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 are GCC v4.8 and Clang v3.4 now, and both basically support "gnu11" already, this seems to be a good choice. Signed-off-by: Thomas Huth <th...@redhat.com> --- configure | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/configure b/configure index 79375af..07f8105 100755 --- a/configure +++ b/configure @@ -107,6 +107,9 @@ update_cxxflags() { -Wstrict-prototypes|-Wmissing-prototypes|-Wnested-externs|\ -Wold-style-declaration|-Wold-style-definition|-Wredundant-decls) ;; + -std=gnu11) + QEMU_CXXFLAGS=${QEMU_CXXFLAGS:+$QEMU_CXXFLAGS }-std=gnu++11 + ;; *) QEMU_CXXFLAGS=${QEMU_CXXFLAGS:+$QEMU_CXXFLAGS }$arg ;; @@ -585,7 +588,7 @@ ARFLAGS="${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=gnu11 $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