Re: [Qemu-devel] [PATCH] mingw: fix build on Fedora 22

[Daniel P. Berrange]

On Tue, Sep 22, 2015 at 04:38:31PM +0300, Michael S. Tsirkin wrote:
> mingw on Fedora 22 replaces localtime_r and gmtime_r
> macros with posix compliant functions in time.h.
> 
> These conflict with QEMU supplied ones.
> 
> Detect this and avoid overriding them.
> 
> We also need to define POSIX_C_SOURCE before including
> time.h for the first time, to make sure these
> are available to all users.
> 
> Reported-by: Stefan Hajnoczi <address@hidden>
> Cc: Stefan Weil <address@hidden>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  include/qemu/osdep.h      | 1 +
>  include/sysemu/os-win32.h | 6 ++++++
>  util/oslib-win32.c        | 4 ++++
>  3 files changed, 11 insertions(+)
> 
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index ab3c876..9920ac3 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -25,6 +25,7 @@
>  #ifndef QEMU_OSDEP_H
>  #define QEMU_OSDEP_H
>  
> +#define _POSIX_C_SOURCE 200809L
>  #include "config-host.h"
>  #include "qemu/compiler.h"
>  #include <stdarg.h>
> diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h
> index 706d85a..74230e7 100644
> --- a/include/sysemu/os-win32.h
> +++ b/include/sysemu/os-win32.h
> @@ -72,11 +72,17 @@
>  #define sigsetjmp(env, savemask) setjmp(env)
>  #define siglongjmp(env, val) longjmp(env, val)
>  
> +#ifdef gmtime_r
>  /* Missing POSIX functions. Don't use MinGW-w64 macros. */
>  #undef gmtime_r
> +#define QEMU_NEED_GMTIME_R
>  struct tm *gmtime_r(const time_t *timep, struct tm *result);
> +#endif

I don't think this is right. There are three possibilities
with mingw

 - No gmtime_r at all  - need replacement
 - gmtime_r defined as a macro - need replacement
 - gmtime_r defined as a function - nothing needed

With this change of yours, if gmtime_r is defined as a macro
QEMU will provide its own replacement. If gmtime_r is not
defined at all, then QEMU doesn't provide its replacement
which is wrong. I believe the change I previously proposed
works in all three cases

https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg01926.html

Regards,
Daniel
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