src/test/ui/consts/miri_unleashed/assoc_const.rs

   1 // build-fail
   2 // compile-flags: -Zunleash-the-miri-inside-of-you
   3
   4 // a test demonstrating why we do need to run static const qualification on associated constants
   5 // instead of just checking the final constant
   6
   7 trait Foo<T> {
   8     const X: T;
   9 }
  10
  11 trait Bar<T, U: Foo<T>> {
  12     const F: u32 = (U::X, 42).1;
  13 }
  14
  15 impl Foo<u32> for () {
  16     const X: u32 = 42;
  17 }
  18 impl Foo<Vec<u32>> for String {
  19     const X: Vec<u32> = Vec::new();
  20 }
  21
  22 impl Bar<u32, ()> for () {}
  23 impl Bar<Vec<u32>, String> for String {}
  24
  25 fn main() {
  26     // this is fine, but would have been forbidden by the static checks on `F`
  27     let x = <() as Bar<u32, ()>>::F;
  28     // this test only causes errors due to the line below, so post-monomorphization
  29     let y = <String as Bar<Vec<u32>, String>>::F; //~ constant
  30 }