The VIXL code includes some equality comparisons between signed and unsigned types. Modern gcc and clang do not complain about these, but older versions of gcc such as gcc 4.6.3 do. Since libvixl is an upstream library, the simplest approach is to suppress the warnings by applying -Wno-sign-compare to the relevant files.
(GCC 4.6 is not quite yet irrelevant for us; it is the gcc shipped with Ubuntu Precise, for example, which is an LTS release not yet out of its support period.) Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> --- I had mistakenly thought these warnings only happened with the totally ancient mingw gcc, but it turns out they're a bit more widespread. In particular this is causing our Travis builds to fail: https://travis-ci.org/qemu/qemu/jobs/101813358 If somebody could review this then I'll apply it to master as a buildfix. --- disas/Makefile.objs | 5 ++++- disas/libvixl/Makefile.objs | 4 +++- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/disas/Makefile.objs b/disas/Makefile.objs index 8dae4da..abeba84 100644 --- a/disas/Makefile.objs +++ b/disas/Makefile.objs @@ -4,7 +4,10 @@ common-obj-$(CONFIG_ARM_DIS) += arm.o common-obj-$(CONFIG_ARM_A64_DIS) += arm-a64.o common-obj-$(CONFIG_ARM_A64_DIS) += libvixl/ libvixldir = $(SRC_PATH)/disas/libvixl -arm-a64.o-cflags := -I$(libvixldir) +# The -Wno-sign-compare is needed only for gcc 4.6, which complains about +# some signed-unsigned equality comparisons in libvixl which later gcc +# versions do not. +arm-a64.o-cflags := -I$(libvixldir) -Wno-sign-compare common-obj-$(CONFIG_CRIS_DIS) += cris.o common-obj-$(CONFIG_HPPA_DIS) += hppa.o common-obj-$(CONFIG_I386_DIS) += i386.o diff --git a/disas/libvixl/Makefile.objs b/disas/libvixl/Makefile.objs index e373cf0..d1e801a 100644 --- a/disas/libvixl/Makefile.objs +++ b/disas/libvixl/Makefile.objs @@ -4,6 +4,8 @@ libvixl_OBJS = vixl/utils.o \ vixl/a64/decoder-a64.o \ vixl/a64/disasm-a64.o -$(addprefix $(obj)/,$(libvixl_OBJS)): QEMU_CFLAGS := -I$(SRC_PATH)/disas/libvixl $(QEMU_CFLAGS) +# The -Wno-sign-compare is needed only for gcc 4.6, which complains about +# some signed-unsigned equality comparisons which later gcc versions do not. +$(addprefix $(obj)/,$(libvixl_OBJS)): QEMU_CFLAGS := -I$(SRC_PATH)/disas/libvixl -Wno-sign-compare $(QEMU_CFLAGS) common-obj-$(CONFIG_ARM_A64_DIS) += $(libvixl_OBJS) -- 1.9.1
