsituted, just insert them with a $ prepended, as follows:

-Fu/usr/lib/fpc/$FPCVERSION/rtl/$FPCOS

This is equivalent to

-Fu/usr/lib/fpc/2.2.2/rtl/linux

if the compiler version is 2.2.2 and the target OS is linux .

These replacements are valid on the command line and also in the configuration file.

On the linux command line, you must be careful to escape the $ since otherwise the shell will attempt to expand the variable for you, which may have undesired effects.

Chapter 6  The IDE

The IDE (Integrated Development Environment) provides a comfortable user interface to the compiler. It contains an editor with syntax highlighting, a debugger, symbol browser etc. The IDE is a text-mode application which has the same look and feel on all supported operating systems. It is modelled after the IDE of Turbo Pascal, so many people should feel comfortable using it.

Currently, the IDE is available for dos , Windows and linux .

6.1  First steps with the IDE

6.1.1  Starting the IDE

The IDE is started by entering the command:

fp

at the command line. It can also be started from a graphical user interface such as Windows .

Remark: Under Windows , it is possible to switch between windowed mode and full screen mode by pressing Alt-Enter.

6.1.2  IDE command line options

When starting the IDE, command line options can be passed:

fp [-option] [-option] ... <file name> ...

Option is one of the following switches (the option letters are case insensitive):

-N
(dos only) Do not use long file names. Windows 95 and later versions of Windows provide an interface to DOS applications to access long file names. The IDE uses this interface by default to access files. Under certain circumstances, this can lead to problems. This switch tells the IDE not to use the long filenames.
-Cfilename
Read IDE options from filename. There should be no whitespace between the file name and the -C.
-F
Use alternative graphic characters. This can be used to run the IDE on linux in an X-term or through a telnet session.
-R
After starting the IDE, change automatically to the directory which was active when the IDE exited the last time.
-S
Disable the mouse. When this option is used, the use of a mouse is disabled, even if a mouse is present.
-Tttyname
(linux /Unix only) Send program output to tty ttyname. This avoids having to continually switch between program output and the IDE.

The files given at the command line are loaded into edit windows automatically.

Remark: Under DOS/Win32, the first character of a command line option can be a / character instead of a - character. So /S is equivalent to -S.

6.1.3  The IDE screen

After start up, the screen of the IDE can look like Figure ?? .


Figure ?? The IDE screen immediately after startup


At the top of the screen the menu bar is visible, at the bottom the status bar. The empty space between them is called the desktop.

The status bar shows the keyboard shortcuts for frequently used commands, and allows quick access to these commands by clicking them with the mouse. At the right edge of the status bar, the current amount of unused memory is displayed. This is only an indication, since the IDE tries to allocate more memory from the operating system if it runs out of memory.

The menu provides access to all of the IDE’s functionality, and at the right edge of the menu, a clock is displayed.

The IDE can be exited by selecting "File|Exit" in the menu 1 or by pressing Alt-X.

Remark: If a file fp.ans is found in the current directory, then it is loaded and used to paint the background. This file should contain ANSI drawing commands to draw on a screen.

6.2  Navigating in the IDE

The IDE can be navigated both with the keyboard and with a mouse, if the system is equipped with a mouse.

6.2.1  Using the keyboard

All functionality of the IDE is available through use of the keyboard.

Remark:

6.2.2  Using the mouse

If the system is equipped with a mouse, it can be used to work with the IDE. The left button is used to select menu items, press buttons, select text blocks etc.

The right mouse button is used to access the local menu, if available. Holding down the Ctrl or Alt key and clicking the right button will execute user defined functions. See section ?? .

Remark:

  1. Occasionally, the manual uses the term "drag the mouse". This means that the mouse is moved while the left mouse button is being pressed.
  2. The action of mouse buttons may be reversed, i.e. the actions of the left mouse button can be assigned to the right mouse button and vice versa 2. Throughout the manual, it is assumed that the actions of the mouse buttons are not reversed.
  3. The mouse is not always available, even if a mouse is installed:
  4. On Windows, the console has an option ’Quick edit’, allowing text to be copied to the clipboard by selecting text in the console window. If this mode is enabled, the mouse will not work. The ’Quick edit’ option should be disabled in the console window’s properties in order for the IDE to receive mouse events.

6.2.3  Navigating in dialogs

Dialogs usually have a lot of elements in them such as buttons, edit fields, memo fields, list boxes and so on. To activate one of these fields, choose one of the following methods:

  1. Click on the element with the mouse.
  2. Press the Tab key till the focus reaches the element.
  3. Press the highlighted letter in the element’s label. If the focus is currently on an element that allows editing, then Alt should be pressed simultaneously with the highlighted letter. For a button, the action associated with the button will then be executed.

Inside edit fields, list boxes and memos, navigation is carried out with the usual arrow key commands.

6.3  Windows

Nowadays, working with windowed applications should be no problem for most Windows and linux users. Nevertheless, the following section describes how the windows work in order to derive the most benefit from the Free Pascal IDE.

6.3.1  Window basics

A common IDE window is displayed in Figure ?? .


Figure ?? A common IDE window


The window is surrounded by a so-called frame, the white double line around the window.

At the top of the window 4 things are displayed:

The right edge and bottom edges of a window contain scrollbars. They can be used to scroll the window contents with the mouse. The arrows at the ends of the scrollbars can be clicked to scroll the contents line by line. Clicking on the dotted area between the arrows and the cyan-coloured rectangle will scroll the window’s content page by page. By dragging the rectangle the content can be scrolled continuously.

The star and the numbers in the lower left corner of the window display information about the contents of the window. They are explained in the section about the editor, see section ?? .

6.3.2  Sizing and moving windows

A window can be moved and sized using the mouse and the keyboard.

To move a window:

To resize a window:

Not all windows can be resized. This applies, for example, to dialog windows (section ?? ).

A window can also be hidden. To hide a window, the Ctrl-F6 key combination can be used, or the "Window|Hide" menu may be selected. To restore a Hidden window, it is necessary to select it from the window list. More information about the window list can be found in the next section.

6.3.3  Working with multiple windows

When working with larger projects, it is likely that multiple windows will appear on the desktop. However, only one of these windows will be the active window; all other windows will be inactive.

An inactive window is identified by a grey frame. An inactive window can be made active in one of several ways:

The windows can be ordered and placed on the IDE desktop by zooming and resizing them with the mouse or keyboard. This is a time-consuming task, and particularly difficult with the keyboard. Instead, the menu items "Window|Tile" and "Window|Cascade" can be used:

Tile
will divide the whole desktop space evenly between all resizable windows.
Cascade
puts all the windows in a cascaded arrangement.

In very rare cases the screen of the IDE may become mixed up. In this case the whole IDE screen can be refreshed by selecting the menu item "Window|Refresh display".

6.3.4  Dialog windows

In many cases the IDE displays a dialog window to get user input. The main difference to normal windows is that other windows cannot be activated while a dialog is active. Also the menu is not accessible while in a dialog. This behaviour is called modal. To activate another window, the modal window or dialog must be closed first.

A typical dialog window is shown in Figure ?? .


Figure ?? A typical dialog window


6.4  The Menu

The main menu (the gray bar at the top of the IDE) provides access to all the functionality of the IDE. It also contains a clock, displaying the current time. The menu is always available, except when a dialog is opened. If a dialog is opened, it must be closed first in order to access the menu.

In certain windows, a local menu is also available. The local menu will appear where the cursor is, and provides additional commands that are context-sensitive.

6.4.1  Accessing the menu

The menu can be accessed in a number of ways:

  1. By using the mouse to select items. The mouse cursor should be located over the desired menu item, and a left mouse click will then select it.
  2. By pressing F10. This will switch the IDE focus to the menu. The arrow keys can then be used to navigate in the menu. The Enter key should be used to select items.
  3. To access menu items directly, Alt-<highlighted menu letter> can be used to select a menu item. Afterwards submenu entries can be selected by pressing the highlighted letter, but without Alt. E.g. Alt-S G is a fast way to display the goto line dialog.

Every menu item is explained by a short text in the status bar.

When a local menu is available, it can be accessed by pressing the right mouse button or Alt-F10.

To exit any menu without taking any action, press the ESC key twice.

In the following, all menu entries and their actions are described.

6.4.2  The File menu

The "File" menu contains all menu items that allow the user to load and save files, as well as to exit the IDE.

New
Opens a new, empty editor window.
New from template
Prompts for a template to be used, asks to fill in any parameters, and then starts a new editor window with the template.
Open
(F3) Presents a file selection dialog, and opens the selected file in a new editor window.
Print
print the contents of the current edit window.
Print setup
set up the printer properties.
Reload
Reload a file from disk.
Save
(F2) Saves the contents of the current edit window with the current filename. If the current edit window does not yet have a filename, a dialog is presented to enter a new filename.
Save as
Presents a dialog in which a filename can be entered. The current window’s contents are then saved to this new filename, and the filename is stored for further save actions.
Save all
Saves the contents of all edit windows.
Change dir
Presents a dialog in which a directory can be selected. The current working directory is then changed to the selected directory.
Command shell
Executes a command shell. After the shell is exited, the IDE resumes. Which command shell is executed depends on the system.
Exit
(ALT-X) Exits the IDE. If any unsaved files are in the editor, the IDE will ask if these files should be saved.

Under the "Exit" menu appear some filenames of recently used files. These entries can be used to quickly reload these files in the editor.

6.4.3  The Edit menu

The "Edit" menu contains entries for accessing the clipboard, and undoing or redoing editing actions. Most of these functions have shortcut keys associated with them.

Undo
(ALT-BKSP) Reverses the effect of the last editing action. The editing actions are stored in a buffer. Selecting this mechanism will move backwards through this buffer, i.e. multiple undo levels are possible. However, any selections that may have been made are not reproduced.
Redo
Repeats the last action that was just undone with Undo. Redo can redo multiple undone actions.
Cut
(Shift-DEL) Deletes the selected text from the window and copies it to the clipboard. Any previous clipboard contents are lost. The new clipboard contents are available for pasting elsewhere.
Copy
(Ctrl-INS) Copies the current selection to the clipboard. Any previous clipboard contents are lost. The new clipboard contents are available for pasting elsewhere.
Paste
(Shift-INS) Inserts the current clipboard contents in the text at the cursor position. The clipboard contents remain as they were.
Clear
(Ctrl-DEL) Clears (i.e. deletes) the current selection.
Select All
Selects all text in the current window. The selected text can then be cut or copied to the clipboard.
Unselect
undo the selection.
Show clipboard
Opens a window in which the current clipboard contents are shown.

When running an IDE under Windows , the "Edit" menu has two additional entries. The IDE maintains a separate clipboard which does not share its contents with the Windows clipboard. To access the Windows clipboard, the following two entries are also present:

Copy to Windows
Copy the selection to the Windows clipboard.
Paste from Windows
Insert the contents of the Windows clipboard (if it contains text) in the edit window at the current cursor position.

6.4.4  The Search menu

The "Search" menu provides access to the search and replace dialogs, as well as access to the symbol browser of the IDE.

Find
(Ctrl-Q F) Presents the search dialog. A search text can be entered, and when the dialog is closed, the entered text is searched for in the active window. If the text is found, it will be selected.
Replace
(Ctrl-Q A) Presents the search and replace dialog. After the dialog is closed, the search text will be replaced by the replace text in the active window.
Search again
(CTRL-L) Repeats the last search or search and replace action, using the same parameters.
Go to line number
(Alt-G) Prompts for a line number, and then jumps to this line number.

When the program and units are compiled with browse information, then the following menu entries are also enabled:

Find procedure
Not yet implemented.
Objects
Asks for the name of an object and opens a browse window for this object.
Modules
Asks for the name of a module and opens a browse window for this module.
Globals
Asks for the name of a global symbol and opens a browse window for this global symbol.
Symbol
Opens a window with all known symbols, so a symbol can be selected. After the symbol is selected, a browse window for that symbol is opened.

6.4.5  The Run menu

The "Run" menu contains all entries related to running a program,

Run
(Ctrl-F9) If the sources were modified, compiles the program. If the compile is successful, the program is executed. If the primary file was set, then that is used to determine which program to execute. See section ?? for more information on how to set the primary file.
Step over
(F8) Run the program until the next source line is reached. If any calls to procedures are made, these will be executed completely as well.
Trace into
(F7) Execute the current line. If the current line contains a call to another procedure, the process will stop at the entry point of the called procedure.
Goto cursor
(F4) Run the program until the execution point matches the line where the cursor is.
Until return
Runs the current procedure until it exits.
Run directory
Set the working directory to change to when executing the program.
Parameters
Permits the entry of parameters that will be passed to the program when it is being executed.
Program reset
(Ctrl-F2) if the program is being run or debugged, the debug session is aborted, and the running program is killed.

6.4.6  The Compile menu

The "Compile" menu contains all entries related to compiling a program or unit.

Compile
(Alt-F9) Compiles the contents of the active window, irrespective of the primary file setting.
Make
(F9) Compiles the contents of the active window, and any files that the unit or program depends on and that were modified since the last compile. If the primary file was set, the primary file is compiled instead.
Build
Compiles the contents of the active window, and any files that the unit or program depends on, whether they were modified or not. If the primary file was set, the primary file is compiled instead.
Target
Sets the target operating system for which the program should be compiled.
Primary file
Sets the primary file. If set, any run or compile command will act on the primary file instead of on the active window. The primary file need not be loaded in the IDE for this to have effect.
Clear primary file
Clears the primary file. After this command, any run or compile action will act on the active window.
Compiler messages
(F12) Displays the compiler messages window. This window will display the messages generated by the compiler during the most recent compile.

6.4.7  The Debug menu

The "Debug" menu contains menu entries to aid in debugging a program, such as setting breakpoints and watches.

Output
Show user program output in a window.
User screen
(Alt-F5) Switches to the screen as it was last left by the running program.
Add watch
(Ctrl-F7) Adds a watch. A watch is an expression that can be evaluated by the IDE and will be shown in a special window. Usually this is the content of some variable.
Watches
Shows the current list of watches in a separate window.
Breakpoint
(Ctrl-F8) Sets a breakpoint at the current line. When debugging, program execution will stop at this breakpoint.
Breakpoint list
Shows the current list of breakpoints in a separate window.
Evaluate
Call stack
(Ctrl-F3) Shows the call stack. The call stack is the list of addresses (and filenames and line numbers, if this information was compiled in) of procedures that are currently being called by the running program.
Disassemble
Shows the call stack.
Registers
Shows the current content of the CPU registers.
Floating point unit
Shows the current content of the FPU registers.
Vector unit
Shows the current content of the MMX (or equivalent) registers.
GDB window
Shows the GDB debugger console. This can be used to interact with the debugger directly; here arbitrary GDB commands can be typed and the result will be shown in the window.

6.4.8  The Tools menu

The "Tools" menu defines some standard tools. If new tools are defined by the user, they are appended to this menu as well.

Messages
(F11) Shows the messages window. This window contains the output from one of the tools. For more information, see section ?? .
Goto next
(Alt-F8) Goes to the next message.
Goto previous
(Alt-F7) Goes to the previous message
Grep
(SHIFT-F2) Prompts for a regular expression and options to be given to grep, and then executes grep with the given expression and options. For this to work, the grep program must be installed on the system, and be in a directory that is in the PATH. For more information, see section ?? .
Calculator
Displays the calculator. For more information, see section ?? .
Ascii table
Displays the ASCII table. For more information, see section ?? .

6.4.9  The Options menu

The "Options" menu is the entry point for all dialogs that are used to set options for the compiler and the IDE, as well as the user preferences.

Mode
Presents a dialog to set the current mode of the compiler. The current mode is shown at the right of the menu entry. For more information, see section ?? .
Compiler
Presents a dialog that can be used to set common compiler options. These options will be used when compiling a program or unit.
Memory sizes
Presents a dialog where the stack size and the heap size for the program can be set. These options will be used when compiling a program.
Linker
Presents a dialog where some linker options can be set. These options will be used when a program or library is compiled.
Debugger
Presents a dialog where the debugging options can be set. These options are used when compiling units or programs. Note that the debugger will not work unless debugging information is generated for the program.
Directories
Presents a dialog where the various directories needed by the compiler can be set. These directories will be used when a program or unit is compiled.
Browser
Presents a dialog where the browser options can be set. The browser options affect the behaviour of the symbol browser of the IDE.
Tools
Presents a dialog to configure the tools menu. For more information, see section ?? .
Environment
Presents a dialog to configure the behaviour of the IDE. A sub menu is presented with the various aspects of the IDE:
Preferences
General preferences, such as whether to save files automatically or not, and which files should be saved. The video mode can also be set here.
Editor
Controls various aspects of the edit windows.
CodeComplete
Used to set the words which can be automatically completed when typing in the editor windows.
Codetemplates
Used to define code templates, which can be inserted in an edit window.
Desktop
Used to control the behaviour of the desktop, i.e. several features can be switched on or off.
Keyboard & Mouse
Can be used to select the cut/copy/paste convention, control the actions of the mouse, and to assign commands to various mouse actions.
Learn keys
Let the IDE learn keystrokes to be assigned to various commands. This is useful mostly on linux and Unix-like platforms, where the actual keys sent to the IDE depend on the terminal emulation.
Open
Presents a dialog in which a file containing editor preferences can be selected. After the dialog is closed, the preferences file will be read and the preferences will be applied.
Save
Saves the current options in the default file.
Save as
Saves the current options in an alternate file. A file selection dialog box will be presented in which the alternate settings file can be specified.

Please note that options are not saved automatically. They should be saved explicitly with the "Options|Save" command.

6.4.10  The Window menu

The "Window" menu provides access to some window functions. More information on all these functions can be found in section ??

Tile
Tiles all opened windows on the desktop.
Cascade
Cascades all opened windows on the desktop.
Close all
Closes all opened windows.
Size/move
(Ctrl-F5) Puts the IDE in Size/move mode; after this command the active window can be moved and resized using the arrow keys.
Zoom
(F5) Zooms or unzooms the current window.
Next
(F6) Activates the next window in the window list.
Previous
(SHIFT-F6) Activates the previous window in the window list.
Hide
(Ctrl-F6) Hides the active window.
Close
(ALT-F3) Closes the active window.
List
(Alt-0) Shows the list of opened windows. From there a window can be activated, closed, shown and hidden.
Refresh display
Redraws the screen.

6.4.11  The Help menu

The "Help" menu provides entry points to all the help functionality of the IDE, as well as the means to customize the help system.

Contents
Shows the help table of contents
Index
(SHIFT-F1) Jumps to the help Index.
Topic search
(CTRL-F1) Jumps to the topic associated with the currently highlighted text.
Previous topic
(ALT-F1) Jumps to the previously visited topic.
Using help
Displays help on using the help system.
Files
Allows the configuration of the help menu. With this menu item, help files can be added to the help system.
About
Displays information about the IDE. See section ?? for more information.

6.5  Editing text

In this section, the basics of editing (source) text are explained. The IDE works like many other text editors in this respect, so mainly the distinguishing points of the IDE will be explained.

6.5.1  Insert modes

Normally, the IDE is in insert mode. This means that any text that is typed will be inserted before text that is present after the cursor.

In overwrite mode, any text that is typed will replace existing text.

When in insert mode, the cursor is a flat blinking line. If the IDE is in overwrite mode, the cursor is a cube with the height of one line. Switching between insert mode and overwrite mode happens with the Insert key or with the Ctrl-V key.

6.5.2  Blocks

The IDE handles selected text just as the Turbo Pascal IDE handles it. This is slightly different from the way e.g. Windows applications handle selected text.

Text can be selected in 3 ways:

  1. Using the mouse, dragging the mouse over existing text selects it.
  2. Using the keyboard, press Ctrl-K B to mark the beginning of the selected text, and Ctrl-K K to mark the end of the selected text.
  3. Using the keyboard, hold the Shift key depressed while navigating with the cursor keys.

There are also some special select commands:

  1. The current line can be selected using Ctrl-K L.
  2. The current word can be selected using Ctrl-K T.

In the Free Pascal IDE, selected text is persistent. After selecting a range of text, the cursor can be moved, and the selection will not be destroyed; hence the term ’block’ is more appropriate for the selection, and will be used henceforth...

Several commands can be executed on a block:

When searching and replacing, the search can be restricted to the block contents.

6.5.3  Setting bookmarks

The IDE provides a feature which allows the setting of a bookmark at the current cursor position. Later, the cursor can be returned to this position by pressing a keyboard shortcut.

Up to 9 bookmarks per source file can be set up; they are set by Ctrl-K <Number> (where number is the number of the bookmark). To go to a previously set bookmark, press Ctrl-Q <Number>.

Remark: Currently, the bookmarks are not saved when the IDE is exited. This may change in future implementations of the IDE.

6.5.4  Jumping to a source line

It is possible to go directly to a specific source line. To do this, open the goto line dialog via the "Search|Goto line number" menu.

In the dialog that appears, the line number the IDE should jump to can be entered. The goto line dialog is shown in Figure ?? .


Figure ?? The goto line dialog.


6.5.5  Syntax highlighting

The IDE is capable of syntax highlighting, i.e. the color of certain Pascal elements can be set. As text is entered in an editor window, the IDE will try to recognise the elements, and set the color of the text accordingly.

The syntax highlighting can be customized in the colors preferences dialog, using the menu option "Options|Environment|Colors". In the colors dialog, the group "Syntax" must be selected. The item list will then display the various syntactical elements that can be colored:

Whitespace
The empty text between words. Note that for whitespace, only the background color will be used.
Comments
All styles of comments in Free Pascal.
Reserved words
All reserved words of Free Pascal. (See also Reference guide ).
Strings
Constant string expressions.
Numbers
Numbers in decimal notation.
Hex numbers
Numbers in hexadecimal notation.
Assembler
Any assembler blocks.
Symbols
Recognised symbols (variables, types).
Directives
Compiler directives.
Tabs
Tab characters in the source can be given a different color than other whitespace.

The editor uses some default settings, but experimentation is the best way to find a suitable color scheme. A good color scheme helps in detecting errors in sources, since errors will result in wrong syntax highlighting.

6.5.6  Code Completion

Code completion means the editor will try to guess the text as it is being typed. It does this by checking what text is typed, and as soon as the typed text can be used to identify a keyword in a list of keywords, the keyword will be presented in a small colored box under the typed text. Pressing the Enter key will complete the word in the text.

There is no code completion yet for filling in function arguments, or choosing object methods as in e.g. the Lazarus or DelphiIDEs.

Code completion can be customized in the Code completion dialog, reachable through the menu option "Options|Preferences|Codecomple". The list of keywords that can be completed can be maintained here. The code completion dialog is shown in Figure ?? .


Figure ?? The code completion dialog.


The dialog shows in alphabetical order the currently defined keywords that are available for completion. The following buttons are available:

Ok
Saves all changes and closes the dialog.
Edit
Pops up a dialog that allows the editing of the currently highlighted keyword.
New
Pops up a dialog that allows the entry of a new keyword which will be added to the list.
Delete
Deletes the currently highlighted keyword from the list.
Cancel
Discards all changes and closes the dialog.

All keywords are saved and are available the next time the IDE is started. Duplicate names are not allowed. If an attempt is made to add a duplicate name to the list, an error will follow.

6.5.7  Code Templates

Code templates are a way to insert large pieces of code at once. Each code templates is identified by a unique name. This name can be used to insert the associated piece of code in the text.

For example, the name ifthen could be associated to the following piece of code:

If | Then
  begin
  end

A code template can be inserted by typing its name, and pressing Ctrl-J when the cursor is positioned right after the template name.

If there is no template name before the cursor, a dialog will pop up to allow selection of a template.

If a vertical bar (|) is present in the code template, the cursor is positioned on it, and the vertical bar is deleted. In the above example, the cursor would be positioned between the if and then, ready to type an expression.

Code templates can be added and edited in the code templates dialog, reachable via the menu option "Options|Environment|CodeTemplates". The code templates dialog is shown in Figure ?? .


Figure ?? The code templates dialog.


The top listbox in the code templates dialog shows the names of all known templates. The bottom half of the dialog shows the text associated with the currently highlighted code template. The following buttons are available:

Ok
Saves all changes and closes the dialog.
Edit
Pops up a dialog that allows the editing of the currently highlighted code template. Both the name and text can be edited.
New
Pops up a dialog that allows the entry of a new code template which will be added to the list. A name must be entered for the new template.
Delete
Deletes the currently highlighted code template from the list.
Cancel
Discards all changes and closes the dialog.

All templates are saved and are available the next time the IDE is started.

Remark: Duplicates are not allowed. If an attempt is made to add a duplicate name to the list, an error will occur.

6.6  Searching and replacing

The IDE allows you to search for text in the active editor window. To search for text, one of the following can be done:

  1. Select "Search|Find" in the menu.
  2. Press Ctrl-Q F.

After that, the dialog shown in Figure ?? will pop up, and the following options can be entered:


Figure ?? The search dialog.


Text to find
The text to be searched for. If a block was active when the dialog was started, the first line of this block is proposed.
Case sensitive
When checked, the search is case sensitive.
Whole words only
When checked, the search text must appear in the text as a complete word.
Direction
The direction in which the search must be conducted, starting from the specified origin.
Scope
Specifies if the search should be on the whole file, or just the selected text.
Origin
Specifies if the search should start from the cursor position or the start of the scope.

After the dialog has closed, the search is performed using the given options.

A search can be repeated (using the same options) in one of 2 ways:

  1. Select "Search|Search again" from the menu.
  2. Press Ctrl-L.

It is also possible to replace occurrences of a text with another text. This can be done in a similar manner to searching for a text:

  1. Select "Search|Replace" from the menu.
  2. Press Ctrl-Q A.

A dialog, similar to the search dialog will pop up, as shown in Figure ?? .


Figure ?? The replace dialog.


In this dialog, in addition to the things that can be filled in in the search dialog, the following things can be entered:

New text
Text that will replace the found text.
Prompt on replace
Before a replacement is made, the IDE will ask for confirmation.

If the dialog is closed with the ’OK’ button, only the next occurrence of the the search text will be replaced. If the dialog is closed with the ’Change All’ button, all occurrences of the search text will be replaced.

6.7  The symbol browser

The symbol browser allows searching all occurrences of a symbol. A symbol can be a variable, type, procedure or constant that occurs in the program or unit sources.

To enable the symbol browser, the program or unit must be compiled with browser information. This can be done by setting the browser information options in the compiler options dialog.

The IDE allows to browse several types of symbols:

Procedures
Allows quick jumping to a procedure definition or implementation.
Objects
Quickly browse for an object.
Modules
Browse a module.
Globals
Browse any global symbol.
Arbitrary symbol
Browse an arbitrary symbol.

In all cases, first a symbol to be browsed must be selected. After that, a browse window appears. In the browse window, all locations where the symbol was encountered are shown. Selecting a location and pressing the space bar will cause the editor to jump to that location; the line containing the symbol will be highlighted.

If the location is in a source file that is not yet displayed, a new window will be opened with the source file loaded.

After the desired location has been reached, the browser window can be closed with the usual commands.

The behaviour of the browser can be customized with the browser options dialog, using the "Options|Browser" menu. The browser options dialog looks like Figure ?? .


Figure ?? The browser options dialog.


The following options can be set in the browser options dialog:

Symbols
Here the types of symbols displayed in the browser can be selected:
Labels
Labels are shown.
Constants
Constants are shown.
Types
Types are shown.
Variables
Variables are shown.
Procedures
Procedures are shown.
Inherited
Sub-browsing
Specifies what the browser should do when displaying the members of a complex symbol such as a record or class:
New browser
The members are shown in a new browser window.
Replace current
The contents of the current window are replaced with the members of the selected complex symbol.
Preferred pane
Specifies what pane is shown in the browser when it is initially opened:
Scope
Reference
Display
Determines how the browser should display the symbols:
Qualified symbols
Sort always
Sorts the symbols in the browser window.

6.8  Running programs

A compiled program can be run straight from the IDE. This can be done in one of several ways:

  1. select the "Run|Run" menu, or
  2. press Ctrl-F9.

If command line parameters should be passed to the program, then these can be set through the "Run|Parameters" menu. The program parameters dialog looks like Figure ?? .


Figure ?? The program parameters dialog.


Once the program has started, it will continue to run, until

  1. the program quits normally,
  2. an error happens,
  3. a breakpoint is encountered, or
  4. the program is reset by the user.

The last alternative is only possible if the program is compiled with debug information.

Alternatively, it is possible to position the cursor somewhere in a source file, and run the program till the execution reaches the source line where the cursor is located. This can be done by

  1. selecting "Run|Goto Cursor" in the menu,
  2. pressing F4.

Again, this is only possible if the program was compiled with debug information.

The program can also executed line by line. Pressing F8 will execute the next line of the program. If the program wasn’t started yet, it is started. Repeatedly pressing F8 will execute the program line by line, and the IDE will show the line to be executed in an editor window. If somewhere in the code a call occurs to a subroutine, then pressing F8 will cause the whole routine to be executed before control returns to the IDE. If the code of the subroutine should be stepped through as well, then F7 should be used instead. Using F7 will cause the IDE to execute line by line any subroutine that is encountered.

If a subroutine is being stepped through, then the "Run|Until return" menu will execute the program till the current subroutine ends.

If the program should be stopped before it quits by itself, then this can be done by

  1. selecting "Run|Program reset" from the menu, or
  2. pressing Ctrl-F2.

The running program will then be aborted.

6.9  Debugging programs

To debug a program, it must be compiled with debug information. Compiling a program with debug information allows you to:

  1. Execute the program line by line.
  2. Run the program up to a certain point (a breakpoint).
  3. Inspect the contents of variables or memory locations while the program is running.

6.9.1  Using breakpoints

Breakpoints will cause a running program to stop when the execution reaches the line where the breakpoint was set. At that moment, control is returned to the IDE, and it is possible to continue execution.

To set a breakpoint on the current source line, use the "Debug|Breakpoint" menu entry, or press Ctrl-F8.

A list of current breakpoints can be obtained through the "Debug|Breakpoint list" menu. The breakpoint list window is shown in Figure ?? .


Figure ?? The breakpoint list window


In the breakpoint list window, the following things can be done:

New
Shows the breakpoint property dialog where the properties for a new breakpoint can be entered.
Edit
Shows the breakpoint property dialog where the properties of the highlighted breakpoint can be changed.
Delete
Deletes the highlighted breakpoint.

The dialog can be closed with the ’Close’ button. The breakpoint properties dialog is shown in Figure ??


