Parse error on let followed by a block should suggest likely alternatives if-let or let-else

[pnkfelix]

Code

fn main() {
    let Some(msg) = opt_msg() {
        dbg!(msg);
    }
}

fn opt_msg() -> Option<&'static str> {
    Some("hello world")
}

Current output

error: expected one of `.`, `;`, `?`, `else`, or an operator, found `{`
 --> src/main.rs:2:31
  |
2 |     let Some(msg) = opt_msg() {
  |                               ^ expected one of `.`, `;`, `?`, `else`, or an operator

error: could not compile `playground` due to previous error

Desired output

error: expected one of `.`, `;`, `?`, `else`, or an operator, found `{`
 --> src/main.rs:2:31
  |
2 |     let Some(msg) = opt_msg() {
  |                               ^ expected one of `.`, `;`, `?`, `else`, or an operator

note: if you intended to write an `if let`, put an `if` in front of the `let`, like so:
  |
2 |     if let Some(msg) = opt_msg() {
  |

note: if you intended to write a `let else`, add an `else` and its block after the scrutinee, like so:

  |
2 |     let Some(msg) = opt_msg() else { ... } {
  |

error: could not compile `playground` due to previous error

Rationale and extra context

Its pretty natural at times to try to flip code from a let to an if let, but the resulting compiler parsing error is not as helpful as it could be.

Other cases

No response

Anything else?

No response