Rename #[doc(spotlight)] to #[doc(notable_trait)]

"spotlight" is not a very specific or self-explaining name.
Additionally, the dialog that it triggers is called "Notable traits".
So, "notable trait" is a better name.

* Rename `#[doc(spotlight)]` to `#[doc(notable_trait)]`
* Rename `#![feature(doc_spotlight)]` to `#![feature(doc_notable_trait)]`
* Update documentation
* Improve documentation

Author: camelid

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -313,7 +313,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                     include => external_doc
                     cfg => doc_cfg
                     masked => doc_masked
-                    spotlight => doc_spotlight
+                    notable_trait => doc_notable_trait
                     keyword => doc_keyword
                 );
             }

compiler/rustc_feature/src/active.rs

@@ -216,6 +216,10 @@ declare_features! (
     /// Renamed from `optin_builtin_traits`.
     (active, auto_traits, "1.50.0", Some(13231), None),
 
+    /// Allows `#[doc(notable_trait)]`.
+    /// Renamed from `doc_spotlight`.
+    (active, doc_notable_trait, "1.52.0", Some(45040), None),
+
     // no-tracking-issue-end
 
     // -------------------------------------------------------------------------
@@ -374,9 +378,6 @@ declare_features! (
     /// Allows `#[doc(masked)]`.
     (active, doc_masked, "1.21.0", Some(44027), None),
 
-    /// Allows `#[doc(spotlight)]`.
-    (active, doc_spotlight, "1.22.0", Some(45040), None),
-
     /// Allows `#[doc(include = "some-file")]`.
     (active, external_doc, "1.22.0", Some(44732), None),
 

compiler/rustc_feature/src/removed.rs

@@ -80,6 +80,11 @@ declare_features! (
      Some("subsumed by `#![feature(allocator_internals)]`")),
     /// Allows identifying crates that contain sanitizer runtimes.
     (removed, sanitizer_runtime, "1.17.0", None, None, None),
+    /// Allows `#[doc(spotlight)]`.
+    /// The attribute was renamed to `#[doc(notable_trait)]`
+    /// and the feature to `doc_notable_trait`.
+    (removed, doc_spotlight, "1.22.0", Some(45040), None,
+     Some("renamed to `doc_notable_trait`")),
     (removed, proc_macro_mod, "1.27.0", Some(54727), None,
      Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
     (removed, proc_macro_expr, "1.27.0", Some(54727), None,

compiler/rustc_passes/src/check_attr.rs

@@ -9,7 +9,7 @@ use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
 
 use rustc_ast::{Attribute, Lit, LitKind, NestedMetaItem};
-use rustc_errors::{pluralize, struct_span_err};
+use rustc_errors::{pluralize, struct_span_err, Applicability};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
@@ -589,10 +589,10 @@ impl CheckAttrVisitor<'tcx> {
                         | sym::masked
                         | sym::no_default_passes
                         | sym::no_inline
+                        | sym::notable_trait
                         | sym::passes
                         | sym::plugins
                         | sym::primitive
-                        | sym::spotlight
                         | sym::test => {}
 
                         _ => {
@@ -601,11 +601,23 @@ impl CheckAttrVisitor<'tcx> {
                                 hir_id,
                                 i_meta.span,
                                 |lint| {
-                                    let msg = format!(
+                                    let mut diag = lint.build(&format!(
                                         "unknown `doc` attribute `{}`",
                                         rustc_ast_pretty::pprust::path_to_string(&i_meta.path),
-                                    );
-                                    lint.build(&msg).emit();
+                                    ));
+                                    if i_meta.has_name(sym::spotlight) {
+                                        diag.note(
+                                            "`doc(spotlight)` was renamed to `doc(notable_trait)`",
+                                        );
+                                        diag.span_suggestion_short(
+                                            i_meta.span,
+                                            "use `notable_trait` instead",
+                                            String::from("notable_trait"),
+                                            Applicability::MachineApplicable,
+                                        );
+                                        diag.note("`doc(spotlight)` is now a no-op");
+                                    }
+                                    diag.emit();
                                 },
                             );
                             is_valid = false;

compiler/rustc_span/src/symbol.rs

@@ -476,6 +476,7 @@ symbols! {
         doc_cfg,
         doc_keyword,
         doc_masked,
+        doc_notable_trait,
         doc_spotlight,
         doctest,
         document_private_items,
@@ -799,6 +800,7 @@ symbols! {
         noreturn,
         nostack,
         not,
+        notable_trait,
         note,
         object_safe_for_dispatch,
         of,

library/core/src/future/future.rs

@@ -24,7 +24,8 @@ use crate::task::{Context, Poll};
 /// `.await` the value.
 ///
 /// [`Waker`]: crate::task::Waker
-#[doc(spotlight)]
+#[cfg_attr(bootstrap, doc(spotlight))]
+#[cfg_attr(not(bootstrap), doc(notable_trait))]
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 #[stable(feature = "futures_api", since = "1.36.0")]
 #[lang = "future_trait"]

