rust@v1

Hygiene checks for Rust projects. Adopt it with:

extends:
  - alint://bundled/rust@v1

This ruleset is gated with when: facts.has_rust (true if any Cargo.toml exists anywhere in the tree) plus a per-rule scope_filter: { has_ancestor: Cargo.toml } on per-file content rules so they only apply to files inside a Rust package — useful in polyglot monorepos where Rust packages sit alongside Node / Python / Go subdirectories. Rules that don't apply stay quiet. (has_rust is declared below; override with your own facts: block if you need a different heuristic.)

What it checks

10 rules. Each links to its section below, which explains the check and shows its definition.

Rule	Reports
rust-cargo-toml-exists error	Rust project: Cargo.toml at the repo root is required.
rust-cargo-lock-exists warning	Committing Cargo.lock ensures reproducible builds for binary crates.
rust-toolchain-pinned info	Pinning a toolchain (rust-toolchain.toml) makes local and CI builds reproducible.
rust-no-tracked-target error	target/ is Cargo's build dir and must never be committed.
rust-sources-snake-case error	Rust module filenames must be snake_case.
rust-sources-final-newline warning	File must end with a single \n.
rust-sources-no-trailing-whitespace info	No line may end with space or tab.
rust-sources-no-bidi error	Trojan Source (CVE-2021-42574): bidi override chars in Rust sources are rejected.
rust-sources-no-zero-width error	Zero-width characters in Rust sources are rejected (review hazard).
rust-no-merge-markers-in-manifests error	Flag <<<<<<<, =======, >>>>>>>, ||||||| markers at the start of a line, almost always left over...

All 10 rules run only when facts.has_rust holds, so the ruleset stays quiet in repositories it doesn't apply to.

Rules

rust-cargo-toml-exists

• kind: file_exists
• level: error
• when: facts.has_rust

Rust project: Cargo.toml at the repo root is required.

- id: rust-cargo-toml-exists
  when: facts.has_rust
  kind: file_exists
  paths: Cargo.toml
  root_only: true
  level: error
  message: "Rust project: Cargo.toml at the repo root is required."

rust-cargo-lock-exists

• kind: file_exists
• level: warning
• when: facts.has_rust
• policy: https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html

Committing Cargo.lock ensures reproducible builds for binary crates. Library-only workspaces may legitimately opt out; set this rule's level: off in that case.

- id: rust-cargo-lock-exists
  when: facts.has_rust
  kind: file_exists
  paths: Cargo.lock
  root_only: true
  level: warning
  message: >-
    Committing Cargo.lock ensures reproducible builds for binary
    crates. Library-only workspaces may legitimately opt out; set
    this rule's `level: off` in that case.
  policy_url: "https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html"

rust-toolchain-pinned

• kind: file_exists
• level: info
• when: facts.has_rust

Pinning a toolchain (rust-toolchain.toml) makes local and CI builds reproducible.

- id: rust-toolchain-pinned
  when: facts.has_rust
  kind: file_exists
  paths: ["rust-toolchain.toml", "rust-toolchain"]
  root_only: true
  level: info
  message: "Pinning a toolchain (rust-toolchain.toml) makes local and CI builds reproducible."

rust-no-tracked-target

• kind: dir_absent
• level: error
• when: facts.has_rust

target/ is Cargo's build dir and must never be committed.

- id: rust-no-tracked-target
  when: facts.has_rust
  kind: dir_absent
  paths: "**/target"
  level: error
  message: "`target/` is Cargo's build dir and must never be committed."

rust-sources-snake-case

Changed in v0.9.18: default-exclude subtrees with deliberately non-snake-case filenames. Three categories surface in rust-lang/rust:

src/doc/**              — doc examples + reference snippets
                          use English-style hyphenation
                          (`rustc-driver-example.rs`,
                          `rust-by-example/...`).
src/tools/miri/tests/** — Miri test fixtures use CamelCase /
                          intentional naming for litmus tests
                          and concurrency-spec semantics
                          (`abi_mismatch_repr_C.rs`,
                          `libc_pthread_mutex_NULL_reentrant.rs`).
src/tools/clippy/tests/ui/** — clippy UI test fixtures use
                          curly braces, hyphens, and other
                          non-snake-case markers as part of
                          the test grammar.
**/*.miri.rs            — `.miri.rs` dot-suffix is a Miri-only
                          override file pattern; the dot in
                          the basename trips snake-case.

