Defer checking of Final so that it can be used with Annotated.

Also tweaks a couple of initializers to let __repr__ work during construction.

Fixes #1110

PiperOrigin-RevId: 424194421

pytype/abstract/_instances.py

@@ -581,8 +581,8 @@ class AnnotationsDict(Dict):
   """__annotations__ dict."""
 
   def __init__(self, annotated_locals, ctx):
-    super().__init__(ctx)
     self.annotated_locals = annotated_locals
+    super().__init__(ctx)
 
   def get_type(self, node, name):
     if name not in self.annotated_locals:

pytype/abstract/_interpreter_function.py

@@ -448,6 +448,7 @@ def __init__(self, name, def_opcode, code, f_locals, f_globals, defaults,
       self.nonstararg_count += self.code.co_kwonlyargcount
     signature = self._build_signature(name, annotations)
     super().__init__(signature, ctx)
+    self._check_annotations(name, annotations)
     self._update_signature_scope()
     self.last_frame = None  # for BuildClass
     self._store_call_records = False
@@ -464,6 +465,13 @@ def record_calls(self):
     yield
     self._store_call_records = old
 
+  def _check_annotations(self, name, annotations):
+    """Validate function annotations."""
+    for ann in annotations.values():
+      if isinstance(ann, _typing.FinalAnnotation):
+        self.ctx.errorlog.invalid_final_type(
+            self.ctx.vm.simple_stack(self.def_opcode))
+
   def _build_signature(self, name, annotations):
     """Build a function.Signature object representing this function."""
     vararg_name = None

pytype/abstract/_typing.py

@@ -422,10 +422,10 @@ def __init__(self, options, ctx):
     self.options = list(options)
     self.cls = self._get_class()
     self.formal = any(t.formal for t in self.options)
+    self._printing = False
     mixin.NestedAnnotation.init_mixin(self)
     mixin.HasSlots.init_mixin(self)
     self.set_slot("__getitem__", self.getitem_slot)
-    self._printing = False
 
   def __repr__(self):
     if self._printing:  # recursion detected
@@ -672,5 +672,4 @@ def __repr__(self):
     return f"Final[{self.annotation}]"
 
   def instantiate(self, node, container=None):
-    self.ctx.errorlog.invalid_final_type(self.ctx.vm.frames)
-    return self.annotation.to_variable(node)
+    return self.to_variable(node)

pytype/tests/test_final.py

@@ -247,10 +247,10 @@ def f(x: Final[int]):  # final-error[e]
         pass
       def g(x: Final):  # final-error
         pass
-      def h(x) -> Final[int]:
-        pass  # bad-return-type # final-error
+      def h(x) -> Final[int]:  # final-error
+        pass  # bad-return-type
       def i(x) -> Final:
-        pass  # bad-return-type # final-error
+        pass  # bad-return-type  # final-error
     """)
     self.assertErrorSequences(
         err, {"e": ["only be used", "assignments", "variable annotations"]})
@@ -262,6 +262,13 @@ def test_cannot_use_in_type_params(self):
       y: Tuple[int, Final[int]] = (1, 2)  # invalid-annotation  # final-error
     """)
 
+  def test_can_use_in_annotated(self):
+    self.CheckWithErrors("""
+      from typing import Annotated, Final, List
+      x: Annotated[Final[List[int]], 'valid'] = [10]
+      y: Annotated[List[Final[int]], 'invalid'] = [10]  # invalid-annotation  # final-error
+    """)
+
 
 class TestFinalDecoratorInPyi(test_base.BaseTest):
   """Test @final in pyi files."""