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Update docs for deprecated attribute (#1338)

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Jacob Pratt 2022-05-12 00:53:26 -04:00 committed by GitHub
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src/stability.md
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@ -121,24 +121,21 @@ Always ping @rust-lang/wg-const-eval if you are adding more
## staged_api ## staged_api
Any crate that uses the `stable`, `unstable`, or `rustc_deprecated` attributes Any crate that uses the `stable` or `unstable` attributes must include the
must include the `#![feature(staged_api)]` attribute on the crate. `#![feature(staged_api)]` attribute on the crate.
## rustc_deprecated ## deprecated
The deprecation system shares the same infrastructure as the stable/unstable Deprecations in the standard library are nearly identical to deprecations in
attributes. The `rustc_deprecated` attribute is similar to the [`deprecated` user code. When `#[deprecated]` is used on an item, it must also have a `stable`
attribute]. It was previously called `deprecated`, but was split off when or `unstable `attribute.
`deprecated` was stabilized. The `deprecated` attribute cannot be used in a
`staged_api` crate, `rustc_deprecated` must be used instead. The deprecated
item must also have a `stable` or `unstable` attribute.
`rustc_deprecated` has the following form: `deprecated` has the following form:
```rust,ignore ```rust,ignore
#[rustc_deprecated( #[deprecated(
since = "1.38.0", since = "1.38.0",
reason = "explanation for deprecation", note = "explanation for deprecation",
suggestion = "other_function" suggestion = "other_function"
)] )]
``` ```
@ -146,13 +143,13 @@ item must also have a `stable` or `unstable` attribute.
The `suggestion` field is optional. If given, it should be a string that can be The `suggestion` field is optional. If given, it should be a string that can be
used as a machine-applicable suggestion to correct the warning. This is used as a machine-applicable suggestion to correct the warning. This is
typically used when the identifier is renamed, but no other significant changes typically used when the identifier is renamed, but no other significant changes
are necessary. are necessary. When the `suggestion` field is used, you need to have
`#![feature(deprecated_suggestion)]` at the crate root.
Another difference from the `deprecated` attribute is that the `since` field is Another difference from user code is that the `since` field is actually checked
actually checked against the current version of `rustc`. If `since` is in a against the current version of `rustc`. If `since` is in a future version, then
future version, then the `deprecated_in_future` lint is triggered which is the `deprecated_in_future` lint is triggered which is default `allow`, but most
default `allow`, but most of the standard library raises it to a warning with of the standard library raises it to a warning with
`#![warn(deprecated_in_future)]`. `#![warn(deprecated_in_future)]`.
[`deprecated` attribute]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute
[blog]: https://www.ralfj.de/blog/2018/07/19/const.html [blog]: https://www.ralfj.de/blog/2018/07/19/const.html