A deprecated
attribute wasn't paired with a stable
/unstable
attribute with #![feature(staged_api)]
enabled.
Erroneous code example:
#![feature(staged_api)] #![allow(internal_features)] #![stable(since = "1.0.0", feature = "test")] #[deprecated( since = "1.0.1", note = "explanation for deprecation" )] // invalid fn _deprecated_fn() {}
To fix this issue, you need to add also an attribute stable
or unstable
. Example:
#![feature(staged_api)] #![allow(internal_features)] #![stable(since = "1.0.0", feature = "test")] #[stable(since = "1.0.0", feature = "test")] #[deprecated( since = "1.0.1", note = "explanation for deprecation" )] // ok! fn _deprecated_fn() {}
See the How Rust is Made and “Nightly Rust” appendix of the Book and the Stability attributes section of the Rustc Dev Guide for more details.