Rust: Improve handling of where clauses in type inference and path resolution #20140
Conversation
![github-advanced-security[bot]](https://avatars.githubusercontent.com/in/57789?s=60&v=4){kind=small}
paldepind
force-pushed
the
rust/type-inference-where
branch
from
955ad03 to
ff4cb51
Compare
There was a problem hiding this comment.
Pull Request Overview
This PR improves how the Rust analyzer handles type bounds added by where clauses in both path resolution and type inference. Previously, the system didn't properly account for all sources of type bounds when resolving paths or inferring types.
- Adds member predicates to traits and type parameters that consolidate bounds from both direct declarations and
whereclauses - Updates path resolution to use the new comprehensive bound-checking predicates
- Updates type inference to leverage these improved bound checks
Reviewed Changes
Copilot reviewed 9 out of 10 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| rust/ql/test/library-tests/type-inference/main.rs | Adds test cases for trait bounds in where clauses and associated types in supertraits |
| rust/ql/test/library-tests/path-resolution/main.rs | Adds test case for trait bounds in where clauses |
| rust/ql/lib/codeql/rust/elements/internal/TypeParamImpl.qll | Implements getTypeBound and getATypeBound predicates for type parameters |
| rust/ql/lib/codeql/rust/elements/internal/TraitImpl.qll | Implements getTypeBound and getATypeBound predicates for traits |
| rust/ql/lib/codeql/rust/internal/TypeInference.qll | Updates type inference to use new comprehensive bound predicates |
| rust/ql/lib/codeql/rust/internal/PathResolution.qll | Updates path resolution to use new comprehensive bound predicates |
| Various .expected files | Updated test expectations reflecting improved resolution |
| exists(WherePred wp | | ||
| wp = this.getWhereClause().getAPredicate() and | ||
| wp.getTypeRepr().(PathTypeRepr).getPath().getText() = "Self" and | ||
| result = wp.getTypeBoundList().getBound(index - this.nrOfDirectTypeBounds()) |
There was a problem hiding this comment.
It appears to be legal to have two where predicates with Self as the path, e.g.:
trait Subtrait
where
Self: Supertrait1,
Self: Supertrait2,
I think at the moment this will break your index numbering.
There was a problem hiding this comment.
You're right, that is legal and the implementation currently does not account for that.
| tbl = this.getTypeBoundList() and offset = 0 | ||
| or | ||
| tbl = this.(TypeParamItemNode).getAWherePred().getTypeBoundList() and | ||
| offset = this.nrOfDirectTypeBounds() |
There was a problem hiding this comment.
Again I think the index numbering breaks if there's more than one applicable WherePred.
It turns out that we don't handle type bounds added by
whereclauses in all cases in path resolution and type inference.This PR improves the situration by adding member predicates to traits and type parameters that take all sources of bounds into account. These are then used in path resolution and type inference.