[3.14] gh-137226: Fix get_type_hints() on generic TypedDict with stringified annotations (GH-138953) #138989
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…h stringified annotations (pythonGH-138953) This issue appears specifically for TypedDicts because the TypedDict constructor code converts string annotations to ForwardRef objects, and those are not evaluated properly by the get_type_hints() stack because of other shenanigans with type parameters. This issue does not affect normal generic classes because their annotations are not pre-converted to ForwardRefs. The fix attempts to restore the pre- pythonGH-137227 behavior in the narrow scenario where the issue manifests. It mostly makes changes only in the paths accessible from get_type_hints(), ensuring that newer APIs (such as evaluate_forward_ref() and annotationlib) are not affected by get_type_hints()'s past odd choices. This PR does not fix issue pythonGH-138949, an older issue I discovered while playing around with this one; we'll need a separate and perhaps more invasive fix for that, but it should wait until after 3.14.0. (cherry picked from commit 6d6aba2) Co-authored-by: Jelle Zijlstra <[email protected]>
This was referenced Sep 16, 2025
AlexWaygood
approved these changes
Sep 16, 2025
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This issue appears specifically for TypedDicts because the TypedDict constructor code converts string annotations to ForwardRef objects, and those are not evaluated properly by the get_type_hints() stack because of other shenanigans with type parameters.
This issue does not affect normal generic classes because their annotations are not pre-converted to ForwardRefs.
The fix attempts to restore the pre- GH-137227 behavior in the narrow scenario where the issue manifests. It mostly makes changes only in the paths accessible from get_type_hints(), ensuring that newer APIs (such as evaluate_forward_ref() and annotationlib) are not affected by get_type_hints()'s past odd choices. This PR does not fix issue GH-138949, an older issue I discovered while playing around with this one; we'll need a separate and perhaps more invasive fix for that, but it should wait until after 3.14.0. (cherry picked from commit 6d6aba2)