https://github.com/python/cpython/commit/158dbbb97fffbc47eb446d2b1576ce887e5c1802 commit: 158dbbb97fffbc47eb446d2b1576ce887e5c1802 branch: main author: David Ellis <[email protected]> committer: JelleZijlstra <[email protected]> date: 2026-04-23T06:22:20-07:00 summary:
gh-148680: Replace internal names with type_reprs of objects in string representations of ForwardRef (#148682) Co-authored-by: Shamil <[email protected]> files: A Misc/NEWS.d/next/Library/2026-04-23-07-38-04.gh-issue-148680.___ePl.rst M Lib/annotationlib.py M Lib/test/test_annotationlib.py diff --git a/Lib/annotationlib.py b/Lib/annotationlib.py index 9fee2564114339..5c9a0812646f81 100644 --- a/Lib/annotationlib.py +++ b/Lib/annotationlib.py @@ -47,6 +47,7 @@ class Format(enum.IntEnum): "__cell__", "__owner__", "__stringifier_dict__", + "__resolved_str_cache__", ) @@ -94,6 +95,7 @@ def __init__( # value later. self.__code__ = None self.__ast_node__ = None + self.__resolved_str_cache__ = None def __init_subclass__(cls, /, *args, **kwds): raise TypeError("Cannot subclass ForwardRef") @@ -113,7 +115,7 @@ def evaluate( """ match format: case Format.STRING: - return self.__forward_arg__ + return self.__resolved_str__ case Format.VALUE: is_forwardref_format = False case Format.FORWARDREF: @@ -258,6 +260,24 @@ def __forward_arg__(self): "Attempted to access '__forward_arg__' on an uninitialized ForwardRef" ) + @property + def __resolved_str__(self): + # __forward_arg__ with any names from __extra_names__ replaced + # with the type_repr of the value they represent + if self.__resolved_str_cache__ is None: + resolved_str = self.__forward_arg__ + names = self.__extra_names__ + + if names: + visitor = _ExtraNameFixer(names) + ast_expr = ast.parse(resolved_str, mode="eval").body + node = visitor.visit(ast_expr) + resolved_str = ast.unparse(node) + + self.__resolved_str_cache__ = resolved_str + + return self.__resolved_str_cache__ + @property def __forward_code__(self): if self.__code__ is not None: @@ -321,7 +341,7 @@ def __repr__(self): extra.append(", is_class=True") if self.__owner__ is not None: extra.append(f", owner={self.__owner__!r}") - return f"ForwardRef({self.__forward_arg__!r}{''.join(extra)})" + return f"ForwardRef({self.__resolved_str__!r}{''.join(extra)})" _Template = type(t"") @@ -357,6 +377,7 @@ def __init__( self.__cell__ = cell self.__owner__ = owner self.__stringifier_dict__ = stringifier_dict + self.__resolved_str_cache__ = None # Needed for ForwardRef def __convert_to_ast(self, other): if isinstance(other, _Stringifier): @@ -1163,3 +1184,14 @@ def _get_dunder_annotations(obj): if not isinstance(ann, dict): raise ValueError(f"{obj!r}.__annotations__ is neither a dict nor None") return ann + + +class _ExtraNameFixer(ast.NodeTransformer): + """Fixer for __extra_names__ items in ForwardRef __repr__ and string evaluation""" + def __init__(self, extra_names): + self.extra_names = extra_names + + def visit_Name(self, node: ast.Name): + if (new_name := self.extra_names.get(node.id, _sentinel)) is not _sentinel: + node = ast.Name(id=type_repr(new_name)) + return node diff --git a/Lib/test/test_annotationlib.py b/Lib/test/test_annotationlib.py index 50cf8fcb6b4ed6..77f2a77882fce2 100644 --- a/Lib/test/test_annotationlib.py +++ b/Lib/test/test_annotationlib.py @@ -1961,6 +1961,15 @@ def test_forward_repr(self): "typing.List[ForwardRef('int', owner='class')]", ) + def test_forward_repr_extra_names(self): + def f(a: undefined | str): ... + + annos = get_annotations(f, format=Format.FORWARDREF) + + self.assertRegex( + repr(annos['a']), r"ForwardRef\('undefined \| str'.*\)" + ) + def test_forward_recursion_actually(self): def namespace1(): a = ForwardRef("A") @@ -2037,6 +2046,17 @@ def test_evaluate_string_format(self): fr = ForwardRef("set[Any]") self.assertEqual(fr.evaluate(format=Format.STRING), "set[Any]") + def test_evaluate_string_format_extra_names(self): + # Test that internal extra_names are replaced when evaluating as strings + def f(a: unknown | str | int | list[str] | tuple[int, ...]): ... + + fr = get_annotations(f, format=Format.FORWARDREF)['a'] + # Test the cache is not populated before access + self.assertIsNone(fr.__resolved_str_cache__) + + self.assertEqual(fr.evaluate(format=Format.STRING), "unknown | str | int | list[str] | tuple[int, ...]") + self.assertEqual(fr.__resolved_str_cache__, "unknown | str | int | list[str] | tuple[int, ...]") + def test_evaluate_forwardref_format(self): fr = ForwardRef("undef") evaluated = fr.evaluate(format=Format.FORWARDREF) diff --git a/Misc/NEWS.d/next/Library/2026-04-23-07-38-04.gh-issue-148680.___ePl.rst b/Misc/NEWS.d/next/Library/2026-04-23-07-38-04.gh-issue-148680.___ePl.rst new file mode 100644 index 00000000000000..d3790079545a07 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-04-23-07-38-04.gh-issue-148680.___ePl.rst @@ -0,0 +1 @@ +``ForwardRef`` objects that contain internal names to represent known objects now show the ``type_repr`` of the known object rather than the internal ``__annotationlib_name_x__`` name when evaluated as strings. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
