postgresql/config/c-compiler.m4
Tom Lane ea473fb2de Add infrastructure for compile-time assertions about variable types.
Currently, the macros only work with fairly recent gcc versions, but there
is room to expand them to other compilers that have comparable features.

Heavily revised and autoconfiscated version of a patch by Andres Freund.
2012-09-30 14:38:31 -04:00

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# Macros to detect C compiler features
# config/c-compiler.m4
# PGAC_C_SIGNED
# -------------
# Check if the C compiler understands signed types.
AC_DEFUN([PGAC_C_SIGNED],
[AC_CACHE_CHECK(for signed types, pgac_cv_c_signed,
[AC_TRY_COMPILE([],
[signed char c; signed short s; signed int i;],
[pgac_cv_c_signed=yes],
[pgac_cv_c_signed=no])])
if test x"$pgac_cv_c_signed" = xno ; then
AC_DEFINE(signed,, [Define to empty if the C compiler does not understand signed types.])
fi])# PGAC_C_SIGNED
# PGAC_C_INLINE
# -------------
# Check if the C compiler understands inline functions.
# Defines: inline, USE_INLINE
AC_DEFUN([PGAC_C_INLINE],
[AC_C_INLINE
AC_CACHE_CHECK([for quiet inline (no complaint if unreferenced)], pgac_cv_c_inline_quietly,
[pgac_cv_c_inline_quietly=no
if test "$ac_cv_c_inline" != no; then
pgac_c_inline_save_werror=$ac_c_werror_flag
ac_c_werror_flag=yes
AC_LINK_IFELSE([AC_LANG_PROGRAM([static inline int fun () {return 0;}],[])],
[pgac_cv_c_inline_quietly=yes])
ac_c_werror_flag=$pgac_c_inline_save_werror
fi])
if test "$pgac_cv_c_inline_quietly" != no; then
AC_DEFINE_UNQUOTED([USE_INLINE], 1,
[Define to 1 if "static inline" works without unwanted warnings from ]
[compilations where static inline functions are defined but not called.])
fi
])# PGAC_C_INLINE
# PGAC_TYPE_64BIT_INT(TYPE)
# -------------------------
# Check if TYPE is a working 64 bit integer type. Set HAVE_TYPE_64 to
# yes or no respectively, and define HAVE_TYPE_64 if yes.
AC_DEFUN([PGAC_TYPE_64BIT_INT],
[define([Ac_define], [translit([have_$1_64], [a-z *], [A-Z_P])])dnl
define([Ac_cachevar], [translit([pgac_cv_type_$1_64], [ *], [_p])])dnl
AC_CACHE_CHECK([whether $1 is 64 bits], [Ac_cachevar],
[AC_TRY_RUN(
[typedef $1 ac_int64;
/*
* These are globals to discourage the compiler from folding all the
* arithmetic tests down to compile-time constants.
*/
ac_int64 a = 20000001;
ac_int64 b = 40000005;
int does_int64_work()
{
ac_int64 c,d;
if (sizeof(ac_int64) != 8)
return 0; /* definitely not the right size */
/* Do perfunctory checks to see if 64-bit arithmetic seems to work */
c = a * b;
d = (c + b) / b;
if (d != a+1)
return 0;
return 1;
}
main() {
exit(! does_int64_work());
}],
[Ac_cachevar=yes],
[Ac_cachevar=no],
[# If cross-compiling, check the size reported by the compiler and
# trust that the arithmetic works.
AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([], [sizeof($1) == 8])],
Ac_cachevar=yes,
Ac_cachevar=no)])])
Ac_define=$Ac_cachevar
if test x"$Ac_cachevar" = xyes ; then
AC_DEFINE(Ac_define, 1, [Define to 1 if `]$1[' works and is 64 bits.])
fi
undefine([Ac_define])dnl
undefine([Ac_cachevar])dnl
])# PGAC_TYPE_64BIT_INT
# PGAC_C_FUNCNAME_SUPPORT
# -----------------------
# Check if the C compiler understands __func__ (C99) or __FUNCTION__ (gcc).
# Define HAVE_FUNCNAME__FUNC or HAVE_FUNCNAME__FUNCTION accordingly.
AC_DEFUN([PGAC_C_FUNCNAME_SUPPORT],
[AC_CACHE_CHECK(for __func__, pgac_cv_funcname_func_support,
[AC_TRY_COMPILE([#include <stdio.h>],
[printf("%s\n", __func__);],
[pgac_cv_funcname_func_support=yes],
[pgac_cv_funcname_func_support=no])])
if test x"$pgac_cv_funcname_func_support" = xyes ; then
AC_DEFINE(HAVE_FUNCNAME__FUNC, 1,
[Define to 1 if your compiler understands __func__.])
