Fix unity issues.

mesonbuild/backend/backends.py

@@ -2082,6 +2082,8 @@ def compile_target_to_generator(self, target: build.CompileTarget) -> build.Gene
                                           target.output_templ, target.depends)
 
     def is_unity(self, target: build.BuildTarget) -> bool:
+        if isinstance(target, build.CompileTarget):
+            return False
         val = self.get_target_option(target, 'unity')
         if val == 'on':
             return True

mesonbuild/build.py

@@ -1014,7 +1014,7 @@ def process_link_depends(self, sources):
                     'Link_depends arguments must be strings, Files, '
                     'or a Custom Target, or lists thereof.')
 
-    def extract_objects(self, srclist: T.List[T.Union['FileOrString', 'GeneratedTypes']]) -> ExtractedObjects:
+    def extract_objects(self, srclist: T.List[T.Union['FileOrString', 'GeneratedTypes']], is_unity: bool) -> ExtractedObjects:
         sources_set = set(self.sources)
         generated_set = set(self.generated)
 
@@ -1037,7 +1037,11 @@ def extract_objects(self, srclist: T.List[T.Union['FileOrString', 'GeneratedType
                 obj_gen.append(src)
             else:
                 raise MesonException(f'Object extraction arguments must be strings, Files or targets (got {type(src).__name__}).')
-        return ExtractedObjects(self, obj_src, obj_gen)
+        eobjs =  ExtractedObjects(self, obj_src, obj_gen)
+        if is_unity:
+            eobjs.check_unity_compatible()
+        return eobjs
+
 
     def extract_all_objects(self, recursive: bool = True) -> ExtractedObjects:
         return ExtractedObjects(self, self.sources, self.generated, self.objects,

mesonbuild/interpreter/interpreterobjects.py

@@ -931,10 +931,10 @@ def extract_objects_method(self, args: T.Tuple[T.List[T.Union[mesonlib.FileOrStr
         unity_value = self.interpreter.coredata.get_option_for_target(tobj, "unity")
         if unity_value == 'on' or \
             (unity_value == 'subprojects' and tobj.subproject != ''):
-            raise mesonlib.MesonException(('Single object files cannot be extracted '
-                                           'in Unity builds. You can only extract all '
-                                           'the object files for each compiler at once.'))
-        return tobj.extract_objects(args[0])
+            is_unity = True
+        else:
+            is_unity = False
+        return tobj.extract_objects(args[0], is_unity)
 
     @noPosargs
     @typed_kwargs(