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" for C code right now ("gnu17" is not available there yet, and "gnu11" is marked as "experimental"), and "gnu++98" for the few C++ code that we have in the repository. Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> Reviewed-by: Richard Henderson <richard.hender...@linaro.org> Signed-off-by: Thomas Huth <th...@redhat.com> --- configure | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/configure b/configure index 8049b71..f4078f6 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=gnu99) + QEMU_CXXFLAGS=${QEMU_CXXFLAGS:+$QEMU_CXXFLAGS }"-std=gnu++98" + ;; *) 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=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