else
AC_CACHE_CHECK(for __FUNCTION__, pgac_cv_funcname_function_support,
[AC_TRY_COMPILE([#include <stdio.h>],
[printf("%s\n", __FUNCTION__);],
[pgac_cv_funcname_function_support=yes],
[pgac_cv_funcname_function_support=no])])
if test x"$pgac_cv_funcname_function_support" = xyes ; then
AC_DEFINE(HAVE_FUNCNAME__FUNCTION, 1,
[Define to 1 if your compiler understands __FUNCTION__.])
fi
fi])# PGAC_C_FUNCNAME_SUPPORT
# PGAC_C_STATIC_ASSERT
# -----------------------
# Check if the C compiler understands _Static_assert(),
# and define HAVE__STATIC_ASSERT if so.
#
# We actually check the syntax ({ _Static_assert(...) }), because we need
# gcc-style compound expressions to be able to wrap the thing into macros.
AC_DEFUN([PGAC_C_STATIC_ASSERT],
[AC_CACHE_CHECK(for _Static_assert, pgac_cv__static_assert,
[AC_TRY_LINK([],
[({ _Static_assert(1, "foo"); })],
[pgac_cv__static_assert=yes],
[pgac_cv__static_assert=no])])
if test x"$pgac_cv__static_assert" = xyes ; then
AC_DEFINE(HAVE__STATIC_ASSERT, 1,
[Define to 1 if your compiler understands _Static_assert.])
fi])# PGAC_C_STATIC_ASSERT
# PGAC_C_TYPES_COMPATIBLE
# -----------------------
# Check if the C compiler understands __builtin_types_compatible_p,
# and define HAVE__BUILTIN_TYPES_COMPATIBLE_P if so.
#
# We check usage with __typeof__, though it's unlikely any compiler would
# have the former and not the latter.
AC_DEFUN([PGAC_C_TYPES_COMPATIBLE],
[AC_CACHE_CHECK(for __builtin_types_compatible_p, pgac_cv__types_compatible,
[AC_TRY_COMPILE([],
[ int x; static int y[__builtin_types_compatible_p(__typeof__(x), int)]; ],
[pgac_cv__types_compatible=yes],
[pgac_cv__types_compatible=no])])
if test x"$pgac_cv__types_compatible" = xyes ; then
AC_DEFINE(HAVE__BUILTIN_TYPES_COMPATIBLE_P, 1,
[Define to 1 if your compiler understands __builtin_types_compatible_p.])
fi])# PGAC_C_TYPES_COMPATIBLE
# PGAC_PROG_CC_CFLAGS_OPT
# -----------------------
# Given a string, check if the compiler supports the string as a
# command-line option. If it does, add the string to CFLAGS.
AC_DEFUN([PGAC_PROG_CC_CFLAGS_OPT],
[define([Ac_cachevar], [AS_TR_SH([pgac_cv_prog_cc_cflags_$1])])dnl
AC_CACHE_CHECK([whether $CC supports $1], [Ac_cachevar],
[pgac_save_CFLAGS=$CFLAGS
CFLAGS="$pgac_save_CFLAGS $1"
ac_save_c_werror_flag=$ac_c_werror_flag
ac_c_werror_flag=yes
_AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
[Ac_cachevar=yes],
[Ac_cachevar=no])
ac_c_werror_flag=$ac_save_c_werror_flag
CFLAGS="$pgac_save_CFLAGS"])
if test x"$Ac_cachevar" = x"yes"; then
CFLAGS="$CFLAGS $1"
fi
undefine([Ac_cachevar])dnl
])# PGAC_PROG_CC_CFLAGS_OPT
# PGAC_PROG_CC_LDFLAGS_OPT
# ------------------------
# Given a string, check if the compiler supports the string as a
# command-line option. If it does, add the string to LDFLAGS.
# For reasons you'd really rather not know about, this checks whether
# you can link to a particular function, not just whether you can link.
# In fact, we must actually check that the resulting program runs :-(
AC_DEFUN([PGAC_PROG_CC_LDFLAGS_OPT],
[define([Ac_cachevar], [AS_TR_SH([pgac_cv_prog_cc_ldflags_$1])])dnl
AC_CACHE_CHECK([whether $CC supports $1], [Ac_cachevar],
[pgac_save_LDFLAGS=$LDFLAGS
LDFLAGS="$pgac_save_LDFLAGS $1"
AC_RUN_IFELSE([AC_LANG_PROGRAM([extern void $2 (); void (*fptr) () = $2;],[])],
[Ac_cachevar=yes],
[Ac_cachevar=no],
[Ac_cachevar="assuming no"])
LDFLAGS="$pgac_save_LDFLAGS"])
if test x"$Ac_cachevar" = x"yes"; then
LDFLAGS="$LDFLAGS $1"
fi
undefine([Ac_cachevar])dnl
])# PGAC_PROG_CC_LDFLAGS_OPT