Figure ?? The breakpoint properties dialog


The following properties can be set:

Type
Set the type of the breakpoint. The following types of breakpoints exist:
function
Function breakpoint. The program will stop when the function with the given name is reached.
file-line
Source line breakpoint. The program will stop when the source file with given name and line is reached.
watch
Expression breakpoint. An expression may be entered, and the program will stop as soon as the expression changes.
awatch
(access watch) Expression breakpoint. An expression that references a memory location may be entered, and the program will stop as soon as the memory indicated by the expression is accessed.
Address
stop as soon as an address is reached.
rwatch
(read watch) Expression breakpoint. An expression that references a memory location may be entered, and the program will stop as soon as the memory indicated by the expression is read.
Name
Name of the function or file where to stop.
Conditions
Here an expression can be entered which must evaluate to True for the program to stop at the breakpoint. The expressions that can be entered must be valid GDB expressions.
Line
Line number in the file where to stop. Only for breakpoints of type file-line.
Ignore count
The number of times the breakpoint will be ignored before the program stops.

Remark:

  1. Because the IDE uses GDB to do its debugging, it is necessary to enter all expressions in uppercase.
  2. Expressions that reference memory locations should be no longer than 16 bytes on linux or go32v2 on an Intel processor, since the Intel processor’s debug registers are used to monitor these locations.
  3. Memory location watches will not function on Win32 unless a special patch is applied.

6.9.2  Using watches

When debugging information is compiled in the program, watches can be used. Watches are expressions which can be evaluated by the IDE and shown in a separate window. When program execution stops (e.g. at a breakpoint) all watches will be evaluated and their current values will be shown.

Setting a new watch can be done with the "Debug|Add watch" menu command or by pressing Ctrl-F7. When this is done, the watch property dialog appears, and a new expression can be entered. The watch property dialog is shown in Figure ?? .


Figure ?? The watch property dialog


In the dialog, the expression can be entered. Any possible previous value and current value are shown.

Remark: Because the IDE uses GDB to do its debugging, it is necessary to enter all expressions in uppercase in FreeBSD .

A list of watches and their present value is available in the watches window, which can be opened with the "Debug|Watches" menu. The watch list window is shown in Figure ?? .


Figure ?? The watch list window.


Pressing Enter or the space bar will show the watch property dialog for the currently highlighted watch in the watches window.

The list of watches is updated whenever the IDE resumes control when debugging a program.

6.9.3  The call stack

The call stack helps in showing the program flow. It shows the list of procedures that are being called at this moment, in reverse order. The call stack window can be shown using the "Debug|Call Stack" menu. It will show the address or procedure name of all currently active procedures with their filename and addresses. If parameters were passed they will be shown as well. The call stack is shown in Figure ?? .


Figure ?? The call stack window.


By pressing the space bar in the call stack window, the line corresponding to the call will be highlighted in the edit window.

6.9.4  The GDB window

The GDB window provides direct interaction with the GDB debugger. In it, GDB commands can be typed as they would be typed in GDB. The response of GDB will be shown in the window.

Some more information on using GDB can be found in section ?? , but the final reference is of course the GDB manual itself 3. The GDB window is shown in Figure ?? .


Figure ?? The GDB window


6.10  Using Tools

The tools menu provides easy access to external tools. It also has three pre-defined tools for programmers: an ASCII table, a grep tool and a calculator. The output of the external tools can be accessed through this menu as well.

6.10.1  The messages window

The output of the external utilities is redirected by the IDE and it will be displayed in the messages window. The messages window is displayed automatically, if an external tool was run. The messages window can also be displayed manually by selecting the menu item "Tools|Messages" or by pressing the F11 key. The messages window is shown in Figure ?? .


Figure ?? The messages window


If the output of the tool contains filenames and line numbers, the messages window can be used to navigate the source as in a browse window:

  1. Pressing Enter or double clicking the output line will jump to the specified source line and close the messages window.
  2. Pressing the space bar will jump to the specified source line, but will leave the messages window open, with the focus on it. This allows the quick selection of another message line with the arrow keys and jump to another location in the sources.

The algorithm which extracts the file names and line numbers from the tool output is quite sophisticated, but in some cases it may fail4.

6.10.2  Grep

One external tool in the Tools menu is already predefined: a menu item to call the grep utility ("Tools|Grep" or Shift-F2). Grep searches for a given string in files and returns the lines which contain the string. The search string can even be a regular expression. For this menu item to work, the grep program must be installed, since it is not distributed with Free Pascal .

The messages window displayed in Figure ?? in the previous section shows the output of a typical grep session. The messages window can be used in combination with grep to find special occurrences in the text.

Grep supports regular expressions. A regular expression is a string with special characters which describe a whole class of expressions. The command line in dos or linux has limited support for regular expressions: entering ls *.pas (or dir *.pas) to get a list of all Pascal files in a directory. *.pas is something similar to a regular expression. It uses a wildcard to describe a whole class of strings: those which end on ".pas". Regular expressions offer much more: for example [A-Z][0-9]+ describes all strings which begin with an upper case letter followed by one or more digits.

It is outside the scope of this manual to describe regular expressions in great detail. Users of a linux system can get more information on grep using man grep on the command line.

6.10.3  The ASCII table

The tools menu also provides an ASCII table ("Tools|Ascii table"). The ASCII table can be used to look up ASCII codes as well as to insert characters into the window which was active when invoking the table.

To reveal the ASCII code of a character in the table, move the cursor onto this character or click it with the mouse. The decimal and hex values of the character are shown at the bottom on the ASCII table window.

To insert a character into an editor window either:

  1. using the mouse, double click it, or,
  2. using the keyboard, press Enter while the cursor is on it.

This is especially useful for pasting graphical characters in a constant string.

The ASCII table remains active till another window is explicitly activated; thus multiple characters can be inserted at once. The ASCII table is shown in Figure ?? .


Figure ?? The ASCII table


6.10.4  The calculator

The calculator allows quick calculations without leaving the IDE. It is a simple calculator, since it does not take care of operator precedence, and bracketing of operations is not (yet) supported.

The result of the calculations can be pasted into the text using the Ctrl-Enter keystroke. The calculator dialog is shown in Figure ?? .


Figure ?? The calculator dialog


The calculator supports all basic mathematical operations such as addition, subtraction, division and multiplication. They are summarised in table (??) .


Table 6.1: Basic mathematical operations
OperationButtonKey
Add two numbers++
Subtract two numbers  
Multiply two numbers**
Divide two numbers//
Delete the last typed digit<-Backspace
Clear displayCC
Change the sign+ 
Do per cent calculation%%
Get result of operation=Enter

But also more sophisticated mathematical operations such as exponentiation and logarithms are supported. The advanced mathematical operations are shown in table (??) .


Table 6.2: Advanced mathematical operations
OperationButtonKey
Calculate powerx^y 
Calculate the inverse value1/x 
Calculate the square rootsqr 
Calculate the natural logarithmlog 
Square the display contentsx^2 
.

Like many calculators, the calculator in the IDE also supports storing a single value in memory, and several operations can be done on this memory value. The available operations are listed in table (??)


Table 6.3: Advanced calculator commands
OperationButtonKey
Add the displayed number to the memoryM+ 
Subtract the displayed number from the memoryM- 
Move the memory contents to the displayM-> 
Move the display contents to the memoryM<- 
Exchange display and memory contentsM<-> 

6.10.5  Adding new tools

The tools menu can be extended with any external program which is command line oriented. The output of such a program will be caught and displayed in the messages window.

Adding a tool to the tools menu can be done using the "Options|Tools" menu. This will display the tools dialog. The tools dialog is shown in Figure ?? .


Figure ?? The tools configuration dialog


In the tools dialog, the following actions are available:

New
Shows the tool properties dialog where the properties of a new tool can be entered.
Edit
Shows the tool properties dialog where the properties of the highlighted tool can be edited.
Delete
Removes the currently highlighted tool.
Cancel
Discards all changes and closes the dialog.
OK
Saves all changes and closes the dialog.

The definitions of the tools are written in the desktop configuration file. So unless auto-saving of the desktop file is enabled, the desktop file should be saved explicitly after the dialog is closed.

6.10.6  Meta parameters

When specifying the command line for the called tool, meta parameters can be used. Meta parameters are variables and and they are replaced by their contents before passing the command line to the tool.

$CAP
Captures the output of the tool.
$CAP_MSG()
Captures the output of the tool and puts it in the messages window.
$CAP_EDIT()
Captures the output of the tool and puts it in a separate editor window.
$COL
Replaced by the column of the cursor in the active editor window. If there is no active window or the active window is a dialog, then it is replaced by 0.
$CONFIG
Replaced by the complete filename of the current configuration file.
$DIR()
Replaced by the full directory of the filename argument, including the trailing directory separator. e.g.
  $DIR('d:\data\myfile.pas')
would return d:\data\.
$DRIVE()
Replaced by the drive letter of the filename argument. e.g.
  $DRIVE('d:\data\myfile.pas')
would return d:.
$EDNAME
Replaced by the complete file name of the file in the active edit window. If there is no active edit window, this is an empty string.
$EXENAME
Replaced by the executable name that would be created if the make command was used. (i.e. from the ’Primary File’ setting or the active edit window).
$EXT()
Replaced by the extension of the filename argument. The extension includes the dot. e.g.
  $EXT('d:\data\myfile.pas')
would return .pas.
$LINE
Replaced by the line number of the cursor in the active edit window. If no edit window is present or active, this is 0.
$NAME()
Replaced by the name part (excluding extension and dot) of the filename argument. e.g.
  $NAME('d:\data\myfile.pas')
would return myfile.
$NAMEEXT()
Replaced by the name and extension part of the filename argument. e.g.
  $NAMEEXT('d:\data\myfile.pas')
would return myfile.pas.
$NOSWAP
Does nothing in the IDE; it is provided only for compatibility with Turbo Pascal .
$PROMPT()
Prompt displays a dialog box that allows editing of all arguments that come after it. Arguments that appear before the $PROMPT keyword are not presented for editing.

$PROMPT() can also take an optional filename argument. If present, $PROMPT() will load a dialog description from the filename argument. E.g.

$PROMPT(cvsco.tdf)

would parse the file cvsco.tdf, construct a dialog with it and display it. After the dialog closed, the information entered by the user is used to construct the tool command line.

See section ?? for more information on how to create a dialog description.

$SAVE
Before executing the command, the active editor window is saved, even if it is not modified.
$SAVE_ALL
Before executing the command, all unsaved editor files are saved without prompting.
$SAVE_CUR
Before executing the command the contents of the active editor window are saved without prompting if they are modified.
$SAVE_PROMPT
Before executing the command, a dialog is displayed asking whether any unsaved files should be saved before executing the command.
$WRITEMSG()
Writes the parsed tool output information to a file with name as in the argument.

6.10.7  Building a command line dialog box

When defining a tool, it is possible to show a dialog to the user, asking for additional arguments, using the $PROMPT(filename) command-macro. The Free Pascal distribution contains some ready-made dialogs, such as a ’grep’ dialog, a ’cvs checkout’ dialog and a ’cvs check in’ dialog. The files for these dialogs are in the binary directory and have an extension .tdf.

In this section, the file format for the dialog description file is explained. The format of this file resembles a windows .INI file, where each section in the file describes an element (or control) in the dialog. An OK and a Cancel button will be added to the bottom of the dialog, so these should not be specified in the dialog definition.

A special section is the Main section. It describes how the result of the dialog will be passed to the command line, and the total size of the dialog.

Remark: Keywords that contain a string value should have the string value enclosed in double quotes as in

Title="Dialog title"

The Main section should contain the following keywords:

Title
The title of the dialog. This will appear in the frame title of the dialog. The string should be enclosed in quotes.
Size
The size of the dialog, this is formatted as (Cols,Rows), so
Size=(59,9)
means the dialog is 59 characters wide, and 9 lines high. This size does not include the border of the dialog.
CommandLine
specifies how the command line will be passed to the program, based on the entries made in the dialog. The text typed here will be passed on after replacing some control placeholders with their values.

A control placeholder is the name of some control in the dialog, enclosed in percent (%) characters. The name of the control will be replaced with the text associated with the control. Consider the following example:

CommandLine="-n %l% %v% %i% %w% %searchstr% %filemask%"

Here the values associated with the controls named l, v, i, w and searchstr and filemask will be inserted in the command line string.

Default
The name of the control that is the default control, i.e. the control that is to have the focus when the dialog is opened.

The following is an example of a valid main section:

[Main]
Title="GNU Grep"
Size=(56,9)
CommandLine="-n %l% %v% %i% %w% %searchstr% %filemask%"
Default="searchstr"

After the Main section, a section must be specified for each control that should appear on the dialog. Each section has the name of the control it describes, as in the following example:

[CaseSensitive]
Type=CheckBox
Name="~C~ase sensitive"
Origin=(2,6)
Size=(25,1)
Default=On
On="-i"

Each control section must have at least the following keywords associated with it:

Type
The type of control. Possible values are:
Label
A plain text label which will be shown on the dialog. A control can be linked to this label, so it will be focused when the user presses the highlighted letter in the label caption (if any).
InputLine
An edit field where a text can be entered.
CheckBox
A checkbox which can be in an on or off state.
Origin
Specifies where the control should be located in the dialog. The origin is specified as (left,top) and the top-left corner of the dialog has coordinate (1,1) (not counting the frame).
Size
Specifies the size of the control, which should be specified as (Cols,Rows).

Each control has some specific keywords associated with it; they will be described below.

A label (Type=Label) has the following extra keywords associated with it:

Text
the text displayed in the label. If one of the letters should be highlighted so it can be used as a shortcut, then it should be enclosed in tilde characters (~). E.g. in
Text="~T~ext to find"
the T will be highlighted.
Link
The name of a control in the dialog may be specified. If specified, pressing the label’s highlighted letter in combination with the Alt key will put the focus on the control specified here.

A label does not contribute to the text of the command line; it is for informational and navigational purposes only. The following is an example of a label description section:

[label2]
Type=Label
Origin=(2,3)
Size=(22,1)
Text="File ~m~ask"
Link="filemask"

An edit control (Type=InputLine) allows entry of arbitrary text. The text of the edit control will be pasted in the command line if it is referenced there. The following keyword can be specified in a inputline control section:

Value
A standard value (text) for the edit control can be specified. This value will be filled in when the dialog appears.

The following is an example of an input line section:

[filemask]
Type=InputLine
Origin=(2,4)
Size=(22,1)
Value="*.pas *.pp *.inc"

A checkbox control (Type=CheckBox) presents a checkbox which can be in one of two states, on or off. With each of these states, a value can be associated which will be passed on to the command line. The following keywords can appear in a checkbox type section:

Name
The text that appears after the checkbox. If there is a highlighted letter in it, this letter can be used to set or unset the checkbox using the Alt-letter combination.
Default
Specifies whether the checkbox is checked or not when the dialog appears (value on or off).
On
The text associated with this checkbox if it is in the checked state.
Off
The text associated with this checkbox if it is in the unchecked state.

The following is an example of a valid checkbox description:

[i]
Type=CheckBox
Name="~C~ase sensitive"
Origin=(2,6)
Size=(25,1)
Default=On
On="-i"

If the checkbox is checked, then the value -i will be added on the command line of the tool. If it is unchecked, no value will be added.

6.11  Project management and compiler options

Project management in Pascal is much easier than with C. The compiler knows from the source which units, sources etc. it needs. So the Free Pascal IDE does not need a full featured project manager like some C development environments offer. Nevertheless there are some settings in the IDE which apply to projects.

6.11.1  The primary file

Without a primary file the IDE compiles/runs the source of the active window when a program is started. If a primary file is specified, the IDE always compiles/runs this source, even if another source window is active. With the menu item "Compile|Primary file..." a file dialog can be opened where the primary file can be selected. Only the menu item "Compile|Compile" compiles the active window regardless. This is useful if a large project is being edited, and only the syntax of the current source should be checked.

The menu item "Compiler|Clear primary file" restores the default behaviour of the IDE, i.e. the ’compile’ and ’run’ commands apply to the active window.

6.11.2  The directory dialog

In the directory dialog, the directories can be specified where the compiler should look for units, libraries, object files. It also says where the output files should be stored. Multiple directories (except for the output directory) can be entered, separated by semicolons. The directories dialog is shown in Figure ?? .


Figure ?? The directories configuration dialog


The following directories can be specified:

EXE & PPU directories
Specifies where the compiled units and executables will go. (-FE, (see ??) on the command line.)
Object directories
Specifies where the compiler looks for external object files. (-Fo, (see ??) on the command line.)
Library directories
Specifies where the compiler (more exactly, the linker) looks for external libraries. (-Fl, (see ??) on the command line.)
Include directories
Specifies where the compiler will look for include files, included with the {$i } directive. (-Fi, (see ??) or -I, (see ??) on the command line.)
Unit directories
Specifies where the compiler will look for compiled units. The compiler always looks first in the current directory, and also in some standard directories. (-Fu, (see ??) on the command line.)

6.11.3  The target operating system

The menu item "Compile|Target" allows specification of the target operating system for which the sources will be compiled. Changing the target doesn’t affect any compiler switches or directories. It does affect some defines defined by the compiler. The settings here correspond to the option on the command line -T, (see ??) . A sample compilation target dialog is shown in Figure ?? : the actual dialog will show only those targets that the IDE actually supports.


Figure ?? The compilation target dialog


The following targets can be set (the list depends on the platform for which the IDE was compiled):

Dos (go32v1)
This switch will dissapear in time as this target is no longer being maintained.
Dos (go32v2)
Compile for dos , using version 2 of the Go32 extender.
FreeBSD
Compile for FreeBSD .
Linux
Compile for linux .
OS/2
Compile for OS/2 (using the EMX extender).
Windows
Compile for Windows .

The currently selected target operating system is shown in the "Target" menu item in the "Compile" menu. Initially, this will be set to the operating system for which the IDE was compiled.

6.11.4  Compiler options

The menu "Options|Compiler" allow the settting of options that affect the compilers behaviour. When this menu item is chosen, a dialog pops up that displays several tabs.

There are six tabs:

Syntax
Here options can be set that affect the various syntax aspects of the code. They correspond mostly to the -S option on the command line (section ?? ).
Code generation
These options control the generated code; they are mostly concerned with the -C and -X command line options.
Verbose
These set the verbosity of the compiler when compiling. The messages of the compiler are shown in the compiler messages window (can be called with F12).
Browser
Options concerning the generated browser information. Browser information needs to be generated for the symbol browser to work.
Assembler
Options concerning the reading of assembler blocks (-R on the command line) and the generated assembler (-A on the command line)
Processor
Here the target processor can be selected.

On each tab page, there are two entry boxes: the first for Conditional defines and the second for additional compiler arguments. The symbols, and arguments, should be separated with semi-colons.

The syntax tab of the compiler options dialog is shown in Figure ?? .


Figure ?? The syntax options tab


In the syntax options dialog, the following options can be set:

Stop after first error
when checked, the compiler stops after the first error. Normally the compiler continues compiling till a fatal error is reached. (-Se, (see ??) on the command line)
Allow label and goto
Allow the use of label declarations and goto statements (-Sg, (see ??) on the command line).
Enable macros
Allow the use of macros (-Sm, (see ??) ).
Allow inline
Allow the use of inlined functions (-Sc, (see ??) on the command line).
Include assertion code
Include Assert statements in the code.
Load kylix compat. unit
Load the Kylix compatibility unit.
Allow STATIC in objects
Allow the Static modifier for object methods (-St, (see ??) on the command line)
C-like operators
Allows the use of some extended operators such as +=, -= etc. (-Sc, (see ??) on the command line).
Compiler mode
select the appropriate compiler mode:
Free Pascal Dialect
The default Free Pascal compiler mode (FPC).
Object pascal extensions on
Enables the use of classes and exceptions (-Sd, (see ??) on the command line).
Turbo pascal compatible
Try to be more Turbo Pascal compatible (-So, (see ??) on the command line).
Delphi compatible
Try to be more Delphicompatible (-Sd, (see ??) on the command line).
Macintosh Pascal dialect
Try to be Macintosh pascal compatible.

The code generation tab of the compiler options dialog is shown in Figure ?? .


Figure ?? The code generation options tab


In the code generation dialog, the following options can be set:

Run-time checks
Controls what run-time checking code is generated. If such a check fails, a run-time error is generated. The following checking code can be generated:
Range checking
Checks the results of enumeration and subset type operations (-Cr, (see ??) command line option).
Stack checking
Checks whether the stack limit is not reached (-Cs, (see ??) command line option).
I/O checking
Checks the result of IO operations (-Ci, (see ??) command line option).
Integer overflow checking
Checks the result of integer operations (-Co, (see ??) command line option).
Object method call checking
Check the validity of the method pointer prior to calling it.
Position independent code
Generate PIC code.
Create smartlinkable units
Create smartlinkable units.
Optimizations
What optimizations should be used when compiling:
Generate faster code
Corresponds to the -OG command line option.
Generate smaller code
Corresponds to the -Og command line option.

More information on these switches can be found in section ?? .

The processor tab of the compiler options dialog is shown in Figure ?? .

In the processor dialog, the target processor can be set. The compiler can use different optimizations for different processors.


Figure ?? The processor selection tab


The verbose tab of the compiler options dialog is shown in Figure ?? .


Figure ?? The verbosity options tab


In this dialog, the following verbosity options can be set (on the command line: -v, (see ??) ):

Warnings
Generate warnings. Corresponds to -vw on the command line.
Notes
Generate notes. Corresponds to -vn on the command line.
Hints
Generate hints. Corresponds to -vh on the command line.
General info
Generate general information. Corresponds to -vi on the command line.
User,tried info
Generate information on used and tried files. Corresponds to -vut on the command line.
All
Switch on full verbosity. Corresponds to -va on the command line.
Show all procedures if error
If an error using overloaded procedure occurs, show all procedures. Corresponds to -vb on the command line.

The browser tab of the compiler options dialog is shown in Figure ?? .


Figure ?? The browser options tab


In this dialog, the browser options can be set:

No browser
(default) No browser information is generated by the compiler.
Only global browser
Browser information is generated for global symbols only, i.e. symbols defined not in a procedure or function (-b on the command line)
Local and global browser
Browser information is generated for all symbols, i.e. also for symbols that are defined in procedures or functions (-bl on the command line)

Remark: If no browser information is generated, the symbol browser of the IDE will not work.

The assembler tab of the compiler options dialog is shown in Figure ?? . The actual dialog may vary, as it depends on the target CPU the IDE was compiled for.


Figure ?? The assembler options tab


In this dialog, the assembler reader and writer options can be set:

Assembler reader
This permits setting the style of the assembler blocks in the sources:
AT&T assembler
The assembler is written in AT&T style assembler (-Ratt on the command line).
Intel style assembler
The assembler is written in Intel style assembler blocks (-Rintel on the command line).
remark that this option is global, but locally the assembler style can be changed with compiler directives.
Assembler info
When writing assembler files, this option decides which extra information is written to the assembler file in comments:
List source
The source lines are written to the assembler files together with the generated assembler (-al on the command line).
List register allocation
The compiler’s internal register allocation/deallocation information is written to the assembler file (-ar on the command line).
List temp allocation
The temporary register allocation/deallocation is written to the assembler file. (-at on the command line).
List node allocation
The node allocation/deallocation is written to the assembler file. (-an on the command line).
use pipe with assembler
use a pipe on unix systems when feeding the assembler code to an external assembler.
The latter three of these options are mainly useful for debugging the compiler itself, it should rarely be necessary to use these.
Assembler output
This option tells the compiler what assembler output should be generated.
Use default output
This depends on the target.
Use GNU as
Assemble using gnu as (-Aas on the command line).
Use NASM coff
Produce NASM coff assembler (go32v2, -Anasmcoff on the command line)
Use NASM elf
Produce NASM elf assembler (linux , -Anasmelf on the command line).
Use NASM obj
Produce NASM obj assembler (-Anasmobj on the command line).
Use MASM
Produce MASM (Microsoft assembler) assembler (-Amasm on the command line).
Use TASM
Produce TASM (Turbo Assembler) assembler (-Atasm on the command line).
Use coff
Write binary coff files directly using the internal assembler (go32v2, -Acoff on the command line).
Use pecoff
Write binary pecoff files files directly using the internal writer. (Win32)

6.11.5  Linker options

The linker options can be set in the menu "Options|Linker". It permits the specification of how libraries and units are linked, and how the linker should be called. The linker options dialog is shown in Figure ?? .


Figure ?? The linker options dialog


The following options can be set:

Call linker after
If this option is set then a script is written which calls the linker. This corresponds to the s option on the command line (-s, (see ??) ).
Only link to static library
Only use static libraries.
Preferred library type
With this option, the type of library to be linked in can be set:
Target default
This depends on the platform.
Dynamic libraries
Tries to link in units in dynamic libraries. (option -XD on the command line.)
Static libraries
Tries to link in units in static libraries. (option -XS on the command line.)
Smart libraries
Tries to link in units in smart-linked libraries. (option -XX on the command line.)

6.11.6  Memory sizes

The memory sizes dialog (reachable via "options|Memory sizes") permits the entry of the memory sizes for the project. The memory sizes dialog is shown in Figure ?? .


Figure ?? The memory sizes dialog


The following sizes can be entered:

Stack size
Sets the size of the stack in bytes (option -Cs on the command line). This size may be ignored on some systems.
Heap size
Sets the size of the heap in bytes; (option -Ch on the command line). Note that the heap grows dynamically as much as the OS allows.

6.11.7  Debug options

In the debug options dialog (reachable via "Options|Debugger"), some options for inclusion of debug information in the binary can be set; it is also possible to add additional compiler options in this dialog. The debug options dialog is shown in Figure ?? .

Figure ?? The debug options dialog


The following options can be set:

Debugging information
tells the compiler which debug information should be compiled in. One of the following options can be chosen:
Strip all debug symbols from executable
Will strip all debug and symbol information from the binary. (option -Xs on the command line).
Skip debug information generation
Do not generate debug information at all.
Generate debug symbol information
Include debug information in the binary (option -g on the command line). Please note that no debug information for units in the Run-Time Library will be included, unless a version of the RTL compiled with debug information is available. Only units specific to the current project will have debug information included.
Generate also backtrace line information
Will compile with debug information, and will additionally include the lineinfo unit in the binary, so that in case of an error the backtrace will contain the file names and line numbers of procedures in the call-stack. (Option -gl on the command line.)
Generate valgrind compatible debug info
Generate debug information that can be read with valgrind (a memory checking tool).
Profiling switches
Tells the compiler whether or not profile code should be included in the binary.
No profile information
Has no effect, as it is the default.
Generate Profile code for gprof
If checked, profiling code is included in the binary (option -p on the command line).
Use another TTY for Debuggee
An attempt will be made to redirect the output of the program being debugged to another window (terminal), whose file name should be entered here.

6.11.8  The switches mode

The IDE allows saving a set of compiler settings under a common name. It provides 3 names under which the switches can be saved:

Normal
For normal (fast) compilation.
Debug
For debugging; intended to set most debug switches on. Also useful for setting conditional defines that e.g. allow including some debug code.
Release
For a compile of the program as it should be released, debug information should be off, the binary should be stripped, and optimizations should be used.

Selecting one of these modes will load the compiler options as they were saved the last time the selected mode was active, i.e. it doesn’t specifically set or unset options.

When setting and saving compiler options, be sure to select the correct switch mode first; it makes little sense to set debug options while the release switch is active. The switches mode dialog is shown in Figure ?? .


Figure ?? The switches mode dialog


6.12  Customizing the IDE

The IDE is configurable over a wide range of parameters: colors can be changed, screen resolution. The configuration settings can be reached via the sub-menu Environment in the Options menu.

6.12.1  Preferences

The preferences dialog is called by the menu item "Options|Environment|Preferences". The preferences dialog is shown in Figure ?? .


Figure ?? The preferences dialog


Video mode
The drop down list at the top of the dialog allows selecting a video mode. The available video modes depend on the system on which the IDE is running.

Remark:

  1. The video mode must be selected by pressing space or clicking on it. If the drop down list is opened while leaving the dialog, the new video mode will not be applied.
  2. For the dos version of the IDE, the following should be noted: When using VESA modes, the display refresh rate may be very low. On older graphics card (1998 and before), it is possible to use the UniVBE driver from SciTech5
Desktop File
Specifies where the desktop file is saved: the current directory, or the directory where the config file was found.
Auto save
Here it is possible to set which files are saved when a program is run or when the IDE is exited:
Editor files
The contents of all open edit windows will be saved.
Environment
The current environment settings will be saved.
Desktop
The desktop file with all desktop settings (open windows, history lists, breakpoints etc.) will be saved.
Options
Some special behaviours of the IDE can be specified here:
Auto track source
Close on go to source
When checked, the messages window is closed when the ’go to source line’ action is executed.
Change dir on open
When a file is opened, the directory of that file is made the current working directory.

6.12.2  The desktop

The desktop preferences dialog allows to specify what elements of the desktop are saved across sessions, i.e. they are saved when the IDE is left, and they are again restored when the IDE is started the next time. They are saved in the file fp.dsk. The desktop preferences dialog is shown in Figure ?? .


Figure ?? The desktop preferences dialog


The following elements can be saved and restored across IDE sessions:

History lists
Most entry boxes have a history list where previous entries are saved and can be selected. When this option is checked, these entries are saved in the desktop file. On by default.
Clipboard content
When checked, the contents of the clipboard are also saved to disk. Off by default.
Watch expressions
When checked, all watch expressions are saved in the desktop file. Off by default.
Breakpoints
When checked, all breakpoints with their properties are saved in the desktop file. Off by default.
Open windows
When checked, the list of files in open editor windows is saved in the desktop file, and the windows will be restored the next time the IDE is run. On by default.
Symbol information
When checked, the information for the symbol browser is saved in the desktop file. Off by default.
CodeComplete wordlist
When checked, the list of codecompletion words is saved. On by default.
CodeTemplates
When checked, the defined code templates are saved. On by default.

Remark: The format of the desktop file changes between editor versions. So when installing a new version, it may be necessary to delete the fp.dsk files wherever the IDE searches for them.

6.12.3  The Editor

Several aspects of the editor window behaviour can be set in this dialog. The editor preferences dialog is shown in Figure ?? . Note that some of these options affect only newly opened windows, not already opened windows (e.g. Vertical Blocks, Highlight Column/Row).


