ForkWith the latest MinGW runtime 5.2, this one-line program:
#include <stdio.h>
doesn't compile if GCC is invoked with a -std= option:
D:\usr\eli\data>gcc -std=c9x -c stdio.c
In file included from stdio.c:1:0:
d:\usr\include\stdio.h:790:34: error: unknown type name '__off64_t'
typedef union { __int64 __value; __off64_t __offset; } fpos_t;
^~~~~~~~~
AFAICT, this happens because stdio.h does this:
#if !(defined __STRICT_ANSI__ || defined (__NO_MINGW_LFS)) \
&& defined (__MSVCRT__)
/* ...while this is required to support our fseeko64() and ftello64()
* implementations, (neither of which is in any way standardized)...
*/
# define __need___off64_t
#endif
/* It is sufficient to test for just one define from each of the two
* preceding groups...
*/
#if defined __need_off_t || defined __need___off64_t
/* ...to identify a requirement for selective inclusion of one or more
* of these type definitions from "sys/types.h"; (note that we use the
* #include "..." form here, to ensure that we get the correct header
* file, relative to the location of this <stdio.h>).
*/
# include "sys/types.h"
#endif
followed by this:
#ifdef __MSVCRT__
typedef union { __int64 __value; __off64_t __offset; } fpos_t;
#else
typedef union { __int32 __value; __off32_t __offset; } fpos_t;
#endif
IOW, __off64_t is defined (in sys/types.h) only if __STRICT_ANSI__ is
_not_ defined, but is then used regardless of __STRICT_ANSI__.
I didn't actually try, but a similar problem will probably happen if
someone uses -std=, but also wants to use the MinGW implementation of
fseek (which also uses the __off64_t data type).