Using `saturating_sub()` here in code which cannot fail brings a false
sense of security. If for any reason a logic error was introduced and
caused `self.loop_depth` to reach 0 before being decremented, using
`saturating_sub(1)` would silently mask the programming error instead of
panicking loudly as it should (at least in dev profile).
Fix while_let_on_iterator dropping loop label when applying fix.
Loop label was not persisted when displaying help and was therefore producing broken rust code when applying fixes.
Solution was to store the `ast::Label` when creating a `higher::WhileLet` from an expression and add the label name to the lint suggestion and diagnostics.
---
Fixes: https://github.com/rust-lang/rust-clippy/issues/13123
changelog: [`while_let_on_iterator`]: Fix issue dropping loop label when displaying help and applying fixes.
* Construct lint passes by taking `Conf` by reference.
* Use `HashSet` configs in less places
* Move some `check_crate` code into the pass constructor when possible.
The `restriction` group contains many lints which are not about
necessarily “bad” things, but style choices — perhaps even style choices
which contradict conventional Rust style — or are otherwise very
situational. This results in silly wording like “Why is this bad?
It isn't, but ...”, which I’ve seen confuse a newcomer at least once.
To improve this situation, this commit replaces the “Why is this bad?”
section heading with “Why restrict this?”, for most, but not all,
restriction lints. I left alone the ones whose placement in the
restriction group is more incidental.
In order to make this make sense, I had to remove the “It isn't, but”
texts from the contents of the sections. Sometimes further changes
were needed, or there were obvious fixes to make, and I went ahead
and made those changes without attempting to split them into another
commit, even though many of them are not strictly necessary for the
“Why restrict this?” project.
Add new lint `while_float`
This PR adds a nursery lint that checks for while loops comparing floating point values.
changelog:
```
changelog: [`while_float`]: Checks for while loops comparing floating point values.
```
Fixes#758
