Fix base and compiler options not reconfigurable.

WIP:
- need to add tests
- need to handle case when a base option is configured with no compilers
  for it.

Fixes #12920.

mesonbuild/compilers/detect.py

@@ -106,7 +106,7 @@ def detect_compiler_for(env: 'Environment', lang: str, for_machine: MachineChoic
     if comp is None:
         return comp
     assert comp.for_machine == for_machine
-    env.coredata.process_new_compiler(lang, comp, env)
+    env.coredata.process_compiler_options(lang, comp, env)
     if not skip_sanity_check:
         comp.sanity_check(env.get_scratch_dir(), env)
     env.coredata.compilers[comp.for_machine][lang] = comp

mesonbuild/coredata.py

@@ -1017,6 +1017,7 @@ def add_compiler_options(self, options: 'MutableKeyedOptionDictType', lang: str,
             value = env.options.get(k)
             if value is not None:
                 o.set_value(value)
+                self.options[k] = o  # override compiler option on reconfigure
             self.options.setdefault(k, o)
 
     def add_lang_args(self, lang: str, comp: T.Type['Compiler'],
@@ -1028,14 +1029,17 @@ def add_lang_args(self, lang: str, comp: T.Type['Compiler'],
         # `self.options.update()`` is perfectly safe.
         self.options.update(compilers.get_global_options(lang, comp, for_machine, env))
 
-    def process_new_compiler(self, lang: str, comp: 'Compiler', env: 'Environment') -> None:
+    def process_compiler_options(self, lang: str, comp: 'Compiler', env: 'Environment') -> None:
         from . import compilers
 
         self.add_compiler_options(comp.get_options(), lang, comp.for_machine, env)
 
         enabled_opts: T.List[OptionKey] = []
         for key in comp.base_options:
             if key in self.options:
+                if key in env.options:
+                    # Override from commandline, when reconfiguring
+                    self.options[key].set_value(env.options[key])
                 continue
             oobj = copy.deepcopy(compilers.base_options[key])
             if key in env.options:

mesonbuild/interpreter/interpreter.py

@@ -1518,6 +1518,9 @@ def add_languages_for(self, args: T.List[str], required: bool, for_machine: Mach
                         continue
                     else:
                         raise
+            else:
+                # update new values from commandline, if it applies
+                self.coredata.process_compiler_options(lang, comp, self.environment)
 
             # Add per-subproject compiler options. They inherit value from main project.
             if self.subproject:

run_project_tests.py

@@ -981,7 +981,7 @@ def have_working_compiler(lang: str, use_tmp: bool) -> bool:
             return False
         if not compiler:
             return False
-        env.coredata.process_new_compiler(lang, compiler, env)
+        env.coredata.process_compiler_options(lang, compiler, env)
         try:
             compiler.sanity_check(env.get_scratch_dir(), env)
         except mesonlib.MesonException: