take override_option('unity=...') into account when allowing extract_objects()

A single target could be picked for unity build, and in that case
extract_objects() should not be allowed.

Likewise for the opposite case, where extract_objects() should be allowed
if unity build is disabled for a single target.  A test that covers that
case is added later.

1 files changed, 5 insertions, 2 deletions

diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index ceff296..d312abd 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -753,8 +753,6 @@ class BuildTarget(Target):
                  sources: T.List['SourceOutputs'], structured_sources: T.Optional[StructuredSources],
                  objects, environment: environment.Environment, compilers: T.Dict[str, 'Compiler'], kwargs):
         super().__init__(name, subdir, subproject, True, for_machine, environment)
-        unity_opt = environment.coredata.get_option(OptionKey('unity'))
-        self.is_unity = unity_opt == 'on' or (unity_opt == 'subprojects' and subproject != '')
         self.all_compilers = compilers
         self.compilers = OrderedDict() # type: OrderedDict[str, Compiler]
         self.objects: T.List[T.Union[str, 'File', 'ExtractedObjects']] = []
@@ -810,6 +808,11 @@ class BuildTarget(Target):
     def __str__(self):
         return f"{self.name}"
 
+    @property
+    def is_unity(self) -> bool:
+        unity_opt = self.get_option(OptionKey('unity'))
+        return unity_opt == 'on' or (unity_opt == 'subprojects' and self.subproject != '')
+
     def validate_install(self):
         if self.for_machine is MachineChoice.BUILD and self.need_install:
             if self.environment.is_cross_build():