Consider this file:
test-gcc.c
-------------------------
#if defined(__clang__)
# if __clang_major__ >= 12
# define FENV_ACCESS_ON _Pragma ("STDC FENV_ACCESS ON")
# endif
#elif defined(_MSC_VER)
# define FENV_ACCESS_ON __pragma (fenv_access (on))
#elif defined(__GNUC__)
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34678
# define FENV_ACCESS_ON \
_Pragma ("GCC diagnostic push") \
_Pragma ("GCC diagnostic ignored \"-Wunknown-pragmas\"") \
_Pragma ("STDC FENV_ACCESS ON") \
_Pragma ("GCC diagnostic pop")
#else
# define FENV_ACCESS_ON _Pragma ("STDC FENV_ACCESS ON")
#endif
FENV_ACCESS_ON
-------------------------
When compiling with -Wall I get an "unknown pragma" warning:
test-gcc.c:18: warning: ignoring '#pragma STDC FENV_ACCESS' [-Wunknown-pragmas]
Yet, if I preprocess separately and compile, I don't get any warning:
gcc -E -P test-gcc.c | gcc -c -Wall -xc -
Anyobdy knows why?
Kind regards,
Luca
