Autogenerate new lints

[bradsherman]

Add option in clippy_dev to automatically generate boilerplate code for adding new lints

example:

./util/dev new_lint --name=iter_nth_zero --type=late

Fixes #4942

changelog: none

[bradsherman]

I will add another commit to update docs once the code is set in stone, but I wanted to push this up before assuming too much.

[flip1995]

Thanks for implementing this!

Initial implementation LGTM overall.

[flip1995]

Only one thing left 🎉

[bradsherman]

Since we seem to be at a good spot with the auto-generated code, I'm going to start working on two more commits for this PR:

1. Update documentation to reflect new process for adding lints
2. Add a new lint using said process to make sure no lints have a description of "default lint description"

[flip1995]

Great! If you have any questions, don't hesitate to ask!

[bradsherman]

I've started updating the docs and adding the new lint, but when trying to build I'm getting a ton of errors like this:

error[E0432]: unresolved import `rustc::declare_lint_pass`
 --> clippy_lints/src/utils/author.rs:5:5
  |
5 | use rustc::declare_lint_pass;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^ no `declare_lint_pass` in the root

error[E0432]: unresolved import `syntax::errors`
 --> clippy_lints/src/utils/diagnostics.rs:8:13
  |
8 | use syntax::errors::DiagnosticBuilder;
  |             ^^^^^^ could not find `errors` in `syntax`

error[E0432]: unresolved import `rustc::declare_lint_pass`
 --> clippy_lints/src/utils/inspector.rs:4:5
  |
4 | use rustc::declare_lint_pass;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^ no `declare_lint_pass` in the root

I've installed the latest Rust from master but still no success. Any ideas?

[krishna-veerareddy]

Since the rustc API isn't guaranteed to be stable we often have breaking changes like the ones you see above. For example rustc::declare_lint_pass would now be rustc_session::declare_lint_pass. There is a rustup fix in the process of being merged into clippy that will fix most of the errors.

Here's the rustup PR: #5040. Once this gets merged you would only need to update changes in this PR to be compatible with the latest rustc API. Hope that helps.

[bradsherman]

okay cool that makes sense, thank you! I will keep an eye on that PR and proceed once it is merged.

[bors]

☔ The latest upstream changes (presumably #5040) made this pull request unmergeable. Please resolve the merge conflicts.

[bradsherman]

I'm not sure how to set up the tests for creating an internal lint ie checking to make sure no lints have default lint description. Could someone point me in the right direction please?

[flip1995]

https://github.com/rust-lang/rust-clippy/blob/master/tests/ui/lint_without_lint_pass.rs

Is an example on how to write tests for lint declarations.

Just create a test file with similar imports and declare a lint with the description "default lint description" and one with another description.

[flip1995]

Documentation update looks great!

[flip1995]

LGTM overrall

[flip1995]

Thanks!

@bors r+

[bors]

📌 Commit 32337a9 has been approved by flip1995

[bors]

⌛ Testing commit 32337a9 with merge d613fd1...

[bors]

💔 Test failed - checks-travis

[flip1995]

@bors retry

[bors]

⌛ Testing commit 32337a9 with merge a5750d2...

[bors]

💔 Test failed - checks-travis

[flip1995]

@bors retry (spurious)

[bors]

⌛ Testing commit 32337a9 with merge 8b72b72...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: flip1995
Pushing 8b72b72 to master...