The since
value is missing in a stability attribute.
Erroneous code example:
#![allow(unused)]
#![feature(staged_api)]
#![allow(internal_features)]
#![stable(since = "1.0.0", feature = "test")]
fn main() {
#[stable(feature = "_stable_fn")]
fn _stable_fn() {}
#[rustc_const_stable(feature = "_stable_const_fn")]
const fn _stable_const_fn() {}
#[stable(feature = "_deprecated_fn", since = "0.1.0")]
#[deprecated(
note = "explanation for deprecation"
)]
fn _deprecated_fn() {}
}
ⓘ
To fix this issue, you need to provide the since
field. Example:
#![allow(unused)]
#![feature(staged_api)]
#![allow(internal_features)]
#![stable(since = "1.0.0", feature = "test")]
fn main() {
#[stable(feature = "_stable_fn", since = "1.0.0")]
fn _stable_fn() {}
#[stable(feature = "_stable_const_fn", since = "1.0.0")]
#[rustc_const_stable(feature = "_stable_const_fn", since = "1.0.0")]
const fn _stable_const_fn() {}
#[stable(feature = "_deprecated_fn", since = "0.1.0")]
#[deprecated(
since = "1.0.0",
note = "explanation for deprecation"
)]
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.