[Qemu-devel] [PATCH v2] configure: Force the C standard to gnu99

[Thomas Huth]

Different versions of GCC and Clang use different versions of the C standard.
This repeatedly caused problems already, e.g. with duplicated typedefs:

 https://lists.gnu.org/archive/html/qemu-devel/2018-11/msg05829.html

or with for-loop variable initializers:

 https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg00237.html

To avoid these problems, we should enforce the C language version to the
same level for all compilers. Since our minimum compiler versions is
GCC v4.8, our best option is "gnu99" right now ("gnu17" is not available
there yet, and "gnu11" is marked as "experimental").

Signed-off-by: Thomas Huth <address@hidden>
---
 v2: Use gnu99 instead of gnu11

 configure | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index b9f34af..721ade7 100755
--- a/configure
+++ b/configure
@@ -105,7 +105,8 @@ update_cxxflags() {
     for arg in $QEMU_CFLAGS; do
         case $arg in
             -Wstrict-prototypes|-Wmissing-prototypes|-Wnested-externs|\
-            -Wold-style-declaration|-Wold-style-definition|-Wredundant-decls)
+            -Wold-style-declaration|-Wold-style-definition|-Wredundant-decls|\
+            -std=gnu99)
                 ;;
             *)
                 QEMU_CXXFLAGS=${QEMU_CXXFLAGS:+$QEMU_CXXFLAGS }$arg
@@ -585,7 +586,7 @@ ARFLAGS="${ARFLAGS-rv}"
 # left shift of signed integers is well defined and has the expected
 # 2s-complement style results. (Both clang and gcc agree that it
 # provides these semantics.)
-QEMU_CFLAGS="-fno-strict-aliasing -fno-common -fwrapv $QEMU_CFLAGS"
+QEMU_CFLAGS="-fno-strict-aliasing -fno-common -fwrapv -std=gnu99 $QEMU_CFLAGS"
 QEMU_CFLAGS="-Wall -Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS"
 QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
 QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE 
$QEMU_CFLAGS"
-- 
1.8.3.1