Rust: Add more Operation subclasses

[geoffw0]

Add more Operation subclasses - ArithmeticOperation, BitwiseOperation, DerefExpr. Follows on from #19535, but I've kept these ones a bit simpler as they're not currently used (except for DerefExpr which I found several uses for). I feel we should have these concepts, like other languages we support, rather than conspicuous gaps.

[Copilot]

Pull Request Overview

Adds new Operation subclasses for arithmetic, bitwise, and dereference expressions, then wires them into tests and existing modules.

• Introduce ArithmeticOperation, BitwiseOperation, and DerefExpr with matching imports
• Update type inference, pointer‐access, and variable modules to use DerefExpr
• Extend test expectations and describe() logic to cover the new subclasses

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
rust/ql/test/library-tests/operations/test.rs	Updated expected classifications for arithmetic, bitwise, and deref tests
rust/ql/test/library-tests/operations/Operations.ql	Extended describe() to handle the new Operation subclasses
rust/ql/lib/rust.qll	Imported ArithmeticOperation, BitwiseOperation, and DerefExpr
rust/ql/lib/codeql/rust/security/AccessInvalidPointerExtensions.qll	Swapped PrefixExpr "*" check for DerefExpr
rust/ql/lib/codeql/rust/internal/TypeInference.qll	Replaced raw PrefixExpr deref checks with DerefExpr
rust/ql/lib/codeql/rust/elements/internal/VariableImpl.qll	Excluded DerefExpr instead of hard‐coding "*" prefix checks
rust/ql/lib/codeql/rust/elements/internal/RefExprImpl.qll	Made RefExpr implement Operation and provided operator/operand overrides
rust/ql/lib/codeql/rust/elements/DerefExpr.qll	Added the DerefExpr class
rust/ql/lib/codeql/rust/elements/BitwiseOperation.qll	Added abstract BitwiseOperationImpl and its concrete subclasses
rust/ql/lib/codeql/rust/elements/ArithmeticOperation.qll	Added abstract ArithmeticOperationImpl and its concrete subclasses

Comments suppressed due to low confidence (1)

rust/ql/test/library-tests/operations/test.rs:53

• Update this test comment to include PrefixExpr (and remove the MISSING: placeholder), e.g.: // $ Operation Op=& Operands=1 RefExpr PrefixExpr so that RefExpr is recognized as both an Operation and a prefix expression.

&x; // $ Operation Op=& Operands=1 RefExpr MISSING: PrefixExpr

[paldepind]

Thanks for working on this. Really cleans things up. Two tiny suggestions but other it looks great.

[geoffw0]

Suggestions accepted, thanks for reviewing!

[paldepind]

🎉