Define a macro with optional arguments as if the macro is defined by a #define preprocessing directive. If no =expansion is specified, the compiler assumes 1.
Predefinitions (not valid in-Xc mode):
The following predefinitions are valid in all modes.
__BUILTIN_VA_ARG_INCR
__SunOS (Solaris Operating System)
__SunOS_n_n (Solaris Operating System)
__amd64 ( x86 with -m64)
__gnu__linux (linux)
__i386 (x86)
__linux (linux)
__linux__ (linux)
__sparc (SPARC)
__SunOS_n_n (Solaris Operating System) (example: __SunOS_5_9)
The following is predefined in-Xa and-Xt modes only:
The compiler also predefines the object-like macro __PRAGMA_REDEFINE_EXTNAME to indicate the pragma will be recognized.