compiler/rustc_error_codes/src/error_codes/E0515.md

   1 A reference to a local variable was returned.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0515
   6 fn get_dangling_reference() -> &'static i32 {
   7     let x = 0;
   8     &x
   9 }
  10 ```
  11
  12 ```compile_fail,E0515
  13 use std::slice::Iter;
  14 fn get_dangling_iterator<'a>() -> Iter<'a, i32> {
  15     let v = vec![1, 2, 3];
  16     v.iter()
  17 }
  18 ```
  19
  20 Local variables, function parameters and temporaries are all dropped before the
  21 end of the function body. So a reference to them cannot be returned.
  22
  23 Consider returning an owned value instead:
  24
  25 ```
  26 use std::vec::IntoIter;
  27
  28 fn get_integer() -> i32 {
  29     let x = 0;
  30     x
  31 }
  32
  33 fn get_owned_iterator() -> IntoIter<i32> {
  34     let v = vec![1, 2, 3];
  35     v.into_iter()
  36 }
  37 ```