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fixed Incorrect type of enum in 'if' clause #20234 #20248

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fixed Incorrect type of enum in 'if' clause #20234 #20248

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b778ff0
fixed Incorrect type of enum in 'if' clause #20234
sherlock2215 Nov 17, 2025
2ea2c81
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Nov 17, 2025
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25 changes: 24 additions & 1 deletion mypy/checker.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6517,7 +6517,6 @@ def comparison_type_narrowing_helper(self, node: ComparisonExpr) -> tuple[TypeMa
# Step 1: Obtain the types of each operand and whether or not we can
# narrow their types. (For example, we shouldn't try narrowing the
# types of literal string or enum expressions).

operands = [collapse_walrus(x) for x in node.operands]
operand_types = []
narrowable_operand_index_to_hash = {}
Expand Down Expand Up @@ -6593,6 +6592,30 @@ def comparison_type_narrowing_helper(self, node: ComparisonExpr) -> tuple[TypeMa
and is_overlapping_erased_types(item_type, collection_item_type)
):
if_map[operands[left_index]] = remove_optional(item_type)
if_map[operands[left_index]] = remove_optional(item_type)
literal_types = []
if isinstance(get_proper_type(iterable_type), TupleType):
Comment on lines +6596 to +6597
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@grayjk grayjk Nov 17, 2025

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Suggested change
literal_types = []
if isinstance(get_proper_type(iterable_type), TupleType):
if isinstance(get_proper_type(iterable_type), TupleType):
literal_types = []

# Check if this is an enum instance that can be narrowed
tuple_type = get_proper_type(iterable_type)
for i, item_type in enumerate(tuple_type.items):
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@grayjk grayjk Nov 17, 2025

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Suggested change
for i, item_type in enumerate(tuple_type.items):
for item_type in tuple_type.items:

if isinstance(item_type, Instance):

if item_type.type.is_enum:
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@grayjk grayjk Nov 17, 2025

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combine with the previous if statement (line 6601)

# Enum values in tuples are represented as Instance types, not LiteralType
if (
hasattr(item_type, "last_known_value")
and item_type.last_known_value
):
# Use the existing literal representation
literal_types.append(item_type.last_known_value)
else:
# using the instance directly
literal_types.append(item_type)
# If we found enum literals in the tuple, narrow the left operand
if literal_types:
union_type = make_simplified_union(literal_types)
# Applying type narrowing for the true branch of the 'in' check
if_map[operands[left_index]] = union_type

if right_index in narrowable_operand_index_to_hash:
if_type, else_type = self.conditional_types_for_iterable(
Expand Down
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