Rust: Model Result.ok and Result.err.

[geoffw0]

Model Result.ok and Result.err, which convert a Result to an Option corresponding to one of its variants.

PR Overview

This PR adds new dataflow tests for modeling the behavior of Rust's Result.ok and Result.err methods and updates the CodeQL model to support these conversions.

• Added a new test function option_ok() in main.rs to verify that Result.ok returns Some for Ok values and Result.err returns Some for Err values.
• Updated the CodeQL standard library model (lang-core.model.yml) to map the ok and err methods to their corresponding Option variants.

Changes

File	Description
rust/ql/test/library-tests/dataflow/local/main.rs	Added option_ok() to test the behavior of Result.ok and Result.err conversions
rust/ql/lib/codeql/rust/frameworks/stdlib/lang-core.model.yml	Included new entries for modeling Result.ok and Result.err conversions to Option

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (2)

rust/ql/test/library-tests/dataflow/local/main.rs:270

• [nitpick] Consider removing the extra space before the colon for type annotations to maintain consistency with the rest of the file (e.g., 'let r1: Result<i64, i64> = Ok(source(21));').

let r1 : Result<i64, i64> = Ok(source(21));

rust/ql/test/library-tests/dataflow/local/main.rs:274

• [nitpick] Consider adding an inline comment indicating that unwrapping o1b is expected to fail (or yield no value flow) since r1.err() returns None in the Ok case.

sink(o1b.unwrap());

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[paldepind]

Note, these models are included in #18787. I think it would make sense to add the tests in this PR but use the generated models.

[geoffw0]

Agreed, and the models are identical, which is reassuring.

I'll update this PR...

[geoffw0]

Updated.

Though the tests will fail until your PR is merged.