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# AC_PROG_CC_C99 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
# ----------------------------------------------------------------
# If the C compiler is not in ISO C99 mode by default, try to add an
# option to output variable CC to make it so. This macro tries
# various options that select ISO C99 on some system or another. It
# considers the compiler to be in ISO C99 mode if it handles _Bool,
# // comments, flexible array members, inline, long long int, mixed
# code and declarations, named initialization of structs, restrict,
# va_copy, varargs macros, variable declarations in for loops and
# variable length arrays.
AC_DEFUN([AC_PROG_CC_C99],
[AC_C_STD_TRY([c99],
[[#include <stdarg.h>
#include <stdbool.h>
#include <stdlib.h>
#include <wchar.h>
#include <stdio.h>
// Check varargs macros. These examples are taken from C99 6.10.3.5.
#define debug(...) fprintf (stderr, __VA_ARGS__)
#define showlist(...) puts (#__VA_ARGS__)
#define report(test,...) ((test) ? puts (#test) : printf (__VA_ARGS__))
static void
test_varargs_macros (void)
{
int x = 1234;
int y = 5678;
debug ("Flag");
debug ("X = %d\n", x);
showlist (The first, second, and third items.);
report (x>y, "x is %d but y is %d", x, y);
}
// Check long long types.
#define BIG64 18446744073709551615ull
#define BIG32 4294967295ul
#define BIG_OK (BIG64 / BIG32 == 4294967297ull && BIG64 % BIG32 == 0)
#if !BIG_OK
your preprocessor is broken;
#endif
#if BIG_OK
#else
your preprocessor is broken;
#endif
static long long int bignum = -9223372036854775807LL;
static unsigned long long int ubignum = BIG64;
struct incomplete_array
{
int datasize;
double data[];
};
struct named_init {
int number;
const wchar_t *name;
double average;
};
typedef const char *ccp;
static inline int
test_restrict (ccp restrict text)
{
// See if C++-style comments work.
// Iterate through items via the restricted pointer.
// Also check for declarations in for loops.
for (unsigned int i = 0; *(text+i) != '\0'; ++i)
continue;
return 0;
}
// Check varargs and va_copy.
static void
test_varargs (const char *format, ...)
{
va_list args;
va_start (args, format);
va_list args_copy;
va_copy (args_copy, args);
const char *str;
int number;
float fnumber;
while (*format)
{
switch (*format++)
{
case 's': // string
str = va_arg (args_copy, const char *);
break;
case 'd': // int
number = va_arg (args_copy, int);
break;
case 'f': // float
fnumber = va_arg (args_copy, double);
break;
default:
break;
}
}
va_end (args_copy);
va_end (args);
}
]],
[[
// Check bool.
_Bool success = false;
// Check restrict.
if (test_restrict ("String literal") == 0)
success = true;
char *restrict newvar = "Another string";
// Check varargs.
test_varargs ("s, d' f .", "string", 65, 34.234);
test_varargs_macros ();
// Check flexible array members.
struct incomplete_array *ia =
malloc (sizeof (struct incomplete_array) + (sizeof (double) * 10));
ia->datasize = 10;
for (int i = 0; i < ia->datasize; ++i)
ia->data[i] = i * 1.234;
// Check named initializers.
struct named_init ni = {
.number = 34,
.name = L"Test wide string",
.average = 543.34343,
};
ni.number = 58;
int dynamic_array[ni.number];
dynamic_array[ni.number - 1] = 543;
// work around unused variable warnings
return (!success || bignum == 0LL || ubignum == 0uLL || newvar[0] == 'x'
|| dynamic_array[ni.number - 1] != 543);
]],
dnl Try
dnl GCC -std=gnu99 (unused restrictive modes: -std=c99 -std=iso9899:1999)
dnl AIX -qlanglvl=extc99 (unused restrictive mode: -qlanglvl=stdc99)
dnl Intel ICC -c99
dnl IRIX -c99
dnl Solaris (unused because it causes the compiler to assume C99 semantics for
dnl library functions, and this is invalid before Solaris 10: -xc99)
dnl Tru64 -c99
dnl with extended modes being tried first.
[[-std=gnu99 -c99 -qlanglvl=extc99]], [$1], [$2])[]dnl
])# AC_PROG_CC_C99
# AC_C_STD_TRY(STANDARD, TEST-PROLOGUE, TEST-BODY, OPTION-LIST,
# ACTION-IF-AVAILABLE, ACTION-IF-UNAVAILABLE)
# --------------------------------------------------------------
# Check whether the C compiler accepts features of STANDARD (e.g `c89', `c99')
# by trying to compile a program of TEST-PROLOGUE and TEST-BODY. If this fails,
# try again with each compiler option in the space-separated OPTION-LIST; if one
# helps, append it to CC. If eventually successful, run ACTION-IF-AVAILABLE,
# else ACTION-IF-UNAVAILABLE.
AC_DEFUN([AC_C_STD_TRY],
[AC_MSG_CHECKING([for $CC option to accept ISO ]m4_translit($1, [c], [C]))
AC_CACHE_VAL(ac_cv_prog_cc_$1,
[ac_cv_prog_cc_$1=no
ac_save_CC=$CC
AC_LANG_CONFTEST([AC_LANG_PROGRAM([$2], [$3])])
for ac_arg in '' $4
do
CC="$ac_save_CC $ac_arg"
_AC_COMPILE_IFELSE([], [ac_cv_prog_cc_$1=$ac_arg])
test "x$ac_cv_prog_cc_$1" != "xno" && break
done
rm -f conftest.$ac_ext
CC=$ac_save_CC
])# AC_CACHE_VAL
case "x$ac_cv_prog_cc_$1" in
x)
AC_MSG_RESULT([none needed]) ;;
xno)
AC_MSG_RESULT([unsupported]) ;;
*)
CC="$CC $ac_cv_prog_cc_$1"
AC_MSG_RESULT([$ac_cv_prog_cc_$1]) ;;
esac
AS_IF([test "x$ac_cv_prog_cc_$1" != xno], [$5], [$6])
])# AC_C_STD_TRY
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