For more information on these options, see Programmer’s Guide
Set language mode to mode, which can be one of the following:
Try to be Delphi compatible. This is more strict than the objfpc mode, since some Free Pascal extensions are switched off.
Free Pascal dialect (default).
Try to be compatible with Macintosh Pascal dialects.
Switch on some Delphi extensions. This is different from Delphi mode, because some Free Pascal constructs are still available.
Try to be TP/BP 7.0 compatible. This means no function overloading etc.
In this mode, the compiler complies with the requirements of level 0 of ISO/IEC 7185.
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:
Use object pascal classes.
Automatically include the ObjPas unit.
Enable the Result identifier for function results.
Allow automatic conversion of null-terminated strings to strings,
Allow the use of the CVAR keyword.
Allow use of nested comments.
Use classical procedural variables.
Use mac-style procedural variables.
Implementation and Forward declaration must match completely.
Allow silent conversion of pointers to procedural variables.
Automatic (silent) dereferencing of typed pointers.
Allow use of Initialization and Finalization
Allow use of ansistrings.
Allow use of the out parameter type.
Allow use of default parameter values.
Support the hint directives (deprecated, platform etc.)
Allow method arguments with the same name as properties in classes.
Allow use of global properties.
Allow inline procedures.
Allow the use of exceptions.
Allow the use of objective C version 1.
Allow the use of objective C version 2.
Allow assigning local procedures to nested procedural variables and defining inline procedural variable types, which can always accept local procedures, in parameter declarations.
Allow a GOTO statement to jump outside the local scope (as ISO Pascal).
Allow the use of advanced records (records with methods/properties)
Treat unary minus like in ISO Pascal: same precedence level as binary minus/plus.
The keyword can be followed by a plus or minus sign to enable or disable the feature. Note that the order of mode and feature switches is important, a mode switch resets the feature list to the default features for that mode.
Specify what kind of assembler you use in your asm assembler code blocks. Here xxx is one of the following:
asm blocks contain AT&T-style assembler. This is the default style.
asm blocks contain Intel-style assembler.
Use the default assembler for the specified target.
Switch on Delphi 2 extensions (objfpc mode). Deprecated, use -Mobjfpc instead.
Include assert statements in compiled code. Omitting this option will cause assert statements to be ignored.
Support C-style operators, i.e. *=, +=, /= and -=.
Try to be Delphi compatible. Deprecated, use -Mdelphi instead.
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.
Enable certain features in compiler and RTL. This allows for finer control over available language features than the mode switch. Possible values are:
Allow heap memory.
Initialization/finalization.
Allow use of RTTI.
Allow use of classes.
Allow use of exceptions.
Allow use of exit code for applications.
Allow use of ansistrings.
Allow use of widestrings.
Allow use of standard Pascal text file I/O.
Allow use of standard Pascal console I/O (text file).
Allow use of standard Pascal binary file I/O.
Allow use of Random() function.
Allow use of variants.
Allow use of TP-style objects.
Allow use of dynamic arrays.
Allow use of threading.
Allow use of command-line arguments.
Allow use of processes.
Enable stack checking.
Allow use of dynamically loadable libraries in the system unit.
Allow (enable) the use of software floating point operations.
Allow use of Objective C support routines.
Allow use of resources.
Allow use of unicode strings.
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 assembler)
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).
Support C++ style INLINE.
Set interfaces style to XXX. Here XXX is one of
COM compatible interfaces (reference counted, descend from IUnknown).
Not reference counted interfaces.
Load the Kylix compatibility unit (fpcylix).
Support C-style macros.
Try to be Borland TP 7.0 compatible. Deprecated, use -Mtp instead.
The name of constructors must be init, and the name of destructors should be done.
Allow the static keyword in objects. This flag is obsolete since Free Pascal 2.6.0.
Support vector processing (uses CPU vector extensions if available)
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.
@pointer returns a typed pointer, this is the same as the $T+ option.
Do not check the unit name. Normally, the unit name is the same as the filename. This option allows them to be different.
Compile a system unit. This option causes the compiler to define only some very basic types.