Rust errors / Attributes, macros and features
Rust compiler error · checked with rustc 1.99.0
Rust error E0547: missing 'issue'
What it meansThe issue value is missing in a stability attribute.
What rustc prints
error[E0547]: missing 'issue'
--> main.rs:5:1
|
5 | #[unstable(feature = "_unstable_fn")] // invalid
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Real output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.
E0547Attributes, macros and features
Activein rustc 1.99.0
5related errors linked below
The compiler team's explanation
The issue value is missing in a stability attribute.
Erroneous code example:
#![feature(staged_api)]
#![allow(internal_features)]
#![stable(since = "1.0.0", feature = "test")]
#[unstable(feature = "_unstable_fn")] // invalid
fn _unstable_fn() {}
#[rustc_const_unstable(feature = "_unstable_const_fn")] // invalid
const fn _unstable_const_fn() {}To fix this issue, you need to provide the issue field. Example:
#![feature(staged_api)]
#![allow(internal_features)]
#![stable(since = "1.0.0", feature = "test")]
#[unstable(feature = "_unstable_fn", issue = "none")] // ok!
fn _unstable_fn() {}
#[rustc_const_unstable(
feature = "_unstable_const_fn",
issue = "none"
)] // ok!
const fn _unstable_const_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.
From rustc --explain E0547 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
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