Commit 7be41675 authored by Thomas Huth's avatar Thomas Huth
Browse files

configure: Force the C standard to gnu99 

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: default avatarPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: default avatarGreg Kurz <groug@kaod.org>
Reviewed-by: default avatarDaniel P. Berrangé <berrange@redhat.com>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarThomas Huth <thuth@redhat.com>
parent e81e7b52

configure

+4 −1
Original line number Diff line number Diff line
@@ -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

                ;;
@@ -584,7 +587,7 @@ 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"