options: accept backend options as pending on first invocation

They must be there when running re-configuring, because the backend cannot
be changed, but they can be pending on the first invocation.

Signed-off-by: Paolo Bonzini <[email protected]>

Author: bonzini

mesonbuild/options.py

@@ -1362,7 +1362,8 @@ def initialize_from_top_level_project_call(self,
                 else:
                     self.pending_options[key] = valstr
 
-    def accept_as_pending_option(self, key: OptionKey, known_subprojects: T.Optional[T.Union[T.Set[str], T.KeysView[str]]] = None) -> bool:
+    def accept_as_pending_option(self, key: OptionKey, known_subprojects: T.Optional[T.Union[T.Set[str], T.KeysView[str]]] = None,
+                                 first_invocation: bool = False) -> bool:
         # Fail on unknown options that we can know must exist at this point in time.
         # Subproject and compiler options are resolved later.
         #
@@ -1373,6 +1374,8 @@ def accept_as_pending_option(self, key: OptionKey, known_subprojects: T.Optional
                 return True
         if self.is_compiler_option(key):
             return True
+        if first_invocation and self.is_backend_option(key):
+            return True
         return (self.is_base_option(key) and
                 key.evolve(subproject=None, machine=MachineChoice.HOST) in COMPILER_BASE_OPTIONS)
 

unittests/optiontests.py

@@ -224,6 +224,12 @@ def test_b_nonexistent(self):
         self.assertTrue(optstore.accept_as_pending_option(OptionKey('b_ndebug')))
         self.assertFalse(optstore.accept_as_pending_option(OptionKey('b_whatever')))
 
+    def test_backend_option_pending(self):
+        optstore = OptionStore(False)
+        # backend options are known after the first invocation
+        self.assertTrue(optstore.accept_as_pending_option(OptionKey('backend_whatever'), set(), True))
+        self.assertFalse(optstore.accept_as_pending_option(OptionKey('backend_whatever'), set(), False))
+
     def test_reconfigure_b_nonexistent(self):
         optstore = OptionStore(False)
         optstore.set_from_configure_command(['b_ndebug=true'], [])