[ty] don't mark entire type-alias scopes as Deferred #20086
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Diagnostic diff on typing conformance testsNo changes detected when running ty on typing conformance tests ✅ |
|
second-ed
pushed a commit
to second-ed/ruff
that referenced
this pull request
Sep 9, 2025
## Summary This has been here for awhile (since our initial PEP 695 type alias support) but isn't really correct. The right-hand-side of a PEP 695 type alias is a distinct scope, and we don't mark it as an "eager" nested scope, so it automatically gets "deferred" resolution of names from outer scopes (just like a nested function). Thus it's redundant/unnecessary for us to use `DeferredExpressionState::Deferred` for resolving that RHS expression -- that's for deferring resolution of individual names within a scope. Using it here causes us to wrongly ignore applicable outer-scope narrowing. ## Test Plan Added mdtest that failed before this PR (the second snippet -- the first snippet always passed.)
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Summary
This has been here for awhile (since our initial PEP 695 type alias support) but isn't really correct. The right-hand-side of a PEP 695 type alias is a distinct scope, and we don't mark it as an "eager" nested scope, so it automatically gets "deferred" resolution of names from outer scopes (just like a nested function). Thus it's redundant/unnecessary for us to use
DeferredExpressionState::Deferredfor resolving that RHS expression -- that's for deferring resolution of individual names within a scope. Using it here causes us to wrongly ignore applicable outer-scope narrowing.Test Plan
Added mdtest that failed before this PR (the second snippet -- the first snippet always passed.)