Rust: Add ComparisonOperation library.

[geoffw0]

Adds a ComparisonOperation library, filling out more of the Operation class tree.

Cleans up some out of place predicates (getGreaterOperand and getLesserOperand) in UncontrolledAllocationSizeExtensions.qll.

[Copilot]

Pull Request Overview

Adds a new ComparisonOperation library to model comparison, equality, and relational operations in Rust QL, updates imports and cleans up legacy operand predicates, and extends library-tests to verify the new classes and operand tags.

• Introduced ComparisonOperation.qll defining comparison, equality, and relational operations with getGreaterOperand/getLesserOperand.
• Updated rust.qll import and refactored UncontrolledAllocationSizeExtensions.qll to use the new API.
• Extended test.rs and Operations.ql to include new tags (ComparisonOperation, EqualityOperation, specific operation classes, and Greater/Lesser).

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
rust/ql/lib/codeql/rust/elements/ComparisonOperation.qll	New file defining ComparisonOperation, its subtypes, and operand accessors.
rust/ql/lib/rust.qll	Imported ComparisonOperation into the Rust library root.
rust/ql/lib/codeql/rust/security/UncontrolledAllocationSizeExtensions.qll	Removed old operand helpers and switched to the new RelationalOperation API.
rust/ql/test/library-tests/operations/Operations.ql	Updated describe and test harness to recognize new operation tags.
rust/ql/test/library-tests/operations/test.rs	Added expected tags for comparison operations and Greater/Lesser values.

[hvitved]

BinaryExpr can be removed

[hvitved]

I think I prefer EqualityOperation.

[geoffw0]

EqualityOperation is "an operation to do with equality", i.e. == or !=.

EqualOperation is specifically ==.

We can't use "EqualityOperation" to describe both.

[geoffw0]

Removed redundant BinaryExpr.

[hvitved]

OK. Then I think I slightly prefer Equal_s_Operation over EqualOperation, but I'll let you decide.

[geoffw0]

Yeah, I agree that's a better name. Updated.

[geoffw0]

Thanks for the review suggestions. I've implemented all but one (see above).