src/librustc_error_codes/error_codes/E0478.md

   1 A lifetime bound was not satisfied.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0478
   6 // Check that the explicit lifetime bound (`'SnowWhite`, in this example) must
   7 // outlive all the superbounds from the trait (`'kiss`, in this example).
   8
   9 trait Wedding<'t>: 't { }
  10
  11 struct Prince<'kiss, 'SnowWhite> {
  12     child: Box<Wedding<'kiss> + 'SnowWhite>,
  13     // error: lifetime bound not satisfied
  14 }
  15 ```
  16
  17 In this example, the `'SnowWhite` lifetime is supposed to outlive the `'kiss`
  18 lifetime but the declaration of the `Prince` struct doesn't enforce it. To fix
  19 this issue, you need to specify it:
  20
  21 ```
  22 trait Wedding<'t>: 't { }
  23
  24 struct Prince<'kiss, 'SnowWhite: 'kiss> { // You say here that 'SnowWhite
  25                                           // must live longer than 'kiss.
  26     child: Box<Wedding<'kiss> + 'SnowWhite>, // And now it's all good!
  27 }
  28 ```