37 lines
691 B
Rust
37 lines
691 B
Rust
//@ run-pass
|
|
|
|
// Cyclic assoc. const defaults don't error unless *used*
|
|
trait Tr {
|
|
const A: u8 = Self::B;
|
|
const B: u8 = Self::A;
|
|
}
|
|
|
|
// This impl is *allowed* unless its assoc. consts are used, matching the
|
|
// behavior without defaults.
|
|
impl Tr for () {}
|
|
|
|
// Overriding either constant breaks the cycle
|
|
impl Tr for u8 {
|
|
const A: u8 = 42;
|
|
}
|
|
|
|
impl Tr for u16 {
|
|
const B: u8 = 0;
|
|
}
|
|
|
|
impl Tr for u32 {
|
|
const A: u8 = 100;
|
|
const B: u8 = 123;
|
|
}
|
|
|
|
fn main() {
|
|
assert_eq!(<u8 as Tr>::A, 42);
|
|
assert_eq!(<u8 as Tr>::B, 42);
|
|
|
|
assert_eq!(<u16 as Tr>::A, 0);
|
|
assert_eq!(<u16 as Tr>::B, 0);
|
|
|
|
assert_eq!(<u32 as Tr>::A, 100);
|
|
assert_eq!(<u32 as Tr>::B, 123);
|
|
}
|