Without these excludes, rust-lang/rust alone surfaced 1,091 false positives — the largest single bundled-rule FP class in the case-study corpus. The excludes are unique to rust-lang/rust + similar compiler/test-fixture projects; they're a no-op for most repos.

• kind: filename_case
• level: error
• when: facts.has_rust
• fix: file_rename (applied by alint fix)

Rust module filenames must be snake_case.

- id: rust-sources-snake-case
  when: facts.has_rust
  kind: filename_case
  paths:
    include: ["**/src/**/*.rs"]
    exclude:
      - "src/doc/**"
      - "src/tools/miri/tests/**"
      - "src/tools/clippy/tests/ui/**"
      - "src/tools/rustfmt/tests/**"
      - "tests/rustdoc-gui/**"
      - "**/*.miri.rs"
  case: snake
  level: error
  message: "Rust module filenames must be snake_case."
  fix:
    file_rename: {}

rust-sources-final-newline

• kind: final_newline
• level: warning
• when: facts.has_rust
• fix: file_append_final_newline (applied by alint fix)

- id: rust-sources-final-newline
  when: facts.has_rust
  kind: final_newline
  paths: "**/*.rs"
  scope_filter:
    has_ancestor: Cargo.toml
  level: warning
  fix:
    file_append_final_newline: {}

rust-sources-no-trailing-whitespace

• kind: no_trailing_whitespace
• level: info
• when: facts.has_rust
• fix: file_trim_trailing_whitespace (applied by alint fix)

- id: rust-sources-no-trailing-whitespace
  when: facts.has_rust
  kind: no_trailing_whitespace
  paths: "**/*.rs"
  scope_filter:
    has_ancestor: Cargo.toml
  level: info
  fix:
    file_trim_trailing_whitespace: {}

rust-sources-no-bidi

• kind: no_bidi_controls
• level: error
• when: facts.has_rust
• policy: https://trojansource.codes/

Trojan Source (CVE-2021-42574): bidi override chars in Rust sources are rejected.

- id: rust-sources-no-bidi
  when: facts.has_rust
  kind: no_bidi_controls
  paths: "**/*.rs"
  scope_filter:
    has_ancestor: Cargo.toml
  level: error
  message: "Trojan Source (CVE-2021-42574): bidi override chars in Rust sources are rejected."
  policy_url: "https://trojansource.codes/"

rust-sources-no-zero-width

• kind: no_zero_width_chars
• level: error
• when: facts.has_rust

Zero-width characters in Rust sources are rejected (review hazard).

- id: rust-sources-no-zero-width
  when: facts.has_rust
  kind: no_zero_width_chars
  paths: "**/*.rs"
  scope_filter:
    has_ancestor: Cargo.toml
  level: error
  message: "Zero-width characters in Rust sources are rejected (review hazard)."

rust-no-merge-markers-in-manifests

• kind: no_merge_conflict_markers
• level: error
• when: facts.has_rust

- id: rust-no-merge-markers-in-manifests
  when: facts.has_rust
  kind: no_merge_conflict_markers
  paths: ["Cargo.toml", "**/Cargo.toml", "Cargo.lock", "**/Cargo.lock"]
  scope_filter:
    has_ancestor: Cargo.toml
  level: error

Facts

The when: clauses above read these facts. Each is resolved once per run; alint facts prints what they resolved to in your repository.

facts:
  - id: has_rust
    any_file_exists: [Cargo.toml, "**/Cargo.toml"]

Customize

Every rule here can be overridden by id from your own .alint.yml: change its level, or set level: off to drop it. An id that doesn't exist is an error at config load, so a typo can't silently pass.

extends:
  - alint://bundled/rust@v1
rules:
  - id: rust-cargo-toml-exists
    level: off
  - id: rust-cargo-lock-exists
    level: error

To take only part of the ruleset, filter it where you extend it with only: or except::

extends:
  - url: alint://bundled/rust@v1
    except: [rust-cargo-toml-exists]

Bundled rulesets covers versioning and how rulesets combine.

Source

The full ruleset definition, comments included, is committed at crates/alint-dsl/rulesets/v1/rust.yml in the alint repo.