[ty] Temporary hack to reduce false positives around builtins.open()
#20367
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Contributor
Diagnostic diff on typing conformance testsNo changes detected when running ty on typing conformance tests ✅ |
Contributor
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| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-argument-type |
0 | 55 | 0 |
invalid-assignment |
0 | 8 | 0 |
no-matching-overload |
0 | 8 | 0 |
invalid-return-type |
0 | 7 | 0 |
unresolved-attribute |
0 | 2 | 0 |
possibly-unbound-attribute |
0 | 1 | 0 |
unused-ignore-comment |
1 | 0 | 0 |
| Total | 1 | 81 | 0 |
Member
Author
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That looks like the kind of ecosystem report I expected! |
AlexWaygood
requested review from
carljm,
dcreager and
sharkdp
as code owners
Member
Author
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(The mypy_primer panic on sympy is happening on multiple PRs right now so is almost certainly unrelated) |
carljm
approved these changes
Sep 12, 2025
Member
Author
|
This just reduces the fallout of a change that's unreleased, so I'll add the |
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Summary
#20165 added a lot of false positives around calls to
builtins.open(), because our missing support for PEP-613 type aliases means that we don't understand typeshed's overloads forbuiltins.open()at all yet, and therefore always select the first overload. This didn't use to matter very much, but now that we have a much stricter implementation of protocol assignability/subtyping it matters a lot, because most of the stdlib functions dealing with I/O (pickle,marshal,io,json, etc.) are annotated in typeshed as taking in protocols of some kind.In lieu of full PEP-613 support, which is blocked on various things and might not land in time for our next alpha release, this PR adds some temporary special-casing for
builtins.open()to avoid the false positives. We just inferTodofor anything that isn't meant to match typeshed's firstopen()overload. This should be easy to rip out again once we have proper support for PEP-613 type aliases, which hopefully should be pretty soon!Test Plan
Added an mdtest