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let_underscore_drop should not suggest drop() ing types that do not impl drop() bounds #10412
Description
Summary
.
Lint Name
let-underscore-drop
Reproducer
I tried this code:
fn bar<T> (it: Box<[T]>)
where
[T] : std::ops::Index<usize>,
{
let _ = it[0];
}
fn main(){}I saw this happen:
cargo clippy --fix --allow-dirty -- -Aclippy::all -Wclippy::let-underscore-drop
clippy suggests
fn bar<T> (it: Box<[T]>)
where
[T] : std::ops::Index<usize>,
{
drop(it[0]); // drop here
}
fn main(){}But this does not compile
error[E0277]: the size for values of type `<[T] as Index<usize>>::Output` cannot be known at compilation time
--> src/main.rs:5:11
|
5 | drop(it[0]);
| ---- ^^^^^ doesn't have a size known at compile-time
| |
| required by a bound introduced by this call
|
= help: the trait `Sized` is not implemented for `<[T] as Index<usize>>::Output`
note: required by a bound in `std::mem::drop`
--> /home/matthias/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/mem/mod.rs:979:13
|
979 | pub fn drop<T>(_x: T) {}
| ^ required by this bound in `drop`
For more information about this error, try `rustc --explain E0277`.
Version
rustc 1.69.0-nightly (49b9cc513 2023-02-27)
binary: rustc
commit-hash: 49b9cc5139dd4d11ef78dc08c1f9170de5b1ca39
commit-date: 2023-02-27
host: x86_64-unknown-linux-gnu
release: 1.69.0-nightly
LLVM version: 15.0.7
Additional Labels
No response
Activity
[-]let_underscore_drop should not suggesr `drop()` ing types that do impl drop() bounds[/-][+]let_underscore_drop should not suggest `drop()` ing types that do not impl drop() bounds[/+]J-ZhengLi commentedon Apr 7, 2023
that repro code doesn't seem trigger the lint you mentioned anymore, maybe it's already fixed.
However, it does trigger
boxed_localand it's really confusing 😂, because if I remove theBoxthere will be compiler errors.