Add configuration options to `--explain`
This PR rearranges some modules, taking `metadata_collector` out of `internal_lints` and making public just the necessary functions for `explain()` to use.
The output looks something like this:
```sh
$ cargo run --bin cargo-clippy --manifest-path ../rust-clippy/Cargo.toml -- --explain cognitive_complexity
### What it does
Checks for methods with high cognitive complexity.
### Why is this bad?
Methods of high cognitive complexity tend to be hard to
both read and maintain. Also LLVM will tend to optimize small methods better.
### Known problems
Sometimes it's hard to find a way to reduce the
complexity.
### Example
You'll see it when you get the warning.
========================================
Configuration for clippy::cognitive_complexity:
- cognitive-complexity-threshold: The maximum cognitive complexity a function can have (default: 25)
```
Fixes#9990
r? `@xFrednet`
---
changelog: Docs: `cargo clippy --explain LINT` now shows possible configuration options for the explained lint
[#10751](https://github.com/rust-lang/rust-clippy/pull/10751)
<!-- changelog_checked -->
Extend `trait_duplication_in_bounds` to cover trait objects
This PR extends `trait_duplication_in_bounds` to cover trait objects.
Currently,
```rs
fn foo(_a: &(dyn Any + Send + Send)) {}
```
generates no warnings. With this PR, it will complain about a duplicate trait and can remove it
Moved from rust-lang/rust#110991
changelog: [`trait_duplication_in_bounds`]: warn on duplicate trait object constraints
fix: `wildcard_imports` ignore `test.rs` files
Adds a check to see if the building crate is a test one, if so, ignore it
---
Closes#10580
changelog:[`wildcard_imports`]: Add a check to ignore files named `test.rs` and `tests.rs`
Ignore `borrow_deref_ref` warnings in code from procedural macros.
Don't linting `borrow_deref_ref` if code was generated by procedural macro.
This PR fixes https://github.com/rust-lang/rust-clippy/issues/8971
changelog: [`borrow_deref_ref`] avoiding warnings in macro-generated code
Fixes#10609: Adds lint to detect construction of unit struct using `default`
Using `default` to construct a unit struct increases code complexity and adds a function call. This can be avoided by simply removing the call to `default` and simply construct by name.
changelog: [`default_constructed_unit_structs`]: detects construction of unit structs using `default`
fixes#10609
Currently a `{D,Subd}iagnosticMessage` can be created from any type that
impls `Into<String>`. That includes `&str`, `String`, and `Cow<'static,
str>`, which are reasonable. It also includes `&String`, which is pretty
weird, and results in many places making unnecessary allocations for
patterns like this:
```
self.fatal(&format!(...))
```
This creates a string with `format!`, takes a reference, passes the
reference to `fatal`, which does an `into()`, which clones the
reference, doing a second allocation. Two allocations for a single
string, bleh.
This commit changes the `From` impls so that you can only create a
`{D,Subd}iagnosticMessage` from `&str`, `String`, or `Cow<'static,
str>`. This requires changing all the places that currently create one
from a `&String`. Most of these are of the `&format!(...)` form
described above; each one removes an unnecessary static `&`, plus an
allocation when executed. There are also a few places where the existing
use of `&String` was more reasonable; these now just use `clone()` at
the call site.
As well as making the code nicer and more efficient, this is a step
towards possibly using `Cow<'static, str>` in
`{D,Subd}iagnosticMessage::{Str,Eager}`. That would require changing
the `From<&'a str>` impls to `From<&'static str>`, which is doable, but
I'm not yet sure if it's worthwhile.
Fix `items_after_test_module`: Ignore imported modules
Fixes#10713. It does a little bit of dark magic, but intention is what really counts.
changelog:[`items_after_test_module`]: Ignore imported modules (`mod foo;`) with no body.
