# - Finds C99 standard support
# This internally calls the check_c_source_compiles macro to determine the
# appropriate flags for a C99 standard compilation.
 
#=============================================================================
# Copyright 2013 Ian Liu Rodrigues <ian.liu88@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#=============================================================================
 
include(CheckCSourceCompiles)
  
set(C99_C_TEST_SOURCE
"#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 _Bool
test_varargs (const char *format, ...)
{
va_list args;
va_start (args, format);
va_list args_copy;
va_copy (args_copy, args);
 
const char *str = NULL;
int number = 0;
float fnumber = 0.0;
 
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);
 
return (number != 0) && (str != NULL) && (fnumber != 0.0);
}
 
int
main ()
{
 
// Check bool.
_Bool success = false;
 
// Check restrict.
if (test_restrict (\"String literal\") == 0)
success = true;
char *restrict newvar = \"Another string\";
 
// Check varargs.
if (!test_varargs (\"s, d' f .\", \"string\", 65, 34.234))
  success = false;
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);
 
;
return 0;
}")
 
set(C99_C_FLAG_CANDIDATES
" "
"-std=gnu99"
"-c99"
"-AC99"
"-xc99=all"
"-qlanglvl=extc99"
)
 
if(DEFINED C99_C_FLAGS)
set(C99_C_FLAG_CANDIDATES)
endif(DEFINED C99_C_FLAGS)
 
set(SAFE_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
foreach(FLAG ${C99_C_FLAG_CANDIDATES})
set(CMAKE_REQUIRED_FLAGS "${FLAG}")
unset(C99_FLAG_DETECTED CACHE)
message(STATUS "Try C99 C flag = [${FLAG}]")
check_c_source_compiles("${C99_C_TEST_SOURCE}" C99_FLAG_DETECTED)
if(C99_FLAG_DETECTED)
set(C99_C_FLAGS_INTERNAL "${FLAG}")
break()
endif(C99_FLAG_DETECTED)
endforeach(FLAG ${C99_C_FLAG_CANDIDATES})
set(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
 
set(C99_C_FLAGS "${C99_C_FLAGS_INTERNAL}"
CACHE STRING "C compiler flags for C99 standard")
 
mark_as_advanced(C99_C_FLAGS)