MSVC: Fix an "incompatible pointer types" compiler warning

In particular, the following warning is issued while compiling
compat/msvc.c:

    ...mingw.c(223) : warning C4133: 'function' : incompatible \
types - from '_stati64 *' to '_stat64 *'

which relates to a call of _fstati64() in the mingw_fstat()
function definition.

This is caused by various layers of macro magic and attempts to
avoid macro redefinition compiler warnings. For example, the call
to _fstati64() mentioned above is actually a call to _fstat64(),
and expects a pointer to a struct _stat64 rather than the struct
_stati64 which is passed to mingw_fstat().

The definition of struct _stati64 given in compat/msvc.h had the
same "shape" as the definition of struct _stat64, so the call to
_fstat64() does not actually cause any runtime errors, but the
structure types are indeed incompatible.

In order to avoid the compiler warning, we add declarations for the
mingw_lstat() and mingw_fstat() functions and supporting macros to
msvc.h, suppressing the corresponding declarations in mingw.h, so
that we can use the appropriate structure type (and function) names
from the msvc headers.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/compat/mingw.h b/compat/mingw.h
index a105dc9a2..afe12ea55 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -209,13 +209,15 @@ int mingw_getpagesize(void);
  * mingw_fstat() instead of fstat() on Windows.
  */
 #define off_t off64_t
-#define stat _stati64
 #define lseek _lseeki64
+#ifndef ALREADY_DECLARED_STAT_FUNCS
+#define stat _stati64
 int mingw_lstat(const char *file_name, struct stat *buf);
 int mingw_fstat(int fd, struct stat *buf);
 #define fstat mingw_fstat
 #define lstat mingw_lstat
 #define _stati64(x,y) mingw_lstat(x,y)
+#endif
 
 int mingw_utime(const char *file_name, const struct utimbuf *times);
 #define utime mingw_utime