Mesa (master): mesa/autoconf: attempt to use gnu99 on older gcc compilers

[Dave Airlie]

Module: Mesa
Branch: master
Commit: ea9ae5d51abb057ca5c200620da46f7339d07617
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ea9ae5d51abb057ca5c200620da46f7339d07617

Author: Dave Airlie <airlied at redhat.com>
Date:   Wed Jan 21 16:40:26 2015 +1000

mesa/autoconf: attempt to use gnu99 on older gcc compilers

anonymous structs/union don't work with c99 but do work with gnu99
on gcc 4.4.

Signed-off-by: Dave Airlie <airlied at redhat.com>

---

 configure.ac |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 2b7f576..c2d775e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -145,6 +145,7 @@ AC_MSG_RESULT([$acv_mesa_CLANG])
 dnl If we're using GCC, make sure that it is at least version 4.2.0.  Older
 dnl versions are explictly not supported.
 GEN_ASM_OFFSETS=no
+USE_GNU99=no
 if test "x$GCC" = xyes -a "x$acv_mesa_CLANG" = xno; then
     AC_MSG_CHECKING([whether gcc version is sufficient])
     major=0
@@ -163,6 +164,9 @@ if test "x$GCC" = xyes -a "x$acv_mesa_CLANG" = xno; then
         AC_MSG_RESULT([yes])
     fi
 
+    if test $GCC_VERSION_MAJOR -lt 4 -o $GCC_VERSION_MAJOR -eq 4 -a $GCC_VERSION_MINOR -lt 6 ; then
+        USE_GNU99=yes
+    fi
     if test "x$cross_compiling" = xyes; then
         GEN_ASM_OFFSETS=yes
     fi
@@ -221,7 +225,13 @@ esac
 
 dnl Add flags for gcc and g++
 if test "x$GCC" = xyes; then
-    CFLAGS="$CFLAGS -Wall -std=c99"
+    CFLAGS="$CFLAGS -Wall"
+
+    if test "x$USE_GNU99" = xyes; then
+	CFLAGS="$CFLAGS -std=gnu99"
+    else
+	CFLAGS="$CFLAGS -std=c99"
+    fi
 
     # Enable -Werror=implicit-function-declaration and
     # -Werror=missing-prototypes, if available, or otherwise, just