Detect unsized expressions that are deref expressions like *""

[estebank]

Code

fn foo() -> impl Sized {
    *""
}

Current output

error[E0277]: the size for values of type `str` cannot be known at compilation time
 --> src/main.rs:1:13
  |
1 | fn foo() -> impl Sized {
  |             ^^^^^^^^^^ doesn't have a size known at compile-time
2 |     *""
  |     --- return type was inferred to be `str` here
  |
  = help: the trait `Sized` is not implemented for `str`

Desired output

error[E0277]: the size for values of type `str` cannot be known at compilation time
 --> src/main.rs:1:13
  |
1 | fn foo() -> impl Sized {
  |             ^^^^^^^^^^ doesn't have a size known at compile-time
2 |     *""
  |     --- return type was inferred to be `str` here
  |
  = help: the trait `Sized` is not implemented for `str`
help: remove the `*` dereference so the expression is of type `&str`, which is `Sized`
  |
2 -     *""
2 +     ""
  |

Rationale and extra context

The change is obvious when presented in isolation, but with a lot of diagnostics (and Sized errors can cause multiple knock-down errors) the problem gets hidden.

Other cases

No response

Rust Version

rustc 1.79.0 (129f3b996 2024-06-10)
binary: rustc
commit-hash: 129f3b9964af4d4a709d1383930ade12dfe7c081
commit-date: 2024-06-10
host: x86_64-unknown-linux-gnu
release: 1.79.0
LLVM version: 18.1.7

Anything else?

No response