Check type argument scope in constructor self annotation #2242
+108
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Per spec for constructor calls https://typing.python.org/en/latest/spec/constructors.html#init-method > Class-scoped type variables should not be used in the self annotation > because such use can lead to ambiguous or nonsensical type evaluation > results. This diff implements this requirement by adding a specific and targeted check. If a type variable is used in the `self` annotation in the `__init__` method, an error will be raised if the type variable is defined in the class scope.
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Diff from mypy_primer, showing the effect of this PR on open source code: mypy (https://github.com/python/mypy)
+ ERROR mypy/typeshed/stdlib/unittest/mock.pyi:248:13-21: `__init__` method self type cannot reference class type parameter `_T` [invalid-annotation]
+ ::error file=mypy/typeshed/stdlib/unittest/mock.pyi,line=248,col=13,endLine=248,endColumn=21,title=Pyrefly invalid-annotation::`__init__` method self type cannot reference class type parameter `_T`
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Summary
Per spec for constructor calls https://typing.python.org/en/latest/spec/constructors.html#init-method
This diff implements this requirement by adding a specific and targeted check. If a type variable is used in the
selfannotation in the__init__method, an error will be raised if the type variable is defined in the class scope.This gives us another file with passing conformance tests.
Test Plan
Added new test case, checking for type parameters declared via both
Generic[T]and syntax.python test.py