src/test/ui/consts/const-eval/issue-50814-2.rs

   1 // build-fail
   2
   3 trait C {
   4     const BOO: usize;
   5 }
   6
   7 trait Foo<T> {
   8     const BAR: usize;
   9 }
  10
  11 struct A<T>(T);
  12
  13 impl<T: C> Foo<T> for A<T> {
  14     const BAR: usize = [5, 6, 7][T::BOO]; //~ ERROR any use of this value will cause an error
  15     //~| WARN this was previously accepted by the compiler but is being phased out
  16 }
  17
  18 fn foo<T: C>() -> &'static usize {
  19     &<A<T> as Foo<T>>::BAR //~ ERROR E0080
  20 }
  21
  22 impl C for () {
  23     const BOO: usize = 42;
  24 }
  25
  26 impl C for u32 {
  27     const BOO: usize = 1;
  28 }
  29
  30 fn main() {
  31     println!("{:x}", foo::<()>() as *const usize as usize);
  32     println!("{:x}", foo::<u32>() as *const usize as usize);
  33     println!("{:x}", foo::<()>());
  34     println!("{:x}", foo::<u32>());
  35 }