gcc-12.0.1-0.8.fc36 is annoying with false positives.
It's related to g_error() and its `for(;;) ;`.
For example:
../src/libnm-glib-aux/nm-shared-utils.c: In function 'nm_utils_parse_inaddr_bin_full':
../src/libnm-glib-aux/nm-shared-utils.c:1145:26: error: dangling pointer to 'error' may be used [-Werror=dangling-pointer=]
1145 | error->message);
| ^~
/usr/include/glib-2.0/glib/gmessages.h:343:32: note: in definition of macro 'g_error'
343 | __VA_ARGS__); \
| ^~~~~~~~~~~
../src/libnm-glib-aux/nm-shared-utils.c:1133:31: note: 'error' declared here
1133 | gs_free_error GError *error = NULL;
| ^~~~~
/usr/include/glib-2.0/glib/gmessages.h:341:25: error: dangling pointer to 'addrbin' may be used [-Werror=dangling-pointer=]
341 | g_log (G_LOG_DOMAIN, \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
342 | G_LOG_LEVEL_ERROR, \
| ~~~~~~~~~~~~~~~~~~~~~~~
343 | __VA_ARGS__); \
| ~~~~~~~~~~~~
../src/libnm-glib-aux/nm-shared-utils.c:1141:13: note: in expansion of macro 'g_error'
1141 | g_error("unexpected assertion failure: could parse \"%s\" as %s, but not accepted by "
| ^~~~~~~
../src/libnm-glib-aux/nm-shared-utils.c:1112:14: note: 'addrbin' declared here
1112 | NMIPAddr addrbin;
| ^~~~~~~
I think the warning could potentially be useful and prevent real bugs.
So don't disable it altogether, but go through the effort to suppress it
at the places where it currently happens.
Note that NM_PRAGMA_WARNING_DISABLE_DANGLING_POINTER macro only expands
to suppressing the warning with __GNUC__ equal to 12. The purpose is to
only suppress the warning where we know we want to. Hopefully other gcc
versions don't have this problem.
I guess, we could also write a NM_COMPILER_WARNING() check in
"m4/compiler_options.m4", to disable the warning if we detect it. But
that seems too cumbersome.
We use clang-format for automatic formatting of our source files.
Since clang-format is actively maintained software, the actual
formatting depends on the used version of clang-format. That is
unfortunate and painful, but really unavoidable unless clang-format
would be strictly bug-compatible.
So the version that we must use is from the current Fedora release, which
is also tested by our gitlab-ci. Previously, we were using Fedora 34 with
clang-tools-extra-12.0.1-1.fc34.x86_64.
As Fedora 35 comes along, we need to update our formatting as Fedora 35
comes with version "13.0.0~rc1-1.fc35".
An alternative would be to freeze on version 12, but that has different
problems (like, it's cumbersome to rebuild clang 12 on Fedora 35 and it
would be cumbersome for our developers which are on Fedora 35 to use a
clang that they cannot easily install).
The (differently painful) solution is to reformat from time to time, as we
switch to a new Fedora (and thus clang) version.
Usually we would expect that such a reformatting brings minor changes.
But this time, the changes are huge. That is mentioned in the release
notes [1] as
Makes PointerAligment: Right working with AlignConsecutiveDeclarations. (Fixes https://llvm.org/PR27353)
[1] https://releases.llvm.org/13.0.0/tools/clang/docs/ReleaseNotes.html#clang-format
This helper code is already used by several of our unit tests.
Compile it as a separate library.
Previously, the source code lingered unmotivated under "shared/",
which is confusing.
