This is output from `defines' version 4.1.1, from your buddies at Newtware!
Mon Apr 16 11:37:33  2012
skyos skyhost 5.0.0 beta i586 unknown unknown skyos
cc = [gcc]

/tmp/def233.c:30032:34: error: _Pragma takes a parenthesized string literal
/tmp/def233.c:30550:8: warning: __VA_ARGS__ can only appear in the expansion of a C99 variadic macro
/tmp/def233.c:50320:8: error: "defined" cannot be used as a macro name
PIC = 1
SKYOS = 1
_Pragma =
_REENTRANT = 1
_X86_ = 1
__BASE_FILE__ = "/tmp/def233.c"
__CHAR_BIT__ = 8
__DATE__ = "Apr 16 2012"
__DECIMAL_DIG__ = 21
__ELF__ = 1
__FILE__ = "/tmp/def233.c"
__FINITE_MATH_ONLY__ = 0
__FLT_EVAL_METHOD__ = 2
__FLT_RADIX__ = 2
__GNUC_MINOR__ = 1
__GNUC_PATCHLEVEL__ = 1
__GNUC__ = 4
__GXX_ABI_VERSION = 1002
__INCLUDE_LEVEL__ = 0
__INTEL__ = 1
__INTMAX_MAX__ = 9223372036854775807LL
__INTMAX_TYPE__ = long long int
__INT_MAX__ = 2147483647
__LINE__ = 30437
__LONG_LONG_MAX__ = 9223372036854775807LL
__LONG_MAX__ = 2147483647L
__NO_INLINE__ = 1
__PIC__ = 1
__PTRDIFF_TYPE__ = int
__REGISTER_PREFIX__ = 
__SCHAR_MAX__ = 127
__SHRT_MAX__ = 32767
__SIZE_TYPE__ = unsigned int
__SKYOS__ = 1
__STDC_HOSTED__ = 1
__STDC__ = 1
__TIME__ = "11:37:38"
__UINTMAX_TYPE__ = long long unsigned int
__USER_LABEL_PREFIX__ = 
__USING_SJLJ_EXCEPTIONS__ = 1
__VERSION__ = "4.1.1"
__WCHAR_MAX__ = 2147483647
__WCHAR_TYPE__ = long int
__WINT_TYPE__ = unsigned int
__i586 = 1
__i586__ = 1
__pentium = 1
__pentium__ = 1
__pic__ = 1
__tune_i586__ = 1
__tune_pentium__ = 1
i386 = 1
unix = 1

Checking other possibilities; should already be listed above:
__DATE__	= "Apr 16 2012"
__FILE__	= "/tmp/def233.c"
__GNUC__	= 4
__LINE__	= 25
__STDC__	= 1
__TIME__	= "11:37:38"

Sizes of basic variable types:
  sizeof(char)           = 8 bits
  sizeof(short)          = 16 bits
  sizeof(int)            = 32 bits
  sizeof(long)           = 32 bits
  sizeof(long long)      = 64 bits
  sizeof(float)          = 32 bits
  sizeof(double)         = 64 bits
  sizeof(long double)    = 96 bits
  sizeof(char *)         = 32 bits
  sizeof(char (*)(char)) = 32 bits