**What it does:** Checks for generics with `std::ops::Drop` as bounds.
**Why is this bad?** `Drop` bounds do not really accomplish anything.
A type may have compiler-generated drop glue without implementing the
`Drop` trait itself. The `Drop` trait also only has one method,
`Drop::drop`, and that function is by fiat not callable in user code.
So there is really no use case for using `Drop` in trait bounds.
**Known problems:** None.
**Example:**
```rust
fn foo<T: Drop>() {}
```
* master: (58 commits)
Rustfmt all the things
Don't make decisions on values that don't represent the decision
Improving comments.
Rustup
Added rustfix to the test.
Improve span shortening.
Added "make_return" and "blockify" convenience methods in Sugg and used them in "needless_bool".
Actually check for constants.
Fixed potential mistakes with nesting. Added tests.
formatting fix
Update clippy_lints/src/needless_bool.rs
formatting fix
Fixing typo in CONTRIBUTING.md
Fix breakage due to rust-lang/rust#57651
needless bool lint suggestion is wrapped in brackets if it is an "else" clause of an "if-else" statement
Fix automatic suggestion on `use_self`.
Remove negative integer literal checks.
Fix `implicit_return` false positives.
Run rustfmt
Fixed breakage due to rust-lang/rust#57489
...
Merge new_without_default_derive into new_without_default
Closes#3525, deprecating new_without_default_derive and moving both lints into new_without_default.
I believe if the user already decided to put underscores in their
literal, Clippy should be willing to believe that they put a number of
underscores that they felt was readable.
This lint looks for:
let mut vec = Vec::with_capacity(len);
vec.set_len(len);
The suggested replacement is `vec![0; len]`.
This is far too opinionated to be a deny-by-default lint because the performance
characteristics of the suggested replacement are totally different.
I am not convinced that this lint has value beyond what deny(unsafe_code) gives
you. Unsafe code is unsafe but please don't deny-by-default lint it if that's
the only reason.
