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Admit that **kwargs mapping subtypes may have no direct type parameters #18850

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Merged
merged 1 commit into from
Mar 29, 2025
Merged

Admit that **kwargs mapping subtypes may have no direct type parameters #18850

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6 changes: 2 additions & 4 deletions mypy/argmap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -249,10 +249,8 @@ def expand_actual_type(
formal_name = (set(actual_type.items.keys()) - self.kwargs_used).pop()
self.kwargs_used.add(formal_name)
return actual_type.items[formal_name]
elif (
isinstance(actual_type, Instance)
and len(actual_type.args) > 1
and is_subtype(actual_type, self.context.mapping_type)
elif isinstance(actual_type, Instance) and is_subtype(
actual_type, self.context.mapping_type
):
# Only `Mapping` type can be unpacked with `**`.
# Other types will produce an error somewhere else.
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2 changes: 1 addition & 1 deletion test-data/unit/check-kwargs.test
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Expand Up @@ -345,7 +345,7 @@ from typing import Mapping
class MappingSubclass(Mapping[str, str]): pass
def f(**kwargs: 'A') -> None: pass
d: MappingSubclass
f(**d)
f(**d) # E: Argument 1 to "f" has incompatible type "**MappingSubclass"; expected "A"
class A: pass
[builtins fixtures/dict.pyi]

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