All of lore.kernel.org
 help / color / mirror / Atom feed
From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Cc: qemu-arm@nongnu.org, "Alex Bennée" <alex.bennee@linaro.org>,
	patches@linaro.org
Subject: [Qemu-devel] [PATCH] disas/libvixl: Suppress gcc 4.6.3 sign-compare warnings
Date: Tue, 12 Jan 2016 13:10:04 +0000	[thread overview]
Message-ID: <1452604204-27202-1-git-send-email-peter.maydell@linaro.org> (raw)

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.maydell@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

             reply	other threads:[~2016-01-12 13:10 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-12 13:10 Peter Maydell [this message]
2016-01-12 16:35 ` [Qemu-devel] [PATCH] disas/libvixl: Suppress gcc 4.6.3 sign-compare warnings Alex Bennée
2016-01-12 17:36   ` Peter Maydell
2016-01-12 19:37     ` Peter Maydell

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1452604204-27202-1-git-send-email-peter.maydell@linaro.org \
    --to=peter.maydell@linaro.org \
    --cc=alex.bennee@linaro.org \
    --cc=patches@linaro.org \
    --cc=qemu-arm@nongnu.org \
    --cc=qemu-devel@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.