Compiler warning about dead code when enum is used in a match against return value of FFI call #85677

#[repr(C)]
#[derive(Debug, PartialEq)]
enum ResultEnumFromC {
    Success = 0,
    FailureOfTypeOne = 1,
    FailureOfTypeTwo = 2,
}

pub enum ErrEnumInRust {
    FailureOfTypeOne = 0,
    FailureOfTypeTwo = 1,
}

extern "C" {
    fn FunctionFromC() -> ResultEnumFromC;
}

pub fn wrapper_around_function_from_c(
) -> Result<(), ErrEnumInRust> {
    match unsafe { FunctionFromC() } {
        ResultEnumFromC::Success => Ok(()),
        ResultEnumFromC::FailureOfTypeOne => Err(ErrEnumInRust::FailureOfTypeOne),
        ResultEnumFromC::FailureOfTypeTwo => Err(ErrEnumInRust::FailureOfTypeTwo),
    }
}

warning: variant is never constructed: `Success`
 --> src/main.rs:4:5
  |
4 |     Success = 0,
  |     ^^^^^^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: variant is never constructed: `FailureOfTypeOne`
 --> src/main.rs:5:5
  |
5 |     FailureOfTypeOne = 1,
  |     ^^^^^^^^^^^^^^^^^^^^

warning: variant is never constructed: `FailureOfTypeTwo`
 --> src/main.rs:6:5
  |
6 |     FailureOfTypeTwo = 2,
  |     ^^^^^^^^^^^^^^^^^^^^

warning: 3 warnings emitted

1.52.1