`manual_unwrap_or_default` generates invalid code for nested pattern match

[kluevi]

Summary

clippy fails to understand nested pattern matches. It treats if let Some(Some(a)) the same as if let Some(a), resulting in invalid code when --fix-ing.

Reproducer

I tried this code:

fn main() {
    let foo = Some(Some(5));
    let num: i32 = if let Some(Some(num)) = foo {
        num
    } else {
        0
    };
    println!("{num}");
}

I expected to see this happen:

Nothing, really.

Instead, this happened:

The following errors were reported:
error[E0308]: mismatched types
 --> src/main.rs:3:20
  |
3 |     let num: i32 = foo.unwrap_or_default();
  |              ---   ^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `Option<{integer}>`
  |              |
  |              expected due to this
  |
  = note: expected type `i32`
             found enum `std::option::Option<{integer}>`
help: consider using `Option::expect` to unwrap the `std::option::Option<{integer}>` value, panicking if the value is an `Option::None`
  |
3 |     let num: i32 = foo.unwrap_or_default().expect("REASON");
  |                                           +++++++++++++++++

Version

No response

Additional Labels

No response

[y21]

This was fixed in #12961. Since that was backported I believe it should be fixed on all channels now (stable, beta, nightly). Do you still see this after updating to a newer version?

[kluevi]

Indeed, it was gone after a rustup update.