[Bug c++/93967] New: switch on exhaustive enum gives control reaches end of non-void function

[gcc at cookiesoft dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93967

            Bug ID: 93967
           Summary: switch on exhaustive enum gives control reaches end of
                    non-void function
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at cookiesoft dot de
  Target Milestone: ---

```
enum class A { X, Y, Z };

int foo(A a) {
    switch (a) {
        case A::X: return 1;
        case A::Y: return 2;
        case A::Z: return 3;
    }
}
```

`g++ input.cpp`

```
<source>: In function 'int foo(A)':
<source>:9:1: warning: control reaches end of non-void function [-Wreturn-type]
    9 | }
      | ^
```

The switch is exhaustive and so there is no way that the function reaches the
code path after the switch. Clang does not emit a warning.

This happens on every version of gcc.

Godbolt: https://cpp.godbolt.org/z/Goii_K