[Qemu-devel] [Bug 1826172] Re: Compilation on MSYS2/MinGW-w64 fails with error: "__USE_MINGW_ANSI_STDIO" redefined

[Thomas Huth]

** Changed in: qemu
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1826172

Title:
  Compilation on MSYS2/MinGW-w64 fails with error:
  "__USE_MINGW_ANSI_STDIO" redefined

Status in QEMU:
  Fix Released

Bug description:
  Compilation against GIT master fails at the following step:

    CC      qga/commands.o
  In file included from qga/commands.c:13:
  C:/Tempy-chan/qemu/include/qemu/osdep.h:97: error: "__USE_MINGW_ANSI_STDIO" 
redefined [-Werror]
   #define __USE_MINGW_ANSI_STDIO 1

  In file included from C:/msys64/mingw64/x86_64-w64-mingw32/include/vadefs.h:9,
                   from 
C:/msys64/mingw64/x86_64-w64-mingw32/include/_mingw_stdarg.h:14,
                   from 
C:/msys64/mingw64/x86_64-w64-mingw32/include/stdarg.h:140,
                   from 
C:/msys64/mingw64/lib/gcc/x86_64-w64-mingw32/8.3.0/include/stdarg.h:1,
                   from C:/Tempy-chan/qemu/include/qemu/osdep.h:88,
                   from qga/commands.c:13:
  C:/msys64/mingw64/x86_64-w64-mingw32/include/_mingw.h:431: note: this is the 
location of the previous definition
   #define __USE_MINGW_ANSI_STDIO 0      /* was not defined so it should be 0 */

  cc1.exe: all warnings being treated as errors
  make: *** [/c/Tempy-chan/qemu/rules.mak:69: qga/commands.o] Error 1

  Passing --extra-cflags="-D__USE_MINGW_ANSI_STDIO" to configure
  resolves the error. Digging deeper in
  x86_64-w64-mingw32/include/_mingw.h, it looks like
  __USE_MINGW_ANSI_STDIO is only defined for _GNU_SOURCE in C++
  compilation. With C only code it's ignored and doesn't define
  __USE_MINGW_ANSI_STDIO as expected:

  /* We are activating __USE_MINGW_ANSI_STDIO for various define indicators.
     Note that we enable it also for _GNU_SOURCE in C++, but not for C case. */
  #if (defined (_POSIX) || defined (_POSIX_SOURCE) || defined (_POSIX_C_SOURCE) 
\
       || defined (_ISOC99_SOURCE) \
       || defined (_XOPEN_SOURCE) || defined (_XOPEN_SOURCE_EXTENDED) \
       || (defined (_GNU_SOURCE) && defined (__cplusplus)) \
       || defined (_SVID_SOURCE)) \
      && !defined(__USE_MINGW_ANSI_STDIO)
  /* Enable __USE_MINGW_ANSI_STDIO if _POSIX defined
   * and If user did _not_ specify it explicitly... */
  #  define __USE_MINGW_ANSI_STDIO                      1
  #endif

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