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Use union for captured vars in or pattern #19710

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Merged
merged 1 commit into from
Aug 22, 2025
Merged

Use union for captured vars in or pattern #19710

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2 changes: 1 addition & 1 deletion mypy/checkpattern.py
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Original file line number Diff line number Diff line change
Expand Up @@ -192,7 +192,7 @@ def visit_or_pattern(self, o: OrPattern) -> PatternType:
for capture_list in capture_types.values():
typ = UninhabitedType()
for _, other in capture_list:
typ = join_types(typ, other)
typ = make_simplified_union([typ, other])

captures[capture_list[0][0]] = typ

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8 changes: 4 additions & 4 deletions test-data/unit/check-python310.test
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Expand Up @@ -1204,13 +1204,13 @@ match m:
case 1 | "foo":
reveal_type(m) # N: Revealed type is "Union[Literal[1], Literal['foo']]"

[case testMatchOrPatterCapturesMissing]
[case testMatchOrPatternCapturesMissing]
from typing import List
m: List[int]

match m:
case [x, y] | list(x): # E: Alternative patterns bind different names
reveal_type(x) # N: Revealed type is "builtins.object"
reveal_type(x) # N: Revealed type is "Union[builtins.int, builtins.list[builtins.int]]"
reveal_type(y) # N: Revealed type is "builtins.int"
[builtins fixtures/list.pyi]

Expand All @@ -1219,7 +1219,7 @@ m: object

match m:
case list(x) | dict(x):
reveal_type(x) # N: Revealed type is "typing.Iterable[Any]"
reveal_type(x) # N: Revealed type is "Union[builtins.list[Any], builtins.dict[Any, Any]]"
[builtins fixtures/dict.pyi]

-- Interactions --
Expand Down Expand Up @@ -1405,7 +1405,7 @@ m: Union[str, bytes, int]

match m:
case str(a) | bytes(a):
reveal_type(a) # N: Revealed type is "builtins.object"
reveal_type(a) # N: Revealed type is "Union[builtins.str, builtins.bytes]"
reveal_type(m) # N: Revealed type is "Union[builtins.str, builtins.bytes]"
case b:
reveal_type(b) # N: Revealed type is "builtins.int"
Expand Down
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