pattern check ignores if guards

Summary

related to https://github.com/Rust-GCC/gccrs/issues/3172

Reproducer

I tried this code:

enum E {
    A(),
    B(),
}

fn f(e: E) {
    match e {
        E::A() if true => {}
        //E::B => {}
    }
}

Does the code make use of any (1.49) nightly feature ?

• Nightly

Godbolt link

https://godbolt.org/z/97fnfov7h

Actual behavior

The current behavior is...

<source>:7:11: error: non-exhaustive patterns: 'E::B()' not covered
    7 |     match e {
      |           ^
Compiler returned: 1

Expected behavior

I expected to see...

error[E0004]: non-exhaustive patterns: `A` and `B` not covered
 --> <source>:7:11
  |
1 | / enum E {
2 | |     A(),
  | |     - not covered
3 | |     B(),
  | |     - not covered
4 | | }
  | |_- `E` defined here
...
7 |       match e {
  |             ^ patterns `A` and `B` not covered
  |
  = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
  = note: the matched value is of type `E`

error: aborting due to previous error

GCC Version

67bc0f69b46b2e4c335017aba3bc1218574aad7a

Start by compiling the Rust reproducer from the issue, or open the provided Godbolt link, and compare its behavior with the expected exhaustiveness diagnostic. Investigate the compiler's pattern-checking path for match arms with if guards; done means the guarded arm is handled correctly and the resulting diagnostic matches the expected non-exhaustive-pattern behavior.