A previous patch (c606671a) pulled in a newer version of
stat-time.h from gnulib, which causes some warnings in older gcc:
CC libvirt_driver_storage_la-storage_backend.lo
cc1: warnings being treated as errors
In file included from ../../src/storage/storage_backend.c:59:
../../gnulib/lib/stat-time.h:55: error: no previous prototype for 'get_stat_atime_ns' [-Wmissing-prototypes]
Upstream gnulib argues that these warnings are stupid (and I agree;
see <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113>), and has
used a modern gcc feature (#pragma GCC diagnostic push) to avoid the
warning. But we still aim to compile on RHEL 6.3, with gcc 4.4.6
(not to mention even older platforms like RHEL 5), and therefore
the warning trips up our default of development with -Werror.
It took me a while to figure out how to make our set of warnings
smaller on older gcc without losing the benefit of the warnings
when using newer gcc (such as the one on Fedora 17), but this
should do the trick.
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Avoid
warnings that gnulib can't silence on older gcc.
The access, birth, modification and change times are added to
storage volumes and corresponding xml representations. This
shows up in the XML in this format:
<timestamps>
<atime>1341933637.027319099</atime>
<mtime>1341933637.027319099</mtime>
</timestamps>
Signed-off-by: Eric Blake <eblake@redhat.com>
While libvirt intentionally avoids -Wundef (after all, C99
guarantees sane semantics of treating undefined macros as 0),
the glibc insanity of #warning on _FORTIFY_SOURCE coupled with
what some people feel is the black magic of autoconf means
that other projects are likely to copy our snippet verbatim.
We can be nicer to other projects by making it easier to
integrate into projects that use -Wundef.
Suggested by Christophe Fergeau.
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Be nice
to other projects using -Wundef.
glibc 2.15 (on Fedora 17) coupled with explicit disabling of
optimization during development dies a painful death:
In file included from /usr/include/limits.h:27:0,
from /usr/lib/gcc/x86_64-redhat-linux/4.7.0/include/limits.h:169,
from /usr/lib/gcc/x86_64-redhat-linux/4.7.0/include/syslimits.h:7,
from /usr/lib/gcc/x86_64-redhat-linux/4.7.0/include/limits.h:34,
from util/bitmap.c:26:
/usr/include/features.h:314:4: error: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Werror=cpp]
cc1: all warnings being treated as errors
Work around this by only conditionally defining _FORTIFY_SOURCE,
in the case where glibc can actually use it. The trick is using
AH_VERBATIM instead of AC_DEFINE.
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Squelch
_FORTIFY_SOURCE when needed to avoid glibc #warnings.
Given that we auto-detect whether each -Wxxxx flag is supported by
GCC, and we are warning-free and use automake silent rules, there
is no compelling reason to allow compile warnings to be disabled.
Replace the --enable-compile-warnings flag with a simpler
--enable-werror flag, which defaults to 'yes' if building
from GIT, or 'no' if building from tar.gz
This helps ensure that everyone writing patches for libvirt will
take care to fix their warning problems before submitting for
review
* autobuild.sh: Force -Werror
* configure.ac: Update for LIBVIRT_COMPILE_WARNINGS macro change
* m4/virt-compile-warnings.m4: Permanently enable all warnings,
auto-enable Werror for GIT builds
Gnulib claims that there are some classes of warnings that are
worth enabling during development, but where silencing those
warnings causes code bloat that is not necessary in an optimized
build. The code bloat to silence the warnings is only enabled
by -Dlint. Follow the lead of coreutils in setting up -Dlint
whenever full warnings are requested.
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Add
-Dlint, and move _FORTIFY_SOURCE to config.h instead of CFLAGS.
Older gcc warns (on every file!) that -Wabi and -Wdeprecated only
make sense on C++ projects. Newer gcc accepts these warnings for
C, but it is not clear that they can do anything useful, so it
is easier to just drop the warnings altogether.
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Silence
-Wabi and -Wdeprecated on older gcc.
Reported by Peter Krempa.
I had previously tested commit 059d746 with -O intentionally omitted
from my CFLAGS; but that means that I missed out on this warning
from gcc 4.6.2 when optimizations are enabled:
util/buf.c: In function 'virBufferGetIndent':
util/buf.c:86:1: error: function might be candidate for attribute 'pure' [-Werror=suggest-attribute=pure]
While it is probably a good idea to add the attributes and silence
this warning, it's also invasive; 'make -k' found more than 75 such
complaints. And it doesn't help that gcc 4.6.2 is still buggy
(coreutils reported a case where gcc 4.6.2 incorrectly suggested
marking a function pure that incremented a global variable; fixed
in gcc 4.7). So the best fix for now is to disable the warning.
It also doesn't help that I stumbled across another problem - gcc
documents that -Wsuggest-attribute=pure only warns if you use -O,
or if you use -fipa-pure-const. But in practice, when I omitted -O
but added -fipa-pure-const, the warnings are fickle - I got warnings
for simple compilation that disappeared when I also added -fPIC.
And the way libtool compiles things is with -fPIC first, then without
-fPIC but with errors sent to /dev/null - which meant that without
disabling -Wsuggest-attribute=pure, I got a compile error with no
message. :( See http://debbugs.gnu.org/cgi/bugreport.cgi?bug=10197
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Silence
-Wsuggest-attribute warnings for now.
* .gnulib: Update to latest, for improved 'make syntax-check' and
compiler warnings.
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS):
Re-silence -Wformat-nonliteral.
* cfg.mk (_test_script_regex): Recognize our test scripts.
* gnulib/local/lib/*.diff: Drop, now that gnulib has this.
* tests/virsh-optparse: Fix use of compare.
* tests/virsh-schedinfo: Likewise.
Make virtTestLoadFile allocate the buffer to read the file into.
Fix logic error in virtTestLoadFile, stop reading on the first empty line.
Use virFileReadLimFD in virtTestCaptureProgramOutput to avoid manual
buffer handling.
Make it so we don't have to 'git add -f' particular files like
po/POTFILES.in all the time (tested by fixing one of our
special-case files as part of the patch).
* .gnulib: Update to latest.
* bootstrap: Resync from coreutils.
* .gitignore: Sort whitelist entries correctly, including ignoring
files rather than directories.
* m4/virt-compile-warnings.m4: Convert tabs to space.
With gcc 4.3.4 I'm seeing the following warning failure
cc1: warnings being treated as errors
cc1: error: -funit-at-a-time is required for inlining of functions
that are only called once [-Wdisabled-optimization]
Add -funit-at-a-time to WARN_CFLAGS.
The GCC Win32 compiler will claim to support -fstack-protector,
but if it actually gets triggered by a suitable code pattern,
linking will fail. Other non-Linux OS likely suffer the same
way with gcc.
* m4/virt-compile-warnings.m4: Only use stack protector when
the build target is Linux.
A couple of functions were declared using the old style foo()
for no-parameters, instead of foo(void)
* src/xen/xen_hypervisor.c, tests/testutils.c: Replace () with (void)
in some function declarations
* m4/virt-compile-warnings.m4: Enable -Wold-style-definition
Split the bit acinclude.m4 file into smaller pieces named
as m4/virt-XXXXX.m4
* .gitignore: Ignore gettext related files
* acinclude.m4: Delete
* m4/virt-compile-warnings.m4: Checks for GCC compiler flags
* m4/virt-pkgconfig-back-compat.m4: Backcompat check for
pkgconfig program
