src/test/ui/loops/loops-reject-lifetime-shadowing-label.rs

   1 // check-pass
   2 #![feature(label_break_value)]
   3 #![allow(dead_code, unused_variables)]
   4
   5 // Issue #21633:  reject duplicate loop labels and block labels in function bodies.
   6 //
   7 // Test rejection of lifetimes in *expressions* that shadow labels.
   8
   9 fn foo() {
  10     // Reusing lifetime `'a` in function item is okay.
  11     fn foo<'a>(x: &'a i8) -> i8 { *x }
  12
  13     // So is reusing `'a` in struct item
  14     struct S1<'a> { x: &'a i8 } impl<'a> S1<'a> { fn m(&self) {} }
  15     // and a method item
  16     struct S2; impl S2 { fn m<'a>(&self) {} }
  17
  18     let z = 3_i8;
  19
  20     'a: loop {
  21         let b = Box::new(|x: &i8| *x) as Box<dyn for <'a> Fn(&'a i8) -> i8>;
  22         //~^ WARN lifetime name `'a` shadows a label name that is already in scope
  23         assert_eq!((*b)(&z), z);
  24         break 'a;
  25     }
  26
  27     'b: {
  28         let b = Box::new(|x: &()| ()) as Box<dyn for <'b> Fn(&'b ())>;
  29         //~^ WARN lifetime name `'b` shadows a label name that is already in scope
  30         break 'b;
  31     }
  32 }
  33
  34 pub fn main() {
  35     foo();
  36 }