Figure ?? The editor preferences dialog


The following elements can be set in the editor preferences dialog:

Create backup files
Whenever an editor file is saved, a backup is made of the old file. On by default.
Insert mode
Start with insert mode.
Auto indent mode
Smart indenting is on. This means that pressing Enter will position the cursor on the next line in the same column where text starts on the current line. On by default.
Use tab characters
When the tab key is pressed, use a tab character. Normally, when the tab key is pressed, spaces are inserted. When this option is checked, tab characters will be inserted instead. Off by default.
Backspace unindents
Pressing the Bksp key will unindent if the beginning of the text on the current line is reached, instead of deleting just the previous character. On by default.
Persistent blocks
When a selection is made, and the cursor is moved, the selection is not destroyed, i.e. the selected block stays selected. On by default.
Syntax highlight
Use syntax highlighting on the files that have an extension which appears in the list of highlight extensions. On by default.
Block insert cursor
The insert cursor is a block instead of an underscore character. By default the overwrite cursor is a block. This option reverses that behaviour. Off by default.
Vertical blocks
When selecting blocks spanning several lines, the selection doesn’t contain the entirety of the lines within the block; instead, it contains the lines as far as the column on which the cursor is located. Off by default.
Highlight column
When checked, the current column (i.e. the column where the cursor is) is highlighted. Off by default.
Highlight row
When checked, the current row (i.e. the row where the cursor is) is highlighted. Off by default.
Auto closing brackets
When an opening bracket character is typed, the closing bracket is also inserted at once. Off by default.
Keep trailing spaces
When saving a file, the spaces at the end of lines are stripped off. This option disables that behaviour; i.e. any trailing spaces are also saved to file. Off by default.
Codecomplete enabled
Enable code completion. On by default.
Enable folds
Enable code folding. Off by default.
Tab size
The number of spaces that are inserted when the Tab key is pressed. The default value is 8.
Indent size
The number of spaces a block is indented when calling the block indent function. The default value is 2.
Highlight extensions
When syntax highlighting is on, the list of file masks entered here will be used to determine which files are highlighted. File masks should be separated with semicolon (;) characters. The default is *.pas;*.pp;*.inc.
File patterns needing tabs
Some files (such as makefiles) need actual tab characters instead of spaces. Here a series of file masks can be entered to indicate files for which tab characters will always be used. Default is make*;make*.*.

Remark: These options will not be applied to already opened windows; only newly opened windows will have these options.

6.12.4  Keyboard & Mouse

The Keyboard & mouse options dialog is called by the menu item "Options|Environment|Keyboard & Mouse". It allows adjusting the behaviour of the keyboard and mouse as well as the sensitivity of the mouse. The keyboard and mouse options dialog is shown in Figure ?? .


Figure ?? The Keyboard & mouse options dialog


Keys for copy, cut and paste
Set the keys to use for clipboard operations:
Mouse double click
The slider can be used to adjust the double click speed. Fast means that the time between two clicks is very short; slow means that the time between two mouse clicks can be quite long.
Reverse mouse buttons
the behaviour of the left and right mouse buttons can be swapped by by checking the checkbox; this is especially useful for left-handed people.
Ctrl+Right mouse button
Assigns an action to a right mouse button click while holding the Ctrl key pressed.
Alt+right mouse button
Assigns an action to right mouse button click while holding the Alt key pressed.

The following actions can be assigned to Ctrl-Right mouse button or Alt-right mouse button:

Nothing
No action is associated to the event.
Topic search
The keyword at the mouse cursor is searched in the help index.
Go to cursor
The program is executed until the line where the mouse cursor is located.
Breakpoint
Set a breakpoint at the mouse cursor position.
Evaluate
Evaluate the value of the variable at the mouse cursor.
Add watch
Add the variable at the mouse cursor to the watch list.
Browse symbol
The symbol at the mouse cursor is displayed in the browser.

6.13  The help system

More information on how to handle the IDE, or about the use of various calls in the RTL, explanations regarding the syntax of a Pascal statement, can be found in the help system. The help system is activated by pressing F1.

6.13.1  Navigating in the help system

The help system contains hyperlinks; these are sensitive locations that lead to another topic in the help system. They are marked by a different color. The hyperlinks can be activated in one of two ways:

  1. by directly clicking the one you want with the mouse, or
  2. by using the Tab and Shift-Tab keys to move between the different hyperlinks of a page and then pressing the Enter key to activate the one you want.

When Shift-F1 is pressed, the contents of the help system are displayed. To go back to the previous help topic, press Alt-F1. This also works if the help window isn’t displayed on the desktop; the help window will then be activated.

6.13.2  Working with help files

The IDE contains a help system which can display the following file formats:

TPH
The help format for the Turbo Pascal help viewer.
INF
The OS/2 help format.
NG
The Norton Guide Help format.
HTML
HTML files.

In future some more formats may be added. However, the above formats should cover already a wide spectrum of available help files.

Remark: Concerning the support for HTML files the following should be noted:

  1. The HTML viewer of the help system is limited, it can only handle the most basic HTML files (graphics excluded), since it is only designed to display the Free Pascal help files. 6.
  2. When the HTML help viewer encounters a graphics file, it will try and find a file with the same name but an extension of .ans; If this file is found, this will be interpreted as a file with ANSI escape sequences, and these will be used to display a text image. The displays of the IDE dialogs in the IDE help files are made in this way.

The menu item "Help|Files" permits help files to be added to, and deleted from, the list of files in the help table of contents. The help files dialog is displayed in Figure ?? .


Figure ?? The help files dialog


The dialog lists the files that will be presented in the table of contents window of the help system. Each entry has a small descriptive title and a filename next to it. The following actions are available when adding help files:

New
Adds a new file. IDE will display a prompt, in which the location of the help file should be entered.

If the added file is an HTML file, a dialog box will be displayed which asks for a title. This title will then be included in the contents of help.

Delete
Deletes the currently highlighted file from the help system. It is not deleted from the hard disk; only the help system entry is removed.
Cancel
Discards all changes and closes the dialog.
OK
Saves the changes and closes the dialog.

The Free Pascal documentation in HTML format can be added to the IDE’s help system. This way the documentation can be viewed from within the IDE. If Free Pascal has been installed using the installer, the installer should have added the FPC documentation to the list of help files, if the documentation was installed as well.

6.13.3  The about dialog

The about dialog, reachable through ("Help|About...") shows some information about the IDE, such as the version number, the date it was built, what compiler and debugger it uses. When reporting bugs about the IDE, please use the information given by this dialog to identify the version of the IDE that was used.

It also displays some copyright information.

6.14  Keyboard shortcuts

A lot of keyboard shortcuts used by the IDE are compatible with WordStar and should be well known to Turbo Pascal users.

Below are the following tables:

  1. In table (??) some shortcuts for handling the IDE windows and Help are listed.
  2. In table (??) the shortcuts for compiling, running and debugging a program are presented.
  3. In table (??) the navigation keys are described.
  4. In table (??) the editing keys are listed.
  5. In table (??) all block command shortcuts are listed.
  6. In table (??) all selection-changing shortcuts are presented.
  7. In table (??) some general shortcuts, which do not fit in the previous categories, are presented.

Table 6.4: General
CommandShortcut keyAlternative
HelpF1 
Goto last help topicAlt-F1 
Search word at cursor position in helpCtrl-F1 
Help indexShift-F1 
Close active windowAlt-F3 
Zoom/Unzoom windowF5 
Move/Zoom active windowCtrl-F5 
Switch to next windowF6 
Switch to last windowShift-F6 
MenuF10 
Local menuAlt-F10 
List of windowsAlt-0 
Active another windowAlt-<digit> 
Call grep utilityShift-F2 
Exit IDEAlt-X 


Table 6.5: Compiler
CommandShortcut keyAlternative
Reset debugger/programCtrl-F2 
Display call stackCtrl-F3 
Run as far as the cursorF4 
Switch to user screenAlt-F5 
Trace intoF7 
Add watchCtrl-F7 
Step overF8 
Set breakpoint at current lineCtrl-F8 
MakeF9 
RunCtrl-F9 
Compile the active source fileAlt-F9 
MessageF11 
Compiler messagesF12 


Table 6.6: Text navigation
CommandShortcut keyAlternative
Char leftArrow leftCtrl-S
Char rightArrow rightCtrl-D
Line upArrow upCtrl-E
Line downArrow downCtrl-X
Word leftCtrl-Arrow leftCtrl-A
Word rightCtrl-Arrow rightCtrl-F
Scroll one line upCtrl-W 
Scroll one line downCtrl-Z 
Page upPageUpCtrl-R
Page downPageDown 
Beginning of LinePos1Ctrl-Q-S
End of LineEndCtrl-Q-D
First line of windowCtrl-HomeCtrl-Q-E
Last line of windowCtrl-EndCtrl-Q-X
First line of fileCtrl-PageUpCtrl-Q-R
Last line of fileCtrl-PageDownCtrl-Q-C
Last cursor positionCtrl-Q-P 
Find matching block delimiterCtrl-Q-[ 
Find last matching block delimiterCtrl-Q-] 


Table 6.7: Edit
CommandShortcut keyAlternative
Delete charDelCtrl-G
Delete left charBackspaceCtrl-H
Delete lineCtrl-Y 
Delete til end of lineCtrl-Q-Y 
Delete wordCtrl-T 
Insert lineCtrl-N 
Toggle insert modeInsertCtrl-V


Table 6.8: Block commands
CommandShortcut keyAlternative
Goto Beginning of selected textCtrl-Q-B 
Goto end of selected textCtrl-Q-K 
Select current lineCtrl-K-L 
Print selected textCtrl-K-P 
Select current wordCtrl-K-T 
Delete selected textCtrl-DelCtrl-K-Y
Copy selected text to cursor positionCtrl-K-C 
Move selected text to cursor positionCtrl-K-V 
Copy selected text to clipboardCtrl-Ins 
Move selected text to the clipboardShift-Del 
Indent block one columnCtrl-K-I 
Unindent block one columnCtrl-K-U 
Insert text from clipboardShift-Insert 
Insert fileCtrl-K-R 
Write selected text to fileCtrl-K-W 
Uppercase current blockCtrl-K-N 
Lowercase current blockCtrl-K-O 
Uppercase wordCtrl-K-E 
Lowercase wordCtrl-K-F 


Table 6.9: Change selection
CommandShortcut keyAlternative
Mark beginning of selected textCtrl-K-B 
Mark end of selected textCtrl-K-K 
Remove selectionCtrl-K-Y 
Extend selection one char to the leftShift-Arrow left 
Extend selection one char to the rightShift-Arrow right 
Extend selection to the beginning of the lineShift-Pos1 
Extend selection to the end of the lineShift-End 
Extend selection to the same column in the last rowShift-Arrow up 
Extend selection to the same column in the next rowShift-Arrow down 
Extend selection to the end of the lineShift-End 
Extend selection one word to the leftCtrl-Shift-Arrow left 
Extend selection one word to the rightCtrl-Shift-Arrow right 
Extend selection one page upShift-PageUp 
Extend selection one page downShift-PageDown 
Extend selection to the beginning of the fileCtrl-Shift-Pos1Ctrl-Shift-PageUp
Extend selection to the end of the fileCtrl-Shift-EndCtrl-Shift-PageUp


Table 6.10: Misc. commands
CommandShortcut keyAlternative
Save fileF2Ctrl-K-S
Open fileF3 
SearchCtrl-Q-F 
Search againCtrl-L  
Search and replaceCtrl-Q-A 
Set markCtrl-K-n (where n can be 0..9) 
Goto markCtrl-Q-n (where n can be 0..9) 
UndoAlt-Backspace 


1
"File|Exit" means select the item ’Exit’ in the menu ’File’.
2
See section ?? for more information on how to reverse the actions of the mouse buttons.
3
Available from the Free Software Foundation website.
4
Suggestions for improvement, or better yet, patches that improve the algorithm, are always welcome.
5
It can be downloaded from http://www.informatik.fh-muenchen.de/ ifw98223/vbehz.htm
6
...but feel free to improve it and send patches to the Free Pascal development team...

Chapter 7  Porting and portable code

7.1  Free Pascal compiler modes

The Free Pascal team tries to create a compiler that can compile as much as possible code produced for Turbo Pascal , Delphi or the Mac pascal compilers: this should make sure that porting code that was written for one of these compilers is as easy as possible.

At the same time, the Free Pascal developers have introduced a lot of extensions in the Object Pascal language. To reconcile these different goals, and to make sure that people can produce code which can still be compiled by the Turbo Pascal and Delphicompilers, the compiler has a concepts of ’compiler modes’. In a certain compiler mode, the compiler has certain functionalities switched on or off. This allows to introduce a compatibility mode in which only features supported by the original compiler are supported. Currently, 5 modes are supported:

FPC
This is the original Free Pascal compiler mode: here all language constructs except classes, interfaces and exceptions are supported. Objects are supported in this mode. This is the default mode of the compiler.
OBJFPC
This is the same mode as FPC mode, but it also includes classes, interfaces and exceptions.
TP
Turbo Pascal compatibility mode. In this mode, the compiler tries to mimic the Turbo Pascal compiler as closely as possible. Obviously, only 32-bit or 64-bit code can be compiled.
DELPHI
Delphi compatibility mode. In this mode, the compiler tries to resemble the Delphi compiler as best as it can: All Delphi 7 features are implemented. Features that were implemented in the .NET versions of Delphi are not implemented.
MACPAS
the Mac Pascal compatibility mode. In this mode, the compiler attempts to allow all constructs that are implemented in Mac pascal. In particular, it attempts to compile the universal interfaces.

The compiler mode can be set on a per-unit basis: each unit can have its own compiler mode, and it is possible to use units which have been compiled in different modes intertwined. The mode can be set in one of 2 ways:

  1. On the command line, with the -M switch.
  2. In the source file, with the {$MODE } directive.

Both ways take the name of the mode as an argument. If the unit or program source file does not specify a mode, the mode specified on the command-line is used. If the source file specifies a mode, then it overrides the mode given on the command-line.

Thus compiling a unit with the -M switch as follows:

fpc -MOBJFPC myunit

is the same as having the following mode directive in the unit:

{$MODE OBJFPC}
Unit myunit;

The MODE directive should always be located before the uses clause of the unit interface or program uses clause, because setting the mode may result in the loading of an additional unit as the first unit to be loaded.

Note that the {$MODE } directive is a global directive, i.e. it is valid for the whole unit; Only one directive can be specified.

The mode has no influence on the availability of units: all available units can be used, independent of the mode that is used to compile the current unit or program.

7.2  Turbo Pascal

Free Pascal was originally designed to resemble Turbo Pascal as closely as possible. There are, of course, restrictions. Some of these are due to the fact that Turbo Pascal was developed for 16-bit architectures whereas Free Pascal is a 32-bit/64-bit compiler. Other restrictions result from the fact that Free Pascal works on more than one operating system.

In general we can say that if you keep your program code close to ANSI Pascal, you will have no problems porting from Turbo Pascal, or even Delphi, to Free Pascal . To a large extent, the constructs defined by Turbo Pascal are supported. This is even more so if you use the -Mtp or -MObjfpc switches.

In the following sections we will list the Turbo Pascal and Delphi constructs which are not supported in Free Pascal , and we will list in what ways Free Pascal extends Turbo Pascal.

7.2.1  Things that will not work

Here we give a list of things which are defined/allowed in Turbo Pascal, but which are not supported by Free Pascal . Where possible, we indicate the reason.

  1. Duplicate case labels are permitted in Turbo Pascal, but not in Free Pascal . This is actually a bug in Turbo Pascal, and so support for it will not be implemented in Free Pascal.
  2. In Turbo Pascal , parameter lists of previously defined functions and procedures did not have to match exactly. In Free Pascal, they must. The reason for this is the function overloading mechanism of Free Pascal . However, the -M, (see ??) option overcomes this restriction.
  3. The Turbo Pascal variables MEM, MEMW, MEML and PORT for memory and port access are not available in the system unit. This is due to the operating system. Under dos , both the system and the extender unit (GO32) implement the mem constuct. Under linux , the ports unit implements such a construct for the Ports variable.
  4. Turbo Pascal allows you to create procedure and variable names using words that are not permitted in that role in Free Pascal. This is because there are certain words that are reserved in Free Pascal (and Delphi) that are not reserved in Turbo Pascal, such as: PROTECTED, PUBLIC, PUBLISHED, TRY, FINALLY, EXCEPT, RAISE. Using the -Mtp switch will solve this problem if you want to compile Turbo Pascal code that uses these words (chapter ?? for a list of all reserved words).
  5. The Turbo Pascal reserved words FAR, NEAR are ignored. This is because their purpose was limited to a 16-bit environment and Free Pascal is a 32-bit/64-bit compiler.
  6. The Turbo Pascal INTERRUPT directive will work only on the Free Pascal dos target. Other operating systems do not allow handling of interrupts by user programs.
  7. By default the Free Pascal compiler uses AT&T assembler syntax. This is mainly because Free Pascal uses gnu as. However, other assembler forms are available. For more information, see the Programmers guide .
  8. Turbo Pascal’s Turbo Vision is available in Free Pascal under the name of FreeVision, which should be almost 100% compatible with Turbo Vision.
  9. Turbo Pascal’s ’overlay’ unit is not available. It also isn’t necessary, since Free Pascal is a 32/64-bit compiler, so program size shouldn’t be an issue.
  10. The command line parameters of the compiler are different.
  11. Compiler switches and directives are mostly the same, but some extra exist.
  12. Units are not binary compatible. That means that you cannot use a .tpu unit file, produced by Turbo Pascal, in a Free Pascal project.
  13. The Free Pascal TextRec structure (for internal description of files) is not binary compatible with TP or Delphi.
  14. Sets are by default 4 bytes in Free Pascal; this means that some typecasts which were possible in Turbo Pascal are no longer possible in Free Pascal. However, there is a switch to set the set size, see Programmers guide for more information.
  15. A file is opened for output only (using fmOutput) when it is opened with Rewrite. In order to be able to read from it, it should be reset with Reset.
  16. Turbo Pascal destructors allowed parameters. This is not permitted in Free Pascal: by default, in Free Pascal , Destructors cannot have parameters. This restriction can be removed by using the -So switch.
  17. Turbo Pascal permits more than one destructor for an object. In Free Pascal , there can be only one destructor. This restriction can also be removed by using the -So switch.
  18. The order in which expressions are evaluated is not necessarily the same. In the following expression:
    a := g(2) + f(3);
    
    it is not guaranteed that g(2) will be evaluated before f(3).
  19. In Free Pascal , you need to use the address @ operator when assigning procedural variables.

7.2.2  Things which are extra

Here we give a list of things which are possible in Free Pascal , but which didn’t exist in Turbo Pascal or Delphi.

  1. Free Pascal functions can also return complex types, such as records and arrays.
  2. In Free Pascal , you can use the function return value in the function itself, as a variable. For example:
    function a : longint;
    
    begin
       a:=12;
       while a>4 do
         begin
            {...}
         end;
    end;
    
    The example above would work with TP, but the compiler would assume that the a>4 is a recursive call. If a recursive call is actually what is desired, you must append () after the function name:
    function a : longint;
    
    begin
       a:=12;
       { this is the recursive call }
       if a()>4 then
         begin
            {...}
         end;
    end;
    
  3. In Free Pascal , there is partial support of Delphi constructs. (See the Programmers guide for more information on this).
  4. The Free Pascal exit call accepts a return value for functions.
    function a : longint;
    
    begin
       a:=12;
       if a>4 then
         begin
            exit(a*67); {function result upon exit is a*67 }
         end;
    end;
    
  5. Free Pascal supports function overloading. That is, you can define many functions with the same name, but with different arguments. For example:
    procedure DoSomething (a : longint);
    begin
    {...}
    end;
    
    procedure DoSomething (a : real);
    begin
    {...}
    end;
    
    You can then call procedure DoSomething with an argument of type Longint or Real.
    This feature has the consequence that a previously declared function must always be defined with the header completely the same:
    procedure x (v : longint); forward;
    
    {...}
    
    procedure x;{ This will overload the previously declared x}
    begin
    {...}
    end;
    
    This construction will generate a compiler error, because the compiler didn’t find a definition of procedure x (v : longint);. Instead you should define your procedure x as:
    procedure x (v : longint);
    { This correctly defines the previously declared x}
    begin
    {...}
    end;
    
    The command line option -So, (see ??) disables overloading. When you use it, the above will compile, as in Turbo Pascal.
  6. Operator overloading. Free Pascal allows operator overloading, e.g. you can define the ’+’ operator for matrices.
  7. On FAT16 and FAT32 systems, long file names are supported.

7.2.3  Turbo Pascal compatibility mode

When you compile a program with the -Mtp switch, the compiler will attempt to mimic the Turbo Pascal compiler in the following ways:

Remark: The MemAvail and MaxAvail functions are no longer available in Free Pascal as of version 2.0. The reason for this incompatibility follows:

On modern operating systems, 1 the idea of "Available Free Memory" is not valid for an application. The reasons are:

  1. One processor cycle after an application asked the OS how much memory is free, another application may have allocated everything.
  2. It is not clear what "free memory" means: does it include swap memory, does it include disk cache memory (the disk cache can grow and shrink on modern OS’es), does it include memory allocated to other applications but which can be swapped out, etc.

Therefore, programs using MemAvail and MaxAvail functions should be rewritten so they no longer use these functions, because it does not make sense any more on modern OS’es. There are 3 possibilities:

  1. Use exceptions to catch out-of-memory errors.
  2. Set the global variable "ReturnNilIfGrowHeapFails" to True and check after each allocation whether the pointer is different from Nil.
  3. Don’t care and declare a dummy function called MaxAvail which always returns High(LongInt) (or some other constant).

7.2.4  A note on long file names under dos

Under Windows 95 and higher, long filenames are supported. Compiling for the Windows target ensures that long filenames are supported in all functions that do file or disk access in any way.

Moreover, Free Pascal supports the use of long filenames in the system unit and the Dos unit also for go32v2 executables. The system unit contains the boolean variable LFNsupport. If it is set to True then all system unit functions and Dos unit functions will use long file names if they are available. This should be so on Windows 95 and 98, but not on Windows NT or Windows 2000. The system unit will check this by calling dos function 71A0h and checking whether long filenames are supported on the C: drive.

It is possible to disable the long filename support by setting the LFNSupport variable to False; but in general it is recommended to compile programs that need long filenames as native Windows applications.

7.3  Porting Delphi code

Porting Delphi code should be quite painless. The Delphi mode of the compiler tries to mimic Delphi as closely as possible. This mode can be enabled using the -Mdelphi command line switch, or by inserting the following code in the sources before the unit or program clause:

{$IFDEF FPC}
{$MODE DELPHI}
{$ENDIF FPC}

This ensures that the code will still compile with both Delphi and FPC.

Nevertheless, there are some things that will not work. Delphi compatibility is relatively complete up to Delphi 7. New constructs in higher versions of Delphi (notably, the versions that work with .NET) are not supported.

7.3.1  Missing language constructs

At the level of language compatibility, FPC is very compatible with Delphi: it can compile most of FreeCLX, the free Widget library that was shipped with Delphi 6, Delphi 7 and Kylix.

Currently, the only missing language constructs are:

  1. Dynamic methods are actually the same as virtual.
  2. Const for a parameter to a procedure does not necessarily mean that the variable or value is passed by reference.
  3. Packages are not supported.

There are some inline assembler constructs which are not supported, and since Free Pascal is designed to be platform independent, it is quite unlikely that these constructs will be supported in the future.

Note that the -Mobjfpc mode switch is to a large degree Delphi compatible, but is more strict than Delphi. The most notable differences are:

  1. Parameters or local variables of methods cannot have the same names as properties of the class in which they are implemented.
  2. The address operator is needed when assigning procedural variables (or event handlers).
  3. AnsiStrings are not switched on by default.

7.3.2  Missing calls / API incompatibilities

Delphi is heavily bound to Windows. Because of this, it introduced a lot of Windows-isms in the API (e.g. file searching and opening, loading libraries).

Free Pascal was designed to be portable, so things that are very Windows specific are missing, although the Free Pascal team tries to minimize this. The following are the main points that should be considered:

7.3.3  Delphi compatibility mode

Switching on Dephi compatibility mode has the following effect:

  1. Support for Classes, exceptions and threadvars is enabled.
  2. The objpas is loaded as the first unit. This unit redefines some basic types: Integer is 32-bit for instance.
  3. The address operator (@) is no longer needed to set event handlers (i.e. assign to procedural variables or properties).
  4. Names of local variables and method parameters in classes can match the name of properties or field of the class.
  5. The String keyword implies AnsiString by default.
  6. Operator overloading is switched off.

7.3.4  Best practices for porting

When encountering differences in Delphi/FPC calls, the best thing to do is not to insert IFDEF statements whenever a difference is encountered, but to create a separate unit which is only used when compiling with FPC. The missing/incompatible calls can then be implemented in that unit. This will keep the code more readable and easier to maintain.

If a language construct difference is found, then the Free Pascal team should be contacted and a bug should be reported.

7.4  Writing portable code

Free Pascal is designed to be cross-platform. This means that the basic RTL units are usable on all platforms, and the compiler behaves the same on all platforms (as far as possible). The Object Pascal language is the same on all platforms. Nevertheless, FPC comes with a lot of units that are not portable, but provide access to all possibilities that a platform provides.

The following are some guidelines to consider when writing portable code:

The system unit contains some constants which describe file access on a system:

AllFilesMask
a file mask that will return all files in a directory. This is * on Unix-like platforms, and *.* on dos and windows like platforms.
LineEnding
A character or string which describes the end-of-line marker used on the current platform. Commonly, this is one of #10, #13#10 or #13.
LFNSupport
A boolean that indicates whether the system supports long filenames (i.e. is not limited to MS-DOS 8.3 filenames).
DirectorySeparator
The character which acts as a separator between directory parts of a path.
DriveSeparator
For systems that support drive letters, this is the character that is used to separate the drive indication from the path.
PathSeparator
The character used to separate items in a list (notably, a PATH).
maxExitCode
The maximum value for a process exitcode.
MaxPathLen
The maximum length of a filename, including a path.
FileNameCaseSensitive
A boolean that indicates whether filenames are handled case sensitively.
UnusedHandle
A value used to indicate an unused/invalid file handle.
StdInputHandle
The value of the standard input file handle. This is not always 0 (zero), as is commonly the case on Unices.
StdOutputHandle
The value of the standard output file handle. This is not always 1, as is commonly the case on Unices.
StdErrorHandle
The value of the standard diagnostics output file handle. This is not always 2, as is commonly the case on Unices.
CtrlZMarksEOF
A boolean that indicates whether the #26 character marks the end of a file (an old MS-DOS convention).

To ease writing portable filesystem code, the Free Pascal file routines in the system unit and sysutils unit treat the common directory separator characters (/ and \) as equivalent. That means that if you use / on a Windows system, it will be transformed to a backslash, and vice versa.

This feature is controlled by 2 (pre-initialized) variables in the system unit:

AllowDirectorySeparators
A set of characters which, when used in filenames, are treated as directory separators. They are transformed to the DirectorySeparator character.
AllowDriveSeparators
A set of characters which, when used in filenames, are treated as drive separator characters. They are transformed to the DriveSeparator character.

1
The DOS extender GO32V2 falls under this definition of "modern" because it can use paged memory and run in multitasked environments.

Chapter 8  Utilities that come with Free Pascal

Besides the compiler and the runtime Library, Free Pascal comes with some utility programs and units. Here we list these programs and units.

8.1  Demo programs and examples

A suite of demonstration programs comes included with the Free Pascal distribution. These programs have no other purpose than to demonstrate the capabilities of Free Pascal . They are located in the demo directory of the sources.

All example programs mentioned in the documentation are available. Check out the directories that are beneath the same directory as the demo directory. The names of these directories end on ex. There you will find all example sources.

8.2  fpcmake

fpcmake is the Free Pascal makefile constructor program.

It reads a Makefile.fpc configuration file and converts it to a Makefile suitable for reading by GNU make to compile your projects. It is similar in functionality to GNU autoconf or Imake for making X projects.

fpcmake accepts filenames of makefile description files as its command line arguments. For each of these files it will create a Makefile in the same directory where the file is located, overwriting any other existing file.

If no options are given, it just attempts to read the file Makefile.fpc in the current directory and tries to construct a makefile from it. Any previously existing Makefile will be erased.

The format of the fpcmake configuration file is described in great detail in the appendices of the Programmers guide .

8.3  fpdoc - Pascal Unit documenter

fpdoc is a program which generates fully cross-referenced documentation for a unit. It generates documentation for each identifier found in the unit’s interface section. The generated documentation can be in many formats, for instance HTML, RTF, Text, man page and LaTeX. Unlike other documentation tools, the documentation can be in a separate file (in XML format), so the sources aren’t cluttered with documentation. Its companion program makeskel creates an empty XML file with entries for all identifiers, or it can update an existing XML file, adding entries for new identifiers.

fpdoc and makeskel are described in the .

8.4  h2pas - C header to Pascal Unit converter

h2pas attempts to convert a C header file to a Pascal unit. it can handle most C constructs that one finds in a C header file, and attempts to translate them to their Pascal counterparts.

See below (constructs) for a full description of what the translator can handle. The unit with Pascal declarations can then be used to access code written in C.

The output of the h2pas program is written to a file with the same name as the C header file that was used as input, but with the extension .pp The output file that h2pas creates can be customized in a number of ways by means of many options.

8.4.1  Options

The output of h2pas can be controlled with the following options:

-d
Use external; for all procedure and function declarations.
-D
Use external libname name ’func_name’ for function and procedure declarations.
-e
Emit a series of constants instead of an enumeration type for the C enum construct.
-i
Create an include file instead of a unit (omits the unit header).
-l
libname specify the library name for external function declarations.
-o
outfile Specify the output file name. Default is the input file name with the extension replaced by .pp
-p
Use the letter P in front of pointer type parameters instead of .
-s
Strip comments from the input file. By default comments are converted to comments, but they may be displaced, since a comment is handled by the scanner.
-t
Prepend typedef type names with the letter T (used to follow Borland’s convention that all types should be defined with T).
-v
Replace pointer parameters with call by reference parameters. Use with care because some calls can expect a Nil pointer.
-w
Header file is a win32 header file (adds support for some special macros).
-x
Handle SYS_TRAP of the PalmOS header files.

