[PATCH] strerror_r-posix: Another fix, for HAVE_DECL_STRERROR_R on mingw

[Eric Blake]

Commit 5ddd9d7 improved strerror_r on glibc systems (where
STRERROR_R_CHAR_P was defined twice with different values), but
missed mingw systems (where HAVE_DECL_STRERROR_R is now defined
twice with different values).  Avoid the AC_CHECK_DECLS[_ONCE]
and AC_CHECK_FUNCS[_ONCE] m4 macros that call AC_DEFINE under the
hood, and instead limit our checks to just setting shell witnesses,
so that compilation on mingw doesn't trigger warnings (and mess up
subsequent tests that use -Werror) about a redefined C preprocessor
macro.

* m4/strerror_r.m4 (gl_FUNC_STRERROR_R, gl_FUNC_STRERROR_R_WORKS):
Avoid calling macros that may supply a conflicting AC_DEFINE().

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog        |  6 ++++++
 m4/strerror_r.m4 | 10 ++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 4eaad70..93be4e9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-14  Eric Blake  <address@hidden>
+
+       strerror_r-posix: Another fix, for HAVE_DECL_STRERROR_R on mingw.
+       * m4/strerror_r.m4 (gl_FUNC_STRERROR_R, gl_FUNC_STRERROR_R_WORKS):
+       Avoid _ONCE variants, which may supply a conflicting AC_DEFINE().
+
 2016-11-14  Pádraig Brady  <address@hidden>

        strptime: fix compile error in recent change
diff --git a/m4/strerror_r.m4 b/m4/strerror_r.m4
index 7fd08a8..aa0ea44 100644
--- a/m4/strerror_r.m4
+++ b/m4/strerror_r.m4
@@ -1,4 +1,4 @@
-# strerror_r.m4 serial 17
+# strerror_r.m4 serial 18
 dnl Copyright (C) 2002, 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,
@@ -14,10 +14,8 @@ AC_DEFUN([gl_FUNC_STRERROR_R],

   dnl Some systems don't declare strerror_r() if _THREAD_SAFE and _REENTRANT
   dnl are not defined.
-  AC_CHECK_DECLS_ONCE([strerror_r])
-  if test $ac_cv_have_decl_strerror_r = no; then
-    HAVE_DECL_STRERROR_R=0
-  fi
+  AC_CHECK_DECL([strerror_r],
+    [HAVE_DECL_STRERROR_R=1], [HAVE_DECL_STRERROR_R=0])
   AC_DEFINE_UNQUOTED([HAVE_DECL_STRERROR_R_ORIG], [$HAVE_DECL_STRERROR_R],
     [Define to 1 if you have the declaration of 'strerror_r' in the system 
include files, or to 0 otherwise.])

@@ -70,7 +68,7 @@ AC_DEFUN([gl_FUNC_STRERROR_R_WORKS],
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   AC_REQUIRE([gl_FUNC_STRERROR_0])

-  AC_CHECK_FUNCS_ONCE([strerror_r])
+  AC_CHECK_FUNC([strerror_r])
   if test $ac_cv_func_strerror_r = yes; then
     if test "$ERRNO_H:$REPLACE_STRERROR_0" = :0; then
       dnl The POSIX prototype is:  int strerror_r (int, char *, size_t);
-- 
2.7.4