Lint `#[level()]` attribute without lint reason (`#![feature(lint_reasons)]`)

[xFrednet]

What it does

It checks for level attributes without a reason.

I think it would be good to have a config value that sets the minimum lint level of the #[level()] attribute. By default, it should only warn for allow end expect

I actually don't think that this actually requires a config value :)

Lint Name

allow_lint_without_reason

Category

restriction

Advantage

Enforces the user to reason about allowed lints

Drawbacks

Updating current code bases will take quite some work

Example

#![feature(lint_reasons)]

#![allow(clippy::some_lint)]

Could be written as:

#![feature(lint_reasons)]

#![allow(clippy::some_lint, reason = "False positive rust-lang/rust-clippy#1002020")]

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