gh-20542: Fix crash in split_for_callable when passing values to variadic generics #20543
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mypy/checkexpr.py
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| return [AnyType(TypeOfAny.from_error)] * len(vars) | ||
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| if not vars or not any(isinstance(v, TypeVarTupleType) for v in vars): |
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What happens if you add or not t.is_type_obj()? Does mypy error later? The error message you added isn't very clear IMO.
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I'm thinking if we added or not t.is_type_obj() to the guard it would return more generic errors. In the test below, the return is Invalid type: try using Literal[1] instead? but with the additional guard I think it would be something like error: Type expected?, which is correct, but not as specific as it could be.
I probably should use the messagebuilder for the error though. :)
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Which one is the current? Neither matches what you have ATM?
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Ah! I'm sorry, I misread what line you were commenting on. You're saying why not turn if not vars or not any(isinstance(v, TypeVarTupleType) for v in vars): to if not vars or not any(isinstance(v, TypeVarTupleType) for v in vars) or not t.is_type_object().
I tried this and we produce the Type application is only supported for generic classes and Invalid type: try using Literal[1] instead? in the test against this part of the code. Looking at it, I'm thinking this is likely a lot cleaner and I would just suggest striking my current changes and changing to simply appending or not t.is_type_object() to line 4966. What do you think?
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Yeah that seems like a better error output, if I'm understanding correctly.
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
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Fixes gh-20542
Small change, previously passing a literal value (fn[1] in the repro case) to a function using
TypeVarTupleassertcaused a crash in split_for_callable incheckexpr.pydue to an assert statement. This PR just replaces the assertion with a proper validation check and error message.