Fix for issue 5355

compiler.get_supported_arguments reports success for certain unsupported
   flags when using the gnu C/ObjC, C++/ObjC++ compilers.  This fix reads
   the stderr on the has_arguments check to ensure the arguments really are
   supported and not valid for the language selection

mesonbuild/compilers/mixins/gnu.py

@@ -334,3 +334,15 @@ class GnuCompiler(GnuLikeCompiler):
 
     def openmp_flags(self) -> typing.List[str]:
         return ['-fopenmp']
+
+    def has_arguments(self, args, env, code, mode):
+        # For some compiler command line arguments, the GNU compilers will
+        # emit a warning on stderr indicating that an option is valid for a
+        # another language, but still complete with exit_success
+        with self._build_wrapper(code, env, args, None, mode, disable_cache=False, want_output=True) as p:
+            result = p.returncode == 0
+            if self.language in {'cpp', 'objcpp'} and 'is valid for C/ObjC' in p.stde:
+                result = False
+            if self.language in {'c', 'objc'} and 'is valid for C++/ObjC++' in p.stde:
+                result = False
+        return result, p.cached