src/test/ui/if/if-no-match-bindings.rs

   1 // Checks for `if` expressions with respect to default match bindings.
   2 // Specifically, we do not accept `if cond { ... }` where `cond: &mut? bool`.
   3 // Meanwhile, `match cond { true => ..., _ => ... }` does accept that.
   4
   5 // FIXME(@rust-lang/lang-team): consider relaxing this?
   6
   7 fn b_ref<'a>() -> &'a bool { &true }
   8 fn b_mut_ref<'a>() -> &'a mut bool { &mut true }
   9
  10 fn main() {
  11     // This is OK:
  12     match b_ref() { true => {}, _ => {} }
  13     match b_mut_ref() { true => {}, _ => {} }
  14     match &true { true => {}, _ => {} }
  15     match &mut true { true => {}, _ => {} }
  16
  17     // This is NOT:
  18     if b_ref() {} //~ ERROR mismatched types [E0308]
  19     if b_mut_ref() {} //~ ERROR mismatched types [E0308]
  20     if &true {} //~ ERROR mismatched types [E0308]
  21     if &mut true {} //~ ERROR mismatched types [E0308]
  22
  23     // This is also NOT:
  24     while b_ref() {} //~ ERROR mismatched types [E0308]
  25     while b_mut_ref() {} //~ ERROR mismatched types [E0308]
  26     while &true {} //~ ERROR mismatched types [E0308]
  27     while &mut true {} //~ ERROR mismatched types [E0308]
  28 }