>From 06b20b158ced12812586d94205609435ef29e3db Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Thu, 3 Apr 2014 17:12:39 +0200
Subject: [PATCH 2/3] Fix configure to test more thoroughly for the compiler's
 capabilities.

The old version of the _Static_assert(), variadic macros,
FLEXIBLE_ARRAY_MEMBER tests succeeded, even if the compiler warned
about the usage of the functionality. That lead to very noisy builds
for compilers instructed to warn about nonstandard functionality being
used.
---
 config/c-compiler.m4 | 28 +++++++++++++++++++++++++---
 configure            | 15 +++++++++++++--
 configure.in         |  2 +-
 3 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/config/c-compiler.m4 b/config/c-compiler.m4
index 4ba3236..5c59d37 100644
--- a/config/c-compiler.m4
+++ b/config/c-compiler.m4
@@ -130,14 +130,18 @@ fi])# PGAC_C_FUNCNAME_SUPPORT
 # gcc-style compound expressions to be able to wrap the thing into macros.
 AC_DEFUN([PGAC_C_STATIC_ASSERT],
 [AC_CACHE_CHECK(for _Static_assert, pgac_cv__static_assert,
-[AC_TRY_LINK([],
+[ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+AC_TRY_LINK([],
 [({ _Static_assert(1, "foo"); })],
 [pgac_cv__static_assert=yes],
 [pgac_cv__static_assert=no])])
 if test x"$pgac_cv__static_assert" = xyes ; then
 AC_DEFINE(HAVE__STATIC_ASSERT, 1,
           [Define to 1 if your compiler understands _Static_assert.])
-fi])# PGAC_C_STATIC_ASSERT
+fi
+ac_c_werror_flag=$ac_save_c_werror_flag
+])# PGAC_C_STATIC_ASSERT
 
 
 
@@ -205,12 +209,15 @@ fi])# PGAC_C_BUILTIN_UNREACHABLE
 # and define HAVE__VA_ARGS if so.
 AC_DEFUN([PGAC_C_VA_ARGS],
 [AC_CACHE_CHECK(for __VA_ARGS__, pgac_cv__va_args,
-[AC_TRY_COMPILE([#include <stdio.h>],
+[ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+AC_TRY_COMPILE([#include <stdio.h>],
 [#define debug(...) fprintf(stderr, __VA_ARGS__)
 debug("%s", "blarg");
 ],
 [pgac_cv__va_args=yes],
 [pgac_cv__va_args=no])])
+ac_c_werror_flag=$ac_save_c_werror_flag
 if test x"$pgac_cv__va_args" = xyes ; then
 AC_DEFINE(HAVE__VA_ARGS, 1,
           [Define to 1 if your compiler understands __VA_ARGS__ in macros.])
@@ -289,3 +296,18 @@ if test x"$Ac_cachevar" = x"yes"; then
 fi
 undefine([Ac_cachevar])dnl
 ])# PGAC_PROG_CC_LDFLAGS_OPT
+
+
+# PGAC_C_FLEXIBLE_ARRAY_MEMBER
+# ------------------------
+# Check whether the compiler supports flexible array members. In
+# contrast to the autoconf version we don't accept any warnings
+# because using flexible array members in compilers that warn about
+# them will just result in a very noisy compile.
+AC_DEFUN([PGAC_C_FLEXIBLE_ARRAY_MEMBER],
+[ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+dnl Just use the autoconf test after forcing -Werror
+AC_C_FLEXIBLE_ARRAY_MEMBER()
+ac_c_werror_flag=$ac_save_c_werror_flag
+])# PGAC_C_FLEXIBLE_ARRAY_MEMBER
diff --git a/configure b/configure
index 122ace7..1f3ed0f 100755
--- a/configure
+++ b/configure
@@ -9751,6 +9751,8 @@ _ACEOF
 
 fi
 
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
 
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for flexible array members" >&5
 $as_echo_n "checking for flexible array members... " >&6; }
@@ -9793,6 +9795,8 @@ $as_echo "#define FLEXIBLE_ARRAY_MEMBER /**/" >>confdefs.h
 
   fi
 
+ac_c_werror_flag=$ac_save_c_werror_flag
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for signed types" >&5
 $as_echo_n "checking for signed types... " >&6; }
 if ${pgac_cv_c_signed+:} false; then :
@@ -9889,7 +9893,9 @@ $as_echo_n "checking for _Static_assert... " >&6; }
 if ${pgac_cv__static_assert+:} false; then :
   $as_echo_n "(cached) " >&6
 else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+  ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -9915,6 +9921,8 @@ if test x"$pgac_cv__static_assert" = xyes ; then
 $as_echo "#define HAVE__STATIC_ASSERT 1" >>confdefs.h
 
 fi
+ac_c_werror_flag=$ac_save_c_werror_flag
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_types_compatible_p" >&5
 $as_echo_n "checking for __builtin_types_compatible_p... " >&6; }
 if ${pgac_cv__types_compatible+:} false; then :
@@ -10011,7 +10019,9 @@ $as_echo_n "checking for __VA_ARGS__... " >&6; }
 if ${pgac_cv__va_args+:} false; then :
   $as_echo_n "(cached) " >&6
 else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+  ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <stdio.h>
 int
@@ -10033,6 +10043,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__va_args" >&5
 $as_echo "$pgac_cv__va_args" >&6; }
+ac_c_werror_flag=$ac_save_c_werror_flag
 if test x"$pgac_cv__va_args" = xyes ; then
 
 $as_echo "#define HAVE__VA_ARGS 1" >>confdefs.h
diff --git a/configure.in b/configure.in
index 0f3e0cc..d1651f2 100644
--- a/configure.in
+++ b/configure.in
@@ -1092,7 +1092,7 @@ fi
 m4_defun([AC_PROG_CC_STDC], []) dnl We don't want that.
 AC_C_BIGENDIAN
 PGAC_C_INLINE
-AC_C_FLEXIBLE_ARRAY_MEMBER
+PGAC_C_FLEXIBLE_ARRAY_MEMBER
 PGAC_C_SIGNED
 PGAC_C_FUNCNAME_SUPPORT
 PGAC_C_STATIC_ASSERT
-- 
1.8.5.rc2.dirty