8.4.2  Constructs

The following C declarations and statements are recognized:

defines
Defines are changed into Pascal constants if they are simple defines. Macros are changed - wherever possible - to functions; however the arguments are all integers, so these must be changed manually. Simple expressions in define staments are recognized, as are most arithmetic operators: addition, substraction, multiplication, division, logical operators, comparison operators, shift operators. The C construct ( A ? B : C) is also recognized and translated to a Pascal construct with an IF statement. (This is buggy, however).
preprocessor statements
The conditional preprocessing commands are recognized and translated into equivalent Pascal compiler directives. The special
#ifdef __cplusplus
is also recognized and removed.
typedef
A typedef statement is changed into a Pascal type statement. The following basic types are recognized: These types are also changed if they appear in the arguments of a function or procedure.
functions and procedures
Functions and procedures are translated as well. Pointer types may be changed to call by reference arguments (using the var argument) by using the -p command line argument. Functions that have a variable number of arguments are changed to a function with a cvar modifier. (This used to be the array of const argument.)
specifiers
The extern specifier is recognized; however it is ignored. The packed specifier is also recognised and changed with the PACKRECORDS directive. The const specifier is also recognized, but is ignored.
modifiers
If the -w option is specified, then the following modifiers are recognized:
STDCALL
CDECL
CALLBACK
PASCAL
WINAPI
APIENTRY
WINGDIAPI
as defined in the win32 headers. If additionally the -x option is specified then the
SYS_TRAP
specifier is also recognized.
enums
Enum constructs are changed into enumeration types. Bear in mind that, in C, enumeration types can have values assigned to them. Free Pascal also allows this to a certain degree. If you know that values are assigned to enums, it is best to use the -e option to change the enumerations to a series of integer constants.
unions
Unions are changed to variant records.
structs
Structs are changed to Pascal records, with C packing.

8.5  h2paspp - preprocessor for h2pas

h2paspp can be used as a simple preprocessor for h2pas. It removes some of the constructs that h2pas has difficulties with. h2paspp reads one or more C header files and preprocesses them, writing the result to files with the same name as the originals as it goes along. It does not accept all preprocesser tokens of C, but takes care of the following preprocessor directives:

#define symbol
Defines the new symbol symbol. Note that macros are not supported.
#if symbol
The text following this directive is included if symbol is defined.
#ifdef symbol
The text following this directive is included if symbol is defined.
#ifndef symbol
The text following this directive is included if symbol is not defined.
#include filename
Include directives are removed, unless the -I option was given, in which case the include file is included and written to the output file.
#undef symbol
The symbol symbol is undefined.

8.5.1  Usage

h2paspp accepts one or more filenames and preprocesses them. It will read the input, and write the output to a file with the same name unless the -o option is given, in which case the file is written to the specified file. Note that only one output filename can be given.

8.5.2  Options

h2paspp has a small number of options to control its behaviour:

-dsymbol
Define the symbol symbol before processing is started.
-h
Emit a small helptext.
-I
Include include files instead of dropping the include statement.
-ooutfile
If this option is given, the output will be written to a file named outfile. Note that only one output file can be given.

8.6  ppudump program

ppudump is a program which shows the contents of a Free Pascal unit. It is distributed with the compiler. You can just issue the following command

  ppudump [options] foo.ppu

to display the contents of the foo.ppu unit. You can specify multiple files on the command line.

The options can be used to change the verbosity of the display. By default, all available information is displayed. You can set the verbosity level using the -Vxxx option. Here, xxx is a combination of the following letters:

h:
Show header info.
i:
Show interface information.
m:
Show implementation information.
d:
Show only (interface) definitions.
s:
Show only (interface) symbols.
b:
Show browser info.
a:
Show everything (default if no -V option is present).

8.7  ppumove program

ppumove is a program to make shared or static libraries from multiple units. It can be compared with the tpumove program that comes with Turbo Pascal.

It is distributed in binary form along with the compiler.

Its usage is very simple:

ppumove [options] unit1.ppu unit2.ppu ... unitn.ppu

where options is a combination of:

-b:
Generate a batch file that will contain the external linking and archiving commands that must be executed. The name of this batch file is pmove.sh on linux (and Unix like OSes), and pmove.bat on Windows and dos .
-d xxx:
Set the directory in which to place the output files to xxx.
-e xxx:
Set the extension of the moved unit files to xxx. By default, this is .ppl. You don’t have to specify the dot.
-o xxx:
Set the name of the output file, i.e. the name of the file containing all the units. This parameter is mandatory when you use multiple files. On linux , ppumove will prepend this name with lib if it isn’t already there, and will add an extension appropriate to the type of library.
-q:
Operate silently.
-s:
Make a static library instead of a dynamic one; By default a dynamic library is made on linux .
-w:
Tell ppumove that it is working under Windows NT . This will change the names of the linker and archiving program to ldw and arw, respectively.
-h or -?:
Display a short help.

The action of the ppumove program is as follows: It takes each of the unit files, and modifies it so that the compiler will know that it should look for the unit code in the library. The new unit files will have an extension .ppu; this can be changed with the -e option. It will then put together all the object files of the units into one library, static or dynamic, depending on the presence of the -s option.

The name of this library must be set with the -o option. If needed, the prefix lib will be prepended under linux . The extension will be set to .a for static libraries, for shared libraries, the extensions are .so on linux, and .dll under Windows NT and os/2 .

As an example, the following command

./ppumove -o both -e ppl ppu.ppu timer.ppu

will generate the following output under linux :

PPU-Mover Version 2.1.1
Copyright (c) 1998-2007 by the Free Pascal Development Team

Processing ppu.ppu... Done.
Processing timer.ppu... Done.
Linking timer.o ppu.o
Done.

And it will produce the following files:

  1. libboth.so : The shared library containing the code from ppu.o and timer.o. Under Windows NT , this file would be called both.dll.
  2. timer.ppl : The unit file that tells the Free Pascal compiler to look for the timer code in the library.
  3. ppu.ppl : The unit file that tells the Free Pascal compiler to look for the ppu code in the library.

You could then use or distribute the files libboth.so, timer.ppl and ppu.ppl.

8.8  ptop - Pascal source beautifier

8.8.1  ptop program

ptop is a source beautifier written by Peter Grogono based on the ancient pretty-printer by Ledgard, Hueras, and Singer, modernized by the Free Pascal team (objects, streams, configurability etc).

This configurability, and the thorough bottom-up design are the advantages of this program over the diverse Turbo Pascal source beautifiers on e.g. SIMTEL.

The program is quite simple to operate:

ptop "[-v] [-i indent] [-b bufsize ][-c optsfile] infile outfile"

The infile parameter is the Pascal file to be processed, and will be written to outfile, overwriting an existing outfile if it exists.

Some options modify the behaviour of ptop:

-h
Write an overview of the possible parameters and command line syntax.
-c ptop.cfg
Read some configuration data from configuration file instead of using the internal defaults then. A config file is not required, the program can operate without one. See also -g.
-i ident
Set the number of indent spaces used for BEGIN END; and other blocks.
-b bufsize
Set the streaming buffersize to bufsize. The default is 255; 0 is considered non-valid and ignored.
-v
Be verbose. Currently only outputs the number of lines read/written and some error messages.
-g ptop.cfg
Write ptop configuration defaults to the file "ptop.cfg". The contents of this file can be changed to your liking, and it can be used with the -c option.

8.8.2  The ptop configuration file

Creating and distributing a configuration file for ptop is not necessary, unless you want to modify the standard behaviour of ptop. The configuration file is never preloaded, so if you want to use it you should always specify it with a -c ptop.cfg parameter.

The structure of a ptop configuration file is a simple building block repeated several (20-30) times, for each Pascal keyword known to the ptop program. (See the default configuration file or ptopu.pp source to find out which keywords are known).

The basic building block of the configuration file consists of one or two lines, describing how ptop should react on a certain keyword. First comes a line without square brackets with the following format:

keyword=option1,option2,option3,...

If one of the options is "dindonkey" (see further below), a second line - with square brackets - is needed:

[keyword]=otherkeyword1,otherkeyword2,otherkeyword3,...

As you can see the block contains two types of identifiers: keywords (keyword and otherkeyword1..3 in above example) and options, (option1..3 above).

Keywords are the built-in valid Pascal structure-identifiers like BEGIN, END, CASE, IF, THEN, ELSE, IMPLEMENTATION. The default configuration file lists most of these.

Besides the real Pascal keywords, some other codewords are used for operators and comment expressions as in table (??) .


Table 8.1: Keywords for operators
Name of codewordOperator
casevar: in a case label ( unequal ’colon’)
becomes:=
delphicomment//
opencomment{ or (*
closecomment} or *)
semicolon;
colon:
equals=
openparen[
closeparen]
period.

The options codewords define actions to be taken when the keyword before the equal sign is found, as listed in table (??) .


Table 8.2: Possible options
Optiondoes what
crsuppSuppress CR before the keyword.
crbeforeForce CR before keyword.
 (do not use with crsupp.)
blinbeforeBlank line before keyword.
dindonkeyDe-indent on associated keywords.
 (see below)
dindentDeindent (always)
spbefSpace before
spaftSpace after
gobsymPrint symbols which follow a
 keyword but which do not
 affect layout. prints until
 terminators occur.
 (terminators are hard-coded in pptop,
 still needs changing)
inbytabIndent by tab.
crafterForce CR after keyword.
upperPrints keyword all uppercase
lowerPrints keyword all lowercase
capitalCapitalizes keyword: 1st letter
 uppercase, rest lowercase.

The option "dindonkey" given in table table (??) requires some further explanation. "dindonkey" is a contraction of "DeINDent ON associated KEYword". When it is present as an option in the first line, then a second, square-bracketed, line is required. A de-indent will be performed when any of the other keywords listed in the second line are encountered in the source.

Example: The lines

else=crbefore,dindonkey,inbytab,upper
[else]=if,then,else

mean the following:

Try to play with the configfile step by step until you find the effect you desire. The configurability and possibilities of ptop are quite large. E.g. I like all keywords uppercased instead of capitalized, so I replaced all capital keywords in the default file by upper.

ptop is still development software. So it is wise to visually check the generated source and try to compile it, to see if ptop hasn’t introduced any errors.

8.8.3  ptopu unit

The source of the PtoP program is conveniently split in two files: one is a unit containing an object that does the actual beautifying of the source, the other is a shell built around this object so it can be used from the command line. This design makes it possible to include the object in a program (e.g. an IDE) and use its features to format code.

The object resides in the PtoPU unit, and is declared as follows

  TPrettyPrinter=Object(TObject)
      Indent : Integer;    { How many characters to indent ? }
      InS    : PStream;
      OutS   : PStream;
      DiagS  : PStream;
      CfgS : PStream;
      Constructor Create;
      Function PrettyPrint : Boolean;
    end;

Using this object is very simple. The procedure is as follows:

  1. Create the object, using its constructor.
  2. Set the InS stream. This is an open stream, from which Pascal source will be read. This is a mandatory step.
  3. Set the OutS stream. This is an open stream, to which the beautified Pascal source will be written. This is a mandatory step.
  4. Set the DiagS stream. Any diagnostics will be written to this stream. This step is optional. If you don’t set this, no diagnostics are written.
  5. Set the CfgS stream. A configuration is read from this stream. (see the previous section for more information about configuration). This step is optional. If you don’t set this, a default configuration is used.
  6. Set the Indent variable. This is the number of spaces to use when indenting. Tab characters are not used in the program. This step is optional. The indent variable is initialized to 2.
  7. Call PrettyPrint. This will pretty-print the source in InS and write the result to OutS. The function returns True if no errors occurred, False otherwise.

So, a minimal procedure would be:

Procedure CleanUpCode;

var
  Ins,OutS : PBufStream;
  PPRinter : TPrettyPrinter;

begin
  Ins:=New(PBufStream,Init('ugly.pp',StopenRead,TheBufSize));
  OutS:=New(PBufStream,Init('beauty.pp',StCreate,TheBufSize));
  PPrinter.Create;
  PPrinter.Ins:=Ins;
  PPrinter.outS:=OutS;
  PPrinter.PrettyPrint;
end;

Using memory streams allows very fast formatting of code, and is particularly suitable for editors.

8.9  rstconv program

The rstconv program converts the resource string files generated by the compiler (when you use resource string sections) to .po files that can be understood by the GNU msgfmt program.

Its usage is very easy; it accepts the following options:

-i file
Use the specified file instead of stdin as input file. This option is optional.
-o file
Write output to the specified file. This option is required.
-f format
Specify the output format. At the moment, only one output format is supported: po for GNU gettext .po format. It is the default format.

As an example:

rstconv -i resdemo.rst -o resdemo.po

will convert the resdemo.rst file to resdemo.po.

More information on the rstconv utility can be found in the Programmers guide , under the chapter about resource strings.

8.10  unitdiff program

8.10.1  Synopsis

unitdiff shows the differences between two unit interface sections.

unitdiff [--disable-arguments] [--disable-private] [--disable-protected] 
[--help] [--lang=language] [--list] [--output=filename] [--sparse] 
file1 file2

8.10.2  Description and usage

Unitdiff scans one or two Free Pascal unit source files and either lists all available identifiers, or describes the differences in identifiers between the two units.

You can invoke unitdiff with an input filename as the only required argument. It will then simply list all available identifiers.

The regular usage is to invoke unitdiff with two arguments:

unitdiff input1 input2

Invoked like this, it will show the difference in interface between the two units, or list the available identifiers in both units. The output of unitdiff will go to standard output by default.

8.10.3  Options

Most of the unitdiff options are not required. Defaults will be used in most cases.

–disable-arguments
Do not check the arguments of functions and procedures. The default action is to check them.
–disable-private
Do not check private fields or methods of classes. The default action is to check them.
–disable-protected
Do not check protected fields or methods of classes. The default action is to check them.
–help
Emit a short help text and exit.
–lang=language
Set the language for the output file. This will mainly set the strings used for the headers in various parts of the documentation files (by default they’re in English). Currently, valid options are:
–list
Display just the list of available identifiers for the unit or units. If only one unit is specified on the command line, this option is automatically assumed.
–output=filename
Specify where the output should go. The default action is to send the output is sent to standard output (the screen).
–sparse
Turn on sparse mode. Output only the identifier names. Do not output types or type descriptions. By default, type descriptions are also written.

Chapter 9  Units that come with Free Pascal

Here we list the units that come with the Free Pascal distribution. Since there is a difference in the supplied units per operating system, we first describe the generic ones, then describe those which are operating system specific.

9.1  Standard units

The following units are standard and are meant to be ported to all platforms supported by Free Pascal . A brief description of each unit is also given.

charset
A unit to provide mapping of character sets.
cmem
Using this unit replaces the Free Pascal memory manager with the memory manager of the C library.
crt
This unit is similar to the unit of the same name of Turbo Pascal. It implements writing to the console in color, moving the text cursor around and reading from the keyboard.
dos
This unit provides basic routines for accessing the operating system. This includes file searching, environment variables access, getting the operating system version, getting and setting the system time. It is to note that some of these routines are duplicated in functionality in the sysutils unit.
dynlibs
Provides cross-platform access to loading dynamical libraries.
getopts
This unit gives you the gnu getopts command line arguments handling mechanism. It also supports long options.
graph
This unit is deprecated. This unit provides basic graphics handling, with routines to draw lines on the screen, display text etc. It provides the same functions as the Turbo Pascal unit.
heaptrc
a unit which debugs the heap usage. When the program exits, it outputs a summary of the used memory, and dumps a summary of unreleased memory blocks (if any).
keyboard
provides basic keyboard handling routines in a platform independent way, and supports writing custom drivers.
macpas
This unit implements several functions available only in MACPAS mode. This unit should not be included; it’s automatically included when the MACPAS mode is used.
math
This unit contains common mathematical routines (trigonometric functions, logarithms, etc.) as well as more complex ones (summations of arrays, normalization functions, etc.).
matrix
A unit providing matrix manipulation routines.
mmx
This unit provides support for mmx extensions in your code.
mouse
Provides basic mouse handling routines in a platform independent way, and supports writing custom drivers.
objects
This unit provides the base object for standard Turbo Pascal objects. It also implements File and Memory stream objects, as well as sorted and non-sorted collections, and string streams.
objpas
Is used for Delphi compatibility. You should never load this unit explicitly; it is automatically loaded if you request Delphi mode.
printer
This unit provides all you need for rudimentary access to the printer using standard I/O routines.
sockets
This gives the programmer access to sockets and TCP/IP programming.
strings
This unit provides basic string handling routines for the pchar type, comparable to similar routines in standard C libraries.
system
This unit is available for all supported platforms. It includes among others, basic file I/O routines, memory management routines, all compiler helper routines, and directory services routines.
strutils
Offers a lot of extended string handling routines.
dateutils
Offers a lot of extended date/time handling routines for almost any date and time math.
sysutils
Is an alternative implementation of the sysutils unit of Delphi. It includes file I/O access routines which takes care of file locking, date and string handling routines, file search, date and string conversion routines.
typinfo
Provides functions to access runtime Type Information, just like Delphi.
variants
Provides basic variant handling.
video
Provides basic screen handling in a platform independent way, and supports writing custom drivers.

9.2  Under DOS

emu387
This unit provides support for the coprocessor emulator.
go32
This unit provides access to capabilities of the GO32 dos extender.
ports
This implements the various port[] constructs for low-level I/O.

9.3  Under Windows

wincrt
This implements a console in a standard GUI window, contrary to the crt unit which is for the Windows console only.
Windows
This unit provides access to all Win32 API calls. Effort has been taken to make sure that it is compatible to the Delphi version of this unit, so code for Delphi is easily ported to Free Pascal .
opengl
Provides access to the low-level opengl functions in Windows .
winmouse
Provides access to the mouse in Windows .
ole2
Provides access to the OLE capabilities of Windows .
winsock
Provides access to the Windows sockets API Winsock.
Jedi windows header translations
The units containing the Jedi translations of the Windows API headers is also distributed with Free Pascal. The names of these units start with jw, followed by the name of the particular API.

9.4  Under Linux and BSD-like platforms

baseunix
Basic Unix operations, basically a subset of the POSIX specification. Using this unit should ensure portability across most unix systems.
clocale
This unit initializes the internationalization settings in the sysutils unit with settings obtained through the C library.
cthreads
This unit should be specified as the first or second unit in the uses clause of your program: it will use the Posix threads implementation to enable threads in your FPC program.
cwstring
If widestring routines are used, then this unit should be inserted as one of the first units in the uses clause of your program: it will initialize the widestring manager in the system unit with routines that use C library functions to handle Widestring conversions and other widestring operations.
errors
Returns a string describing an operating system error code.
Libc
This is the interface to GLibc on a linux I386 system. It will not work for other platforms, and is in general provided for Kylix compatibility.
oldlinux
This unit is deprecated. This unit provides access to the linux operating system. It provides most file and I/O handling routines that you may need. It implements most of the standard C library constructs that you will find on a Unix system. It is recommended, however, that you use the baseunix, unixtype and unix units. They are more portable.
ports
This implements the various port[] constructs. These are provided for compatibility only, and it is not recommended to use them extensively. Programs using this construct must be run as root or setuid root, and are a serious security risk on your system.
termio
Terminal control routines, which are compatible to the C library routines.
unix
Extended Unix operations.
unixtype
All types used commonly on Unix platforms.

9.5  Under OS/2

doscalls
Interface to doscalls.dll.
dive
Interface to dive.dll
emx
Provides access to the EMX extender.
pm*
Interface units for the Presentation Manager (PM) functions (GUI).
viocalls
Interface to viocalls.dll screen handling library.
moucalls
Interface to moucalls.dll mouse handling library.
kbdcalls
Interface to kbdcalls.dll keyboard handling library.
moncalls
Interface to moncalls.dll monitoring handling library.
winsock
Provides access to the (emulated) Windows sockets API Winsock.
ports
This implements the various port[] constructs for low-level I/O.

9.6  Unit availability

Standard unit availability for each of the supported platforms is given in the FAQ / Knowledge base.

Chapter 10  Debugging your programs

Free Pascal supports debug information for the gnu debugger gdb, or its derivatives Insight on win32 or ddd on linux . It can write 2 kinds of debug information:

stabs
The old debug information format.
dwarf
The new debug information format.

Both are understood by GDB.

This chapter briefly describes how to use this feature. It doesn’t attempt to describe completely the gnu debugger, however. For more information on the workings of the gnu debugger, see the GDB User Manual.

Free Pascal also suports gprof, the gnu profiler. See section ?? for more information on profiling.

10.1  Compiling your program with debugger support

First of all, you must be sure that the compiler is compiled with debugging support. Unfortunately, there is no way to check this at run time, except by trying to compile a program with debugging support.

To compile a program with debugging support, just specify the -g option on the command line, as follows:

fpc -g hello.pp

This will incorporate debugging information in the executable generated from your program source. You will notice that the size of the executable increases substantially because of this1.

Note that the above will only incorporate debug information for the code that has been generated when compiling hello.pp. This means that if you used some units (the system unit, for instance) which were not compiled with debugging support, no debugging support will be available for the code in these units.

There are 2 solutions for this problem.

  1. Recompile all units manually with the -g option.
  2. Specify the ’build’ option (-B) when compiling with debugging support. This will recompile all units, and insert debugging information in each of the units.

The second option may have undesirable side effects. It may be that some units aren’t found, or compile incorrectly due to missing conditionals, etc.

If all went well, the executable now contains the necessary information with which you can debug it using gnu gdb.

10.2  Using gdb to debug your program

To use gdb to debug your program, you can start the debugger, and give it as an option the full name of your program:

gdb hello

Or, under dos :

gdb hello.exe

This starts the debugger, and the debugger immediately loads your program into memory, but it does not run the program yet. Instead, you are presented with the following (more or less) message, followed by the gdb prompt ’(gdb)’:

GNU gdb 6.6.50.20070726-cvs
Copyright (C) 2007 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-suse-linux".
(gdb)

The actual prompt will vary depending on your operating system and installed version of gdb, of course.

To start the program you can use the run command. You can optionally specify command line parameters, which will then be fed to your program, for example:

(gdb) run -option -anotheroption needed_argument

If your program runs without problems, gdb will inform you of this, and return the exit code of your program. If the exit code was zero, then the message ’Program exited normally’ is displayed.

If something went wrong (a segmentation fault or such), gdb will stop the execution of your program, and inform you of this with an appropriate message. You can then use the other gdb commands to see what happened. Alternatively, you can instruct gdb to stop at a certain point in your program, with the break command.

Here is a short list of gdb commands, which you are likely to need when debugging your program:

quit
Exit the debugger.
kill
Stop a running program.
help
Give help on all gdb commands.
file
Load a new program into the debugger.
directory
Add a new directory to the search path for source files.

Remark: My copy of gdb needs ’.’ to be added explicitly to the search path, otherwise it doesn’t find the sources.

list
List the program sources in chunks of 10 lines. As an option you can specify a line number or function name.
break
Set a breakpoint at a specified line or function.
awatch
Set a watch-point for an expression. A watch-point stops execution of your program whenever the value of an expression is either read or written.

In appendix ?? a sample init file for gdb is presented. It produces good results when debugging Free Pascal programs.

For more information, refer to the gdb User Manual, or use the ’help’ function in gdb.

The text mode IDE and Lazarus both use GDB as a debugging backend. It may be preferable to use that, as they hide much of the details of the debugger in an easy-to-use user interface.

10.3  Caveats when debugging with gdb

There are some peculiarities of Free Pascal which you should be aware of when using gdb. We list the main ones here:

  1. Free Pascal generates information for GDB in uppercase letters. This is a consequence of the fact that Pascal is a case insensitive language. So, when referring to a variable or function, you need to make its name all uppercase.

    As an example, if you want to watch the value of a loop variable count, you should type

    watch COUNT
    

    Or if you want to stop when a certain function (e.g MyFunction) is called, type

    break MYFUNCTION
    
  2. gdb does not know sets.
  3. gdb doesn’t know strings. Strings are represented in gdb as records with a length field and an array of char containing the string.

    You can also use the following user function to print strings:

    define pst
    set $pos=&$arg0
    set $strlen = {byte}$pos
    print {char}&$arg0.st@($strlen+1)
    end
    
    document pst
      Print out a Pascal string
    end
    

    If you insert it in your gdb.ini file, you can look at a string with this function. There is a sample gdb.ini in appendix ??.

  4. Objects are difficult to handle, mainly because gdb is oriented towards C and C++. The workaround implemented in Free Pascal is that object methods are represented as functions, with an extra parameter this (all lowercase!). The name of this function is a concatenation of the object type and the function name, separated by two underscore characters.

    For example, the method TPoint.Draw would be converted to TPOINT__DRAW, and you could stop at it by using:

    break TPOINT__DRAW
    
  5. Global overloaded functions confuse gdb because they have the same name. Thus you cannot set a breakpoint at an overloaded function, unless you know its line number, in which case you can set a breakpoint at the starting line number of the function.

10.4  Support for gprof, the gnu profiler

You can compile your programs with profiling support. For this, you just have to use the compiler switch -pg. The compiler will insert the necessary stuff for profiling.

When you have done this, you can run your program as you would normally run it:

yourexe

Where yourexe is the name of your executable.

When your program finishes, a file called gmon.out is generated. Then you can start the profiler to see the output. You can benefit from redirecting the output to a file, because it could be quite a lot:

gprof yourexe > profile.log

Hint: you can use the --flat option to reduce the amount of output of gprof. It will then only output the information about the timings.

For more information on the gnu profiler gprof, see its manual.

10.5  Detecting heap memory leaks

Free Pascal has a built in mechanism to detect memory leaks. There is a plug-in unit for the memory manager that analyses the memory allocation/deallocation and prints a memory usage report after the program exits.

The unit that does this is called heaptrc. If you want to use it, you should include it as the first unit in your uses clause. Alternatively, you can supply the -gh switch to the compiler, and it will include the unit automatically for you.

After the program exits, you will get a report looking like this:

Marked memory at 0040FA50 invalid
Wrong size : 128 allocated 64 freed
  0x00408708
  0x0040CB49
  0x0040C481
Call trace for block 0x0040FA50 size 128
  0x0040CB3D
  0x0040C481

The output of the heaptrc unit is customizable by setting some variables. Output can also be customized using environment variables.

You can find more information about the usage of the heaptrc unit in the Unit reference .

10.6  Line numbers in run-time error backtraces

Normally, when a run-time error occurs, you are presented with a list of addresses that represent the call stack backtrace, i.e. the addresses of all procedures that were invoked when the run-time error occurred.

This list is not very informative, so there exists a unit that generates the file names and line numbers of the called procedures using the addresses of the stack backtrace. This unit is called lineinfo.

You can use this unit by giving the -gl option to the compiler. The unit will be automatically included. It is also possible to use the unit explicitly in your uses clause, but you must make sure that you compile your program with debug info.

Here is an example program:

program testline;

procedure generateerror255;

begin
  runerror(255);
end;

procedure generateanerror;

begin
  generateerror255;
end;

begin
  generateanerror;
end.

When compiled with -gl, the following output is generated:

Runtime error 255 at 0x0040BDE5
  0x0040BDE5  GENERATEERROR255,  line 6 of testline.pp
  0x0040BDF0  GENERATEANERROR,  line 13 of testline.pp
  0x0040BE0C  main,  line 17 of testline.pp
  0x0040B7B1

This is more understandable than the normal message. Make sure that all units you use are compiled with debug info, because if they are not, no line number and filename can be found.

10.7  Combining heaptrc and lineinfo

If you combine the lineinfo and the heaptrc information, then the output of the heaptrc unit will contain the names of the files and line numbers of the procedures that occur in the stack backtrace.

In such a case, the output will look something like this:

Marked memory at 00410DA0 invalid
Wrong size : 128 allocated 64 freed
  0x004094B8
  0x0040D8F9  main,  line 25 of heapex.pp
  0x0040D231
Call trace for block 0x00410DA0 size 128
  0x0040D8ED  main,  line 23 of heapex.pp
  0x0040D231

If lines without filename / line number occur, this means there is a unit which has no debug info included (in the above case, the getmem call itself).


