Suggestion: run clippy for specific package in workspace

[bjgill]

We now have the --all option, and this is very helpful when testing a workspace.

However, when developing, it would be convenient to be able to run clippy over only a specified package in the workspace. i.e. similar to the cargo test option -p SPEC, --package SPEC ... Package to run tests for.

Unless anyone objects, I'll have a look at implementing this - it should be a fairly simple extension of the current handling for --all.

[bjgill]

I've started prototyping. It looks as if cargo is busy transitioning over to use clap - see rust-lang/cargo#4177. Do we want to do the same?

I think we would end up with a help message like that below (c.f. the current one at https://github.com/rust-lang-nursery/rust-clippy/blob/master/src/main.rs#L14).

Thoughts? It'll be a minor functional change (you can no longer specify --all anywhere - it must be at the start), and the help message will look different (though I could probably retain the old look if that is desirable). We'll gain, however, since main.rs will no longer need to parse the contents of std::env::args(), instead relying on clap.

Clippy 0.0.188
Checks a package to catch common mistakes and improve your Rust code.

USAGE:
    cargo-clippy [OPTIONS] [--] [CMD]...

OPTIONS:
        --all                  Run over all packages in the current workspace
    -h, --help                 Prints help information
    -p, --package <SPEC>...    Package(s) to check
    -V, --version              Prints version information

ARGS:
    <CMD>...    Commands to pass through to cargo rustc

Other options are the same as `cargo rustc`.

To allow or deny a lint from the command line you can use `cargo clippy --`
with:

    -W --warn OPT       Set lint warnings
    -A --allow OPT      Set lint allowed
    -D --deny OPT       Set lint denied
    -F --forbid OPT     Set lint forbidden

The feature `cargo-clippy` is automatically defined for convenience. You can use
it to allow or deny lints from the code, eg.:

    #[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]

[oli-obk]

yes please! no more args parsing!

[mimoo]

not sure why this was closed, it looks like you still can't run clippy on a specific package in your workspace

[ebroto]

@mimoo could you share an example of what does not work for you? cargo clippy -p <package> should work with both simple and virtual workspaces.

If you refer to the ability of running Clippy only on the package, excluding its dependencies (#3025), that will be fixed in a couple of days after rust-lang/cargo#8758 is merged.

[mimoo]

Ah, indeed I was getting hits on its dependencies (which are other packages in my workspace) and didn't understand why

[mleonhard]

If one package depends on another package the workspace, clippy will still check the extra package. To avoid that, pass the --no-deps flag (recently added). With this flag, you can even run clippy in the crate directory and it will check only that crate:

$ cd workspace1/crate1/
$ cargo clippy --all-features -- -D clippy::pedantic --no-deps

If you run clippy as part of a script that runs other cargo commands, clippy may just exit right away without reporting any errors. The workaround is to clean the package just before running clippy:

$ cd workspace1/crate1/
$ cargo clean --package "$(basename "$PWD")"
$ cargo clippy --all-features -- -D clippy::pedantic --no-deps