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Add redundant-annotation warning #20238

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Add redundant-annotation warning #20238

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5910e0d
Add redundant-annotation warning
grayjk Nov 14, 2025
a72ba7a
use is_class_var
grayjk Nov 15, 2025
593d4e0
skip bare ClassVar
grayjk Nov 15, 2025
d851922
correct context for --pretty
grayjk Nov 15, 2025
1082552
add confval
grayjk Nov 16, 2025
ebf40a5
additional tests
grayjk Nov 16, 2025
32a696f
func local
grayjk Nov 24, 2025
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skip bare ClassVar
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@grayjk
grayjk committed Nov 15, 2025
commit 593d4e097612e48b2169c443ae24f0ffa1bc09ea
8 changes: 6 additions & 2 deletions mypy/checker.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3271,8 +3271,12 @@ def check_redundant_annotation(self, s: AssignmentStmt) -> None:
and not is_same_type(s.type, AnyType(TypeOfAny.special_form))
and is_same_type(s.type, self.expr_checker.accept(s.rvalue))
):
# skip ClassVar
if any(isinstance(lvalue, NameExpr) and is_class_var(lvalue) for lvalue in s.lvalues):
# skip bare ClassVar
if (
any(isinstance(lvalue, NameExpr) and is_class_var(lvalue) for lvalue in s.lvalues)
and isinstance(s.unanalyzed_type, UnboundType)
and not s.unanalyzed_type.args
):
return

# skip dataclass and NamedTuple
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14 changes: 10 additions & 4 deletions test-data/unit/check-warnings.test
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Expand Up @@ -78,14 +78,20 @@ b: int = a
[out]
main:3: error: Annotation "int" is redundant (inferred type is the same)

[case testRedundantAnnotationSkips]
[case testRedundantAnnotationClassVar]
# flags: --warn-redundant-annotation
from dataclasses import dataclass
from typing import ClassVar, NamedTuple
from typing import ClassVar

class a:
b: ClassVar[int] = 1
c: ClassVar = 1
c: ClassVar = "test"
[out]
main:5: error: Annotation "int" is redundant (inferred type is the same)

[case testRedundantAnnotationSkips]
# flags: --warn-redundant-annotation
from dataclasses import dataclass
from typing import NamedTuple

class d(NamedTuple):
e: int = 1
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