When building libvirt with clang we get bogus warnings about
'double' being promoted to 'long double' when calling isnan().

  https://bugzilla.redhat.com/show_bug.cgi?id=1472437

Detect this broken isnan() / compiler combination and disable
the -Wdouble-promotion flag.
Reviewed-by: NPavel Hrdina <phrdina@redhat.com>
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

GCC 7.1 introduces a new -Wformat-truncation warning
flag that reports if it thinks the maximum possible
size of the formatted output will exceed the provided
fixed buffer. This is enabled automatically by the
-Wformat warning flag. There are quite a few places
hit by this in libvirt which need rewriting. This is
non-trivial work in some places, so temporarily
disable the new warning until those fixes can be
implemented.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Depending on the platform/architecture, a number of conditionals
in libvirt code expand the same on both branches. This is expected
behaviour and harmless, so disable the warning to avoid creating
unexpected build failures

Two examples, mingw32:

../../src/util/vircommand.c: In function 'virCommandWait':
../../src/util/vircommand.c:2562:51: error: this condition has identical branches [-Werror=duplicated-branches]
             *exitstatus = cmd->rawStatus ? status : WEXITSTATUS(status);
                                                   ^
and gcc7.1

In file included from util/virobject.c:28:0:
util/virobject.c: In function 'virClassNew':
util/viratomic.h:176:46: error: this condition has identical branches [-Werror=duplicated-branches]
            (void)(0 ? *(atomic) ^ *(atomic) : 0);                      \
                                             ^
util/virobject.c:144:20: note: in expansion of macro 'virAtomicIntInc'
    klass->magic = virAtomicIntInc(&magicCounter);
                   ^~~~~~~~~~~~~~~
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Introduce STRICT_FRAME_LIMIT_CFLAGS that will be used for
production code and RELAXED_FRAME_LIMIT_CFLAGS for tests.

Raising the limit for tests allows building them with clang
with optimizations disabled.

Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

fdstream.c: In function 'virFDStreamWrite':
fdstream.c:390:29: error: logical 'or' of equal expressions [-Werror=logical-op]
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
                            ^~

Fedora rawhide now uses gcc 6.0 and there is a bug with -Wlogical-op
producing false warnings.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69602

Use GCC pragma push/pop and ignore -Wlogical-op for GCC that supports
push/pop pragma and also has this bug.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

Time to update to new gnulib before a release.

gcc 5.1 introduced a new -Wformat-signedness, and new gnulib now
turns it on by default.  However, it is still rather lame at the
moment, because it warns for enums, even though there is no way
to control the signeness of an enum which does not use any members
that are negative or larger than INT_MAX, and even though such an
enum would always print the same for both %d and %u:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66249

In file included from ../../src/util/virarch.c:26:0:
../../src/util/virarch.c: In function 'virArchFromHost':
../../src/util/virarch.c:180:15: error: format '%d' expects argument of type 'int', but argument 9 has type 'unsigned int' [-Werror=format=]
     VIR_DEBUG("Mapped %s to %d (%s)",

So this patch turns off the new warning as part of enabling all
other new gcc 5.1 warnings that gnulib now enables.

* .gnulib: Update to latest, in part for gcc 5.1 interaction.
* m4/virt-compile-warnings.m4: Ignore -Wformat-signedness, for now.
Signed-off-by: NEric Blake <eblake@redhat.com>

Many GCC versions don't understand -Wno-suggest-attribute=format
so the pragma must only be used when supported

Try -fstack-protector-strong first on Linux. If that fails,
fall back to -fstack-protector-all.

This option only makes sense for -fstack-protector.
With -fstack-protector-all or -fstack-protector-strong,
functions are protected regardless of buffer size.

https://bugzilla.redhat.com/show_bug.cgi?id=1105456

These warnings have already been added to $dontwarn.

I'm using gcc-4.8.2-7.fc21.aarch64 which does not appear to support
this option.

