compilers: force clang to error on unknown warning options

[tristan957]

gcc seems to error by default if an unknown warning option is passed to it:

CC=gcc meson setup build -Dc_args=-Wbad

gcc will fail in the project() call during the sanity check. clang does not currently doing that:

CC=clang meson setup build -Dc_args=-Wbad
...will continue until an actual compilation like cc.compiles()

from meson-log.txt...
Sanity check compile stderr:
warning: unknown warning option '-Wbad' [-Wunknown-warning-option]

We should error in the sanity check to notify the user as soon as possible that they have errors in their environment.

[bonzini]

always_args is a pretty heavy hammer. A better choice is to call get_compiler_check_args from _sanity_check_compile_args.

Also it's probably best to take the occasion and synchronize the handling of clang (which adds the arguments in get_compiler_check_args) and clang-cl (which does it in has_arguments).

[dcbaker]

I agree with bonzini, using the sanity check args makes more sense. I'm also concerned putting it in always args is going to break builds of projects that blinding add arguments on "is linux" or "is clang"

[tristan957]

Great suggestions! Here is an update...4 months later 😆.

[tristan957]

This is blocked by #16142.

[thesamesam]

['Failed to import test module: unittests.internaltests\nTraceback (most recent call last):\n File "/usr/lib/python3.14/unittest/loader.py", line 433, in _find_test_path\n module = self._get_module_from_name(name)\n File "/usr/lib/python3.14/unittest/loader.py", line 374, in _get_module_from_name\n import(name)\n ~~~~~~~~~~^^^^^^\n File "/__w/meson/meson/unittests/internaltests.py", line 32\n <<<<<<< HEAD\n ^^\nSyntaxError: invalid syntax\n']

Whoops ;)

[tristan957]

Silly...

[bonzini]

Do not do change-detector tests

I agree with @thesamesam that the change is good, but can you please remove the internaltests change? Having test_sanity_check_fails_on_bad_c_args is enough, which command line arguments are needed on clang/clang-cl to achieve it is not worth being covered by a specific tests.