bpo-45166: fixes get_type_hints failure on Final

python · ambv · Sep 25, 2021 · Sep 10, 2021 · Sep 23, 2021 · Sep 24, 2021
commit 1d46e26aed40340a0f4a3442ec0cb9d431f139f5
diff --git a/Lib/test/ann_module5.py b/Lib/test/ann_module5.py
@@ -0,0 +1,8 @@
+from __future__ import annotations
+
+from typing import Final
+
+name: Final[str] = "final"
+
+class MyClass:
+    value: Final = 3000
@@ -2975,7 +2975,7 @@ async def __aexit__(self, etype, eval, tb):
 
 # Definitions needed for features introduced in Python 3.6
 
-from test import ann_module, ann_module2, ann_module3
+from test import ann_module, ann_module2, ann_module3, ann_module5
 from typing import AsyncContextManager
 
 class A:
@@ -3339,6 +3339,14 @@ class C(Generic[T]): pass
                          (
8000
Concatenate[int, P], int))
         self.assertEqual(get_args(list | str), (list, str))
 
+    def test_forward_ref_and_final(self):
+        # https://bugs.python.org/issue45166
+        hints = get_type_hints(ann_module5)
+        self.assertEqual(hints, {'name': Final[str]})
+
+        hints = get_type_hints(ann_module5.MyClass)
+        self.assertEqual(hints, {'value': Final})
+
 
 class CollectionsAbcTests(BaseTestCase):
 

@@ -171,7 +171,7 @@ def _type_check(arg, msg, is_argument=True, module=None):
     if (isinstance(arg, _GenericAlias) and
             arg.__origin__ in invalid_generic_forms):
         raise TypeError(f"{arg} is not valid as type argument")
-    if arg in (Any, NoReturn):
+    if arg in (Any, NoReturn, Final):
         return arg
     if isinstance(arg, _SpecialForm) or arg in (Generic, Protocol):
         raise TypeError(f"Plain {arg} is not valid as type argument")
@@ -1831,7 +1831,8 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False):
         if value is None:
             value = type(None)
         if isinstance(value, str):
-            value = ForwardRef(value)
+            value = ForwardRef(
+                value, is_argument=not isinstance(obj, types.ModuleType))
         value = _eval_type(value, globalns, localns)
         if name in defaults and defaults[name] is None:
             value = Optional[value]

diff --git a/Misc/NEWS.d/next/Library/2021-09-10-21-35-53.bpo-45166.UHipXF.rst b/Misc/NEWS.d/next/Library/2021-09-10-21-35-53.bpo-45166.UHipXF.rst
@@ -0,0 +1,2 @@
+Fixes that ``Final`` wrapped in ``ForwardRef`` was failing during
+``get_type_hints``.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Fixes that ``Final`` wrapped in ``ForwardRef`` was failing during
		``get_type_hints``.
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