Add Clippy version to Clippy's lint list
Hey, hey, the semester is finally over, and I wanted to get back into hacking on Clippy. It has also been some time since our metadata collection monster has been feed. So, this PR adds a new attribute `clippy::version` to document which version a lint was stabilized. I considered using `git blame` but that would be very hacky and probably not accurate.
I'm also thinking that this attribute can be used to have a `clippy::nightly` lint group which is allow-by-default that delays setting the actual lint group until the defined version is reached. Just something to consider regarding #6623🙃
This PR only adds the version to 4 lints to keep it reviewable. I'll do a followup PR to add the version to other lints if the implementation is accepted 🙃
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Also, mobile approved xD
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r? `@flip1995`
cc: #7172closes: #6492
changelog: [Clippy's lint list](https://rust-lang.github.io/rust-clippy/master/index.html) now displays the version a lint was added. 🎉
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Example lint declaration after this update:
```rs
declare_clippy_lint! {
/// [...]
///
/// ### Example
/// ```rust
/// // Bad
/// let x = 3.14;
/// // Good
/// let x = std::f32::consts::PI;
/// ```
#[clippy::version = "pre 1.29.0"]
pub APPROX_CONSTANT,
correctness,
"the approximate of a known float constant (in `std::fXX::consts`)"
}
```