src/librustc_error_codes/error_codes/E0744.md

   1 A control-flow expression was used inside a const context.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0744
   6 const _: i32 = {
   7     let mut x = 0;
   8
   9     for i in 0..4 { // error!
  10         x += i;
  11     }
  12 };
  13 ```
  14
  15 At the moment, `if` and `match`, as well as the looping constructs `for`,
  16 `while`, and `loop`, are forbidden inside a `const`, `static`, or `const fn`.
  17
  18 This will be allowed at some point in the future, but the implementation is not
  19 yet complete. See the tracking issue for [conditionals] or [loops] in a const
  20 context for the current status.
  21
  22 [conditionals]: https://github.com/rust-lang/rust/issues/49146
  23 [loops]: https://github.com/rust-lang/rust/issues/52000