src/test/ui/loops/loops-reject-duplicate-labels.rs

   1 // build-pass (FIXME(62277): could be check-pass?)
   2
   3 // ignore-tidy-linelength
   4
   5 // Issue #21633: reject duplicate loop labels in function bodies.
   6 // This is testing the exact cases that are in the issue description.
   7
   8 #[allow(unused_labels)]
   9 fn foo() {
  10     'fl: for _ in 0..10 { break; }
  11     'fl: loop { break; }           //~ WARN label name `'fl` shadows a label name that is already in scope
  12
  13     'lf: loop { break; }
  14     'lf: for _ in 0..10 { break; } //~ WARN label name `'lf` shadows a label name that is already in scope
  15     'wl: while 2 > 1 { break; }
  16     'wl: loop { break; }           //~ WARN label name `'wl` shadows a label name that is already in scope
  17     'lw: loop { break; }
  18     'lw: while 2 > 1 { break; }    //~ WARN label name `'lw` shadows a label name that is already in scope
  19     'fw: for _ in 0..10 { break; }
  20     'fw: while 2 > 1 { break; }    //~ WARN label name `'fw` shadows a label name that is already in scope
  21     'wf: while 2 > 1 { break; }
  22     'wf: for _ in 0..10 { break; } //~ WARN label name `'wf` shadows a label name that is already in scope
  23     'tl: while let Some(_) = None::<i32> { break; }
  24     'tl: loop { break; }           //~ WARN label name `'tl` shadows a label name that is already in scope
  25     'lt: loop { break; }
  26     'lt: while let Some(_) = None::<i32> { break; }
  27                                    //~^ WARN label name `'lt` shadows a label name that is already in scope
  28 }
  29
  30 // Note however that it is okay for the same label to be reused in
  31 // different methods of one impl, as illustrated here.
  32
  33 struct S;
  34 impl S {
  35     fn m1(&self) { 'okay: loop { break 'okay; } }
  36     fn m2(&self) { 'okay: loop { break 'okay; } }
  37 }
  38
  39
  40 pub fn main() {
  41     let s = S;
  42     s.m1();
  43     s.m2();
  44     foo();
  45 }