build: Use python 3.6 annotation syntax for Build initializer

mesonbuild/build.py

@@ -179,18 +179,18 @@ class Build:
         self.project_version = None
         self.environment = environment
         self.projects = {}
-        self.targets = OrderedDict()                  # type: T.Dict[str, 'Target']
-        self.run_target_names = set() # type: T.Set[T.Tuple[str, str]]
-        self.global_args = PerMachine({}, {})         # type: PerMachine[T.Dict[str, T.List[str]]]
-        self.projects_args = PerMachine({}, {})       # type: PerMachine[T.Dict[str, T.List[str]]]
-        self.global_link_args = PerMachine({}, {})    # type: PerMachine[T.Dict[str, T.List[str]]]
-        self.projects_link_args = PerMachine({}, {})  # type: PerMachine[T.Dict[str, T.List[str]]]
-        self.tests = []                               # type: T.List['Test']
-        self.benchmarks = []                          # type: T.List['Test']
+        self.targets: T.MutableMapping[str, 'Target'] = OrderedDict()
+        self.run_target_names: T.Set[T.Tuple[str, str]] = set()
+        self.global_args: PerMachine[T.Dict[str, T.List[str]]] = PerMachine({}, {})
+        self.projects_args: PerMachine[T.Dict[str, T.List[str]]] = PerMachine({}, {})
+        self.global_link_args: PerMachine[T.Dict[str, T.List[str]]] = PerMachine({}, {})
+        self.projects_link_args: PerMachine[T.Dict[str, T.List[str]]] = PerMachine({}, {})
+        self.tests: T.List['Test'] = []
+        self.benchmarks: T.List['Test'] = []
         self.headers: T.List[Headers] = []
         self.man: T.List[Man] = []
         self.data: T.List[Data] = []
-        self.static_linker = PerMachine(None, None)   # type: PerMachine[StaticLinker]
+        self.static_linker: PerMachine[StaticLinker] = PerMachine(None, None)
         self.subprojects = {}
         self.subproject_dir = ''
         self.install_scripts = []
@@ -200,7 +200,7 @@ class Build:
         self.dep_manifest_name = None
         self.dep_manifest = {}
         self.stdlibs = PerMachine({}, {})
-        self.test_setups = {}                         # type: T.Dict[str, TestSetup]
+        self.test_setups: T.Dict[str, TestSetup] = {}
         self.test_setup_default_name = None
         self.find_overrides = {}
         self.searched_programs = set() # The list of all programs that have been searched for.