compiler/rustc_error_codes/src/error_codes/E0546.md

   1 The `feature` value is missing in a stability attribute.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0546
   6 #![feature(staged_api)]
   7 #![stable(since = "1.0.0", feature = "test")]
   8
   9 #[unstable(issue = "none")] // invalid
  10 fn unstable_fn() {}
  11
  12 #[stable(since = "1.0.0")] // invalid
  13 fn stable_fn() {}
  14 ```
  15
  16 To fix this issue, you need to provide the `feature` field. Example:
  17
  18 ```
  19 #![feature(staged_api)]
  20 #![stable(since = "1.0.0", feature = "test")]
  21
  22 #[unstable(feature = "unstable_fn", issue = "none")] // ok!
  23 fn unstable_fn() {}
  24
  25 #[stable(feature = "stable_fn", since = "1.0.0")] // ok!
  26 fn stable_fn() {}
  27 ```
  28
  29 See the [How Rust is Made and “Nightly Rust”][how-rust-made-nightly] appendix
  30 of the Book and the [Stability attributes][stability-attributes] section of the
  31 Rustc Dev Guide for more details.
  32
  33 [how-rust-made-nightly]: https://doc.rust-lang.org/book/appendix-07-nightly-rust.html
  34 [stability-attributes]: https://rustc-dev-guide.rust-lang.org/stability.html