xref: /third_party/rust/crates/minimal-lexical/docs/Development.md

# Getting Started

In order to build and test lexical, only a Rust toolchain (1.31+) is required. However, for reasons described below, we highly recommend you install a recent (1.55+) nightly toolchain.


```bash
cargo +nightly build
cargo +nightly test
```

# Code Structure

Functionality is generally made **public** to separate the tests from the implementation, although non-documented members is not stable, and any changes to this code is not considered a breaking change. Tests are separated from the actual implementation, and comprehensively test each individual component.

Furthermore, any unsafe code uses the following conventions:

1. Each unsafe function must contain a `# Safety` section.
2. Unsafe operations/calls in unsafe functions must be marked as unsafe, with their safety guarantees clearly documented via a `// SAFETY:` section.

# Dependencies

In order to fully test and develop lexical, a recent, nightly compiler along with following Rust dependencies is required:

- Clippy
- Rustfmt
- Miri
- Valgrind
- Tarpaulin
- Fuzz
- Count

These dependencies may be installed via:

```bash
rustup toolchain install nightly
rustup +nightly component add clippy
rustup +nightly component add rustfmt
rustup +nightly component add miri
cargo +nightly install cargo-valgrind
cargo +nightly install cargo-tarpaulin
cargo +nightly install cargo-fuzz
cargo +nightly install cargo-count
```

In addition, the following non-Rust dependencies must be installed:

- Python3.6+
- python-magic (python-magic-win64 on Windows)
- Valgrind

# Development Process

The [scripts](https://github.com/Alexhuszagh/minimal_lexical/tree/main/scripts) directory contains numerous scripts for testing, fuzzing, analyzing, and formatting code. Since many development features are nightly-only, this ensures the proper compiler features are used. This requires a nightly compiler installed via Rustup, which can be invoked as `cargo +nightly`.

- [check.sh](https://github.com/Alexhuszagh/minimal_lexical/blob/main/scripts/check.sh): Check rustfmt and clippy without formatting any code.
- [fmt.sh](https://github.com/Alexhuszagh/minimal_lexical/blob/main/scripts/fmt.sh): Run `cargo fmt` and `cargo clippy` in all projects and workspaces, on nightly.
- [hooks.sh](https://github.com/Alexhuszagh/minimal_lexical/blob/main/scripts/hooks.sh): Install formatting and lint hooks on commits.

All PRs must pass the following checks:

```bash
# Check all safety sections and other features are properly documented.
RUSTFLAGS="--deny warnings" cargo +nightly build --features=lint
# Ensure all rustfmt and clippy checks pass.
scripts/check.sh
```

# Safety

In order to ensure memory safety even when using unsafe features, we have the following requirements.

- All code with local unsafety must be marked as an `unsafe` function.
- All unsafe macros must have a `# Safety` section in the documentation.
- All unsafe functions must have a `# Safety` section in the documentation.
- All code using `unsafe` functionality must have a `// SAFETY:` section on the previous line, and must contain an `unsafe` block, even in `unsafe` functions.
- If multiple lines have similar safety guarantees, a `// SAFETY:` section can be used for a block or small segment of code.

In order to very that the safety guarantees are met, any changes to `unsafe` code must be fuzzed, the test suite must be run with Valgrind, and must pass the following commands:

```bash
# Ensure `unsafe` blocks are used within `unsafe` functions.
RUSTFLAGS="--deny warnings" cargo +nightly build --features=lint
# Ensure clippy checks pass for `# Safety` sections.
cargo +nightly clippy --all-features -- --deny warnings
```

# Algorithm Changes

The "docs" directory containing detailed descriptions of algorithms and benchmarks. If you make any substantial changes to an algorithm, you should both update the algorithm description and the provided benchmarks.