1
A good reason not to include debug information in an executable you plan to distribute.

Appendix A  Alphabetical listing of command line options

The following is an alphabetical listing of all command line options, as generated by the compiler:

Free Pascal Compiler version 2.4.4-3 [2011/11/07] for i386
Copyright (c) 1993-2010 by Florian Klaempfl
/usr/lib/fpc/2.4.4/ppc386 [options] <inputfile> [options]
Put + after a boolean switch option to enable it, - to disable it
  -a     The compiler doesn't delete the generated assembler file
      -al        List sourcecode lines in assembler file
      -an        List node info in assembler file
      -ap        Use pipes instead of creating temporary assembler files
      -ar        List register allocation/release info in assembler file
      -at        List temp allocation/release info in assembler file
  -A<x>  Output format:
      -Adefault  Use default assembler
      -Aas       Assemble using GNU AS
      -Anasmcoff COFF (Go32v2) file using Nasm
      -Anasmelf  ELF32 (Linux) file using Nasm
      -Anasmwin32Win32 object file using Nasm
      -AnasmwdosxWin32/WDOSX object file using Nasm
      -Awasm     Obj file using Wasm (Watcom)
      -Anasmobj  Obj file using Nasm
      -Amasm     Obj file using Masm (Microsoft)
      -Atasm     Obj file using Tasm (Borland)
      -Aelf      ELF (Linux) using internal writer
      -Acoff     COFF (Go32v2) using internal writer
      -Apecoff   PE-COFF (Win32) using internal writer
  -b     Generate browser info
      -bl        Generate local symbol info
  -B     Build all modules
  -C<x>  Code generation options:
      -Ca<x>     Select ABI, see fpc -i for possible values
      -Cb        Generate big-endian code
      -Cc<x>     Set default calling convention to <x>
      -CD        Create also dynamic library (not supported)
      -Ce        Compilation with emulated floating point opcodes
      -Cf<x>     Select fpu instruction set to use, see fpc -i for possible values
      -CF<x>     Minimal floating point constant precision (default, 32, 64)
      -Cg        Generate PIC code
      -Ch<n>     <n> bytes heap (between 1023 and 67107840)
      -Ci        IO-checking
      -Cn        Omit linking stage
      -Co        Check overflow of integer operations
      -CO        Check for possible overflow of integer operations
      -Cp<x>     Select instruction set, see fpc -i for possible values
      -CP<x>=<y>  packing settings
         -CPPACKSET=<y> <y> set allocation: 0, 1 or DEFAULT or NORMAL, 2, 4 and 8
      -Cr        Range checking
      -CR        Verify object method call validity
      -Cs<n>     Set stack checking size to <n>
      -Ct        Stack checking (for testing only, see manual)
      -CX        Create also smartlinked library
  -d<x>  Defines the symbol <x>
  -D     Generate a DEF file
      -Dd<x>     Set description to <x>
      -Dv<x>     Set DLL version to <x>
  -e<x>  Set path to executable
  -E     Same as -Cn
  -fPIC  Same as -Cg
  -F<x>  Set file names and paths:
      -Fa<x>[,y] (for a program) load units <x> and [y] before uses is parsed
      -Fc<x>     Set input codepage to <x>
      -FC<x>     Set RC compiler binary name to <x>
      -Fd        Disable the compiler's internal directory cache
      -FD<x>     Set the directory where to search for compiler utilities
      -Fe<x>     Redirect error output to <x>
      -Ff<x>     Add <x> to framework path (Darwin only)
      -FE<x>     Set exe/unit output path to <x>
      -Fi<x>     Add <x> to include path
      -Fl<x>     Add <x> to library path
      -FL<x>     Use <x> as dynamic linker
      -Fm<x>     Load unicode conversion table from <x>.txt in the compiler dir
      -Fo<x>     Add <x> to object path
      -Fr<x>     Load error message file <x>
      -FR<x>     Set resource (.res) linker to <x>
      -Fu<x>     Add <x> to unit path
      -FU<x>     Set unit output path to <x>, overrides -FE
      -FW<x>     Store generated whole-program optimization feedback in <x>
      -Fw<x>     Load previously stored whole-program optimization feedback from <x>
  -g     Generate debug information (default format for target)
      -gc        Generate checks for pointers
      -gh        Use heaptrace unit (for memory leak/corruption debugging)
      -gl        Use line info unit (show more info with backtraces)
      -go<x>     Set debug information options
         -godwarfsets Enable DWARF 'set' type debug information (breaks gdb < 6.5)
         -gostabsabsincludes Store absolute/full include file paths in Stabs
         -godwarfmethodclassprefix Prefix method names in DWARF with class name
      -gp        Preserve case in stabs symbol names
      -gs        Generate Stabs debug information
      -gt        Trash local variables (to detect uninitialized uses)
      -gv        Generates programs traceable with Valgrind
      -gw        Generate DWARFv2 debug information (same as -gw2)
      -gw2       Generate DWARFv2 debug information
      -gw3       Generate DWARFv3 debug information
  -i     Information
      -iD        Return compiler date
      -iV        Return short compiler version
      -iW        Return full compiler version
      -iSO       Return compiler OS
      -iSP       Return compiler host processor
      -iTO       Return target OS
      -iTP       Return target processor
  -I<x>  Add <x> to include path
  -k<x>  Pass <x> to the linker
  -l     Write logo
  -M<x>  Set language mode to <x>
      -Mfpc      Free Pascal dialect (default)
      -Mobjfpc   FPC mode with Object Pascal support
      -Mdelphi   Delphi 7 compatibility mode
      -Mtp       TP/BP 7.0 compatibility mode
      -Mmacpas   Macintosh Pascal dialects compatibility mode
  -n     Do not read the default config files
  -N<x>  Node tree optimizations
      -Nu        Unroll loops
  -o<x>  Change the name of the executable produced to <x>
  -O<x>  Optimizations:
      -O-        Disable optimizations
      -O1        Level 1 optimizations (quick and debugger friendly)
      -O2        Level 2 optimizations (-O1 + quick optimizations)
      -O3        Level 3 optimizations (-O2 + slow optimizations)
      -Oa<x>=<y> Set alignment
      -Oo[NO]<x> Enable or disable optimizations, see fpc -i for possible values
      -Op<x>     Set target cpu for optimizing, see fpc -i for possible values
      -OW<x>     Generate whole-program optimization feedback for optimization <x>, see fpc -i for possible values
      -Ow<x>     Perform whole-program optimization <x>, see fpc -i for possible values
      -Os        Optimize for size rather than speed
  -pg    Generate profile code for gprof (defines FPC_PROFILE)
  -R<x>  Assembler reading style:
      -Rdefault  Use default assembler for target
      -Ratt      Read AT&T style assembler
      -Rintel    Read Intel style assembler
  -S<x>  Syntax options:
      -S2        Same as -Mobjfpc
      -Sc        Support operators like C (*=,+=,/= and -=)
      -Sa        Turn on assertions
      -Sd        Same as -Mdelphi
      -Se<x>     Error options. <x> is a combination of the following:
         <n> : Compiler halts after the <n> errors (default is 1)
         w : Compiler also halts after warnings
         n : Compiler also halts after notes
         h : Compiler also halts after hints
      -Sg        Enable LABEL and GOTO (default in -Mtp and -Mdelphi)
      -Sh        Use ansistrings by default instead of shortstrings
      -Si        Turn on inlining of procedures/functions declared as "inline"
      -Sk        Load fpcylix unit
      -SI<x>     Set interface style to <x>
         -SIcom     COM compatible interface (default)
         -SIcorba   CORBA compatible interface
      -Sm        Support macros like C (global)
      -So        Same as -Mtp
      -Ss        Constructor name must be init (destructor must be done)
      -St        Allow static keyword in objects
      -Sx        Enable exception keywords (default in Delphi/ObjFPC modes)
  -s     Do not call assembler and linker
      -sh        Generate script to link on host
      -st        Generate script to link on target
      -sr        Skip register allocation phase (use with -alr)
  -T<x>  Target operating system:
      -Temx      OS/2 via EMX (including EMX/RSX extender)
      -Tfreebsd  FreeBSD
      -Tgo32v2   Version 2 of DJ Delorie DOS extender
      -Tlinux    Linux
      -Tnetbsd   NetBSD
      -Tnetware  Novell Netware Module (clib)
      -Tnetwlibc Novell Netware Module (libc)
      -Topenbsd  OpenBSD
      -Tos2      OS/2 / eComStation
      -Tsunos    SunOS/Solaris
      -Tsymbian  Symbian OS
      -Twatcom   Watcom compatible DOS extender
      -Twdosx    WDOSX DOS extender
      -Twin32    Windows 32 Bit
      -Twince    Windows CE
  -u<x>  Undefines the symbol <x>
  -U     Unit options:
      -Un        Do not check where the unit name matches the file name
      -Ur        Generate release unit files (never automatically recompiled)
      -Us        Compile a system unit
  -v<x>  Be verbose. <x> is a combination of the following letters:
      e : Show errors (default)       0 : Show nothing (except errors)
      w : Show warnings               u : Show unit info
      n : Show notes                  t : Show tried/used files
      h : Show hints                  c : Show conditionals
      i : Show general info           d : Show debug info
      l : Show linenumbers            r : Rhide/GCC compatibility mode
      s : Show time stamps            q : Show message numbers
      a : Show everything             x : Executable info (Win32 only)
      b : Write file names messages   p : Write tree.log with parse tree
          with full path              v : Write fpcdebug.txt with
                                          lots of debugging info
      m<x>,<y> : Don't show messages numbered <x> and <y>
  -W<x>  Target-specific options (targets)
      -Wb        Create a bundle instead of a library (Darwin)
      -WB        Create a relocatable image (Windows)
      -WC        Specify console type application (EMX, OS/2, Windows)
      -WD        Use DEFFILE to export functions of DLL or EXE (Windows)
      -We        Use external resources (Darwin)
      -WF        Specify full-screen type application (EMX, OS/2)
      -WG        Specify graphic type application (EMX, OS/2, Windows)
      -Wi        Use internal resources (Darwin)
      -WN        Do not generate relocation code, needed for debugging (Windows)
      -WR        Generate relocation code (Windows)
      -WX        Enable executable stack (Linux)
  -X     Executable options:
      -Xc        Pass --shared/-dynamic to the linker (BeOS, Darwin, FreeBSD, Linux)
      -Xd        Do not use standard library search path (needed for cross compile)
      -Xe        Use external linker
      -Xg        Create debuginfo in a separate file and add a debuglink section to executable
      -XD        Try to link units dynamically      (defines FPC_LINK_DYNAMIC)
      -Xi        Use internal linker
      -Xm        Generate link map
      -XM<x>     Set the name of the 'main' program routine (default is 'main')
      -XP<x>     Prepend the binutils names with the prefix <x>
      -Xr<x>     Set the linker's rlink-path to <x> (needed for cross compile, see the ld manual for more information) (BeOS, Linux)
      -XR<x>     Prepend <x> to all linker search paths (BeOS, Darwin, FreeBSD, Linux, Mac OS, Solaris)
      -Xs        Strip all symbols from executable
      -XS        Try to link units statically (default, defines FPC_LINK_STATIC)
      -Xt        Link with static libraries (-static is passed to linker)
      -XX        Try to smartlink units             (defines FPC_LINK_SMART)
  
  -?     Show this help
  -h     Shows this help without waiting

Appendix B  Alphabetical list of reserved words

absolute
abstract
and
array
as
asm
assembler
begin
break
case
cdecl
class
const
constructor
continue
cppclass
deprecated
destructor
div
do
downto
else
end
except 
exit
export
exports
external
experimental
fail
false
far
file
finally 
for
forward
function
goto
if
implementation
in
index
inherited
initialization 
inline
interface
interrupt
is
label
library
mod
name
near
nil
not
object
of
on
operator
or
otherwise
packed
popstack
private
procedure
program
property 
protected
public
raise
record
reintroduce
repeat
self
set
shl
shr
stdcall
string
then
to
true
try
type
unimplemented
unit
until
uses
var
virtual
while
with
xor

Appendix C  Compiler messages

This appendix is meant to list all the compiler messages. The list of messages is generated from he compiler source itself, and should be fairly complete. At this point, only assembler errors are not in the list.

For an explanation of how to control the messages, section ?? .

C.1  General compiler messages

This section gives the compiler messages which are not fatal, but which display useful information. The number of such messages can be controlled with the various verbosity level -v switches.

Compiler: arg1
When the -vt switch is used, this line tells you what compiler is used.
Compiler OS: arg1
When the -vd switch is used, this line tells you what the source operating system is.
Info: Target OS: arg1
When the -vd switch is used, this line tells you what the target operating system is.
Using executable path: arg1
When the -vt switch is used, this line tells you where the compiler looks for its binaries.
Using unit path: arg1
When the -vt switch is used, this line tells you where the compiler looks for compiled units. You can set this path with the -Fu option.
Using include path: arg1
When the -vt switch is used, this line tells you where the compiler looks for its include files (files used in {$I xxx} statements). You can set this path with the -Fi option.
Using library path: arg1
When the -vt switch is used, this line tells you where the compiler looks for the libraries. You can set this path with the -Fl option.
Using object path: arg1
When the -vt switch is used, this line tells you where the compiler looks for object files you link in (files used in {$L xxx} statements). You can set this path with the -Fo option.
Info: arg1 lines compiled, arg2 sec arg3
When the -vi switch is used, the compiler reports the number of lines compiled, and the time it took to compile them (real time, not program time).
Fatal: No memory left
The compiler doesn’t have enough memory to compile your program. There are several remedies for this:
Info: Writing Resource String Table file: arg1
This message is shown when the compiler writes the Resource String Table file containing all the resource strings for a program.
Error: Writing Resource String Table file: arg1
This message is shown when the compiler encounters an error when writing the Resource String Table file.
Info: Fatal:
Prefix for Fatal Errors.
Info: Error:
Prefix for Errors.
Info: Warning:
Prefix for Warnings.
Info: Note:
Prefix for Notes.
Info: Hint:
Prefix for Hints.
Error: Path "arg1" does not exist
The specified path does not exist.
Fatal: Compilation aborted
Compilation was aborted.
bytes code
The size of the generated executable code, in bytes.
bytes data
The size of the generated program data, in bytes.
Info: arg1 warning(s) issued
Total number of warnings issued during compilation.
Info: arg1 hint(s) issued
Total number of hints issued during compilation.
Info: arg1 note(s) issued
Total number of notes issued during compilation.

C.2  Scanner messages.

This section lists the messages that the scanner emits. The scanner takes care of the lexical structure of the pascal file, i.e. it tries to find reserved words, strings, etc. It also takes care of directives and conditional compilation handling.

Fatal: Unexpected end of file
This typically happens in one of the following cases:
Fatal: String exceeds line
There is a missing closing ’ in a string, so it occupies multiple lines.
Fatal: illegal character "arg1" (arg2)
An illegal character was encountered in the input file.
Fatal: Syntax error, "arg1" expected but "arg2" found
This indicates that the compiler expected a different token than the one you typed. It can occur almost anywhere it is possible to make an error against the Pascal language.
Start reading includefile arg1
When you provide the -vt switch, the compiler tells you when it starts reading an included file.
Warning: Comment level arg1 found
When the -vw switch is used, then the compiler warns you if it finds nested comments. Nested comments are not allowed in Turbo Pascal and Delphi, and can be a possible source of errors.
Note: Ignored compiler switch "arg1"
With -vn on, the compiler warns if it ignores a switch.
Warning: Illegal compiler switch "arg1"
You included a compiler switch (i.e. {$... }) which the compiler does not recognise.
Warning: Misplaced global compiler switch
The compiler switch is misplaced, and should be located at the start of the unit or program.
Error: Illegal char constant
This happens when you specify a character with its ASCII code, as in #96, but the number is either illegal, or out of range.
Fatal: Can’t open file "arg1"
Free Pascal cannot find the program or unit source file you specified on the command line.
Fatal: Can’t open include file "arg1"
Free Pascal cannot find the source file you specified in a {$include ..} statement.
Error: Illegal record alignment specifier "arg1"
You are specifying {$PACKRECORDS n} or {$ALIGN n} with an illegal value for n. For $PACKRECORDS valid alignments are 1, 2, 4, 8, 16, 32, C, NORMAL, DEFAULT, and for $ALIGN valid alignments are 1, 2, 4, 8, 16, 32, ON, OFF. Under mode MacPas $ALIGN also supports MAC68K, POWER and RESET.
Error: Illegal enum minimum-size specifier "arg1"
You are specifying the {$PACKENUM n} with an illegal value for n. Only 1,2,4, NORMAL or DEFAULT is valid here.
Error: $ENDIF expected for arg1 arg2 defined in arg3 line arg4
Your conditional compilation statements are unbalanced.
Error: Syntax error while parsing a conditional compiling expression
There is an error in the expression following the {$if ..}, {$ifc } or {$setc } compiler directives.
Error: Evaluating a conditional compiling expression
There is an error in the expression following the {$if ..}, ifc or setc compiler directives.
Warning: Macro contents are limited to 255 characters in length
The contents of macros cannot be longer than 255 characters.
Error: ENDIF without IF(N)DEF
Your {$IFDEF ..} and {$ENDIF} statements aren’t balanced.
Fatal: User defined: arg1
A user defined fatal error occurred. See also the Programmers guide .
Error: User defined: arg1
A user defined error occurred. See also the Programmers guide .
Warning: User defined: arg1
A user defined warning occurred. See also the Programmers guide .
Note: User defined: arg1
A user defined note was encountered. See also the Programmers guide .
Hint: User defined: arg1
A user defined hint was encountered. See also the Programmers guide .
Info: User defined: arg1
User defined information was encountered. See also the Programmers guide .
Error: Keyword redefined as macro has no effect
You cannot redefine keywords with macros.
Fatal: Macro buffer overflow while reading or expanding a macro
Your macro or its result was too long for the compiler.
Warning: Expanding of macros exceeds a depth of 16.
When expanding a macro, macros have been nested to a level of 16. The compiler will expand no further, since this may be a sign that recursion is used.
Warning: compiler switches aren’t supported in // styled comments
Compiler switches should be in normal Pascal style comments.
Handling switch "arg1"
When you set debugging info on (-vd) the compiler tells you when it is evaluating conditional compile statements.
ENDIF arg1 found
When you turn on conditional messages (-vc), the compiler tells you where it encounters conditional statements.
IFDEF arg1 found, arg2
When you turn on conditional messages (-vc), the compiler tells you where it encounters conditional statements.
IFOPT arg1 found, arg2
When you turn on conditional messages (-vc), the compiler tells you where it encounters conditional statements.
IF arg1 found, arg2
When you turn on conditional messages (-vc), the compiler tells you where it encounters conditional statements.
IFNDEF arg1 found, arg2
When you turn on conditional messages (-vc), the compiler tells you where it encounters conditional statements.
ELSE arg1 found, arg2
When you turn on conditional messages (-vc), the compiler tells you where it encounters conditional statements.
Skipping until...
When you turn on conditional messages (-vc), the compiler tells you where it encounters conditional statements, and whether it is skipping or compiling parts.
Info: Press <return> to continue
When the -vi switch is used, the compiler stops compilation and waits for the Enter key to be pressed when it encounters a {$STOP} directive.
Warning: Unsupported switch "arg1"
When warnings are turned on (-vw), the compiler warns you about unsupported switches. This means that the switch is used in Delphi or Turbo Pascal, but not in Free Pascal .
Warning: Illegal compiler directive "arg1"
When warnings are turned on (-vw), the compiler warns you about unrecognised switches. For a list of recognised switches, see the Programmers guide .
Back in arg1
When you use the -vt switch, the compiler tells you when it has finished reading an include file.
Warning: Unsupported application type: "arg1"
You get this warning if you specify an unknown application type with the directive {$APPTYPE}.
Warning: APPTYPE is not supported by the target OS
The {$APPTYPE} directive is supported by certain operating systems only.
Warning: DESCRIPTION is not supported by the target OS
The {$DESCRIPTION} directive is not supported on this target OS.
Note: VERSION is not supported by target OS
The {$VERSION} directive is not supported on this target OS.
Note: VERSION only for exes or DLLs
The {$VERSION} directive is only used for executable or DLL sources.
Warning: Wrong format for VERSION directive "arg1"
The {$VERSION} directive format is majorversion.minorversion where majorversion and minorversion are words.
Error: Illegal assembler style specified "arg1"
When you specify an assembler mode with the {$ASMMODE xxx} directive, the compiler didn’t recognize the mode you specified.
Warning: ASM reader switch is not possible inside asm statement, "arg1" will be effective only for next
It is not possible to switch from one assembler reader to another inside an assembler block. The new reader will be used for next assembler statements only.
Error: Wrong switch toggle, use ON/OFF or +/-
You need to use ON or OFF or a + or - to toggle the switch.
Error: Resource files are not supported for this target
The target you are compiling for doesn’t support resource files.
Warning: Include environment "arg1" not found in environment
The included environment variable can’t be found in the environment; it will be replaced by an empty string instead.
Error: Illegal value for FPU register limit
Valid values for this directive are 0..8 and NORMAL/DEFAULT.
Warning: Only one resource file is supported for this target
The target you are compiling for supports only one resource file. The first resource file found is used, the others are discarded.
Warning: Macro support has been turned off
A macro declaration has been found, but macro support is currently off, so the declaration will be ignored. To turn macro support on compile with -Sm on the command line or add {$MACRO ON} in the source.
Error: Illegal interface type specified. Valids are COM, CORBA or DEFAULT.
The interface type that was specified is not supported.
Warning: APPID is only supported for PalmOS
The {$APPID} directive is only supported for the PalmOS target.
Warning: APPNAME is only supported for PalmOS
The {$APPNAME} directive is only supported for the PalmOS target.
Error: Constant strings can’t be longer than 255 chars
A single string constant can contain at most 255 chars. Try splitting up the string into multiple smaller parts and concatenate them with a + operator.
Fatal: Including include files exceeds a depth of 16.
When including include files the files have been nested to a level of 16. The compiler will expand no further, since this may be a sign that recursion is used.
Fatal: Too many levels of PUSH
A maximum of 20 levels is allowed. This error occurs only in mode MacPas.
Error: A POP without a preceding PUSH
This error occurs only in mode MacPas.
Error: Macro or compile time variable "arg1" does not have any value
Thus the conditional compile time expression cannot be evaluated.
Error: Wrong switch toggle, use ON/OFF/DEFAULT or +/-/*
You need to use ON or OFF or DEFAULT or a + or - or * to toggle the switch.
Error: Mode switch "arg1" not allowed here
A mode switch has already been encountered, or, in the case of option -Mmacpas, a mode switch occurs after UNIT.
Error: Compile time variable or macro "arg1" is not defined.
Thus the conditional compile time expression cannot be evaluated. Only in mode MacPas.
Error: UTF-8 code greater than 65535 found
Free Pascal handles UTF-8 strings internally as widestrings, i.e. the char codes are limited to 65535.
Error: Malformed UTF-8 string
The given string isn’t a valid UTF-8 string.
UTF-8 signature found, using UTF-8 encoding
The compiler found a UTF-8 encoding signature ($ef, $bb, $bf) at the beginning of a file, so it interprets it as a UTF-8 file.
Error: Compile time expression: Wanted arg1 but got arg2 at arg3
The type-check of a compile time expression failed.
Note: APPTYPE is not supported by the target OS
The {$APPTYPE} directive is supported by certain operating systems only.
Error: Illegal optimization specified "arg1"
You specified an optimization with the {$OPTIMIZATION xxx} directive, and the compiler didn’t recognize the optimization you specified.
Warning: SETPEFLAGS is not supported by the target OS
The {$SETPEFLAGS} directive is not supported by the target OS.
Warning: IMAGEBASE is not supported by the target OS
The {$IMAGEBASE} directive is not supported by the target OS.
Warning: MINSTACKSIZE is not supported by the target OS
The {$MINSTACKSIZE} directive is not supported by the target OS.
Warning: MAXSTACKSIZE is not supported by the target OS
The {$MAXSTACKSIZE} directive is not supported by the target OS.
Error: Illegal state for $WARN directive
Only ON and OFF can be used as state with a {$WARN} compiler directive.
Error: Illegal set packing value
Only 0, 1, 2, 4, 8, DEFAULT and NORMAL are allowed as packset parameters.
Warning: PIC directive or switch ignored
Several targets, such as Windows , do not support nor need PIC, so the PIC directive and switch are ignored.
Warning: The switch "arg1" is not supported by the currently selected target
Some compiler switches like $E are not supported by all targets.
Warning: Framework-related options are only supported for Darwin/Mac OS X
Frameworks are not a known concept, or at least not supported by FPC, on operating systems other than Darwin/Mac OS X.
Error: Illegal minimal floating point constant precision "arg1"
Valid minimal precisions for floating point constants are default, 32 and 64, which mean respectively minimal (usually 32 bit), 32 bit and 64 bit precision.
Warning: Overriding name of "main" procedure multiple times, was previously set to "arg1"
The name for the main entry procedure is specified more than once. Only the last name will be used.

C.3  Parser messages

This section lists all parser messages. The parser takes care of the semantics of you language, i.e. it determines if your Pascal constructs are correct.

Error: Parser - Syntax Error
An error against the Turbo Pascal language was encountered. This typically happens when an illegal character is found in the source file.
Error: INTERRUPT procedure can’t be nested
An INTERRUPT procedure must be global.
Warning: Procedure type "arg1" ignored
The specified procedure directive is ignored by FPC programs.
Error: Not all declarations of "arg1" are declared with OVERLOAD
When you want to use overloading using the OVERLOAD directive, then all declarations need to have OVERLOAD specified.
Error: Duplicate exported function name "arg1"
Exported function names inside a specific DLL must all be different.
Error: Duplicate exported function index arg1
Exported function indexes inside a specific DLL must all be different.
Error: Invalid index for exported function
DLL function index must be in the range 1..$FFFF.
Warning: Relocatable DLL or executable arg1 debug info does not work, disabled.
It is currently not possible to include debug information in a relocatable DLL.
Warning: To allow debugging for win32 code you need to disable relocation with -WN option
Stabs debug info is wrong for relocatable DLL or EXES. Use -WN if you want to debug win32 executables.
Error: Constructor name must be INIT
You are declaring an object constructor with a name which is not init, and the -Ss switch is in effect. See the switch -Ss, (see ??) .
Error: Destructor name must be DONE
You are declaring an object destructor with a name which is not done, and the -Ss switch is in effect. See the switch -Ss, (see ??) .
Error: Procedure type INLINE not supported
You tried to compile a program with C++ style inlining, and forgot to specify the -Si option (-Si, (see ??) ). The compiler doesn’t support C++ styled inlining by default.
Warning: Constructor should be public
Constructors must be in the ’public’ part of an object (class) declaration.
Warning: Destructor should be public
Destructors must be in the ’public’ part of an object (class) declaration.
Note: Class should have one destructor only
You can declare only one destructor for a class.
Error: Local class definitions are not allowed
Classes must be defined globally. They cannot be defined inside a procedure or function.
Fatal: Anonymous class definitions are not allowed
An invalid object (class) declaration was encountered, i.e. an object or class without methods that isn’t derived from another object or class. For example:
 Type o = object
          a : longint;
          end;
 
will trigger this error.
Note: The object "arg1" has no VMT
This is a note indicating that the declared object has no virtual method table.
Error: Illegal parameter list
You are calling a function with parameters that are of a different type than the declared parameters of the function.
Error: Wrong number of parameters specified for call to "arg1"
There is an error in the parameter list of the function or procedure – the number of parameters is not correct.
Error: overloaded identifier "arg1" isn’t a function
The compiler encountered a symbol with the same name as an overloaded function, but it is not a function it can overload.
Error: overloaded functions have the same parameter list
You’re declaring overloaded functions, but with the same parameter list. Overloaded function must have at least 1 different parameter in their declaration.
Error: function header doesn’t match the previous declaration "arg1"
You declared a function with the same parameters but different result type or function modifiers.
Error: function header "arg1" doesn’t match forward : var name changes arg2 => arg3
You declared the function in the interface part, or with the forward directive, but defined it with a different parameter list.
Note: Values in enumeration types have to be ascending
Free Pascal allows enumeration constructions as in C. Examine the following two declarations:
 type a = (A_A,A_B,A_E:=6,A_UAS:=200);
 type a = (A_A,A_B,A_E:=6,A_UAS:=4);
 
The second declaration would produce an error. A_UAS needs to have a value higher than A_E, i.e. at least 7.
Error: With cannot be used for variables in a different segment
With stores a variable locally on the stack, but this is not possible if the variable belongs to another segment.
Error: function nesting > 31
You can nest function definitions only 31 levels deep.
Error: range check error while evaluating constants
The constants are out of their allowed range.
Warning: range check error while evaluating constants
The constants are out of their allowed range.
Error: duplicate case label
You are specifying the same label 2 times in a case statement.
Error: Upper bound of case range is less than lower bound
The upper bound of a case label is less than the lower bound and this is useless.
Error: typed constants of classes or interfaces are not allowed
You cannot declare a constant of type class or object.
Error: functions variables of overloaded functions are not allowed
You are trying to assign an overloaded function to a procedural variable. This is not allowed.
Error: string length must be a value from 1 to 255
The length of a shortstring in Pascal is limited to 255 characters. You are trying to declare a string with length less than 1 or greater than 255.
Warning: use extended syntax of NEW and DISPOSE for instances of objects
If you have a pointer a to an object type, then the statement new(a) will not initialize the object (i.e. the constructor isn’t called), although space will be allocated. You should issue the new(a,init) statement. This will allocate space, and call the constructor of the object.
Warning: use of NEW or DISPOSE for untyped pointers is meaningless
Error: use of NEW or DISPOSE is not possible for untyped pointers
You cannot use new(p) or dispose(p) if p is an untyped pointer because no size is associated to an untyped pointer. It is accepted for compatibility in TP and DELPHI modes, but the compiler will still warn you if it finds such a construct.
Error: class identifier expected
This happens when the compiler scans a procedure declaration that contains a dot, i.e., an object or class method, but the type in front of the dot is not a known type.
Error: type identifier not allowed here
You cannot use a type inside an expression.
Error: method identifier expected
This identifier is not a method. This happens when the compiler scans a procedure declaration that contains a dot, i.e., an object or class method, but the procedure name is not a procedure of this type.
Error: function header doesn’t match any method of this class "arg1"
This identifier is not a method. This happens when the compiler scans a procedure declaration that contains a dot, i.e., an object or class method, but the procedure name is not a procedure of this type.
procedure/function arg1
When using the -vd switch, the compiler tells you when it starts processing a procedure or function implementation.
Error: Illegal floating point constant
The compiler expects a floating point expression, and gets something else.
Error: FAIL can be used in constructors only
You are using the fail keyword outside a constructor method.
Error: Destructors can’t have parameters
You are declaring a destructor with a parameter list. Destructor methods cannot have parameters.
Error: Only class methods can be referred with class references
This error occurs in a situation like the following:
 Type :
    Tclass = Class of Tobject;

 Var C : TClass;

 begin
 ...
 C.free
 
Free is not a class method and hence cannot be called with a class reference.
Error: Only class methods can be accessed in class methods
This is related to the previous error. You cannot call a method of an object from inside a class method. The following code would produce this error:
 class procedure tobject.x;

 begin
   free
 
Because free is a normal method of a class it cannot be called from a class method.
Error: Constant and CASE types do not match
One of the labels is not of the same type as the case variable.
Error: The symbol can’t be exported from a library
You can only export procedures and functions when you write a library. You cannot export variables or constants.
Warning: An inherited method is hidden by "arg1"
A method that is declared virtual in a parent class, should be overridden in the descendant class with the override directive. If you don’t specify the override directive, you will hide the parent method; you will not override it.
Error: There is no method in an ancestor class to be overridden: "arg1"
You are trying to override a virtual method of a parent class that does not exist.
Error: No member is provided to access property
You specified no read directive for a property.
Warning: Stored property directive is not yet implemented
This message is no longer used, as the stored directive has been implemented.
Error: Illegal symbol for property access
There is an error in the read or write directives for an array property. When you declare an array property, you can only access it with procedures and functions. The following code would cause such an error.
 tmyobject = class
   i : integer;
   property x [i : integer]: integer read I write i;
 
