src/test/ui/consts/const_discriminant.rs

   1 // run-pass
   2 #![feature(const_discriminant)]
   3 #![feature(bench_black_box)]
   4 #![allow(dead_code)]
   5
   6 use std::mem::{discriminant, Discriminant};
   7 use std::hint::black_box;
   8
   9 enum Test {
  10     A(u8),
  11     B,
  12     C { a: u8, b: u8 },
  13 }
  14
  15 const TEST_A: Discriminant<Test> = discriminant(&Test::A(5));
  16 const TEST_A_OTHER: Discriminant<Test> = discriminant(&Test::A(17));
  17 const TEST_B: Discriminant<Test> = discriminant(&Test::B);
  18
  19 enum Void {}
  20
  21 enum SingleVariant {
  22     V,
  23     Never(Void),
  24 }
  25
  26 const TEST_V: Discriminant<SingleVariant> = discriminant(&SingleVariant::V);
  27
  28 fn main() {
  29     assert_eq!(TEST_A, TEST_A_OTHER);
  30     assert_eq!(TEST_A, discriminant(black_box(&Test::A(17))));
  31     assert_eq!(TEST_B, discriminant(black_box(&Test::B)));
  32     assert_ne!(TEST_A, TEST_B);
  33     assert_ne!(TEST_B, discriminant(black_box(&Test::C { a: 42, b: 7 })));
  34
  35     assert_eq!(TEST_V, discriminant(black_box(&SingleVariant::V)));
  36 }