[Qemu-devel] [PATCH] build: disable -Wmissing-braces on older compilers

[Paolo Bonzini <pbonzini@redhat.com>]

GCC 4.9 and newer stopped warning for missing braces around the
"universal" C zero initializer {0}.  One such initializer sneaked
into scsi/qemu-pr-helper.c and is breaking the build with such
older GCC versions.

Detect the lack of support for the idiom, and disable the warning
in that case.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
        Of course it's always possible to use "memset", but {0}
        is neater in my opinion.

 configure | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/configure b/configure
index 7766e74125..0b2d595c6e 100755
--- a/configure
+++ b/configure
@@ -1651,6 +1651,19 @@ EOF
   fi
 fi
 
+# Disable -Wmissing-braces on older compilers that warn even for
+# the "universal" C zero initializer {0}.
+cat > $TMPC << EOF
+struct {
+  int a[2];
+} x = {0};
+EOF
+if compile_object "-Werror" "" ; then
+  :
+else
+  QEMU_CFLAGS="$QEMU_CFLAGS -Wno-missing-braces"
+fi
+
 # Workaround for http://gcc.gnu.org/PR55489.  Happens with -fPIE/-fPIC and
 # large functions that use global variables.  The bug is in all releases of
 # GCC, but it became particularly acute in 4.6.x and 4.7.x.  It is fixed in
-- 
2.14.2