Difference between revisions of "local compiler directives"

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{{local compiler directives}}
{{local compiler directives}}
Local compiler directives may be used more than once in a Pascal [[Source code|source code]] file.
Local [[Compiler directive|compiler directives]] may be used more than once in a Pascal [[Source code|source code]] file.
== Syntax ==
== Syntax ==

Revision as of 05:24, 7 May 2020

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Local compiler directives may be used more than once in a Pascal source code file.


Data layout

Code generation


For x86 processors only

  • {$asmMode} determines the syntax the assembler reader expects. Previously, this has been the {$i386…} directives.
  • {$MMX} enables optimizations for MMX processors.
  • {$safeFPUExceptions}, whether fwait instructions are inserted
  • {$saturation} (in conjunction with {$MMX}) enables saturation operations.
  • {$maxFPUregisters} determines the maximum number of floating-points registers to use.


  • {$linkFramework} inserts a framework. This directive is only available on Darwin-based operating systems.

Data inclusion

Compile-time context

  • {$define} defines a symbol. In {$mode MacPas} the directive {$defineC} is considered, too.
  • {$include} or {$I} reads a file as source or includes certain compile-time/compiler information.
  • {$push} and {$pop} store and restore the compiler settings.
  • {$setC} sets a compile-time variable, if the current mode allows it.
  • {$undef} dismisses the definition of a previously defined symbol. In {$mode MacPas} the directive {$undefC} is recognized, too.

Conditional compilation

Conditional compilation can be achieved via the directives

  • {$if}
  • {$else}
  • {$elseIf}
  • {$endIf}
  • {$ifDef}
  • {$ifNDef}
  • {$ifOpt}

Additionally, in {$mode MacPas} the directives

  • {$ifC},
  • {$elseC},
  • {$elIfC}, and
  • {$endC}

are allowed, too.

Compile-time behavior

With {$wait}, the compiler waits till the user hits ↵ Enter, and then resumes compilation.

Self-defined messages can be triggered with the directives:

  • {$message}, and the shortcuts
    • {$stop}, which also aborts compilation
    • {$fatal}, which also aborts compilation
    • {$error} (in {$mode MacPas} the directive {$errorC} is accepted, too)
    • {$warning}
    • {$hint}
    • {$note}
  • {$info}

Emission of messages can be controlled via the directives:

  • {$warn} for specific warnings, or
  • all messages of one kind in one go:
    • {$warnings}
    • {$hints}
    • {$notes}


Since FPC intends to be sort of compatible to some other compilers, some very common compiler directives stemming from the non-FPC-lands are recognized – not generating an illegal directive error – and ignored. Those are:

  • {$F} (far or near functions)
  • {$extendedSym}
  • {$externalSym}
  • {$hppEmit}
  • {$libExport}
  • {$noDefine}
  • {$region} and {$endRegion}
  • {$stringChecks} which in Delphi, this would control the generation of code that checks the sanity of string variables and arguments.

See also

Directives, definitions and conditionals definitions
global compiler directives • local compiler directives

Conditional Compiler Options • Conditional compilation • Macros and Conditionals • Platform defines