The python binding now lives in

  http://libvirt.org/git/?p=libvirt-python.git

that repo also provides an RPM which is upgrade compatible
with the old libvirt-python sub-RPM.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Since we're about to freeze, it's time to pick up the latest
upstream gnulib.  Among other changes, gnulib now guarantees the
use of some -f flags that we were previously manually adding.

* .gnulib: Update to latest, in part for warning improvements.
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Drop
flags that are now guaranteed by gnulib.
* bootstrap: Resync to gnulib.
Signed-off-by: NEric Blake <eblake@redhat.com>

Rather than inlining gl_WARN_ADD loads of time, we can shave about
17k size off of the configure script by delaying it to a cleanup
shell loop.

* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Track a
list of things to check, rather than inlining multiple checks.
Signed-off-by: NEric Blake <eblake@redhat.com>

https://bugzilla.redhat.com/show_bug.cgi?id=994589 complained that
even when using a cross-compiler not named 'gcc', the configure
output confusingly referred to gcc.

* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Use a
more generic statement in configure output.
Signed-off-by: NEric Blake <eblake@redhat.com>

Partially revert cdd703f4's revert of c1634100, as linking with clang
with --param=ssp-buffer-size=4 still fails with:
"argument unused during compilation".

The latest mingw headers on Fedora 19 fail to build with gnulib
without an update.

Meanwhile, now that upstream gnulib has better handling of -W
probing for clang, we can drop some of our own solutions in
favor of upstream; thus this reverts commit c1634100, "Correctly
detect warning flags with clang".

* .gnulib: Update to latest, for mingw and clang.
Signed-off-by: NEric Blake <eblake@redhat.com>

FreeBSD ships an old gcc 4.2.1 which generates
bogus code, e.g. getsockopt() call returns
struct xucred with bogus values, which doesn't even
allow to connect to libvirtd:

error: Failed to find group record for gid '1284660778': No error: 0

So roll back to just -fstack-protector on FreeBSD.

Automake already passes all CFLAGS to the linker too, so it
is not necessary to set WARN_LDFLAGS in addition to the
WARN_CFLAGS variable.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Clang will happily claim to support any warning flags
unless the -Werror and -Wunknown-warning-option flags
are set. Thus we need to make sure these are set when
testing for clags.

We must also set the clang specific warning flags
-Wno-unused-command-line-argument to avoid a warning
from the ssp-buffer-size flag when linking .o files.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

The virt-compile-warnings.m4 file would do an explicit
check for whether the compile could use the 'diagnostic'
pragma push/pop feature. The src/internal.h file would
then only enable it for GCC >= 4.6

This breaks with clang which supports the pragma but
does not claim GCC 4.6 compat. Export a variable from
the m4 check to the header file so they are consistent.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

There are a number of places which generate cast alignment
warnings, which are difficult or impossible to address. Use
pragmas to disable the warnings in these few places

conf/nwfilter_conf.c: In function 'virNWFilterRuleDetailsParse':
conf/nwfilter_conf.c:1806:16: warning: cast increases required alignment of target type [-Wcast-align]
         item = (nwItemDesc *)((char *)nwf + att[idx].dataIdx);
conf/nwfilter_conf.c: In function 'virNWFilterRuleDefDetailsFormat':
conf/nwfilter_conf.c:3238:16: warning: cast increases required alignment of target type [-Wcast-align]
         item = (nwItemDesc *)((char *)def + att[i].dataIdx);

storage/storage_backend_mpath.c: In function 'virStorageBackendCreateVols':
storage/storage_backend_mpath.c:247:17: warning: cast increases required alignment of target type [-Wcast-align]
         names = (struct dm_names *)(((char *)names) + next);

nwfilter/nwfilter_dhcpsnoop.c: In function 'virNWFilterSnoopDHCPDecode':
nwfilter/nwfilter_dhcpsnoop.c:994:15: warning: cast increases required alignment of target type [-Wcast-align]
         pip = (struct iphdr *) pep->eh_data;
nwfilter/nwfilter_dhcpsnoop.c:1004:11: warning: cast increases required alignment of target type [-Wcast-align]
     pup = (struct udphdr *) ((char *) pip + (pip->ihl << 2));

