rust-no-modrs

Rust modules (no mod.rs)

Rule

For a module named foo:

• Preferred: foo.rs (module root) and foo/ (child modules live here as foo/bar.rs, etc.).
• Avoid: foo/mod.rs as the root of foo. Do not introduce new mod.rs files; migrate away when touching that area.

lib.rs / main.rs follow the same idea: mod foo; resolves to foo.rs or foo/mod.rs — choose foo.rs + foo/.

Layout sketch

src/
  lib.rs
  foo.rs          # pub mod bar; mod util;
  foo/
    bar.rs
    util.rs

Not:

src/
  lib.rs
  foo/
    mod.rs        # avoid
    bar.rs

When editing or adding modules

1. Add submodules as parent/child.rs and declare them in parent.rs (the file next to the parent/ directory).
2. If you see path/to/mod.rs, plan a move to path/to.rs beside path/to/ (same module tree, different root file location). Keep mod declarations and pub use behavior equivalent.
3. Do not create new mod.rs for convenience or “convention from old tutorials.”

Exceptions (rare)

• Generated code or vendored third-party trees — leave as-is unless the user asks to normalize.
• If the project’s documented standard still requires mod.rs, follow the repo; otherwise apply this skill.

Doc anchor

Rust book: modules can be module_name.rs or module_name/mod.rs; prefer the module_name.rs + module_name/ form for new work and refactors.