[Rust] Scaffold uast4rust CLI with minimal valid output

[KinomotoMio]

Summary

Track ongoing Rust parser implementation in YASA-UAST from branch feat/rust-parser.

Scope in this PR

• Incremental parser-first changes for parser-Rust / uast4rust
• Single-file parsing and project-mode parsing improvements
• Cargo metadata output and package tree shaping
• UAST lowering coverage expansion with test/golden updates
• README updates for Rust parser usage

Out of scope

• YASA-Engine integration
• Rust analyzer implementation
• Rust taint checker implementation

Related issues

• Part of [Rust] Add standalone Rust parser for YASA-UAST #50

Contributor note

This work is delivered incrementally with small, reviewable commits.
AI is used as an assistant in a reasonable way, and implementation aims to follow standard software engineering practices.

Status note

This PR tracks exploratory work and does not guarantee mergeability at this stage.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request establishes the foundational components for a Rust UAST parser. It sets up the basic project structure, defines the command-line interface for interacting with the parser, and outlines the initial data model for the UAST output. The changes enable basic UAST generation for individual Rust files and projects, ensuring that the output includes essential metadata while laying the groundwork for more complex AST lowering in future iterations.

Highlights

• New Rust Parser Crate and CLI: Introduced the parser-Rust crate and the uast4rust command-line interface for generating Universal Abstract Syntax Trees (UASTs) from Rust code.
• CLI Argument Support: Implemented support for essential CLI arguments: -rootDir to specify the input path, -output for the output file, and -single to enable single-file parsing mode.
• Minimal UAST Output Structure: Defined and implemented the minimal required top-level fields in the UAST output JSON, including packageInfo, moduleName, cargoTomlPath, and numOfCargoToml.
• Rust Language Identification: Ensured that the generated compile unit skeleton correctly identifies the source language as rust.
• Smoke Tests and Fixtures: Added initial smoke tests with in-repository synthetic fixtures to validate the basic functionality of the CLI in both single-file and project modes.

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Changelog

• parser-Rust/Cargo.lock
  • Added a new Cargo.lock file, specifying exact dependencies for the uast4rust crate.
• parser-Rust/Cargo.toml
  • Added a new Cargo.toml file, defining the uast4rust crate and its dependencies.
• parser-Rust/README.md
  • Added a README file, detailing build and usage instructions for the CLI.
• parser-Rust/src/lib.rs
  • Implemented CLI argument parsing, file/project processing, and UAST output writing.
• parser-Rust/src/main.rs
  • Created the main entry point for the uast4rust CLI application.
• parser-Rust/src/model.rs
  • Defined the data structures for the Universal Abstract Syntax Tree (UAST) output.
• parser-Rust/testdata/project/basic/Cargo.toml
  • Added a sample Cargo.toml for project mode testing.
• parser-Rust/testdata/project/basic/src/main.rs
  • Added a sample Rust source file for project mode testing.
• parser-Rust/testdata/single/basic.rs
  • Added a sample Rust source file for single-file mode testing.
• parser-Rust/tests/cli_smoke.rs
  • Added integration tests to verify CLI functionality and UAST output.

Activity

• The author performed cargo fmt --all to ensure code formatting consistency.
• All cargo test commands passed successfully, indicating functional correctness.
• Manual CLI checks were conducted for single-file and project mode outputs, as well as for invalid argument handling.
• This PR is part of issue [Rust] Add standalone Rust parser for YASA-UAST #50 and closes issue [Rust] Scaffold uast4rust CLI with minimal valid output #51.

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[gemini-code-assist]

Code Review

This pull request successfully scaffolds the uast4rust CLI, including argument parsing, basic single-file and project mode logic, and minimal JSON output. The code is a solid foundation. I've added a few suggestions to improve error handling, efficiency, and code structure, which are particularly valuable at this early stage of development.

[KinomotoMio]

/gemini review

[gemini-code-assist]

Code Review

This pull request sets up a solid foundation for the uast4rust CLI. The code is well-structured with clear separation of concerns for models, library logic, and the main binary. Error handling is robust, and the inclusion of smoke tests is great for ensuring correctness from the start. My only suggestion is to consider using a dedicated CLI parsing library like clap to improve long-term maintainability and adopt standard CLI conventions, as detailed in my comment.

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[KinomotoMio]

For incremental review, I’m currently managing this branch as a stacked PR in my fork (same head branch):
KinomotoMio#3

I will keep this upstream PR aligned as changes are validated.