Error: Cannot access a protected field of an object here
Fields that are declared in a protected section of an object or class declaration cannot be accessed outside the module where the object is defined, or outside descendent object methods.
Error: Cannot access a private field of an object here
Fields that are declared in a private section of an object or class declaration cannot be accessed outside the module where the class is defined.
Error: Overridden methods must have the same return type: "arg2" is overridden by "arg1" which has another return type
If you declare overridden methods in a class definition, they must have the same return type.
Error: EXPORT declared functions can’t be nested
You cannot declare a function or procedure within a function or procedure that was declared as an export procedure.
Error: Methods can’t be EXPORTed
You cannot declare a procedure that is a method for an object as exported.
Error: Call by var for arg no. arg1 has to match exactly: Got "arg2" expected "arg3"
When calling a function declared with var parameters, the variables in the function call must be of exactly the same type. There is no automatic type conversion.
Error: Class isn’t a parent class of the current class
When calling inherited methods, you are trying to call a method of a non-related class. You can only call an inherited method of a parent class.
Error: SELF is only allowed in methods
You are trying to use the self parameter outside an object’s method. Only methods get passed the self parameters.
Error: Methods can be only in other methods called direct with type identifier of the class
A construction like sometype.somemethod is only allowed in a method.
Error: Illegal use of ’:’
You are using the format : (colon) 2 times on an expression that is not a real expression.
Error: range check error in set constructor or duplicate set element
The declaration of a set contains an error. Either one of the elements is outside the range of the set type, or two of the elements are in fact the same.
Error: Pointer to object expected
You specified an illegal type in a new statement. The extended syntax of new needs an object as a parameter.
Error: Expression must be constructor call
When using the extended syntax of new, you must specify the constructor method of the object you are trying to create. The procedure you specified is not a constructor.
Error: Expression must be destructor call
When using the extended syntax of dispose, you must specify the destructor method of the object you are trying to dispose of. The procedure you specified is not a destructor.
Error: Illegal order of record elements
When declaring a constant record, you specified the fields in the wrong order.
Error: Expression type must be class or record type
A with statement needs an argument that is of the type record or class. You are using with on an expression that is not of this type.
Error: Procedures can’t return a value
In Free Pascal , you can specify a return value for a function when using the exit statement. This error occurs when you try to do this with a procedure. Procedures cannot return a value.
Error: constructors and destructors must be methods
You’re declaring a procedure as destructor or constructor, when the procedure isn’t a class method.
Error: Operator is not overloaded
You’re trying to use an overloaded operator when it is not overloaded for this type.
Error: Impossible to overload assignment for equal types
You cannot overload assignment for types that the compiler considers as equal.
Error: Impossible operator overload
The combination of operator, arguments and return type are incompatible.
Error: Re-raise isn’t possible there
You are trying to re-raise an exception where it is not allowed. You can only re-raise exceptions in an except block.
Error: The extended syntax of new or dispose isn’t allowed for a class
You cannot generate an instance of a class with the extended syntax of new. The constructor must be used for that. For the same reason, you cannot call dispose to de-allocate an instance of a class, the destructor must be used for that.
Error: Procedure overloading is switched off
When using the -So switch, procedure overloading is switched off. Turbo Pascal does not support function overloading.
Error: It is not possible to overload this operator. Related overloadable operators (if any) are: arg1
You are trying to overload an operator which cannot be overloaded. The following operators can be overloaded :
    +, -, *, /, =, >, <, <=, >=, is, as, in, **, :=
 
Error: Comparative operator must return a boolean value
When overloading the = operator, the function must return a boolean value.
Error: Only virtual methods can be abstract
You are declaring a method as abstract, when it is not declared to be virtual.
Fatal: Use of unsupported feature!
You’re trying to force the compiler into doing something it cannot do yet.
Error: The mix of different kind of objects (class, object, interface, etc) isn’t allowed
You cannot derive objects, classes, cppclasses and interfaces intertwined. E.g. a class cannot have an object as parent and vice versa.
Warning: Unknown procedure directive had to be ignored: "arg1"
The procedure directive you specified is unknown.
Error: absolute can only be associated to one variable
You cannot specify more than one variable before the absolute directive. Thus, the following construct will provide this error:
 Var Z : Longint;
     X,Y : Longint absolute Z;
 
Error: absolute can only be associated with a var or const
The address of an absolute directive can only point to a variable or constant. Therefore, the following code will produce this error:
   Procedure X;

  var p : longint absolute x;
 
Error: Only one variable can be initialized
You cannot specify more than one variable with a initial value in Delphi mode.
Error: Abstract methods shouldn’t have any definition (with function body)
Abstract methods can only be declared, you cannot implement them. They should be overridden by a descendant class.
Error: This overloaded function can’t be local (must be exported)
You are defining an overloaded function in the implementation part of a unit, but there is no corresponding declaration in the interface part of the unit.
Warning: Virtual methods are used without a constructor in "arg1"
If you declare objects or classes that contain virtual methods, you need to have a constructor and destructor to initialize them. The compiler encountered an object or class with virtual methods that doesn’t have a constructor/destructor pair.
Macro defined: arg1
When -vc is used, the compiler tells you when it defines macros.
Macro undefined: arg1
When -vc is used, the compiler tells you when it undefines macros.
Macro arg1 set to arg2
When -vc is used, the compiler tells you what values macros get.
Info: Compiling arg1
When you turn on information messages (-vi), the compiler tells you what units it is recompiling.
Parsing interface of unit arg1
This tells you that the reading of the interface of the current unit has started
Parsing implementation of arg1
This tells you that the code reading of the implementation of the current unit, library or program starts
Compiling arg1 for the second time
When you request debug messages (-vd) the compiler tells you what units it recompiles for the second time.
Error: No property found to override
You want to override a property of a parent class, when there is, in fact, no such property in the parent class.
Error: Only one default property is allowed
You specified a property as Default, but the class already has a default property, and a class can have only one default property.
Error: The default property must be an array property
Only array properties of classes can be made default properties.
Error: Virtual constructors are only supported in class object model
You cannot have virtual constructors in objects. You can only have them in classes.
Error: No default property available
You are trying to access a default property of a class, but this class (or one of its ancestors) doesn’t have a default property.
Error: The class can’t have a published section, use the {$M+} switch
If you want a published section in a class definition, you must use the {$M+} switch, which turns on generation of type information.
Error: Forward declaration of class "arg1" must be resolved here to use the class as ancestor
To be able to use an object as an ancestor object, it must be defined first. This error occurs in the following situation:
  Type ParentClas = Class;
       ChildClass = Class(ParentClass)
         ...
       end;
 
where ParentClass is declared but not defined.
Error: Local operators not supported
You cannot overload locally, i.e. inside procedures or function definitions.
Error: Procedure directive "arg1" not allowed in interface section
This procedure directive is not allowed in the interface section of a unit. You can only use it in the implementation section.
Error: Procedure directive "arg1" not allowed in implementation section
This procedure directive is not allowed in the implementation section of a unit. You can only use it in the interface section.
Error: Procedure directive "arg1" not allowed in procvar declaration
This procedure directive cannot be part of a procedural or function type declaration.
Error: Function is already declared Public/Forward "arg1"
You will get this error if a function is defined as forward twice. Or if it occurs in the interface section, and again as a forward declaration in the implementation section.
Error: Can’t use both EXPORT and EXTERNAL
These two procedure directives are mutually exclusive.
Warning: "arg1" not yet supported inside inline procedure/function
Inline procedures don’t support this declaration.
Warning: Inlining disabled
Inlining of procedures is disabled.
Info: Writing Browser log arg1
When information messages are on, the compiler warns you when it writes the browser log (generated with the {$Y+ } switch).
Hint: may be pointer dereference is missing
The compiler thinks that a pointer may need a dereference.
Fatal: Selected assembler reader not supported
The selected assembler reader (with {$ASMMODE xxx} is not supported. The compiler can be compiled with or without support for a particular assembler reader.
Error: Procedure directive "arg1" has conflicts with other directives
You specified a procedure directive that conflicts with other directives. For instance cdecl and pascal are mutually exclusive.
Error: Calling convention doesn’t match forward
This error happens when you declare a function or procedure with e.g. cdecl; but omit this directive in the implementation, or vice versa. The calling convention is part of the function declaration, and must be repeated in the function definition.
Error: Property can’t have a default value
Set properties or indexed properties cannot have a default value.
Error: The default value of a property must be constant
The value of a default declared property must be known at compile time. The value you specified is only known at run time. This happens e.g. if you specify a variable name as a default value.
Error: Symbol can’t be published, can be only a class
Only class type variables can be in a published section of a class if they are not declared as a property.
Error: This kind of property can’t be published
Properties in a published section cannot be array properties. They must be moved to public sections. Properties in a published section must be an ordinal type, a real type, strings or sets.
Error: An import name is required
Some targets need a name for the imported procedure or a cdecl specifier.
Error: Division by zero
A division by zero was encounted.
Error: Invalid floating point operation
An operation on two real type values produced an overflow or a division by zero.
Error: Upper bound of range is less than lower bound
The upper bound of an array declaration is less than the lower bound and this is not possible.
Warning: string "arg1" is longer than "arg2"
The size of the constant string is larger than the size you specified in string type definition.
Error: string length is larger than array of char length
The size of the constant string is larger than the size you specified in the Array[x..y] of char definition.
Error: Illegal expression after message directive
Free Pascal supports only integer or string values as message constants.
Error: Message handlers can take only one call by ref. parameter
A method declared with the message directive as message handler can take only one parameter which must be declared as call by reference. Parameters are declared as call by reference using the var-directive.
Error: Duplicate message label: "arg1"
A label for a message is used twice in one object/class.
Error: Self can only be an explicit parameter in methods which are message handlers
The Self parameter can only be passed explicitly to a method which is declared as message handler.
Error: Threadvars can be only static or global
Threadvars must be static or global; you can’t declare a thread local to a procedure. Local variables are always local to a thread, because every thread has its own stack and local variables are stored on the stack.
Fatal: Direct assembler not supported for binary output format
You can’t use direct assembler when using a binary writer. Choose an other output format or use another assembler reader.
Warning: Don’t load OBJPAS unit manually, use \{\$mode objfpc\} or \{\$mode delphi\} instead
You are trying to load the ObjPas unit manually from a uses clause. This is not a good idea. Use the {$MODE OBJFPC} or {$mode delphi} directives which load the unit automatically.
Error: OVERRIDE can’t be used in objects
Override is not supported for objects, use virtual instead to override a method of a parent object.
Error: Data types which require initialization/finalization can’t be used in variant records
Some data types (e.g. ansistring) need initialization/finalization code which is implicitly generated by the compiler. Such data types can’t be used in the variant part of a record.
Error: Resourcestrings can be only static or global
Resourcestring cannot be declared local, only global or using the static directive.
Error: Exit with argument can’t be used here
An exit statement with an argument for the return value can’t be used here. This can happen for example in try..except or try..finally blocks.
Error: The type of the storage symbol must be boolean
If you specify a storage symbol in a property declaration, it must be a boolean type.
Error: This symbol isn’t allowed as storage symbol
You can’t use this type of symbol as storage specifier in property declaration. You can use only methods with the result type boolean, boolean class fields or boolean constants.
Error: Only classes which are compiled in $M+ mode can be published
A class-typed field in the published section of a class can only be a class which was compiled in {$M+} or which is derived from such a class. Normally such a class should be derived from TPersistent.
Error: Procedure directive expected
This error is triggered when you have a {$Calling} directive without a calling convention specified. It also happens when declaring a procedure in a const block and you used a ; after a procedure declaration which must be followed by a procedure directive. Correct declarations are:
 const
   p : procedure;stdcall=nil;
   p : procedure stdcall=nil;
 
Error: The value for a property index must be of an ordinal type
The value you use to index a property must be of an ordinal type, for example an integer or enumerated type.
Error: Procedure name too short to be exported
The length of the procedure/function name must be at least 2 characters long. This is because of a bug in dlltool which doesn’t parse the .def file correctly with a name of length 1.
Error: No DEFFILE entry can be generated for unit global vars
Error: Compile without -WD option
You need to compile this file without the -WD switch on the command line.
Fatal: You need ObjFpc (-S2) or Delphi (-Sd) mode to compile this module
You need to use {$MODE OBJFPC} or {$MODE DELPHI} to compile this file. Or use the corresponding command line switch, either -Mobjfpc or -MDelphi.
Error: Can’t export with index under arg1
Exporting of functions or procedures with a specified index is not supported on this target.
Error: Exporting of variables is not supported under arg1
Exporting of variables is not supported on this target.
Error: Improper GUID syntax
The GUID indication does not have the proper syntax. It should be of the form
 {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}
 
Where each X represents a hexadecimal digit.
Warning: Procedure named "arg1" not found that is suitable for implementing the arg2.arg3
The compiler cannot find a suitable procedure which implements the given method of an interface. A procedure with the same name is found, but the arguments do not match.
Error: interface identifier expected
This happens when the compiler scans a class declaration that contains interface function name mapping code like this:
 type
   TMyObject = class(TObject, IDispatch)
     function IUnknown.QueryInterface=MyQueryInterface;
     ....
 
and the interface before the dot is not listed in the inheritance list.
Error: Type "arg1" can’t be used as array index type
Types like qword or int64 aren’t allowed as array index type.
Error: Con- and destructors aren’t allowed in interfaces
Constructor and destructor declarations aren’t allowed in interfaces. In the most cases method QueryInterface of IUnknown can be used to create a new interface.
Error: Access specifiers can’t be used in INTERFACES
The access specifiers public, private, protected and published can’t be used in interfaces because all methods of an interface must be public.
Error: An interface can’t contain fields
Declarations of fields aren’t allowed in interfaces. An interface can contain only methods and properties with method read/write specifiers.
Error: Can’t declare local procedure as EXTERNAL
Declaring local procedures as external is not possible. Local procedures get hidden parameters that will make the chance of errors very high.
Warning: Some fields coming before "arg1" weren’t initialized
In Delphi mode, not all fields of a typed constant record have to be initialized, but the compiler warns you when it detects such situations.
Error: Some fields coming before "arg1" weren’t initialized
In all syntax modes but Delphi mode, you can’t leave some fields uninitialized in the middle of a typed constant record.
Warning: Some fields coming after "arg1" weren’t initialized
You can leave some fields at the end of a type constant record uninitialized (The compiler will initialize them to zero automatically). This may be the cause of subtle problems.
Error: VarArgs directive (or ’...’ in MacPas) without CDecl/CPPDecl/MWPascal and External
The varargs directive (or the “...” varargs parameter in MacPas mode) can only be used with procedures or functions that are declared with external and one of cdecl, cppdecl and mwpascal. This functionality is only supported to provide a compatible interface to C functions like printf.
Error: Self must be a normal (call-by-value) parameter
You can’t declare Self as a const or var parameter, it must always be a call-by-value parameter.
Error: Interface "arg1" has no interface identification
When you want to assign an interface to a constant, then the interface must have a GUID value set.
Error: Unknown class field or method identifier "arg1"
Properties must refer to a field or method in the same class.
Warning: Overriding calling convention "arg1" with "arg2"
There are two directives in the procedure declaration that specify a calling convention. Only the last directive will be used.
Error: Typed constants of the type "procedure of object" can only be initialized with NIL
You can’t assign the address of a method to a typed constant which has a ’procedure of object’ type, because such a constant requires two addresses: that of the method (which is known at compile time) and that of the object or class instance it operates on (which cannot be known at compile time).
Error: Default value can only be assigned to one parameter
It is not possible to specify a default value for several parameters at once. The following is invalid:
 Procedure MyProcedure (A,B : Integer = 0);
 
Instead, this should be declared as
 Procedure MyProcedure (A : Integer = 0; B : Integer = 0);
 
Error: Default parameter required for "arg1"
The specified parameter requires a default value.
Warning: Use of unsupported feature!
You’re trying to force the compiler into doing something it cannot do yet.
Hint: C arrays are passed by reference
Any array passed to a C function is passed by a pointer (i.e. by reference).
Error: C array of const must be the last argument
You cannot add any other argument after an array of const for cdecl functions, as the size pushed on stack for this argument is not known.
Hint: Type "arg1" redefinition
This is an indicator that a previously declared type is being redefined as something else. This may, or may not be, a potential source of errors.
Warning: cdecl’ared functions have no high parameter
Functions declared with the cdecl modifier do not pass an extra implicit parameter.
Warning: cdecl’ared functions do not support open strings
Openstring is not supported for functions that have the cdecl modifier.
Error: Cannot initialize variables declared as threadvar
Variables declared as threadvar cannot be initialized with a default value. The variables will always be filled with zero at the start of a new thread.
Error: Message directive is only allowed in Classes
The message directive is only supported for Class types.
Error: Procedure or Function expected
A class method can only be specified for procedures and functions.
Warning: Calling convention directive ignored: "arg1"
Some calling conventions are supported only by certain CPUs. I.e. most non-i386 ports support only the standard ABI calling convention of the CPU.
Error: REINTRODUCE can’t be used in objects
reintroduce is not supported for objects.
Error: Each argument must have its own location
If locations for arguments are specified explicitly as it is required by some syscall conventions, each argument must have its own location. Things like
 procedure p(i,j : longint 'r1');
 
aren’t allowed.
Error: Each argument must have an explicit location
If one argument has an explicit argument location, all arguments of a procedure must have one.
Error: Unknown argument location
The location specified for an argument isn’t recognized by the compiler.
Error: 32 Bit-Integer or pointer variable expected
The libbase for MorphOS/AmigaOS can be given only as longint, dword or any pointer variable.
Error: Goto statements aren’t allowed between different procedures
It isn’t allowed to use goto statements referencing labels outside the current procedure. The following example shows the problem:
 ...
   procedure p1;
   label
     l1;

     procedure p2;
     begin
       goto l1; // This goto ISN'T allowed
     end;

   begin
     p2
   l1:
   end;
 ...

 
Fatal: Procedure too complex, it requires too many registers
Your procedure body is too long for the compiler. You should split the procedure into multiple smaller procedures.
Error: Illegal expression
This can occur under many circumstances. Usually when trying to evaluate constant expressions.
Error: Invalid integer expression
You made an expression which isn’t an integer, and the compiler expects the result to be an integer.
Error: Illegal qualifier
One of the following is happening :
Error: High range limit < low range limit
You are declaring a subrange, and the high limit is less than the low limit of the range.
Error: Exit’s parameter must be the name of the procedure it is used in
Non local exit is not allowed. This error occurs only in mode MacPas.
Error: Illegal assignment to for-loop variable "arg1"
The type of a for loop variable must be an ordinal type. Loop variables cannot be reals or strings. You also cannot assign values to loop variables inside the loop (Except in Delphi and TP modes). Use a while or repeat loop instead if you need to do something like that, since those constructs were built for that.
Error: Can’t declare local variable as EXTERNAL
Declaring local variables as external is not allowed. Only global variables can reference external variables.
Error: Procedure is already declared EXTERNAL
The procedure is already declared with the EXTERNAL directive in an interface or forward declaration.
Warning: Implicit uses of Variants unit
The Variant type is used in the unit without any used unit using the Variants unit. The compiler has implicitly added the Variants unit to the uses list. To remove this warning the Variants unit needs to be added to the uses statement.
Error: Class and static methods can’t be used in INTERFACES
The specifier class and directive static can’t be used in interfaces because all methods of an interface must be public.
Error: Overflow in arithmetic operation
An operation on two integer values produced an overflow.
Error: Protected or private expected
strict can be only used together with protected or private.
Error: SLICE can’t be used outside of parameter list
slice can be used only for arguments accepting an open array parameter.
Error: A DISPINTERFACE can’t have a parent class
A DISPINTERFACE is a special type of interface which can’t have a parent class.
Error: A DISPINTERFACE needs a guid
A DISPINTERFACE always needs an interface identification (a GUID).
Warning: Overridden methods must have a related return type. This code may crash, it depends on a Delphi parser bug ("arg2" is overridden by "arg1" which has another return type)
If you declare overridden methods in a class definition, they must have the same return type. Some versions of Delphi allow you to change the return type of interface methods, and even to change procedures into functions, but the resulting code may crash depending on the types used and the way the methods are called.
Error: Dispatch IDs must be ordinal constants
The dispid keyword must be followed by an ordinal constant (the dispid index).
Error: The range of the array is too large
Regardless of the size taken up by its elements, an array cannot have more than high(ptrint) elements. Additionally, the range type must be a subrange of ptrint.
Error: The address cannot be taken of bit packed array elements and record fields
If you declare an array or record as packed in Mac Pascal mode (or as packed in any mode with {$bitpacking on}), it will be packed at the bit level. This means it becomes impossible to take addresses of individual array elements or record fields. The only exception to this rule is in the case of packed arrays elements whose packed size is a multple of 8 bits.
Error: Dynamic arrays cannot be packed
Only regular (and possibly in the future also open) arrays can be packed.
Error: Bit packed array elements and record fields cannot be used as loop variables
If you declare an array or record as packed in Mac Pascal mode (or as packed in any mode with {$bitpacking on}), it will be packed at the bit level. For performance reasons, they cannot be used as loop variables.
Error: VAR and TYPE are allowed only in generics
The usage of VAR and TYPE to declare new types inside an object is allowed only inside generics.
Error: This type can’t be a generic
Only Classes, Objects, Interfaces and Records are allowed to be used as generic.
Warning: Don’t load LINEINFO unit manually, Use the -gl compiler switch instead
Do not use the lineinfo unit directly, Use the -gl switch which automatically adds the correct unit for reading the selected type of debugging information. The unit that needs to be used depends on the type of debug information used when compiling the binary.
Error: No function result type specified for function "arg1"
The first time you declare a function you have to declare it completely, including all parameters and the result type.
Error: Specialization is only supported for generic types
Types which are not generics can’t be specialized.
Error: Generics can’t be used as parameters when specializing generics
When specializing a generic, only non-generic types can be used as parameters.
Error: Constants of objects containing a VMT aren’t allowed
If an object requires a VMT either because it contains a constructor or virtual methods, it’s not allowed to create constants of it. In TP and Delphi mode this is allowed for compatibility reasons.
Error: Taking the address of labels defined outside the current scope isn’t allowed
It isn’t allowed to take the address of labels outside the current procedure.
Error: Cannot initialize variables declared as external
Variables declared as external cannot be initialized with a default value.
Error: Illegal function result type
Some types like file types cannot be used as function result.
Error: No common type possible between "arg1" and "arg2"
To perform an operation on integers, the compiler converts both operands to their common type, which appears to be an invalid type. To determine the common type of the operands, the compiler takes the minimum of the minimal values of both types, and the maximum of the maximal values of both types. The common type is then minimum..maximum.
Error: Generics without specialization cannot be used as a type for a variable
Generics must be always specialized before being used as variable type.
Warning: Register list is ignored for pure assembler routines
When using pure assembler routines, the list with modified registers is ignored.
Error: Implements property must have class or interface type
A property which implements an interface must be of type class or interface.
Error: Implements-property must implement interface of correct type, found "arg1" expected "arg2"
A property which implements an interface actually implements a different interface.
Error: Implements-property must have read specifier
A property which implements an interface must have at least a read specifier.
Error: Implements-property must not have write-specifier
A property which implements an interface may not have a write specifier.
Error: Implements-property must not have stored-specifier
A property which implements an interface may not have a stored specifier.
Error: Implements-property used on unimplemented interface: "arg1"
The interface which is implemented by a property is not an interface implemented by the class.
Error: Floating point not supported for this target
The compiler parsed a floating point expression, but it is not supported.
Error: Class "arg1" does not implement interface "arg2"
The delegated interface is not implemented by the class given in the implements clause.
Error: Type used by implements must be an interface
The implements keyword must be followed by an interface type.
Error: Variables cannot be exported with a different name on this target, add the name to the declaration using the "export" directive (variable name: arg1, declared export name: arg2)
On most targets it is not possible to change the name under which a variable is exported inside the exports statement of a library. In that case, you have to specify the export name at the point where the variable is declared, using the export and alias directives.
Error: Weak external symbols are not supported for the current target
A "weak external" symbol is a symbol which may or may not exist at (either static or dynamic) link time. This concept may not be available (or implemented yet) on the current cpu/OS target.
Error: Forward type definition does not match
Classes and interfaces being defined forward must have the same type when being implemented. A forward interface cannot be changed into a class.
Note: Virtual method "arg1" has a lower visibility (arg2) than parent class arg3 (arg4)
The virtual method overrides an method that is declared with a higher visibility. This might give unexpected results. In case the new visibility is private than it might be that a call to inherited in a new child class will call the higher visible method in a parent class and ignores the private method.
Error: Fields cannot appear after a method or property definition, start a new visibility section first
Once a method or property has been defined in a class or object, you cannot define any fields afterwards without starting a new visibility section (such as public, private, etc.). The reason is that otherwise the source code can appear ambiguous to the compiler, since it is possible to use modifiers such as default and register also as field names.
Error: Parameters cannot contain local type definitions. Use a separate type definition in a type block.
In Pascal, types are not considered to be identical simply because they are semantically equivalent. Two variables or parameters are only considered to be of the same type if they refer to the same type definition. As a result, it is not allowed to define new types inside parameter lists, because then it is impossible to refer to the same type definition in the procedure headers of the interface and implementation of a unit (both procedure headers would define a separate type). Keep in mind that expressions such as “file of byte” or “string[50]” also define a new type.
Error: ABSTRACT and SEALED conflict
ABSTRACT and SEALED cannot be used together in one declaration
Error: Cannot create a descendant of the sealed class "arg1"
Sealed means that class cannot be derived by another class.
Error: SEALED class cannot have an ABSTRACT method
Sealed means that class cannot be derived. Therefore no one class is able to override an abstract method in a sealed class.
Error: Only virtual methods can be final
You are declaring a method as final, when it is not declared to be virtual.
Error: Final method cannot be overridden: "arg1"
You are trying to override a virtual method of a parent class that does not exist.
Error: Invalid enumerator identifier: "arg1"
Only "MoveNext" and "Current" enumerator identifiers are supported.
Error: Enumerator identifier required
"MoveNext" or "Current" identifier must follow the enumerator modifier.
Error: Enumerator MoveNext pattern method is not valid. Method must be a function with the Boolean return type and no required arguments.
"MoveNext" enumerator pattern method must be a function with Boolean return type and no required arguments
Error: Enumerator Current pattern property is not valid. Property must have a getter.
"Current" enumerator pattern property must have a getter
Error: Only one enumerator MoveNext method is allowed per class/object
Class or Object can have only one enumerator MoveNext declaration.
Error: Only one enumerator Current property is allowed per class/object
Class or Object can have only one enumerator Current declaration.
Error: For in loop cannot be used for the type "arg1"
For in loop can be used not for all types. For example it cannot be used for the enumerations with jumps.

C.4  Type checking errors

This section lists all errors that can occur when type checking is performed.

Error: Type mismatch
This can happen in many cases:
Error: Incompatible types: got "arg1" expected "arg2"
There is no conversion possible between the two types. Another possiblity is that they are declared in different declarations:
 Var
    A1 : Array[1..10] Of Integer;
    A2 : Array[1..10] Of Integer;

 Begin
    A1:=A2; { This statement also gives this error. It
              is due to the strict type checking of Pascal }
 End.
 
Error: Type mismatch between "arg1" and "arg2"
The types are not equal.
Error: Type identifier expected
The identifier is not a type, or you forgot to supply a type identifier.
Error: Variable identifier expected
This happens when you pass a constant to a routine (such as Inc var or Dec) when it expects a variable. You can only pass variables as arguments to these functions.
Error: Integer expression expected, but got "arg1"
The compiler expects an expression of type integer, but gets a different type.
Error: Boolean expression expected, but got "arg1"
The expression must be a boolean type. It should be return True or False.
Error: Ordinal expression expected
The expression must be of ordinal type, i.e., maximum a Longint. This happens, for instance, when you specify a second argument to Inc or Dec that doesn’t evaluate to an ordinal value.
Error: pointer type expected, but got "arg1"
The variable or expression isn’t of the type pointer. This happens when you pass a variable that isn’t a pointer to New or Dispose.
Error: class type expected, but got "arg1"
The variable or expression isn’t of the type class. This happens typically when
  1. The parent class in a class declaration isn’t a class.
  2. An exception handler (On) contains a type identifier that isn’t a class.
Error: Can’t evaluate constant expression
This error can occur when the bounds of an array you declared do not evaluate to ordinal constants.
Error: Set elements are not compatible
You are trying to perform an operation on two sets, when the set element types are not the same. The base type of a set must be the same when taking the union.
Error: Operation not implemented for sets
several binary operations are not defined for sets. These include: div, mod, **, >= and <=. The last two may be defined for sets in the future.
Warning: Automatic type conversion from floating type to COMP which is an integer type
An implicit type conversion from a real type to a comp is encountered. Since comp is a 64 bit integer type, this may indicate an error.
Hint: use DIV instead to get an integer result
When hints are on, then an integer division with the ’/’ operator will produce this message, because the result will then be of type real.
Error: string types doesn’t match, because of $V+ mode
When compiling in {$V+} mode, the string you pass as a parameter should be of the exact same type as the declared parameter of the procedure.
Error: succ or pred on enums with assignments not possible
If you declare an enumeration type which has C-like assignments in it, such as in the following:
   Tenum = (a,b,e:=5);
 
then you cannot use the Succ or Pred functions with this enumeration.
Error: Can’t read or write variables of this type
You are trying to read or write a variable from or to a file of type text, which doesn’t support that variable’s type. Only integer types, reals, pchars and strings can be read from or written to a text file. Booleans can only be written to text files.
Error: Can’t use readln or writeln on typed file
readln and writeln are only allowed for text files.
Error: Can’t use read or write on untyped file.
read and write are only allowed for text or typed files.
Error: Type conflict between set elements
There is at least one set element which is of the wrong type, i.e. not of the set type.
Warning: lo/hi(dword/qword) returns the upper/lower word/dword
Free Pascal supports an overloaded version of lo/hi for longint/dword/int64/qword which returns the lower/upper word/dword of the argument. Turbo Pascal always uses a 16 bit lo/hi which always returns bits 0..7 for lo and the bits 8..15 for hi. If you want the Turbo Pascal behavior you have to type cast the argument to a word or integer.
Error: Integer or real expression expected
The first argument to str must be a real or integer type.
Error: Wrong type "arg1" in array constructor
You are trying to use a type in an array constructor which is not allowed.
Error: Incompatible type for arg no. arg1: Got "arg2", expected "arg3"
You are trying to pass an invalid type for the specified parameter.
Error: Method (variable) and Procedure (variable) are not compatible
You can’t assign a method to a procedure variable or a procedure to a method pointer.
Error: Illegal constant passed to internal math function
The constant argument passed to a ln or sqrt function is out of the definition range of these functions.
Error: Can’t take the address of constant expressions
It is not possible to get the address of a constant expression, because they aren’t stored in memory. You can try making it a typed constant. This error can also be displayed if you try to pass a property to a var parameter.
Error: Argument can’t be assigned to
Only expressions which can be on the left side of an assignment can be passed as call by reference arguments.

