Fix false positive "Expected TypedDict key to be string literal" for Union[TypedDict, dict[K, V]]#21511
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…Union[TypedDict, dict[int, float]] When matching a dict literal against a union type containing both a TypedDict and a plain dict (e.g. `Union[Foo, dict[int, float]]`), `match_typeddict_call_with_dict` was emitting an error while probing whether the literal matched the TypedDict alternative. Suppress errors during matching so they are only reported during actual type checking. Fixes python#21510
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
ilevkivskyi
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May 19, 2026
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OK, this one looks reasonable.
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When a variable is typed as
Union[TypedDict, dict[int, float]], mypy incorrectlyraised
Expected TypedDict key to be string literalwhen assigning a dict literalwith non-string keys like
{1: 5.2}. The plaindict[int, float]alternative makesthe assignment valid, so this was a false positive.
The root cause was that
match_typeddict_call_with_dict, which is used as a probe tocheck whether a dict literal could match a TypedDict, was emitting errors from
validate_typeddict_kwargsduring the matching phase rather than silently returningFalse. Wrapping the call infilter_errors()suppresses those spurious diagnostics.Fixes #21510