New Lint: inspect_then_for_each
**Work In Progress**
This PR addresses [Issue 5209](https://github.com/rust-lang/rust-clippy/issues/5209) and adds a new lint called `inspect_then_for_each`.
Current seek some guidance.
If you added a new lint, here's a checklist for things that will be
checked during review or continuous integration.
- \[x] Followed [lint naming conventions][lint_naming]
- \[x] Added passing UI tests (including committed `.stderr` file)
- \[x] `cargo test` passes locally
- \[x] Executed `cargo dev update_lints`
- \[x] Added lint documentation
- \[x] Run `cargo dev fmt`
[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
---
changelog: Add [`inspect_for_each`] lint for the use of `inspect().for_each()` on `Iterators`.
This makes it possible to pass the `Impl` directly to functions, instead
of having to pass each of the many fields one at a time. It also
simplifies matches in many cases.
Lint also in trait def for `wrong_self_convention`
Extends `wrong_self_convention` to lint also in trait definition.
By the way, I think the `wrong_pub_self_convention` [example](dd826b4626/clippy_lints/src/methods/mod.rs (L197)) is misleading.
On [playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=32615ab3f6009e7e42cc3754be0ca17f), it fires `wrong_self_convention`, so the example (or the lint maybe?) needs to be reworked.
The difference with `wrong_self_convention` [example](dd826b4626/clippy_lints/src/methods/mod.rs (L172)) is mainly the `pub` keyword on the method `as_str`, but the lint doesn't use the function visibility as condition to choose which lint to fire (in fact it uses the visibility of the impl item).
fixes: #6307
changelog: Lint `wrong_self_convention` lint in trait def also
instead of `find()` follows by `is_some()` on strings
Update clippy_lints/src/find_is_some_on_strs.rs
Co-authored-by: Takayuki Nakata <f.seasons017@gmail.com>
Update clippy_lints/src/methods/mod.rs
Co-authored-by: Philipp Krones <hello@philkrones.com>
Use const sym where possible
I ran a regex search and replace to use const `sym` values where possible. This should give some performance boost by avoiding string interning at runtime.
Con: It is not as consistent as always using `sym!`.
I also changed an internal lint to suggest using `sym::{}`, making an assumption that this will always work for diagnostic items.
changelog: none
Add lint: from_iter_instead_of_collect
Fixes#5679
This implements lint for `::from_iter()` from #5679 not the general issue (`std::ops::Add::add`, etc.).
This lint checks if expression is function call with `from_iter` name and if it's implementation of the `std::iter::FromIterator` trait.
changelog: Introduce from_iter_instead_of_collect lint