Remark: Properties can be used on the left side of an assignment, nevertheless they cannot be used as arguments.

Error: Can’t assign local procedure/function to procedure variable
It’s not allowed to assign a local procedure/function to a procedure variable, because the calling convention of a local procedure/function is different. You can only assign local procedure/function to a void pointer.
Error: Can’t assign values to an address
It is not allowed to assign a value to an address of a variable, constant, procedure or function. You can try compiling with -So if the identifier is a procedure variable.
Error: Can’t assign values to const variable
It’s not allowed to assign a value to a variable which is declared as a const. This is normally a parameter declared as const. To allow changing the value, pass the parameter by value, or a parameter by reference (using var).
Error: Array type required
If you are accessing a variable using an index ’[<x>]’ then the type must be an array. In FPC mode a pointer is also allowed.
Error: interface type expected, but got "arg1"
The compiler expected to encounter an interface type name, but got something else. The following code would produce this error:
 Type
   TMyStream = Class(TStream,Integer)
 
Hint: Mixing signed expressions and longwords gives a 64bit result
If you divide (or calculate the modulus of) a signed expression by a longword (or vice versa), or if you have overflow and/or range checking turned on and use an arithmetic expression (+, -, *, div, mod) in which both signed numbers and longwords appear, then everything has to be evaluated in 64-bit arithmetic which is slower than normal 32-bit arithmetic. You can avoid this by typecasting one operand so it matches the result type of the other one.
Warning: Mixing signed expressions and cardinals here may cause a range check error
If you use a binary operator (and, or, xor) and one of the operands is a longword while the other one is a signed expression, then, if range checking is turned on, you may get a range check error because in such a case both operands are converted to longword before the operation is carried out. You can avoid this by typecasting one operand so it matches the result type of the other one.
Error: Typecast has different size (arg1 -> arg2) in assignment
Type casting to a type with a different size is not allowed when the variable is used in an assignment.
Error: enums with assignments can’t be used as array index
When you declared an enumeration type which has C-like assignments, such as in the following:
   Tenum = (a,b,e:=5);
 
you cannot use it as the index of an array.
Error: Class or Object types "arg1" and "arg2" are not related
There is a typecast from one class or object to another while the class/object are not related. This will probably lead to errors.
Warning: Class types "arg1" and "arg2" are not related
There is a typecast from one class to another while the classes are not related. This will probably lead to errors.
Error: Class or interface type expected, but got "arg1"
The compiler expected a class or interface name, but got another type or identifier.
Error: Type "arg1" is not completely defined
This error occurs when a type is not complete: i.e. a pointer type which points to an undefined type.
Warning: String literal has more characters than short string length
The size of the constant string, which is assigned to a shortstring, is longer than the maximum size of the shortstring (255 characters).
Warning: Comparison is always false due to range of values
There is a comparison between an unsigned value and a signed constant which is less than zero. Because of type promotion, the statement will always evaluate to false. Explicitly typecast the constant to the correct range to avoid this problem.
Warning: Comparison is always true due to range of values
There is a comparison between an unsigned value and a signed constant which is less than zero. Because of type promotion, the statement will always evaluate to true. Explicitly typecast the constant to the correct range to avoid this problem.
Warning: Constructing a class "arg1" with abstract method "arg2"
An instance of a class is created which contains non-implemented abstract methods. This will probably lead to a runtime error 211 in the code if that routine is ever called. All abstract methods should be overridden.
Hint: The left operand of the IN operator should be byte sized
The left operand of the in operator is not an ordinal or enumeration which fits within 8 bits. This may lead to range check errors. The in operator currently only supports a left operand which fits within a byte. In the case of enumerations, the size of an element of an enumeration can be controlled with the {$PACKENUM} or {$Zn} switches.
Warning: Type size mismatch, possible loss of data / range check error
There is an assignment to a smaller type than the source type. This means that this may cause a range-check error, or may lead to possible loss of data.
Hint: Type size mismatch, possible loss of data / range check error
There is an assignment to a smaller type than the source type. This means that this may cause a range-check error, or may lead to possible loss of data.
Error: The address of an abstract method can’t be taken
An abstract method has no body, so the address of an abstract method can’t be taken.
Error: Assignments to formal parameters and open arrays are not possible
You are trying to assign a value to a formal (untyped var, const or out) parameter, or to an open array.
Error: Constant Expression expected
The compiler expects an constant expression, but gets a variable expression.
Error: Operation "arg1" not supported for types "arg2" and "arg3"
The operation is not allowed for the supplied types.
Error: Illegal type conversion: "arg1" to "arg2"
When doing a type-cast, you must take care that the sizes of the variable and the destination type are the same.
Hint: Conversion between ordinals and pointers is not portable
If you typecast a pointer to a longint (or vice-versa), this code will not compile on a machine using 64 bits addressing.
Warning: Conversion between ordinals and pointers is not portable
If you typecast a pointer to an ordinal type of a different size (or vice-versa), this can cause problems. This is a warning to help in finding the 32-bit specific code where cardinal/longint is used to typecast pointers to ordinals. A solution is to use the ptrint/ptruint types instead.
Error: Can’t determine which overloaded function to call
You’re calling overloaded functions with a parameter that doesn’t correspond to any of the declared function parameter lists. e.g. when you have declared a function with parameters word and longint, and then you call it with a parameter which is of type integer.
Error: Illegal counter variable
The type of a for loop variable must be an ordinal type. Loop variables cannot be reals or strings.
Warning: Converting constant real value to double for C variable argument, add explicit typecast to prevent this.
In C, constant real values are double by default. For this reason, if you pass a constant real value to a variable argument part of a C function, FPC by default converts this constant to double as well. If you want to prevent this from happening, add an explicit typecast around the constant.
Error: Class or COM interface type expected, but got "arg1"
Some operators, such as the AS operator, are only applicable to classes or COM interfaces.
Error: Constant packed arrays are not yet supported
You cannot declare a (bit)packed array as a typed constant.
Error: Incompatible type for arg no. arg1: Got "arg2" expected "(Bit)Packed Array"
The compiler expects a (bit)packed array as the specified parameter.
Error: Incompatible type for arg no. arg1: Got "arg2" expected "(not packed) Array"
The compiler expects a regular (i.e., not packed) array as the specified parameter.
Error: Elements of packed arrays cannot be of a type which need to be initialised
Support for packed arrays of types that need initialization (such as ansistrings, or records which contain ansistrings) is not yet implemented.
Error: Constant packed records and objects are not yet supported
You cannot declare a (bit)packed array as a typed constant at this time.
Warning: Arithmetic "arg1" on untyped pointer is unportable to {$T+}, suggest typecast
Addition/subtraction from an untyped pointer may work differently in {$T+}. Use a typecast to a typed pointer.
Error: Can’t take address of a subroutine marked as local
The address of a subroutine marked as local can’t be taken.
Error: Can’t export subroutine marked as local from a unit
A subroutine marked as local can’t be exported from a unit.
Error: Type is not automatable: "arg1"
Only byte, integer, longint, smallint, currency, single, double, ansistring, widestring, tdatetime, variant, olevariant, wordbool and all interfaces are automatable.
Hint: Converting the operands to "arg1" before doing the add could prevent overflow errors.
Adding two types can cause overflow errors. Since you are converting the result to a larger type, you could prevent such errors by converting the operands to this type before doing the addition.
Hint: Converting the operands to "arg1" before doing the subtract could prevent overflow errors.
Subtracting two types can cause overflow errors. Since you are converting the result to a larger type, you could prevent such errors by converting the operands to this type before doing the subtraction.
Hint: Converting the operands to "arg1" before doing the multiply could prevent overflow errors.
Multiplying two types can cause overflow errors. Since you are converting the result to a larger type, you could prevent such errors by converting the operands to this type before doing the multiplication.
Warning: Converting pointers to signed integers may result in wrong comparison results and range errors, use an unsigned type instead.
The virtual address space on 32-bit machines runs from $00000000 to $ffffffff. Many operating systems allow you to allocate memory above $80000000. For example both Windows and linux allow pointers in the range $0000000 to $bfffffff. If you convert pointers to signed types, this can cause overflow and range check errors, but also $80000000 < $7fffffff. This can cause random errors in code like "if p>q".
Error: Interface type arg1 has no valid GUID
When applying the as-operator to an interface or class, the desired interface (i.e. the right operand of the as-operator) must have a valid GUID.
Error: Invalid selector name
An Objective-C selector cannot be empty, must be a valid identifier or a single colon, and if it contains at least one colon it must also end in one.
Error: Expected Objective-C method, but got arg1
A selector can only be created for Objective-C methods, not for any other kind of procedure/function/method.
Error: Expected Objective-C method or constant method name
A selector can only be created for Objective-C methods, either by specifying the name using a string constant, or by using an Objective-C method identifier that is visible in the current scope.
Error: No type info available for this type
Type information is not generated for some types, such as enumerations with gaps in their value range (this includes enumerations whose lower bound is different from zero).

C.5  Symbol handling

This section lists all the messages that concern the handling of symbols. This means all things that have to do with procedure and variable names.

Error: Identifier not found "arg1"
The compiler doesn’t know this symbol. Usually happens when you misspell the name of a variable or procedure, or when you forget to declare a variable.
Fatal: Internal Error in SymTableStack()
An internal error occurred in the compiler; If you encounter such an error, please contact the developers and try to provide an exact description of the circumstances in which the error occurs.
Error: Duplicate identifier "arg1"
The identifier was already declared in the current scope.
Hint: Identifier already defined in arg1 at line arg2
The identifier was already declared in a previous scope.
Error: Unknown identifier "arg1"
The identifier encountered has not been declared, or is used outside the scope where it is defined.
Error: Forward declaration not solved "arg1"
This can happen in two cases:
Error: Error in type definition
There is an error in your definition of a new array type. One of the range delimiters in an array declaration is erroneous. For example, Array [1..1.25] will trigger this error.
Error: Forward type not resolved "arg1"
A symbol was forward defined, but no declaration was encountered.
Error: Only static variables can be used in static methods or outside methods
A static method of an object can only access static variables.
Fatal: record or class type expected
The variable or expression isn’t of the type record or class.
Error: Instances of classes or objects with an abstract method are not allowed
You are trying to generate an instance of a class which has an abstract method that wasn’t overridden.
Warning: Label not defined "arg1"
A label was declared, but not defined.
Error: Label used but not defined "arg1"
A label was declared and used, but not defined.
Error: Illegal label declaration
This error should never happen; it occurs if a label is defined outside a procedure or function.
Error: GOTO and LABEL are not supported (use switch -Sg)
You must use the -Sg switch to compile a program which has labels and goto statements. By default, label and goto aren’t supported.
Error: Label not found
A goto label was encountered, but the label wasn’t declared.
Error: identifier isn’t a label
The identifier specified after the goto isn’t of type label.
Error: label already defined
You are defining a label twice. You can define a label only once.
Error: illegal type declaration of set elements
The declaration of a set contains an invalid type definition.
Error: Forward class definition not resolved "arg1"
You declared a class, but you did not implement it.
Hint: Unit "arg1" not used in arg2
The unit referenced in the uses clause is not used.
Hint: Parameter "arg1" not used
The identifier was declared (locally or globally) but was not used (locally or globally).
Note: Local variable "arg1" not used
You have declared, but not used, a variable in a procedure or function implementation.
Hint: Value parameter "arg1" is assigned but never used
The identifier was declared (locally or globally) and assigned to, but is not used (locally or globally) after the assignment.
Note: Local variable "arg1" is assigned but never used
The variable in a procedure or function implementation is declared and assigned to, but is not used after the assignment.
Hint: Local arg1 "arg2" is not used
A local symbol is never used.
Note: Private field "arg1.arg2" is never used
The indicated private field is defined, but is never used in the code.
Note: Private field "arg1.arg2" is assigned but never used
The indicated private field is declared and assigned to, but never read.
Note: Private method "arg1.arg2" never used
The indicated private method is declared but is never used in the code.
Error: Set type expected
The variable or expression is not of type set. This happens in an in statement.
Warning: Function result does not seem to be set
You can get this warning if the compiler thinks that a function return value is not set. This will not be displayed for assembler procedures, or procedures that contain assembler blocks.
Warning: Type "arg1" is not aligned correctly in current record for C
Arrays with sizes not multiples of 4 will be wrongly aligned for C structures.
Error: Unknown record field identifier "arg1"
The field doesn’t exist in the record/object definition.
Warning: Local variable "arg1" does not seem to be initialized
This message is displayed if the compiler thinks that a variable will be used (i.e. it appears in the right-hand side of an expression) when it was not initialized first (i.e. appeared in the left-hand side of an assignment).
Warning: Variable "arg1" does not seem to be initialized
This message is displayed if the compiler thinks that a variable will be used (i.e. it appears in the right-hand side of an expression) when it was not initialized first (i.e. appeared in the left-hand side of an assignment).
Error: identifier idents no member "arg1"
This error is generated when an identifier of a record, field or method is accessed while it is not defined.
Hint: Found declaration: arg1
You get this when you use the -vh switch.In the case of an overloaded procedure not being found. Then all candidate overloaded procedures are listed, with their parameter lists.
Error: Data element too large
You get this when you declare a data element whose size exceeds the prescribed limit (2 Gb on 80386+/68020+ processors).
Error: No matching implementation for interface method "arg1" found
There was no matching method found which could implement the interface method. Check argument types and result type of the methods.
Warning: Symbol "arg1" is deprecated
This means that a symbol (a variable, routine, etc...) which is declared as deprecated is used. Deprecated symbols may no longer be available in newer versions of the unit / library. Use of this symbol should be avoided as much as possible.
Warning: Symbol "arg1" is not portable
This means that a symbol (a variable, routine, etc...) which is declared as platform is used. This symbol’s value, use and availability is platform specific and should not be used if the source code must be portable.
Warning: Symbol "arg1" is not implemented
This means that a symbol (a variable, routine, etc...) which is declared as unimplemented is used. This symbol is defined, but is not yet implemented on this specific platform.
Error: Can’t create unique type from this type
Only simple types like ordinal, float and string types are supported when redefining a type with type newtype = type oldtype;.
Hint: Local variable "arg1" does not seem to be initialized
This message is displayed if the compiler thinks that a variable will be used (i.e. it appears in the right-hand side of an expression) when it was not initialized first (i.e. it did not appear in the left-hand side of an assignment).
Hint: Variable "arg1" does not seem to be initialized
This message is displayed if the compiler thinks that a variable will be used (i.e. it appears in the right-hand side of an expression) when it was not initialized first (i.e. t did not appear in the left-hand side of an assignment).
Warning: Function result variable does not seem to initialized
This message is displayed if the compiler thinks that the function result variable will be used (i.e. it appears in the right-hand side of an expression) before it is initialized (i.e. before it appeared in the left-hand side of an assignment).
Hint: Function result variable does not seem to be initialized
This message is displayed if the compiler thinks that the function result variable will be used (i.e. it appears in the right-hand side of an expression) before it is initialized (i.e. it appears in the left-hand side of an assignment)
Warning: Variable "arg1" read but nowhere assigned
You have read the value of a variable, but nowhere assigned a value to it.
Hint: Found abstract method: arg1
When getting a warning about constructing a class/object with abstract methods you get this hint to assist you in finding the affected method.
Warning: Symbol "arg1" is experimental
This means that a symbol (a variable, routine, etc...) which is declared as experimental is used. Experimental symbols might disappear or change semantics in future versions. Usage of this symbol should be avoided as much as possible.
Warning: Forward declaration "arg1" not resolved, assumed external
This happens if you declare a function in the interface of a unit in macpas mode, but do not implement it.
Warning: Symbol "arg1" is belongs to a library
This means that a symbol (a variable, routine, etc...) which is declared as library is used. Library symbols may not be available in other libraries.
Warning: Symbol "arg1" is deprecated: "arg2"
This means that a symbol (a variable, routine, etc...) which is declared as deprecated is used. Deprecated symbols may no longer be available in newer versions of the unit / library. Use of this symbol should be avoided as much as possible.
Error: Cannot find an enumerator for the type "arg1"
This means that compiler cannot find an apropriate enumerator to use in the for-in loop. To create an enumerator you need to defind an operator enumerator or add a public or published GetEnumerator method to the class or object definition.
Error: Cannot find a "MoveNext" method in enumerator "arg1"
This means that compiler cannot find a public MoveNext method with the Boolean return type in the enumerator class or object definition.
Error: Cannot find a "Current" property in enumerator "arg1"
This means that compiler cannot find a public Current property in the enumerator class or object definition.

C.6  Code generator messages

This section lists all messages that can be displayed if the code generator encounters an error condition.

Error: Parameter list size exceeds 65535 bytes
The I386 processor limits the parameter list to 65535 bytes. (The RET instruction causes this.)
Error: File types must be var parameters
You cannot specify files as value parameters, i.e., they must always be declared var parameters.
Error: The use of a far pointer isn’t allowed there
Free Pascal doesn’t support far pointers, so you cannot take the address of an expression which has a far reference as a result. The mem construct has a far reference as a result, so the following code will produce this error:
 var p : pointer;
 ...
 p:=@mem[a000:000];
 
Error: EXPORT declared functions can’t be called
No longer in use.
Warning: Possible illegal call of constructor or destructor
The compiler detected that a constructor or destructor is called within a a method. This will probably lead to problems, since constructors / destructors require parameters on entry.
Note: Inefficient code
Your statement seems dubious to the compiler.
Warning: unreachable code
You specified a construct which will never be executed. Example:
 while false do
   begin
   {.. code ...}
   end;
 
Error: Abstract methods can’t be called directly
You cannot call an abstract method directly. Instead, you must call an overriding child method, because an abstract method isn’t implemented.
Register arg1 weight arg2 arg3
Debugging message. Shown when the compiler considers a variable for keeping in the registers.
Stack frame is omitted
Some procedure/functions do not need a complete stack-frame, so it is omitted. This message will be displayed when the -vd switch is used.
Error: Object or class methods can’t be inline.
You cannot have inlined object methods.
Error: Procvar calls cannot be inline.
A procedure with a procedural variable call cannot be inlined.
Error: No code for inline procedure stored
The compiler couldn’t store code for the inline procedure.
Error: Element zero of an ansi/wide- or longstring can’t be accessed, use (set)length instead
You should use setlength to set the length of an ansi/wide/longstring and length to get the length of such string type.
Error: Constructors or destructors cannot be called inside a ’with’ clause
Inside a with clause you cannot call a constructor or destructor for the object you have in the with clause.
Error: Cannot call message handler methods directly
A message method handler method cannot be called directly if it contains an explicit Self argument.
Error: Jump in or outside of an exception block
It is not allowed to jump in or outside of an exception block like try..finally..end;. For example, the following code will produce this error:
 label 1;

 ...

 try
    if not(final) then
      goto 1;   // this line will cause an error
 finally
   ...
 end;
 1:
 ...
 
Error: Control flow statements aren’t allowed in a finally block
It isn’t allowed to use the control flow statements break, continue and exit inside a finally statement. The following example shows the problem:
 ...
   try
      p;
   finally
      ...
      exit;  // This exit ISN'T allowed
   end;
 ...

 
If the procedure p raises an exception the finally block is executed. If the execution reaches the exit, it’s unclear what to do: exit the procedure or search for another exception handler.
Warning: Parameters size exceeds limit for certain cpu’s
This indicates that you are declaring more than 64K of parameters, which might not be supported on other processor targets.
Warning: Local variable size exceed limit for certain cpu’s
This indicates that you are declaring more than 32K of local variables, which might not be supported on other processor targets.
Error: Local variables size exceeds supported limit
This indicates that you are declaring more than 32K of local variables, which is not supported by this processor.
Error: BREAK not allowed
You’re trying to use break outside a loop construction.
Error: CONTINUE not allowed
You’re trying to use continue outside a loop construction.
Fatal: Unknown compilerproc "arg1". Check if you use the correct run time library.
The compiler expects that the runtime library contains certain subroutines. If you see this error and you didn’t change the runtime library code, it’s very likely that the runtime library you’re using doesn’t match the compiler in use. If you changed the runtime library this error means that you removed a subroutine which the compiler needs for internal use.
Fatal: Cannot find system type "arg1". Check if you use the correct run time library.
The compiler expects that the runtime library contains certain type definitions. If you see this error and you didn’t change the runtime library code, it’s very likely that the runtime library you’re using doesn’t match the compiler in use. If you changed the runtime library this error means that you removed a type which the compiler needs for internal use.
Hint: Inherited call to abstract method ignored
This message appears only in Delphi mode when you call an abstract method of a parent class via inherited;. The call is then ignored.
Error: Goto label "arg1" not defined or optimized away
The label used in the goto definition is not defined or optimized away by the unreachable code elemination.

C.7  Errors of assembling/linking stage

This section lists errors that occur when the compiler is processing the command line or handling the configuration files.

Warning: Source operating system redefined
The source operating system is redefined.
Info: Assembling (pipe) arg1
Assembling using a pipe to an external assembler.
Error: Can’t create assembler file: arg1
The mentioned file can’t be created. Check if you have access permissions to create this file.
Error: Can’t create object file: arg1
The mentioned file can’t be created. Check if you have got access permissions to create this file.
Error: Can’t create archive file: arg1
The mentioned file can’t be created. Check if you have access permissions to create this file.
Error: Assembler arg1 not found, switching to external assembling
The assembler program was not found. The compiler will produce a script that can be used to assemble and link the program.
Using assembler: arg1
An informational message saying which assembler is being used.
Error: Error while assembling exitcode arg1
There was an error while assembling the file using an external assembler. Consult the documentation of the assembler tool to find out more information on this error.
Error: Can’t call the assembler, error arg1 switching to external assembling
An error occurred when calling an external assembler. The compiler will produce a script that can be used to assemble and link the program.
Info: Assembling arg1
An informational message stating which file is being assembled.
Info: Assembling with smartlinking arg1
An informational message stating which file is being assembled using smartlinking.
Warning: Object arg1 not found, Linking may fail !
One of the object files is missing, and linking will probably fail. Check your paths.
Warning: Library arg1 not found, Linking may fail !
One of the library files is missing, and linking will probably fail. Check your paths.
Error: Error while linking
Generic error while linking.
Error: Can’t call the linker, switching to external linking
An error occurred when calling an external linker. The compiler will produce a script that can be used to assemble and link the program.
Info: Linking arg1
An informational message, showing which program or library is being linked.
Error: Util arg1 not found, switching to external linking
An external tool was not found. The compiler will produce a script that can be used to assemble and link or postprocess the program.
Using util arg1
An informational message, showing which external program (usually a postprocessor) is being used.
Error: Creation of Executables not supported
Creating executable programs is not supported for this platform, because it was not yet implemented in the compiler.
Error: Creation of Dynamic/Shared Libraries not supported
Creating dynamically loadable libraries is not supported for this platform, because it was not yet implemented in the compiler.
Info: Closing script arg1
Informational message showing when writing of the external assembling and linking script is finished.
Error: resource compiler "arg1" not found, switching to external mode
An external resource compiler was not found. The compiler will produce a script that can be used to assemble, compile resources and link or postprocess the program.
Info: Compiling resource arg1
An informational message, showing which resource is being compiled.
unit arg1 can’t be statically linked, switching to smart linking
Static linking was requested, but a unit which is not statically linkable was used.
unit arg1 can’t be smart linked, switching to static linking
Smart linking was requested, but a unit which is not smart-linkable was used.
unit arg1 can’t be shared linked, switching to static linking
Shared linking was requested, but a unit which is not shared-linkable was used.
Error: unit arg1 can’t be smart or static linked
Smart or static linking was requested, but a unit which cannot be used for either was used.
Error: unit arg1 can’t be shared or static linked
Shared or static linking was requested, but a unit which cannot be used for either was used.
Calling resource compiler "arg1" with "arg2" as command line
An informational message showing which command line is used for the resource compiler.
Error: Error while compiling resources
The resource compiler or converter returned an error.
Error: Can’t call the resource compiler "arg1", switching to external mode
An error occurred when calling a resource compiler. The compiler will produce a script that can be used to assemble, compile resources and link or postprocess the program.
Error: Can’t open resource file "arg1"
An error occurred resource file cannot be opened.
Error: Can’t write resource file "arg1"
An error occurred resource file cannot be written.

C.8  Executable information messages.

This section lists all messages that the compiler emits when an executable program is produced, and only when the internal linker is used.

Fatal: Can’t post process executable arg1
Fatal error when the compiler is unable to post-process an executable.
Fatal: Can’t open executable arg1
Fatal error when the compiler cannot open the file for the executable.
Size of Code: arg1 bytes
Informational message showing the size of the produced code section.
Size of initialized data: arg1 bytes
Informational message showing the size of the initialized data section.
Size of uninitialized data: arg1 bytes
Informational message showing the size of the uninitialized data section.
Stack space reserved: arg1 bytes
Informational message showing the stack size that the compiler reserved for the executable.
Stack space committed: arg1 bytes
Informational message showing the stack size that the compiler committed for the executable.

C.9  Linker messages

This section lists messages produced by internal linker.

Fatal: Executable image size is too big for arg1 target.
Fatal error when resulting executable is too big.
Warning: Object file "arg1" contains 32-bit absolute relocation to symbol "arg2".
Warning when 64-bit object file contains 32-bit absolute relocations. In such case an executable image can be loaded into lower 4Gb of address space only.

C.10  Unit loading messages.

This section lists all messages that can occur when the compiler is loading a unit from disk into memory. Many of these messages are informational messages.

Unitsearch: arg1
When you use the -vt option, the compiler tells you where it tries to find unit files.
PPU Loading arg1
When the -vt switch is used, the compiler tells you what units it loads.
PPU Name: arg1
When you use the -vu flag, the unit name is shown.
PPU Flags: arg1
When you use the -vu flag, the unit flags are shown.
PPU Crc: arg1
When you use the -vu flag, the unit CRC check is shown.
PPU Time: arg1
When you use the -vu flag, the time the unit was compiled is shown.
PPU File too short
The ppufile is too short, not all declarations are present.
PPU Invalid Header (no PPU at the begin)
A unit file contains as the first three bytes the ASCII codes of the characters PPU.
PPU Invalid Version arg1
This unit file was compiled with a different version of the compiler, and cannot be read.
PPU is compiled for another processor
This unit file was compiled for a different processor type, and cannot be read.
PPU is compiled for another target
This unit file was compiled for a different target, and cannot be read.
PPU Source: arg1
When you use the -vu flag, the unit source file name is shown.
Writing arg1
When you specify the -vu switch, the compiler will tell you where it writes the unit file.
Fatal: Can’t Write PPU-File
An error occurred when writing the unit file.
Fatal: Error reading PPU-File
This means that the unit file was corrupted, and contains invalid information. Recompilation will be necessary.
Fatal: unexpected end of PPU-File
Unexpected end of file. This may mean that the PPU file is corrupted.
Fatal: Invalid PPU-File entry: arg1
The unit the compiler is trying to read is corrupted, or generated with a newer version of the compiler.
Fatal: PPU Dbx count problem
There is an inconsistency in the debugging information of the unit.
Error: Illegal unit name: arg1
The name of the unit does not match the file name.
Fatal: Too much units
Free Pascal has a limit of 1024 units in a program. You can change this behavior by changing the maxunits constant in the fmodule.pas file of the compiler, and recompiling the compiler.
Fatal: Circular unit reference between arg1 and arg2
Two units are using each other in the interface part. This is only allowed in the implementation part. At least one unit must contain the other one in the implementation section.
Fatal: Can’t compile unit arg1, no sources available
A unit was found that needs to be recompiled, but no sources are available.
Fatal: Can’t find unit arg1 used by arg2
You tried to use a unit of which the PPU file isn’t found by the compiler. Check your configuration file for the unit paths.
Warning: Unit arg1 was not found but arg2 exists
This error message is no longer used.
Fatal: Unit arg1 searched but arg2 found
dos truncation of 8 letters for unit PPU files may lead to problems when unit name is longer than 8 letters.
Warning: Compiling the system unit requires the -Us switch
When recompiling the system unit (it needs special treatment), the -Us switch must be specified.
Fatal: There were arg1 errors compiling module, stopping
When the compiler encounters a fatal error or too many errors in a module then it stops with this message.
Load from arg1 (arg2) unit arg3
When you use the -vu flag, which unit is loaded from which unit is shown.
Recompiling arg1, checksum changed for arg2
The unit is recompiled because the checksum of a unit it depends on has changed.
Recompiling arg1, source found only
When you use the -vu flag, these messages tell you why the current unit is recompiled.
Recompiling unit, static lib is older than ppufile
When you use the -vu flag, the compiler warns if the static library of the unit is older than the unit file itself.
Recompiling unit, shared lib is older than ppufile
When you use the -vu flag, the compiler warns if the shared library of the unit is older than the unit file itself.
Recompiling unit, obj and asm are older than ppufile
When you use the -vu flag, the compiler warns if the assembler or object file of the unit is older than the unit file itself.
Recompiling unit, obj is older than asm
When you use the -vu flag, the compiler warns if the assembler file of the unit is older than the object file of the unit.
Parsing interface of arg1
When you use the -vu flag, the compiler warns that it starts parsing the interface part of the unit.
Parsing implementation of arg1
When you use the -vu flag, the compiler warns that it starts parsing the implementation part of the unit.
Second load for unit arg1
When you use the -vu flag, the compiler warns that it starts recompiling a unit for the second time. This can happen with interdependent units.
PPU Check file arg1 time arg2
When you use the -vu flag, the compiler shows the filename and date and time of the file on which a recompile depends.
Warning: Can’t recompile unit arg1, but found modifed include files
A unit was found to have modified include files, but some source files were not found, so recompilation is impossible.
File arg1 is newer than PPU file arg2
A modified source file for a compiler unit was found.
Trying to use a unit which was compiled with a different FPU mode
Trying to compile code while using units which were not compiled with the same floating point format mode. Either all code should be compiled with FPU emulation on, or with FPU emulation off.
Loading interface units from arg1
When you use the -vu flag, the compiler warns that it is starting to load the units defined in the interface part of the unit.
Loading implementation units from arg1
When you use the -vu flag, the compiler warns that it is starting to load the units defined in the implementation part of the unit.
Interface CRC changed for unit arg1
When you use the -vu flag, the compiler warns that the CRC calculated for the interface has been changed after the implementation has been parsed.
Implementation CRC changed for unit arg1
When you use the -vu flag, the compiler warns that the CRC calculated has been changed after the implementation has been parsed.
Finished compiling unit arg1
When you use the -vu flag, the compiler warns that it has finished compiling the unit.
Add dependency of arg1 to arg2
When you use the -vu flag, the compiler warns that it has added a dependency between the two units.
No reload, is caller: arg1
When you use the -vu flag, the compiler warns that it will not reload the unit because it is the unit that wants to load this unit.
No reload, already in second compile: arg1
When you use the -vu flag, the compiler warns that it will not reload the unit because it is already in a second recompile.
Flag for reload: arg1
When you use the -vu flag, the compiler warns that it has to reload the unit.
Forced reloading
When you use the -vu flag, the compiler warns that it is reloading the unit because it was required.
Previous state of arg1: arg2
When you use the -vu flag, the compiler shows the previous state of the unit.
Already compiling arg1, setting second compile
When you use the -vu flag, the compiler warns that it is starting to recompile a unit for the second time. This can happen with interdependent units.
Loading unit arg1
When you use the -vu flag, the compiler warns that it starts loading the unit.
Finished loading unit arg1
When you use the -vu flag, the compiler warns that it finished loading the unit.
Registering new unit arg1
When you use the -vu flag, the compiler warns that it has found a new unit and is registering it in the internal lists.
Re-resolving unit arg1
When you use the -vu flag, the compiler warns that it has to recalculate the internal data of the unit.
Skipping re-resolving unit arg1, still loading used units
When you use the -vu flag, the compiler warns that it is skipping the recalculation of the internal data of the unit because there is no data to recalculate.
Unloading resource unit arg1 (not needed)
When you use the -vu flag, the compiler warns that it is unloading the resource handling unit, since no resources are used.
Error: Unit arg1 was compiled using a different whole program optimization feedback input (arg2, arg3); recompile it without wpo or use the same wpo feedback input file for this compilation invocation
When a unit has been compiled using a particular whole program optimization (wpo) feedback file (-FW<x> -OW<x>), this compiled version of the unit is specialised for that particular compilation scenario and cannot be used in any other context. It has to be recompiled before you can use it in another program or with another wpo feedback input file.

