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Date: Fri, 05 Jun 2015 19:18:53 +0200
From: Stefan Weil <sw@weilnetz.de>
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Subject: Re: [Qemu-devel] Redundant redeclaration of 'gmtime_r' with mingw64
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>

Am 05.06.2015 um 16:38 schrieb Stefan Hajnoczi:
> Hi Stefan,
> I get the following compiler warning in Fedora 22
> (mingw32-headers-4.0.2-1.fc22):
>
> In file included from qemu/include/qemu-common.h:47:0,
>                   from qemu/include/qemu/timer.h:5,
>                   from qemu/include/sysemu/sysemu.h:8,
>                   from os-win32.c:34:
> qemu/include/sysemu/os-win32.h:77:12: warning: redundant redeclaration
> of 'gmtime_r' [-Wredundant-decls]
>   struct tm *gmtime_r(const time_t *timep, struct tm *result);
>              ^
> In file included from os-win32.c:30:0:
> /usr/i686-w64-mingw32/sys-root/mingw/include/time.h:272:107: note:
> previous definition of 'gmtime_r' was here
>
> QEMU has its own (non-reentrant) gmtime_r() and localtime_r()
> functions on Windows.  os-win32.h redefines the functions so the
> compiler is right to complain.
>
> I thought about adding qemu_gmtime_r() and qemu_localtime_r()
> functions to avoid the name clash.
>
> Do you have any new thoughts on this commit which introduced the
> os-win32.h definitions?

The version provided by Debian Jessie (mingw-w64 3.2.0)
still uses macros to implement those functions - that's why
I don't see that compiler warnings.

I'd prefer a solution which conditionally includes the QEMU
declaration (include/sysemu/os-win32.h) and the implementation
(util/oslib-win32.c), either depending on the mingw-w64 version
or on the result of a configuration check done while running
configure.

Regards
Stefan