The maximum value of an enum was reached, so it cannot be automatically
set in the next enum value. Erroneous code example:
```compile_fail,E0370
#[repr(i64)]
enum Foo {
X = 0x7fffffffffffffff,
Y, // error: enum discriminant overflowed on value after
// 9223372036854775807: i64; set explicitly via
// Y = -9223372036854775808 if that is desired outcome
}
```
To fix this, please set manually the next enum value or put the enum variant
with the maximum value at the end of the enum. Examples:
```
#[repr(i64)]
enum Foo {
X = 0x7fffffffffffffff,
Y = 0, // ok!
}
```
Or:
```
#[repr(i64)]
enum Foo {
Y = 0, // ok!
X = 0x7fffffffffffffff,
}
```