8000 Additional validation for TypeVar defaults (PEP 696) by cdce8p · Pull Request #15442 · python/mypy · GitHub
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Additional validation for TypeVar defaults (PEP 696) #15442

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Merged
merged 2 commits into from
Jun 15, 2023
Merged

Additional validation for TypeVar defaults (PEP 696) #15442

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cebfe02
Additional TypeVar defaults validation
cdce8p Mar 12, 2023
7d039a4
Fix __match_args__ for TypeVarLikeExpr
cdce8p Jun 7, 2023
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Additional TypeVar defaults validation
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@cdce8p
cdce8p committed Jun 15, 2023
commit cebfe024b4582cbdf61edd1acb042205396d458d
9 changes: 9 additions & 0 deletions mypy/checkexpr.py
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9 changes: 9 additions & 0 deletions test-data/unit/check-typevar-defaults.test
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Original file line number Diff line number Diff line change
Expand Up @@ -5197,6 +5197,15 @@ def visit_temp_node(self, e: TempNode) -> Type:
return e.type

def visit_type_var_expr(self, e: TypeVarExpr) -> Type:
p_default = get_proper_type(e.default)
if not (
isinstance(p_default, AnyType)
and p_default.type_of_any == TypeOfAny.from_omitted_generics
):
if not is_subtype(p_default, e.upper_bound):
self.chk.fail("TypeVar default must be a subtype of the bound type", e)
if e.values and not any(p_default == value for value in e.values):
self.chk.fail("TypeVar default must be one of the constraint types", e)
return AnyType(TypeOfAny.special_form)

def visit_paramspec_expr(self, e: ParamSpecExpr) -> Type:
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Original file line number Diff line number Diff line change
Expand Up @@ -72,3 +72,12 @@ Ts1 = TypeVarTuple("Ts1", default=2) # E: The default argument to TypeVarTuple m
Ts2 = TypeVarTuple("Ts2", default=int) # E: The default argument to TypeVarTuple must be an Unpacked tuple
Ts3 = TypeVarTuple("Ts3", default=Tuple[int]) # E: The default argument to TypeVarTuple must be an Unpacked tuple
[builtins fixtures/tuple.pyi]

[case testTypeVarDefaultsInvalid2]
from typing import TypeVar, List, Union

T1 = TypeVar("T1", bound=str, default=int) # E: TypeVar default must be a subtype of the bound type
T2 = TypeVar("T2", bound=List[str], default=List[int]) # E: TypeVar default must be a subtype of the bound type
T3 = TypeVar("T3", int, str, default=bytes) # E: TypeVar default must be one of the constraint types
T4 = TypeVar("T4", int, str, default=Union[int, str]) # E: TypeVar default must be one of the constraint types
T5 = TypeVar("T5", float, str, default=int) # E: TypeVar default must be one of the constraint types
0