nwfilter/nwfilter_learnipaddr.c: In function 'procDHCPOpts':
nwfilter/nwfilter_learnipaddr.c:327:33: warning: cast increases required alignment of target type [-Wcast-align]
                 uint32_t *tmp = (uint32_t *)&dhcpopt->value;
nwfilter/nwfilter_learnipaddr.c: In function 'learnIPAddressThread':
nwfilter/nwfilter_learnipaddr.c:501:43: warning: cast increases required alignment of target type [-Wcast-align]
                     struct iphdr *iphdr = (struct iphdr*)(packet +
nwfilter/nwfilter_learnipaddr.c:538:43: warning: cast increases required alignment of target type [-Wcast-align]
                     struct iphdr *iphdr = (struct iphdr*)(packet +
nwfilter/nwfilter_learnipaddr.c:544:48: warning: cast increases required alignment of target type [-Wcast-align]
                         struct udphdr *udphdr= (struct udphdr *)
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Commit 8b8fcdea introduced a check for broken gcc -Wlogical-op,
but did not guard the check against non-gcc compilers, which might
lead to spurious failures when another compiler encounters an
unknown pragma.  Additionally, all of our compiler warning logic
should belong in a single file, and use cache variables to allow
overriding the decision at configure time if necessary.

* configure.ac (BROKEN_GCC_WLOGICALOP): Move...
* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): ...here,
and update to modern autoconf idioms.

Based on this coreutils bug report, since coreutils copied what
libvirt had done:
https://lists.gnu.org/archive/html/bug-coreutils/2012-10/msg00121.html

* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Allow
for user to pre-define _FORTIFY_SOURCE.

Commit c579d6b3 added a sledgehammer to silence spurious warnings from
gcc 4.2, but in the process, it also silenced useful warnings from
gcc 4.3 through 4.5.  As a result, a bug slipped in to commit 0caccb58.

Tested with FreeBSD (gcc 4.2.1), RHEL 6.3 (gcc 4.4), and F17 (gcc 4.7.2),
where the former didn't trip on spurious warnings, and where the latter
two detected a revert of 2b804cfa.

* m4/virt-compile-warnings.m4 (-Wno-format): Probe for the actual
spurious message, to once again allow gcc 4.4 to use -Wformat.

On RHEL 6.2, gcc 4.4.6 complains:
cc1: warning: command line option "-Wenum-compare" is valid for C++/ObjC++ but not for C
which in turn breaks a -Werror build.

Meanwhile, in Fedora 17, gcc 4.7.0, -Wenum-compare has been enhanced
to also work on C, but at the same time, it is documented that -Wall
now implicitly includes -Wenum-compare.

Therefore, it is sufficient to remove explicit checks for this option,
avoiding the warning from older gcc while still getting the
compile-time safety from newer gcc.

* m4/virt-compile-warnings.m4 (-Wenum-compare): Omit explicit check.

OpenBSD ships with gcc 4.2.1, which annoyingly treats all format
strings as though they were also attribute((nonnull)).  The two
concepts are orthogonal, though, as evidenced by the number of
spurious warnings it generates on uses where we know that
virReportError specifically handles NULL instead of a format
string; worse, since we now force -Werror on git builds, it
prevents development builds on OpenBSD.

I hate to do this, as it disables ALL format checking on older
gcc, and therefore misses out on some useful checks (code that
happened to compile on Linux may still have type mismatches
when compiled on other platforms, as evidenced by the number
of times I have fixed formatting mismatches for uid_t as found
by warnings on Cygwin), but I don't see any other way to keep
-Werror alive and still compile on OpenBSD.

A more invasive change would be to make virReportError() mark
its format attribute as nonnull, and fix (a lot of) fallout;
we may end up doing that anyways as part of danpb's error
refactoring improvements, but not today.

* src/internal.h (ATTRIBUTE_FMT_PRINTF): Use preferred spellings.
* m4/virt-compile-warnings.m4 (-Wformat): Disable on older gcc.

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: NEric 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 059d746d 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.