C.11  Command line handling errors

This section lists errors that occur when the compiler is processing the command line or handling the configuration files.

Warning: Only one source file supported, changing source file to compile from "arg1" into "arg2"
You can specify only one source file on the command line. The last one will be compiled, others will be ignored. This may indicate that you forgot a ’-’ sign.
Warning: DEF file can be created only for OS/2
This option can only be specified when you’re compiling for OS/2.
Error: nested response files are not supported
You cannot nest response files with the @file command line option.
Fatal: No source file name in command line
The compiler expects a source file name on the command line.
Note: No option inside arg1 config file
The compiler didn’t find any option in that config file.
Error: Illegal parameter: arg1
You specified an unknown option.
Hint: -? writes help pages
When an unknown option is given, this message is diplayed.
Fatal: Too many config files nested
You can only nest up to 16 config files.
Fatal: Unable to open file arg1
The option file cannot be found.
Reading further options from arg1
Displayed when you have notes turned on, and the compiler switches to another options file.
Warning: Target is already set to: arg1
Displayed if more than one -T option is specified.
Warning: Shared libs not supported on DOS platform, reverting to static
If you specify -CD for the dos platform, this message is displayed. The compiler supports only static libraries under dos .
Fatal: In options file arg1 at line arg2 too many \var{\#IF(N)DEFs} encountered
The #IF(N)DEF statements in the options file are not balanced with the #ENDIF statements.
Fatal: In options file arg1 at line arg2 unexpected \var{\#ENDIFs} encountered
The #IF(N)DEF statements in the options file are not balanced with the #ENDIF statements.
Fatal: Open conditional at the end of the options file
The #IF(N)DEF statements in the options file are not balanced with the #ENDIF statements.
Warning: Debug information generation is not supported by this executable
It is possible to have a compiler executable that doesn’t support the generation of debugging info. If you use such an executable with the -g switch, this warning will be displayed.
Hint: Try recompiling with -dGDB
It is possible to have a compiler executable that doesn’t support the generation of debugging info. If you use such an executable with the -g switch, this warning will be displayed.
Warning: You are using the obsolete switch arg1
This warns you when you use a switch that is not needed/supported anymore. It is recommended that you remove the switch to overcome problems in the future, when the meaning of the switch may change.
Warning: You are using the obsolete switch arg1, please use arg2
This warns you when you use a switch that is not supported anymore. You must now use the second switch instead. It is recommended that you change the switch to overcome problems in the future, when the meaning of the switch may change.
Note: Switching assembler to default source writing assembler
This notifies you that the assembler has been changed because you used the -a switch, which can’t be used with a binary assembler writer.
Warning: Assembler output selected "arg1" is not compatible with "arg2"
Warning: "arg1" assembler use forced
The assembler output selected cannot generate object files with the correct format. Therefore, the default assembler for this target is used instead.
Reading options from file arg1
Options are also read from this file.
Reading options from environment arg1
Options are also read from this environment string.
Handling option "arg1"
Debug info that an option is found and will be handled.
*** press enter ***
Message shown when help is shown page per page. When pressing the ENTER Key, the next page of help is shown. If you press q and then ENTER, the compiler exits.
Hint: Start of reading config file arg1
Start of configuration file parsing.
Hint: End of reading config file arg1
End of configuration file parsing.
interpreting option "arg1"
The compiler is interpreting an option
interpreting firstpass option "arg1"
The compiler is interpreting an option for the first time.
interpreting file option "arg1"
The compiler is interpreting an option which it read from the configuration file.
Reading config file "arg1"
The compiler is starting to read the configuration file.
found source file name "arg1"
Additional information about options. Displayed when you have the debug option turned on.
Error: Unknown code page
An unknown code page for the source files was requested. The compiler is compiled with support for several code pages built-in. The requested code page is not in that list. You will need to recompile the compiler with support for the codepage you need.
Fatal: Config file arg1 is a directory
Directories cannot be used as configuration files.
Warning: Assembler output selected "arg1" cannot generate debug info, debugging disabled
The selected assembler output cannot generate debugging information, debugging option is therefore disabled.
Warning: Use of ppc386.cfg is deprecated, please use fpc.cfg instead
Using ppc386.cfg is still supported for historical reasons, however, for a multiplatform system the naming makes no sense anymore. Please continue to use fpc.cfg instead.
Fatal: In options file arg1 at line arg2 \var{\#ELSE} directive without \var{\#IF(N)DEF} found
An #ELSE statement was found in the options file without a matching #IF(N)DEF statement.
Fatal: Option "arg1" is not, or not yet, supported on the current target platform
Not all options are supported or implemented for all target platforms. This message informs you that a chosen option is incompatible with the currently selected target platform.
Fatal: The feature "arg1" is not, or not yet, supported on the selected target platform
Not all features are supported or implemented for all target platforms. This message informs you that a chosen feature is incompatible with the currently selected target platform.
Note: DWARF debug information cannot be used with smart linking on this target, switching to static linking
Smart linking is currently incompatble with DWARF debug information on most platforms, so smart linking is disabled in such cases.
Warning: Option "arg1" is ignored for the current target platform.
Not all options are supported or implemented for all target platforms. This message informs you that a chosen option is ignored for the currently selected target platform.

C.12  Whole program optimization messages

This section lists errors that occur when the compiler is performing whole program optimization.

Fatal: Cannot open whole program optimization feedback file "arg1"
The compiler cannot open the specified feedback file with whole program optimization information.
Processing whole program optimization information in wpo feedback file "arg1"
The compiler starts processing whole program optimization information found in the named file.
Finished processing the whole program optimization information in wpo feedback file "arg1"
The compiler has finished processing the whole program optimization information found in the named file.
Error: Expected section header, but got "arg2" at line arg1 of wpo feedback file
The compiler expected a section header in the whole program optimization file (starting with %), but did not find it.
Warning: No handler registered for whole program optimization section "arg2" at line arg1 of wpo feedback file, ignoring
The compiler has no handler to deal with the mentioned whole program optimization information section, and will therefore ignore it and skip to the next section.
Found whole program optimization section "arg1" with information about "arg2"
The compiler encountered a section with whole program optimization information, and according to its handler this section contains information usable for the mentioned purpose.
Fatal: The selected whole program optimizations require a previously generated feedback file (use -Fw to specify)
The compiler needs information gathered during a previous compilation run to perform the selected whole program optimizations. You can specify the location of the feedback file containing this information using the -Fw switch.
Error: No collected information necessary to perform "arg1" whole program optimization found
While you pointed the compiler to a file containing whole program optimization feedback, it did not contain the information necessary to perform the selected optimizations. You most likely have to recompile the program using the appropate -OWxxx switch.
Fatal: Specify a whole program optimization feedback file to store the generated info in (using -FW)
You have to specify the feedback file in which the compiler has to store the whole program optimization feedback that is generated during the compilation run. This can be done using the -FW switch.
Error: Not generating any whole program optimization information, yet a feedback file was specified (using -FW)
The compiler was instructed to store whole program optimization feedback into a file specified using -FW, but not to actually generated any whole program optimization feedback. The classes of to be generated information can be speciied using -OWxxx.
Error: Not performing any whole program optimizations, yet an input feedback file was specified (using -Fw)
The compiler was not instructed to perform any whole program optimizations (no -Owxxx parameters), but nevertheless an input file with such feedback was specified (using -Fwyyy). Since this can indicate that you forgot to specify an -Owxxx parameter, the compiler generates an error in this case.
Skipping whole program optimization section "arg1", because not needed by the requested optimizations
The whole program optimization feedback file contains a section with information that is not required by the selected whole program optimizations.
Warning: Overriding previously read information for "arg1" from feedback input file using information in section "arg2"
The feedback file contains multiple sections that provide the same class of information (e.g., information about which virtual methods can be devirtualized). In this case, the information in last encountered section is used. Turn on debugging output (-vd) to see which class of information is provided by each section.
Error: Cannot extract symbol liveness information from program when stripping symbols, use -Xs-
Certain symbol liveness collectors extract the symbol information from the linked program. If the symbol information is stripped (option -Xs), this is not possible.
Error: Cannot extract symbol liveness information from program when when not linking
Certain symbol liveness collectors extract the symbol information from the linked program. If the program is not linked by the compiler, this is not possible.
Fatal: Cannot find "arg1" or "arg2" to extract symbol liveness information from linked program
Certain symbol liveness collectors need a helper program to extract the symbol information from the linked program. This helper program is normally ’nm’, which is part of the GNU binutils.
Error: Error during reading symbol liveness information produced by "arg1"
An error occurred during the reading of the symbol liveness file that was generated using the ’nm’ or ’objdump’ program. The reason can be that it was shorter than expected, or that its format was not understood.
Fatal: Error executing "arg1" (exitcode: arg2) to extract symbol information from linked program
Certain symbol liveness collectors need a helper program to extract the symbol information from the linked program. The helper program produced the reported error code when it was run on the linked program.
Error: Collection of symbol liveness information can only help when using smart linking, use -CX -XX
Whether or not a symbol is live is determined by looking whether it exists in the final linked program. Without smart linking/dead code stripping, all symbols are always included, regardless of whether they are actually used or not. So in that case all symbols will be seen as live, which makes this optimization ineffective.
Error: Cannot create specified whole program optimisation feedback file "arg1"
The compiler is unable to create the file specified using the -FW parameter to store the whole program optimisation information.

C.13  Assembler reader errors.

This section lists the errors that are generated by the inline assembler reader. They are not the messages of the assembler itself.

C.13.1  General assembler errors

Divide by zero in asm evaluator
This fatal error is reported when a constant assembler expression performs a division by zero.
Evaluator stack overflow, Evaluator stack underflow
These fatal error is reported when a constant assembler expression is too big to be evaluated by the constant parser. Try reducing the number of terms.
Invalid numeric format in asm evaluator
This fatal error is reported when a non-numeric value is detected by the constant parser. Normally this error should never occur.
Invalid Operator in asm evaluator
This fatal error is reported when a mathematical operator is detected by the constant parser. Normally this error should never occur.
Unknown error in asm evaluator
This fatal error is reported when an internal error is detected by the constant parser. Normally this error should never occur.
Invalid numeric value
This warning is emitted when a conversion from octal, binary or hexadecimal to decimal is outside of the supported range.
Escape sequence ignored
This error is emitted when a non ANSI C escape sequence is detected in a C string.
Asm syntax error - Prefix not found
This occurs when trying to use a non-valid prefix instruction.
Asm syntax error - Trying to add more than one prefix
This occurs when you try to add more than one prefix instruction.
Asm syntax error - Opcode not found
You have tried to use an unsupported or unknown opcode.
Constant value out of bounds
This error is reported when the constant parser determines that the value you are using is out of bounds, either with the opcode or with the constant declaration used.
Non-label pattern contains @
This only applied to the m68k and Intel styled assembler. This is reported when you try to use a non-label identifier with an ’@’ prefix.
Internal error in Findtype()
Internal Error in ConcatOpcode()
Internal Errror converting binary
Internal Errror converting hexadecimal
Internal Errror converting octal
Internal Error in BuildScaling()
Internal Error in BuildConstant()
internal error in BuildReference()
internal error in HandleExtend()
Internal error in ConcatLabeledInstr()
These errors should never occur. If they do then you have found a new bug in the assembler parsers. Please contact one of the developers.
Opcode not in table, operands not checked
This warning only occurs when compiling the system unit, or related files. No checking is performed on the operands of the opcodes.
@CODE and @DATA not supported
This Turbo Pascal construct is not supported.
SEG and OFFSET not supported
This Turbo Pascal construct is not supported.
Modulo not supported
Modulo constant operation is not supported.
Floating point binary representation ignored
Floating point hexadecimal representation ignored
Floating point octal representation ignored
These warnings occur when a floating point constant is declared in a base other than decimal. No conversion can be done on these formats. You should use a decimal representation instead.
Identifier supposed external
This warning occurs when a symbol is not found in the symbol table. It is therefore considered external.
Functions with void return value can’t return any value in asm code
Only routines with a return value can have a return value set.
Error in binary constant
Error in octal constant
Error in hexadecimal constant
Error in integer constant
These errors are reported when you tried using a constant expression that is invalid or whose value is out of range.
Invalid labeled opcode
Asm syntax error - error in reference
Invalid Opcode
Invalid combination of opcode and operands
Invalid size in reference
Invalid middle sized operand
Invalid three operand opcode
Assembler syntax error
Invalid operand type
You tried using an invalid combination of opcode and operands. Check the syntax and if you are sure it is correct, please contact one of the developers.
Unknown identifier
The identifier you are trying to access does not exist, or is not within the current scope.
Trying to define an index register more than once
Trying to define a segment register twice
Trying to define a base register twice
You are trying to define an index/segment register more than once.
Invalid field specifier
The record or object field you are trying to access does not exist, or is incorrect.
Invalid scaling factor
Invalid scaling value
Scaling value only allowed with index
Allowed scaling values are 1,2,4 or 8.
Cannot use SELF outside a method
You are trying to access the SELF identifier for objects outside a method.
Invalid combination of prefix and opcode
This opcode cannot be prefixed by this instruction.
Invalid combination of override and opcode
This opcode cannot be overriden by this combination.
Too many operands on line
At most three operand instructions exist on the m68k, and i386, you are probably trying to use an invalid syntax for this opcode.
Duplicate local symbol
You are trying to redefine a local symbol, such as a local label.
Unknown label identifer
Undefined local symbol
local symbol not found inside asm statement
This label does not seem to have been defined in the current scope.
Assemble node syntax error
Not a directive or local symbol
The assembler statement is invalid, or you are not using a recognized directive.

C.13.2  I386 specific errors

repeat prefix and a segment override on <= i386 ...
A problem with interrupts and a prefix instruction may occur and may cause false results on 386 and earlier computers.
Fwait can cause emulation problems with emu387
This warning is reported when using the FWAIT instruction. It can cause emulation problems on systems which use the em387.dxe emulator.
You need GNU as version >= 2.81 to compile this MMX code
MMX assembler code can only be compiled using GAS v2.8.1 or later.
NEAR ignored
FAR ignored
NEAR and FAR are ignored in the Intel assemblers, but are still accepted for compatiblity with the 16-bit code model.
Invalid size for MOVSX/MOVZX
16-bit base in 32-bit segment
16-bit index in 32-bit segment
16-bit addressing is not supported. You must use 32-bit addressing.
Constant reference not allowed
It is not allowed to try to address a constant memory address in protected mode.
Segment overrides not supported
Intel style (eg: rep ds stosb) segment overrides are not supported by the assembler parser.
Expressions of the form [sreg:reg...] are currently not supported
To access a memory operand in a different segment, you should use the sreg:[reg...] snytax instead of [sreg:reg...]
Size suffix and destination register do not match
In intel AT&T syntax, you are using a register size which does not concord with the operand size specified.
Invalid assembler syntax. No ref with brackets
Trying to use a negative index register
Local symbols not allowed as references
Invalid operand in bracket expression
Invalid symbol name:
Invalid Reference syntax
Invalid string as opcode operand:
Null label references are not allowed
Using a defined name as a local label
Invalid constant symbol
Invalid constant expression
/ at beginning of line not allowed
NOR not supported
Invalid floating point register name
Invalid floating point constant:
Asm syntax error - Should start with bracket
Asm syntax error - register:
Asm syntax error - in opcode operand
Invalid String expression
Constant expression out of bounds
Invalid or missing opcode
Invalid real constant expression
Parenthesis are not allowed
Invalid Reference
Cannot use __SELF outside a method
Cannot use __OLDEBP outside a nested procedure
Invalid segment override expression
Strings not allowed as constants
Switching sections is not allowed in an assembler block
Invalid global definition
Line separator expected
Invalid local common definition
Invalid global common definition
assembler code not returned to text
invalid opcode size
Invalid character: <
Invalid character: >
Unsupported opcode
Invalid suffix for intel assembler
Extended not supported in this mode
Comp not supported in this mode
Invalid Operand:
Override operator not supported

C.13.3  m68k specific errors.

Increment and Decrement mode not allowed together
You are trying to use dec/inc mode together.
Invalid Register list in movem/fmovem
The register list is invalid. Normally a range of registers should be separated by - and individual registers should be separated by a slash.
Invalid Register list for opcode
68020+ mode required to assemble

Appendix D  Run-time errors

Applications generated by Free Pascal might generate run-time errors when certain abnormal conditions are detected in the application. This appendix lists the possible run-time errors and gives information on why they might be produced.

1 Invalid function number
An invalid operating system call was attempted.
2 File not found
Reported when trying to erase, rename or open a non-existent file.
3 Path not found
Reported by the directory handling routines when a path does not exist or is invalid. Also reported when trying to access a non-existent file.
4 Too many open files
The maximum number of files currently opened by your process has been reached. Certain operating systems limit the number of files which can be opened concurrently, and this error can occur when this limit has been reached.
5 File access denied
Permission to access the file is denied. This error might be caused by one of several reasons:
6 Invalid file handle
If this happens, the file variable you are using is trashed; it indicates that your memory is corrupted.
12 Invalid file access code
Reported when a reset or rewrite is called with an invalid FileMode value.
15 Invalid drive number
The number given to the Getdir or ChDir function specifies a non-existent disk.
16 Cannot remove current directory
Reported when trying to remove the currently active directory.
17 Cannot rename across drives
You cannot rename a file such that it would end up on another disk or partition.
100 Disk read error
An error occurred when reading from disk. Typically happens when you try to read past the end of a file.
101 Disk write error
Reported when the disk is full, and you’re trying to write to it.
102 File not assigned
This is reported by Reset, Rewrite, Append, Rename and Erase, if you call them with an unassigned file as a parameter.
103 File not open
Reported by the following functions : Close, Read, Write, Seek, EOf, FilePos, FileSize, Flush, BlockRead, and BlockWrite if the file is not open.
104 File not open for input
Reported by Read, BlockRead, Eof, Eoln, SeekEof or SeekEoln if the file is not opened with Reset.
105 File not open for output
Reported by write if a text file isn’t opened with Rewrite.
106 Invalid numeric format
Reported when a non-numeric value is read from a text file, and a numeric value was expected.
150 Disk is write-protected
(Critical error)
151 Bad drive request struct length
(Critical error)
152 Drive not ready
(Critical error)
154 CRC error in data
(Critical error)
156 Disk seek error
(Critical error)
157 Unknown media type
(Critical error)
158 Sector Not Found
(Critical error)
159 Printer out of paper
(Critical error)
160 Device write fault
(Critical error)
161 Device read fault
(Critical error)
162 Hardware failure
(Critical error)
200 Division by zero
The application attempted to divide a number by zero.
201 Range check error
If you compiled your program with range checking on, then you can get this error in the following cases:
  1. An array was accessed with an index outside its declared range.
  2. Trying to assign a value to a variable outside its range (for instance an enumerated type).
202 Stack overflow error
The stack has grown beyond its maximum size (in which case the size of local variables should be reduced to avoid this error), or the stack has become corrupt. This error is only reported when stack checking is enabled.
203 Heap overflow error
The heap has grown beyond its boundaries. This is caused when trying to allocate memory explicitly with New, GetMem or ReallocMem, or when a class or object instance is created and no memory is left. Please note that, by default, Free Pascal provides a growing heap, i.e. the heap will try to allocate more memory if needed. However, if the heap has reached the maximum size allowed by the operating system or hardware, then you will get this error.
204 Invalid pointer operation
You will get this if you call Dispose or Freemem with an invalid pointer (notably, Nil).
205 Floating point overflow
You are trying to use or produce real numbers that are too large.
206 Floating point underflow
You are trying to use or produce real numbers that are too small.
207 Invalid floating point operation
Can occur if you try to calculate the square root or logarithm of a negative number.
210 Object not initialized
When compiled with range checking on, a program will report this error if you call a virtual method without having called its object’s constructor.
211 Call to abstract method
Your program tried to execute an abstract virtual method. Abstract methods should be overridden, and the overriding method should be called.
212 Stream registration error
This occurs when an invalid type is registered in the objects unit.
213 Collection index out of range
You are trying to access a collection item with an invalid index (objects unit).
214 Collection overflow error
The collection has reached its maximal size, and you are trying to add another element (objects unit).
215 Arithmetic overflow error
This error is reported when the result of an arithmetic operation is outside of its supported range. Contrary to Turbo Pascal, this error is only reported for 32-bit or 64-bit arithmetic overflows. This is due to the fact that everything is converted to 32-bit or 64-bit before doing the actual arithmetic operation.
216 General Protection fault
The application tried to access invalid memory space. This can be caused by several problems:
  1. Dereferencing a nil pointer.
  2. Trying to access memory which is out of bounds (for example, calling move with an invalid length).
217 Unhandled exception occurred
An exception occurred, and there was no exception handler present. The sysutils unit installs a default exception handler which catches all exceptions and exits gracefully.
219 Invalid typecast

Thrown when an invalid typecast is attempted on a class using the as operator. This error is also thrown when an object or class is typecast to an invalid class or object and a virtual method of that class or object is called. This last error is only detected if the -CR compiler option is used.

222 Variant dispatch error
No dispatch method to call from variant.
223 Variant array create
The variant array creation failed. Usually when there is not enough memory.
224 Variant is not an array
This error occurs when a variant array operation is attempted on a variant which is not an array.
225 Var Array Bounds check error
This error occurs when a variant array index is out of bounds.
227 Assertion failed error
An assertion failed, and no AssertErrorProc procedural variable was installed.
229 Safecall error check
This error occurs is a safecall check fails, and no handler routine is available.
231 Exception stack corrupted
This error occurs when the exception object is retrieved and none is available.
232 Threads not supported
Thread management relies on a separate driver on some operating systems (notably, Unixes). The unit with this driver needs to be specified on the uses clause of the program, preferably as the first unit (cthreads on unix).

Appendix E  A sample gdb.ini file

Here you have a sample gdb.ini file listing, which gives better results when using gdb. Under linux you should put this in a .gdbinit file in your home directory or the current directory.

set print demangle off
set gnutarget auto
set verbose on
set complaints 1000
dir ./rtl/dosv2
set language c++
set print vtbl on
set print object on
set print sym on
set print pretty on
disp /i $eip

define pst
set $pos=&$arg0
set $strlen = {byte}$pos
print {char}&$arg0.st@($strlen+1)
end

document pst
  Print out a Pascal string
end

Appendix F  Options and settings

In table (??) a summary of available boolean compiler directives and the corresponding command line options are listed. Other directives and the corresponding options are shown in table (??) . For more information about the command-line options, see chapter ?? . For more information about the directives, see the Programmers guide .


Table F.1: Boolean Options and directves
ShortlongOptExplanation
$A[+/-]$ALIGN[ON/OFF] Data alignment
$B[+/-]$BOOLEVAL[ON/OFF] Boolean evaluation mode
$C[+/-]$ASSERTIONS[ON/OFF]-SaInclude assertions
$D[+/-]$DEBUGINFO[ON/OFF]-gInclude debug info
$E[+/-]  Coprocessor emulation
$F[+/-]  Far or near function (ignored)
$G[+/-]  Generate 80286 code (ignored)
 $GOTO[ON/OFF]-SgSupport GOTO and Label
 $HINTS[ON/OFF]-vhShow hints
$H[+/-]$LONGSTRINGS[ON/OFF]-ShUse ansistrings
$I[+/-]$IOCHECKS[ON/OFF]-CiCheck I/O operation result
 $INLINE[ON/OFF]-SiAllow inline code
$L[+/-]$LOCALSYMBOLS[ON/OFF] Local symbol information
$M[+/-]$TYPEINFO[ON/OFF] Generate RTTI for classes
 $MMX[ON/OFF] Intel MMX support
$N[+/-]  Floating point support
 $NOTES[ON/OFF]-vnEmit notes
$O[+/-]  Support overlays (ignored)
$P[+/-]$OPENSTRINGS[ON/OFF] Support open strings
$Q[+/-]$OVERFLOWCHECKS[ON/OFF]-CoOverflow checking
$R[+/-]$RANGECHECKS[ON/OFF]-CrRange checks
$S[+/-] -CtStack checks
 $SMARTLINK[ON/OFF]-CXUse smartlinking
 $STATIC[ON/OFF]-StAllow use of static
$T[+/-]$TYPEDADDRESS[ON/OFF] Typed addresses


Table F.2: Options and directives
ShortlongOptExplanation
 $APPTYPE-WApplication type (Win32/OS2)
 $ASMMODE-RAssembler reader mode
 $DEFINE-dDefine symbol
 $DESCRIPTION Set program description
 $ELSE Conditional compilation switch
 $ENDIF Conditional compilation end
 $FATAL Report fatal error
 $HINT Emit hint message
$I file$INCLUDE Include file or literal text
 $IF Conditional compilation start
 $IFDEF NAME Conditional compilation start
 $IFNDEF Conditional compilation start
 $IFOPT Conditional compilation start
 $INCLUDEPATH-FiSet include path
 $INFO Emit information message
$L file$LINK Link object file
 $LIBRARYPATH-FlSet library path
 $LINKLIB name Link library
$M MIN,MAX$MEMORY Set memory sizes
 $MACRO-SmAllow use of macros
 $MESSAGE Emit message
 $MODE Set compatibility mode
 $NOTE Emit note message
 $OBJECTPATH-FoSet object path
 $OUTPUT-ASet output format
 $PACKENUM Enumeration type size
 $PACKRECORDS Record element alignment
 $SATURATION Saturation (ignored)
 $STOP Stop compilation
 $UNDEF-uUndefine symbol

Appendix G  Getting the latest sources or installers

Free Pascal is under continuous development. From time to time, a new set of installers with what are considered stable sources are made: these are the releases. They can be downloaded from the Free Pascal website. The downloads usually contain the sources from which the release is made.

If for some reason, a newer set of files is needed - for instance, because certain bugs that prevent a program from functioning correctly have been fixed, it is possible to download the latest source files and recompile them.

Note that the latest sources may or may not compile: sometimes things get broken, and then the downloaded sources are useless. For the fixes branches (mentioned below) the sources should always compile, so it may be best to use these only.

There are 3 ways to get the latest version.

G.1  Download via Subversion

All Free Pascal sources are in subversion, and can be downloaded anonymously from the Subversion server. With a suitable Subversion client, the following locations can be used:

http://svn.freepascal.org/svn/fpc/trunk/

This repository contains the latest sources of the compiler, RTL and packages. This is the active development branch.

The documentation and all examples from the documentation are in the following repository

http://svn.freepascal.org/svn/fpcdocs/trunk/

All the files needed to make a release can be retrieved from

http://svn.freepascal.org/svn/fpcbuild/trunk/

This repository contains external links to the other 2 repositories, and contains all scripts, demos and other files needed to construct a new release of Free Pascal.

Free Pascal maintains a fixes branch, which is used to create new releases after a major version change. The branches are located in

http://svn.freepascal.org/svn/fpc/branches/fpc_X_Y

Where X and Y make up the major release number of Free Pascal. For instance, the fixes used to make the 2.2.x versions of Free Pascal are available in

http://svn.freepascal.org/svn/fpc/branches/fixes_2_2

The Subversion archive is mirrored on the server

svn2.freepascal.org

G.2  Downloading a source zip

Every day, a zip is made which contains the sources as they are on this day, they are available from the FTP site:

http://ftp.freepascal.org/develop.var

This will lead to a download of the sources of the development branch:

ftp://ftp.freepascal.org/pub/fpc/snapshot/trunk/source/fpc.zip

and also of the fixes branch:

ftp://ftp.freepascal.org/pub/fpc/snapshot/fixes/source/fpc.zip

The creation of the zip files is an automated process, and so these files are created every day.

G.3  Downloading a snapshot

Some members of the Free Pascal team also maintain installable snapshots. These are installers, made with the sources of that day. Since the sources are not guaranteed to work, a snapshot of a certain day may not be available, or the person responsible for it didn’t have the opportunity to make one: these snapshots may or may not be available. They can be downloaded from the same page as the daily source zip:

http://ftp.freepascal.org/develop.var

The snapshots are made for the development branch as well as for the fixes branch. They are available from

ftp://ftp.freepascal.org/pub/fpc/snapshot/trunk/

and

ftp://ftp.freepascal.org/pub/fpc/snapshot/fixes/

respectively.

The FTP site is mirrored, it may be faster to use a mirror.


This document was translated from LATEX by HEVEA.