[PATCH] stdio: don't redefine __USE_MINGW_ANSI_STDIO

[Paul Eggert]

* m4/stdio_h.m4 (gl_STDIO_H): Don't define __USE_MINGW_ANSI_STDIO
if it is already defined.  Apparently GNU Emacs relies on this.  See:
http://lists.gnu.org/archive/html/emacs-devel/2016-09/msg00416.html
---
 ChangeLog     |  7 +++++++
 m4/stdio_h.m4 | 10 ++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 8d0b408..6609e2b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-09-16  Paul Eggert  <address@hidden>
+
+       stdio: don't redefine __USE_MINGW_ANSI_STDIO
+       * m4/stdio_h.m4 (gl_STDIO_H): Don't define __USE_MINGW_ANSI_STDIO
+       if it is already defined.  Apparently GNU Emacs relies on this.  See:
+       http://lists.gnu.org/archive/html/emacs-devel/2016-09/msg00416.html
+
 2016-09-15  Eric Blake  <address@hidden>
 
        sys_types: avoid glibc 2.25 warnings about major()
diff --git a/m4/stdio_h.m4 b/m4/stdio_h.m4
index 5149981..eaa25a0 100644
--- a/m4/stdio_h.m4
+++ b/m4/stdio_h.m4
@@ -1,4 +1,4 @@
-# stdio_h.m4 serial 47
+# stdio_h.m4 serial 48
 dnl Copyright (C) 2007-2016 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,7 +6,13 @@ dnl with or without modifications, as long as this notice is 
preserved.
 
 AC_DEFUN([gl_STDIO_H],
 [
-  AC_DEFINE([__USE_MINGW_ANSI_STDIO], 1, [Use GNU style printf and scanf.])
+  AH_VERBATIM([MINGW_ANSI_STDIO],
+[/* Use GNU style printf and scanf.  */
+#ifndef __USE_MINGW_ANSI_STDIO
+# undef __USE_MINGW_ANSI_STDIO
+#endif
+])
+  AC_DEFINE([__USE_MINGW_ANSI_STDIO])
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   gl_NEXT_HEADERS([stdio.h])
 
-- 
2.7.4