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

   1 // Copyright 2018 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 #![feature(const_let)]
  12
  13 fn main() {
  14     // Tests the Collatz conjecture with an incorrect base case (0 instead of 1).
  15     // The value of `n` will loop indefinitely (4 - 2 - 1 - 4).
  16     let _ = [(); {
  17         //~^ WARNING Constant evaluating a complex constant, this might take some time
  18         let mut n = 113383; // #20 in https://oeis.org/A006884
  19         while n != 0 { //~ ERROR constant contains unimplemented expression type
  20             n = if n % 2 == 0 { n/2 } else { 3*n + 1 };
  21             //~^ ERROR evaluation of constant value failed
  22         }
  23         n
  24     }];
  25 }