src/test/ui/consts/const-eval/const_fn_ptr.rs

   1 // run-pass
   2 // compile-flags: -Zunleash-the-miri-inside-of-you
   3 #![feature(const_fn)]
   4
   5 fn double(x: usize) -> usize { x * 2 }
   6 const fn double_const(x: usize) -> usize { x * 2 }
   7
   8 const X: fn(usize) -> usize = double;
   9 const X_const: fn(usize) -> usize = double_const;
  10
  11 const fn bar(x: usize) -> usize {
  12     X(x)
  13 }
  14
  15 const fn bar_const(x: usize) -> usize {
  16     X_const(x)
  17 }
  18
  19 const fn foo(x: fn(usize) -> usize, y: usize)  -> usize {
  20     x(y)
  21 }
  22
  23 fn main() {
  24     const Y: usize = bar_const(2);
  25     assert_eq!(Y, 4);
  26     let y = bar_const(2);
  27     assert_eq!(y, 4);
  28     let y = bar(2);
  29     assert_eq!(y, 4);
  30
  31     const Z: usize = foo(double_const, 2);
  32     assert_eq!(Z, 4);
  33     let z = foo(double_const, 2);
  34     assert_eq!(z, 4);
  35     let z = foo(double, 2);
  36     assert_eq!(z, 4);
  37 }