src/librustc_error_codes/error_codes/E0738.md

   1 `#[track_caller]` cannot be used in traits yet. This is due to limitations in
   2 the compiler which are likely to be temporary. See [RFC 2091] for details on
   3 this and other restrictions.
   4
   5 Erroneous example with a trait method implementation:
   6
   7 ```compile_fail,E0738
   8 #![feature(track_caller)]
   9
  10 trait Foo {
  11     fn bar(&self);
  12 }
  13
  14 impl Foo for u64 {
  15     #[track_caller]
  16     fn bar(&self) {}
  17 }
  18 ```
  19
  20 Erroneous example with a blanket trait method implementation:
  21
  22 ```compile_fail,E0738
  23 #![feature(track_caller)]
  24
  25 trait Foo {
  26     #[track_caller]
  27     fn bar(&self) {}
  28     fn baz(&self);
  29 }
  30 ```
  31
  32 Erroneous example with a trait method declaration:
  33
  34 ```compile_fail,E0738
  35 #![feature(track_caller)]
  36
  37 trait Foo {
  38     fn bar(&self) {}
  39
  40     #[track_caller]
  41     fn baz(&self);
  42 }
  43 ```
  44
  45 Note that while the compiler may be able to support the attribute in traits in
  46 the future, [RFC 2091] prohibits their implementation without a follow-up RFC.
  47
  48 [RFC 2091]: https://github.com/rust-lang/rfcs/blob/master/text/2091-inline-semantic.md