Fix narrowing on match with function subject #16503
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Fixes python#12998 mypy can't narrow match statements with functions subjects because the callexpr node is not a literal node. This adds a 'dummy' literal node that the match statement visitor can use to do the type narrowing. The python grammar describes the the match subject as a named expression so this uses that nameexpr node as it's literal.
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hauntsaninja
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Dec 25, 2023
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Thank you @hauntsaninja! Could we generate random identifiers (maybe uuidv4s?) to avoid the clashes. |
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
hauntsaninja
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Feb 17, 2024
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Okay, I fixed a bug where because the constructed NameExpr didn't have an associated node, we ended up extending narrowing to all nested match subjects (due to the code in literal_hash)
I'm wary of adding anything nondeterministic to mypy. I added the function name into the ID, we can see how it goes in practice.
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Thank you again @hauntsaninja! |
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Fixes python#12998 mypy can't narrow match statements with functions subjects because the callexpr node is not a literal node. This adds a 'dummy' literal node that the match statement visitor can use to do the type narrowing. The python grammar describes the the match subject as a named expression so this uses that nameexpr node as it's literal. --------- Co-authored-by: hauntsaninja <hauntsaninja@gmail.com>
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Fixes #12998
mypy can't narrow match statements with functions subjects because the callexpr node is not a literal node. This adds a 'dummy' literal node that the match statement visitor can use to do the type narrowing.
The python grammar describes the the match subject as a named expression so this uses that nameexpr node as it's literal.