Rust: Add another type inference debug predicate

[hvitved]

No description provided.

[Copilot]

Pull Request Overview

Adds new debug predicates to count and identify the maximum number of type inferences for AST nodes in Rust CodeQL.

• Introduces countTypes to tally how many times a type is inferred for a node and path.
• Introduces maxTypes to 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]

[Copilot]

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
	)

[geoffw0]

Looks fine to me, do you just use maxTypes for ad-hoc debugging or is it going to be part of some tests / metrics???

[hvitved]

Looks fine to me, do you just use maxTypes for ad-hoc debugging or is it going to be part of some tests / metrics???

Just for ad-hoc debugging.