rust/src/test/ui/enum/enum-discrim-autosizing.rs

// With no repr attribute the discriminant will default to isize.
// On 32-bit architectures this is equivalent to i32 so the variants
// collide. On other architectures we need compilation to fail anyway,
// so force the repr.
#[cfg_attr(not(target_pointer_width = "32"), repr(i32))]
enum Eu64 {
    Au64 = 0, //~NOTE first use of `0`
    Bu64 = 0x8000_0000_0000_0000
    //~^ ERROR discriminant value `0` already exists
    //~| NOTE enum already has `0` (overflowed from `9223372036854775808`)
}

fn main() {}