rust/clippy_dev/README.md

# Clippy Dev Tool

The Clippy Dev Tool is a tool to ease Clippy development, similar to `rustc`s
`x.py`.

Functionalities (incomplete):

## `lintcheck`

Runs clippy on a fixed set of crates read from
`clippy_dev/lintcheck_crates.toml` and saves logs of the lint warnings into the
repo.  We can then check the diff and spot new or disappearing warnings.

From the repo root, run:

```
cargo run --target-dir clippy_dev/target --package clippy_dev \
--bin clippy_dev --manifest-path clippy_dev/Cargo.toml --features lintcheck -- lintcheck
```

or

```
cargo dev-lintcheck
```

By default the logs will be saved into
`lintcheck-logs/lintcheck_crates_logs.txt`.

You can set a custom sources.toml by adding `--crates-toml custom.toml` or using
`LINTCHECK_TOML="custom.toml"` where `custom.toml` must be a relative path from
the repo root.

The results will then be saved to `lintcheck-logs/custom_logs.toml`.

### Configuring the Crate Sources

The sources to check are saved in a `toml` file. There are three types of
sources.

1. Crates-io Source

   ```toml
   bitflags = {name = "bitflags", versions = ['1.2.1']}
   ```
   Requires a "name" and one or multiple "versions" to be checked.

2. `git` Source
   ````toml
   puffin = {name = "puffin", git_url = "https://github.com/EmbarkStudios/puffin", git_hash = "02dd4a3"}
   ````
   Requires a name, the url to the repo and unique identifier of a commit,
   branch or tag which is checked out before linting.  There is no way to always
   check `HEAD` because that would lead to changing lint-results as the repo
   would get updated.  If `git_url` or `git_hash` is missing, an error will be
   thrown.

3. Local Dependency
   ```toml
   clippy = {name = "clippy", path = "/home/user/clippy"}
   ```
   For when you want to add a repository that is not published yet.

#### Command Line Options (optional)

```toml
bitflags = {name = "bitflags", versions = ['1.2.1'], options = ['-Wclippy::pedantic', '-Wclippy::cargo']}
```

It is possible to specify command line options for each crate. This makes it
possible to only check a crate for certain lint groups. If no options are
specified, the lint groups `clippy::all`, `clippy::pedantic`, and
`clippy::cargo` are checked. If an empty array is specified only `clippy::all`
is checked.

**Note:** `-Wclippy::all` is always enabled by default, unless `-Aclippy::all`
is explicitly specified in the options.