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| -rw-r--r-- | src/doc/rustdoc/src/unstable-features.md | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md index 32b35007490..c6c05e30090 100644 --- a/src/doc/rustdoc/src/unstable-features.md +++ b/src/doc/rustdoc/src/unstable-features.md @@ -197,6 +197,35 @@ To do so, the `#[doc(keyword = "...")]` attribute is used. Example: mod empty_mod {} ``` +## Effects of other nightly features + +These nightly-only features are not primarily related to Rustdoc, +but have convenient effects on the documentation produced. + +### `fundamental` types + +Annotating a type with `#[fundamental]` primarily influences coherence rules about generic types, +i.e., they alter whether other crates can provide implementations for that type. +The unstable book [links to further information][unstable-fundamental]. + +[unstable-fundamental]: https://doc.rust-lang.org/unstable-book/language-features/fundamental.html + +For documentation, this has an additional side effect: +If a method is implemented on `F<T>` (or `F<&T>`), +where `F` is a fundamental type, +then the method is not only documented at the page about `F`, +but also on the page about `T`. +In a sense, it makes the type transparent to Rustdoc. +This is especially convenient for types that work as annotated pointers, +such as `Pin<&mut T>`, +as it ensures that methods only implemented through those annotated pointers +can still be found with the type they act on. + +If the `fundamental` feature's effect on coherence is not intended, +such a type can be marked as fundamental only for purposes of documentation +by introducing a custom feature and +limiting the use of `fundamental` to when documentation is built. + ## Unstable command-line arguments These features are enabled by passing a command-line flag to Rustdoc, but the flags in question are |