Rust: Add another type inference debug predicate #19728
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Pull Request Overview
Adds new debug predicates to count and identify the maximum number of type inferences for AST nodes in Rust CodeQL.
- Introduces
countTypesto tally how many times a type is inferred for a node and path. - Introduces
maxTypesto select the node–type combinations with the highest inference counts.
Comments suppressed due to low confidence (2)
rust/ql/lib/codeql/rust/internal/TypeInference.qll:1521
- The function signature for countTypes uses Type t as an input parameter but then binds t inside the body, which can be confusing. Consider converting countTypes into a predicate with separate output parameters for the inferred type and count, or remove the t parameter if it’s not meant as an input.
private int countTypes(AstNode n, TypePath path, Type t) {
rust/ql/lib/codeql/rust/internal/TypeInference.qll:1520
- The new debug predicates countTypes and maxTypes lack documentation. Adding a brief comment explaining their purpose and usage will improve maintainability.
pragma[nomagic]
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| predicate maxTypes(AstNode n, TypePath path, Type t, int c) { | ||
| c = countTypes(n, path, t) and | ||
| c = max(countTypes(_, _, _)) |
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Calling max over an unbounded countTypes(_, _, _) may lead to an expensive computation over all AST nodes and types. If this is purely for debugging, consider constraining the domain or caching results to reduce runtime cost.
Suggested change
| c = max(countTypes(_, _, _)) | |
| c = max(countTypes(n0, path0, t0) | | |
| n0 = getRelevantLocatable() and | |
| path0 = path and | |
| t0 = t | |
| ) |
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geoffw0
approved these changes
Jun 12, 2025
Just for ad-hoc debugging. |
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