src/test/ui/const-generics/array-size-in-generic-struct-param.rs

   1 // Tests that array sizes that depend on const-params are checked using `ConstEvaluatable`.
   2 // revisions: full min
   3
   4 #![cfg_attr(full, feature(const_generics))]
   5 #![cfg_attr(full, allow(incomplete_features))]
   6 #![cfg_attr(min, feature(min_const_generics))]
   7
   8 #[allow(dead_code)]
   9 struct ArithArrayLen<const N: usize>([u32; 0 + N]);
  10 //[full]~^ ERROR constant expression depends on a generic parameter
  11 //[min]~^^ ERROR generic parameters may not be used in const operations
  12
  13 #[derive(PartialEq, Eq)]
  14 struct Config {
  15     arr_size: usize,
  16 }
  17
  18 struct B<const CFG: Config> {
  19     //[min]~^ ERROR `Config` is forbidden
  20     arr: [u8; CFG.arr_size],
  21     //[full]~^ ERROR constant expression depends on a generic parameter
  22     //[min]~^^ ERROR generic parameters may not be used in const operations
  23 }
  24
  25 const C: Config = Config { arr_size: 5 };
  26
  27 fn main() {
  28     let b = B::<C> { arr: [1, 2, 3, 4, 5] };
  29     assert_eq!(b.arr.len(), 5);
  30 }