Tools

The src/tools/ directory plus src/bootstrap/ and src/librustdoc/ hold every tool shipped with rustup (rustdoc, miri, clippy, rustfmt, rust-analyzer) plus dozens of internal helpers used to build, test, document, and ship rustc. Most of the major tools are vendored from external repositories as git subtrees; this page describes them at a glance and links to dedicated pages where one exists.

Pages in this section

• Bootstrap — x.py and the src/bootstrap/ Rust binary that drives all builds
• rustdoc — cargo doc's engine; HTML/JSON documentation
• Compiletest — the tests/ test runner
• Other tools — miri, clippy, rustfmt, rust-analyzer, tidy, and the long tail

Tool categories

Tools shipped to users

These are part of every standard rustup installation:

Tool	Lives in	Repo of record
rustc	compiler/ (binary in compiler/rustc/)	rust-lang/rust
rustdoc	src/librustdoc/ + src/tools/rustdoc/	rust-lang/rust
cargo	submodule	rust-lang/cargo
clippy-driver / cargo-clippy	src/tools/clippy/ (subtree)	rust-lang/rust-clippy
rustfmt / cargo-fmt	src/tools/rustfmt/ (subtree)	rust-lang/rustfmt
rust-analyzer	src/tools/rust-analyzer/ (submodule)	rust-lang/rust-analyzer
miri (rustup component)	src/tools/miri/ (subtree)	rust-lang/miri

Tools used during the build

Not shipped to users; needed to build rustc + library + tools:

Tool	Purpose
src/bootstrap/	The x.py Rust binary that drives Cargo
src/build_helper/	Shared helpers used by bootstrap and tools
src/tools/x/	Standalone "x" launcher (a tiny wrapper)
src/tools/build-manifest/	Generates release manifests for rustup
src/tools/bump-stage0/	Bumps the pinned beta toolchain
src/tools/replace-version-placeholder/	Substitutes version strings at release-cut
src/tools/rust-installer/	Builds rustup-compatible installers
src/tools/lld-wrapper/	Thin wrapper used to invoke bundled lld
src/tools/wasm-component-ld/	wasm-component linking shim
src/tools/llvm-bitcode-linker/	Custom bitcode linker for LTO

Tools used during testing

Tool	Purpose
src/tools/compiletest/	Drives the tests/ suites
src/tools/run-make-support/	Helper library for tests/run-make/
src/tools/tidy/	Repo-wide lint
src/tools/jsondocck/	Assertions for rustdoc JSON tests
src/tools/jsondoclint/	Validate rustdoc JSON output
src/tools/html-checker/	HTML validation for rustdoc HTML
src/tools/linkchecker/	Find broken links in built docs
src/tools/cargotest/	Test that user crates still compile
src/tools/coverage-dump/	Decode coverage data for tests
src/tools/miropt-test-tools/	Helpers for tests/mir-opt/
src/tools/rustdoc-themes/	Verify rustdoc CSS themes
src/tools/rustdoc-gui-test/	Drive rustdoc GUI tests
src/tools/test-float-parse/	Stress-test float parsing
src/tools/lint-docs/	Check the lint reference docs
src/tools/tier-check/	Verify platform-tier policies
src/tools/libcxx-version/	Check libcxx version on macOS CI

Tools for documentation

Tool	Purpose
src/tools/rustbook/	Wrapper around mdBook used for all the books
src/tools/error_index_generator/	Builds the rustc error index
src/tools/unstable-book-gen/	Generates the unstable book from rustc_feature
src/tools/unicode-table-generator/	Regenerates Unicode tables in core
src/tools/generate-copyright/	Produces COPYRIGHT-thirdparty.md
src/tools/collect-license-metadata/	Collects license info
src/tools/features-status-dump/	Dump feature status JSON
src/tools/generate-windows-sys/	Regenerates Windows API bindings used by std

Tools for cross-compilation testing

Tool	Purpose
src/tools/remote-test-client/	Runs tests on a remote target
src/tools/remote-test-server/	The matching server on the device
src/tools/opt-dist/	PGO/BOLT optimization driver for releases

Subtree / submodule tools

These are entire other projects vendored into this repo:

Tool	Type	Repo of record
clippy	subtree	rust-lang/rust-clippy
miri	subtree	rust-lang/miri
rustfmt	subtree	rust-lang/rustfmt
rust-analyzer	submodule	rust-lang/rust-analyzer
cargo	submodule	rust-lang/cargo
rustc-perf	submodule	rust-lang/rustc-perf
enzyme	submodule	EnzymeAD/Enzyme

Why so many tools

Different tools solve different parts of the "ship a Rust compiler" problem:

• rustc + std are the actual deliverable
• rustdoc, clippy, rustfmt, miri, rust-analyzer are user-facing dev tools that ship with rustup
• bootstrap, tidy, compiletest are internal tools required to build and test the deliverable
• build-manifest, bump-stage0, generate-copyright are release-cut tooling
• rustbook + mdBook are documentation tooling
• opt-dist, llvm-bitcode-linker are release-time optimization tooling

This division explains why src/tools/ has nearly 50 entries — most of them are small Rust binaries with a single, focused job.