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Rust errors / Attributes, macros and features

Rust compiler error · checked with rustc 1.99.0

Rust error E0543: missing 'note'

What it meansThe note value is missing in a stability attribute.

What rustc prints

error[E0543]: missing 'note'
 --> main.rs:6:1
  |
6 | / #[deprecated(
7 | |     since = "1.0.0"
8 | | )] // 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.

E0543Attributes, macros and features
Activein rustc 1.99.0
5related errors linked below

The compiler team's explanation

The note value is missing in a stability attribute.

Erroneous code example:

#![feature(staged_api)]
#![allow(internal_features)]
#![stable(since = "1.0.0", feature = "test")]

#[stable(since = "0.1.0", feature = "_deprecated_fn")]
#[deprecated(
    since = "1.0.0"
)] // invalid
fn _deprecated_fn() {}

To fix this issue, you need to provide the note field. Example:

#![feature(staged_api)]
#![allow(internal_features)]
#![stable(since = "1.0.0", feature = "test")]

#[stable(since = "0.1.0", feature = "_deprecated_fn")]
#[deprecated(
    since = "1.0.0",
    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.

From rustc --explain E0543 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.

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All 518 Rust error codes · Rust crate data · Glossary

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