This repository is a structured workshop for learning to write Rust procedural macros. It contains five project skeletons covering derive macros (Builder, CustomDebug), function-like macros (seq!), attribute macros (#[sorted], #[bitfield]). Each project includes incremental test cases using the trybuild test harness, guiding learners from basic parsing to advanced code generation and error reporting. The actual macro implementations are stubs (unimplemented!()), so the repository serves as a starting template for hands-on learning rather than a functional codebase. The architecture demonstrates best practices for organizing proc-macro projects, including separation of proc-macro and library crates in the bitfield project. The codebase is intentionally incomplete, intended for educational use.

Rust Quiz is a monolith application that hosts a collection of medium-to-hard Rust quiz questions. The core function is to parse Markdown question files and corresponding Rust source files, compile and execute the Rust code to verify correct answers, and generate a JavaScript bundle for a static website. It uses a parallel worker pool (rayon) for efficient validation and includes a local HTTP server based on hyper for development. The codebase is well-structured with clean error handling (thiserror) and modern Rust practices. While the primary value is the question content, the build tooling is a robust example of a Rust code snippet tester with output validation and warning checking.

Trybuild is a Rust library that provides a test harness for compiler diagnostics, commonly known as UI tests. It allows developers to write test cases that compile Rust source files and assert that the compiler's error messages match expected output stored in `.stderr` files. The library is widely used for testing procedural macros and other compile-time error reporting. The API is minimal: `TestCases::new()`, `.pass(path)`, and `.compile_fail(path)`. Under the hood, trybuild creates a temporary Cargo project for each test suite, compiles each test case individually using `cargo check` or `cargo build`, captures the compiler's JSON output, normalizes file paths and other machine-specific details, and compares the result against saved snapshots. It supports both pass and compile-fail tests, glob patterns, workspace inheritance, path dependencies, and various normalization strategies to keep snapshots stable across environments. The codebase is exceptionally well-structured, with clean separation of concerns, a sophisticated normalization engine that maintains backward compatibility through multiple normalization variations, and robust file locking for concurrent test execution. It is actively maintained by David Tolnay and is a cornerstone of the Rust procedural macro ecosystem.