Add colored help to be consistent with Cargo

[blyxyas]

On rust-lang/cargo#12578, a new colored help message format was introduced. This PR introduces the same styling from that cargo help message to our cargo clippy --help message.

More information is provided in the original PR, fixes #11482. The perfect reviewing process would be that the reviewer installs this branch and checks for themselves, but here are some screenshots, there are some more screenshots in the original issue.

(Note that the actual text may change in the actual commit, that screenshot is just to test the colors).
Also note that the color-print version should always be synced with Cargo's color-print version to avoid increasing build times in the rust-lang/rust repo.

changelog:Add colors to the cargo clippy --help output 🎉.

[rustbot]

r? @giraffate

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[flip1995]

Blocker: This doesn't work when piping the output to a file:

LD_LIBRARY_PATH=$(rustc --print=sysroot)/lib ./target/debug/cargo-clippy --help > test

results in:

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

�[32m�[1mUsage�[39m�[22m:
    �[36m�[1mcargo clippy�[39m�[22m �[36m[OPTIONS] [--] [<ARGS>...]�[39m

�[32m�[1mCommon options:�[39m�[22m
    �[36m�[1m--no-deps�[39m�[22m                Run Clippy only on the given crate, without linting the dependencies
    �[36m�[1m--fix�[39m�[22m                    Automatically apply lint suggestions. This flag implies �[36m--no-deps�[39m and �[36m--all-targets�[39m
    �[36m�[1m-h, --help�[39m�[22m               Print this message
    �[36m�[1m-V, --version�[39m�[22m            Print version info and exit
    �[36m�[1m--explain [LINT]�[39m�[22m           Print the documentation for a given lint

See all options with �[36m�[1mcargo check --help�[39m�[22m.

�[32m�[1mAllowing / Denying lints�[39m�[22m

To allow or deny a lint from the command line you can use �[36m�[1mcargo clippy --�[39m�[22m with:

    �[36m�[1m-W�[39m�[22m / �[36m�[1m--warn�[39m�[22m �[36m[LINT]�[39m       Set lint warnings
    �[36m�[1m-A�[39m�[22m / �[36m�[1m--allow�[39m�[22m �[36m[LINT]�[39m      Set lint allowed
    �[36m�[1m-D�[39m�[22m / �[36m�[1m--deny�[39m�[22m �[36m[LINT]�[39m       Set lint denied
    �[36m�[1m-F�[39m�[22m / �[36m�[1m--forbid�[39m�[22m �[36m[LINT]�[39m     Set lint forbidden

You can use tool lints to allow or deny lints from your code, e.g.:

    �[33m�[1m#[allow(clippy::needless_lifetimes)]�[39m�[22m

[blyxyas]

OK, this new approach fixes Philipp's comment but introduces kind of a lot of bloat. On the original PR, this bloat isn't there because clap handles a lot of minute things (and removing formatting when piping to a file is one of them, I think). But as we don't use clap, we have to manually check where output is going.

[flip1995]

But as we don't use clap, we have to manually check where output is going.

Should we use clap? Should we nominate this PR for discussion?

[blyxyas]

Adding clap as a dependency would add 55Kb, but it adds some QOL improvements and overall more readability. I think nominating this is the best option, as the pros and cons are pretty similar and subjective, so we'll have to know what the team thinks.

Also note that, if we use clap, the kinda clunky syntax of cargo clippy -- -W [LINT] would change to a slightly better cargo clippy -W [LINT]

[flip1995]

the kinda clunky syntax of cargo clippy -- -W [LINT] would change to a slightly better cargo clippy -W [LINT]

Sadly the clunky syntax is probably there to stay for backwards compat...

[blyxyas]

There's probably a way to maintain this backwards compatibility while also providing a better solution.

[epage]

As an alternative to pulling in all of clap, you can use the anstream library that clap uses that wraps stdout/stderr with the ability to strip ansi escape codes when needed.

[blyxyas]

The current commit also checks if we're on a terminal and adjusts the output to that information. Pulling a dependency just to avoid an if check would not be the best decision (it would also hurt runtime performance)

[epage]

Help output performance isn't the biggest deal and the dependency helps with (1) only having one instance of the help to avoid subtle issues with them being out of sync and (2) it covers more situations (NOCOLOR, CLI_COLOR, legacy windows, etc).

[flip1995]

You found a bug in ignored_unit_patterns: Needs an external macro check.

[blyxyas]

Needs an external macro check.

The lint uses check_pat, and sadly we cannot use is_from_proc_macro with hir::Pats yet. I'll add it to the backlog for when the is_from_proc_macro update is merged.

[flip1995]

Suggested change

	<cyan,bold>--explain [LINT]</> Print the documentation for a given lint
	<cyan,bold>--explain [LINT]</> Print the documentation for a given lint

[flip1995]

Still some work to be done on the clippy-driver help message.

[flip1995]

r? @flip1995

[flip1995]

Please fix the alignment of the --explain and the --rustc flags and this should be good to go.

Optionally address this comment: #11495 (comment)

[flip1995]

Suggested change

	"Checks a package to catch common mistakes and improve your Rust code. Run <cyan>clippy-driver</> with the same arguments you use for <cyan>rustc</>
	"Checks a file to catch common mistakes and improve your Rust code.
	Run <cyan>clippy-driver</> with the same arguments you use for <cyan>rustc</>

[blyxyas]

Optionally address this comment: #11495 (comment)

#[allow] attributes cannot be applied println! since it's a macro invocation.

error: unused attribute `allow`
   --> src/driver.rs:217:13
    |
217 |             #[allow(clippy::ignored_unit_patterns)]
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
note: the built-in attribute `allow` will be ignored, since it's applied to the macro invocation `println`
   --> src/driver.rs:218:13
    |
218 |             println!("{version_info}");
    |

Truly a sad cowboy moment.

[flip1995]

Thanks! r=me after squashing the commits 🚀

[blyxyas]

@bors r=flip1995

[bors]

📌 Commit 6ad218c has been approved by flip1995

It is now in the queue for this repository.

[bors]

⌛ Testing commit 6ad218c with merge 78ddc8d...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995
Pushing 78ddc8d to master...