let_underscore_drop should not suggest `drop()` ing types that do not impl drop() bounds

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

Start at the let-underscore-drop lint entry point and reproduce the issue with the Rust snippet and cargo clippy command shown. Check the lint's handling of unsized Index output types; done means it no longer suggests drop() when the suggested code fails to compile.