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Fix PEP 695 type alias with mix of type args (PEP 696) #18919

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Merged
merged 1 commit into from
Apr 17, 2025
Merged

Fix PEP 695 type alias with mix of type args (PEP 696) #18919

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2 changes: 1 addition & 1 deletion mypy/semanal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5591,7 +5591,7 @@ def visit_type_alias_stmt(self, s: TypeAliasStmt) -> None:
self.msg.unimported_type_becomes_any("Type alias target", res, s)
res = make_any_non_unimported(res)
eager = self.is_func_scope()
if isinstance(res, ProperType) and isinstance(res, Instance) and not res.args:
if isinstance(res, ProperType) and isinstance(res, Instance):
fix_instance(res, self.fail, self.note, disallow_any=False, options=self.options)
alias_node = TypeAlias(
res,
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21 changes: 20 additions & 1 deletion test-data/unit/check-python313.test
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Original file line number Diff line number Diff line change
Expand Up @@ -219,7 +219,7 @@ def func_a1(
reveal_type(b) # N: Revealed type is "builtins.dict[builtins.float, builtins.str]"
reveal_type(c) # N: Revealed type is "builtins.dict[builtins.float, builtins.float]"
reveal_type(d) # N: Revealed type is "builtins.dict[builtins.int, builtins.str]"
[builtins fixtures/tuple.pyi]
[builtins fixtures/dict.pyi]
[typing fixtures/typing-full.pyi]

[case testPEP695TypeParameterDefaultTypeAlias2]
Expand Down Expand Up @@ -255,3 +255,22 @@ def func_c1(

[builtins fixtures/tuple.pyi]
[typing fixtures/typing-full.pyi]

[case testPEP695TypeParameterDefaultTypeAlias4]
# flags: --disallow-any-generics
class A[L = int, M = str]: ...
TD1 = A[float]
type TD2 = A[float]

def func_d1(
a: TD1,
b: TD1[float], # E: Bad number of arguments for type alias, expected 0, given 1
c: TD2,
d: TD2[float], # E: Bad number of arguments for type alias, expected 0, given 1
) -> None:
reveal_type(a) # N: Revealed type is "__main__.A[builtins.float, builtins.str]"
reveal_type(b) # N: Revealed type is "__main__.A[builtins.float, builtins.str]"
reveal_type(c) # N: Revealed type is "__main__.A[builtins.float, builtins.str]"
reveal_type(d) # N: Revealed type is "__main__.A[builtins.float, builtins.str]"
[builtins fixtures/tuple.pyi]
[typing fixtures/typing-full.pyi]