Add names of rust linter and formatter config files

[BaumiCoder]

In Rust there is a default formatter, called rustfmt, and a default linter, called clippy. This Pull Request adds the names (with and without leading dot) of their config files (see commit message for links to the respective documentations).
Furthermore, the single file name for cargo-deny, a linter focused on cargo / Rust dependencies.

(Useful, when running them with pre-commit and only want to run, if relevant files have changed, i.e., rust files, Cargo.toml or the config file in the repository. Example pre-commit config for a Rust project here)

[asottile]

I don't see how this can be useful? why wouldn't this just use files to match these? they're already matched by toml without special conventions

[BaumiCoder]

With that changes, for example I would use this for rustfmt:

types_or: [cargo, rust, rustfmt]

I am not sure, what your alternative approach with the same filtering would be. For example this would not match anymore the *.rs files, because there is an "and" between files and types_or, isn't it?

files: "\\.?rustfmt\\.toml"
types_or: [cargo, rust, toml]

So everything, needs to be defined with files in this way,

files: "(\\.?rustfmt\\.toml|Cargo.toml|.+\\.rs)"

which is not that readable.

Only using types_or would also include other TOML files, which are not relevant for rustfmt

types_or: [cargo, rust, toml]

[asottile]

that doesn't really make sense, you would just use types: [rust] such that pre-commit passes just the rust files to the hook

[BaumiCoder]

I call it on the whole repository:

      - id: rustfmt
        name: rustfmt
        description: The Rust default formatter (see .rustfmt.toml for config)
        # Run via cargo to use edition from Cargo.toml
        entry: cargo fmt --check --verbose
        language: rust
        types_or: [cargo, rust]
        pass_filenames: false

Running rustfmt via cargo allows getting the edition property from the Cargo.toml. Furthermore, I want to run it also when it config changes (i.e., the rustfmt.toml) to avoid that a config change makes the formatting invalid in respect to the new config.

Similar is for the two linter, which are also called on the whole repository and config changes are relevant.

      - id: cargo-deny
        name: cargo-deny
        description: A Linter which checks Rust dependencies (e.g., regarding licenses)
        entry: cargo deny check
        language: rust
        types_or: [cargo, cargo-lock]
        pass_filenames: false
        additional_dependencies: [cli:cargo-deny:0.18.*]
      - id: clippy
        name: clippy
        description: The Rust default linter
        entry: cargo clippy
        language: rust
        types_or: [cargo, rust]
        pass_filenames: false
        stages: [pre-push]

[asottile]

I call it on the whole repository

yeah I'd say you're holding it wrong then. part of the point of pre-commit is to only run on the things that change

[BaumiCoder]

Okay, so is the right way to run rustfmt only on the changed *.rs files and run the on the whole directory only if the config file changes (with two separate hooks)?

Furthermore, cargo-deny only process the config files (from cargo and from deny) as it only considers the dependencies of a project. For clippy as a normal linter, I would expect a support for processing single files, but that seems to be missing (see Issue).

[BaumiCoder]

I reworked my pre-commit config, but I still see the need for these new types, even for rustfmt. These would allow using types_or instead of the files in these lines:

• line for rustfmt
• line for clippy
• line for cargo-deny

[asottile]

no I wouldn't bother with a "run everything" hook. just do that manually and you should be running everything in ci already anyway.

[BaumiCoder]

In my CI (at Codeberg) I plan to use pre-commit run --all-files -v --hook-stage manual. This avoids a separate config for linters (and their versions) as pre-commit handles the installation of all necessary linters for the CI.

[asottile]

indeed so you don't really need this:

and run the on the whole directory only if the config file changes (with two separate hooks)?

[BaumiCoder]

Okay, I understand your point of view now. The CI is enough to ensure that the project and its config fits together and the pre-commit checks for this is not necessary, and you do not need to spend computation time on them. The other perspective is to avoid CI fails as much as possible with pre-commit checks to fix issues earlier. Something like this is always a trade-off.