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gh-136316: Make typing.evaluate_forward_ref better at evaluating nested forwardrefs (#136319)
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4 files changed

+23
-3
lines changed

4 files changed

+23
-3
lines changed

Lib/test/test_typing.py

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Original file line numberDiff line numberDiff line change
@@ -7326,6 +7326,12 @@ def test_partial_evaluation(self):
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list[EqualToForwardRef('A')],
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)
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def test_with_module(self):
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from test.typinganndata import fwdref_module
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typing.evaluate_forward_ref(
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fwdref_module.fw,)
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class CollectionsAbcTests(BaseTestCase):
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@@ -0,0 +1,6 @@
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from typing import ForwardRef
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MyList = list[int]
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MyDict = dict[str, 'MyList']
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fw = ForwardRef('MyDict', module=__name__)

Lib/typing.py

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -438,7 +438,7 @@ def __repr__(self):
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def _eval_type(t, globalns, localns, type_params, *, recursive_guard=frozenset(),
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format=None, owner=None):
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format=None, owner=None, parent_fwdref=None):
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"""Evaluate all forward references in the given type t.
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For use of globalns and localns see the docstring for get_type_hints().
@@ -456,7 +456,7 @@ def _eval_type(t, globalns, localns, type_params, *, recursive_guard=frozenset()
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if isinstance(t, (_GenericAlias, GenericAlias, Union)):
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if isinstance(t, GenericAlias):
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args = tuple(
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_make_forward_ref(arg) if isinstance(arg, str) else arg
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_make_forward_ref(arg, parent_fwdref=parent_fwdref) if isinstance(arg, str) else arg
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for arg in t.__args__
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)
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else:
@@ -936,7 +936,12 @@ def run(arg: Child | Unrelated):
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return _GenericAlias(self, (item,))
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def _make_forward_ref(code, **kwargs):
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def _make_forward_ref(code, *, parent_fwdref=None, **kwargs):
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if parent_fwdref is not None:
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if parent_fwdref.__forward_module__ is not None:
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kwargs['module'] = parent_fwdref.__forward_module__
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if parent_fwdref.__owner__ is not None:
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kwargs['owner'] = parent_fwdref.__owner__
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forward_ref = _lazy_annotationlib.ForwardRef(code, **kwargs)
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# For compatibility, eagerly compile the forwardref's code.
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forward_ref.__forward_code__
@@ -1001,6 +1006,7 @@ def evaluate_forward_ref(
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recursive_guard=_recursive_guard | {forward_ref.__forward_arg__},
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format=format,
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owner=owner,
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parent_fwdref=forward_ref,
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)
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@@ -0,0 +1,2 @@
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Improve support for evaluating nested forward references in
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:func:`typing.evaluate_forward_ref`.

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