library/core/src/iter/traits/iterator.rs

@@ -92,7 +92,8 @@ fn _assert_is_object_safe(_: &dyn Iterator<Item = ()>) {}
     label = "`{Self}` is not an iterator",
     message = "`{Self}` is not an iterator"
 )]
-#[doc(spotlight)]
+#[cfg_attr(bootstrap, doc(spotlight))]
+#[cfg_attr(not(bootstrap), doc(notable_trait))]
 #[rustc_diagnostic_item = "Iterator"]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 pub trait Iterator {

library/core/src/lib.rs

@@ -108,7 +108,8 @@
 #![feature(custom_inner_attributes)]
 #![feature(decl_macro)]
 #![feature(doc_cfg)]
-#![feature(doc_spotlight)]
+#![cfg_attr(bootstrap, feature(doc_spotlight))]
+#![cfg_attr(not(bootstrap), feature(doc_notable_trait))]
 #![feature(duration_consts_2)]
 #![feature(duration_saturating_ops)]
 #![feature(extended_key_value_attributes)]

library/std/src/io/mod.rs

@@ -505,7 +505,8 @@ pub(crate) fn default_read_exact<R: Read + ?Sized>(this: &mut R, mut buf: &mut [
 /// [`std::io`]: self
 /// [`File`]: crate::fs::File
 #[stable(feature = "rust1", since = "1.0.0")]
-#[doc(spotlight)]
+#[cfg_attr(bootstrap, doc(spotlight))]
+#[cfg_attr(not(bootstrap), doc(notable_trait))]
 pub trait Read {
     /// Pull some bytes from this source into the specified buffer, returning
     /// how many bytes were read.
@@ -1291,7 +1292,8 @@ impl Initializer {
 ///
 /// [`write_all`]: Write::write_all
 #[stable(feature = "rust1", since = "1.0.0")]
-#[doc(spotlight)]
+#[cfg_attr(bootstrap, doc(spotlight))]
+#[cfg_attr(not(bootstrap), doc(notable_trait))]
 pub trait Write {
     /// Write a buffer into this writer, returning how many bytes were written.
     ///

library/std/src/lib.rs

@@ -257,7 +257,8 @@
 #![feature(doc_cfg)]
 #![feature(doc_keyword)]
 #![feature(doc_masked)]
-#![feature(doc_spotlight)]
+#![cfg_attr(bootstrap, feature(doc_spotlight))]
+#![cfg_attr(not(bootstrap), feature(doc_notable_trait))]
 #![feature(dropck_eyepatch)]
 #![feature(duration_constants)]
 #![feature(duration_zero)]

src/doc/rustdoc/src/unstable-features.md

@@ -88,26 +88,28 @@ Book][unstable-doc-cfg] and [its tracking issue][issue-doc-cfg].
 [unstable-doc-cfg]: ../unstable-book/language-features/doc-cfg.html
 [issue-doc-cfg]: https://github.com/rust-lang/rust/issues/43781
 
-### Adding your trait to the "Important Traits" dialog
-
-Rustdoc keeps a list of a few traits that are believed to be "fundamental" to a given type when
-implemented on it. These traits are intended to be the primary interface for their types, and are
-often the only thing available to be documented on their types. For this reason, Rustdoc will track
-when a given type implements one of these traits and call special attention to it when a function
-returns one of these types. This is the "Important Traits" dialog, visible as a circle-i button next
-to the function, which, when clicked, shows the dialog.
-
-In the standard library, the traits that qualify for inclusion are `Iterator`, `io::Read`, and
-`io::Write`. However, rather than being implemented as a hard-coded list, these traits have a
-special marker attribute on them: `#[doc(spotlight)]`. This means that you could apply this
-attribute to your own trait to include it in the "Important Traits" dialog in documentation.
-
-The `#[doc(spotlight)]` attribute currently requires the `#![feature(doc_spotlight)]` feature gate.
-For more information, see [its chapter in the Unstable Book][unstable-spotlight] and [its tracking
-issue][issue-spotlight].
-
-[unstable-spotlight]: ../unstable-book/language-features/doc-spotlight.html
-[issue-spotlight]: https://github.com/rust-lang/rust/issues/45040
+### Adding your trait to the "Notable traits" dialog
+
+Rustdoc keeps a list of a few traits that are believed to be "fundamental" to
+types that implement them. These traits are intended to be the primary interface
+for their implementers, and are often most of the API available to be documented
+on their types. For this reason, Rustdoc will track when a given type implements
+one of these traits and call special attention to it when a function returns one
+of these types. This is the "Notable traits" dialog, accessible as a circled `i`
+button next to the function, which, when clicked, shows the dialog.
+
+In the standard library, some of the traits that are part of this list are
+`Iterator`, `Future`, `io::Read`, and `io::Write`. However, rather than being
+implemented as a hard-coded list, these traits have a special marker attribute
+on them: `#[doc(notable_trait)]`. This means that you can apply this attribute
+to your own trait to include it in the "Notable traits" dialog in documentation.
+
+The `#[doc(notable_trait)]` attribute currently requires the `#![feature(doc_notable_trait)]`
+feature gate. For more information, see [its chapter in the Unstable Book][unstable-notable_trait]
+and [its tracking issue][issue-notable_trait].
+
+[unstable-notable_trait]: ../unstable-book/language-features/doc-notable-trait.html
+[issue-notable_trait]: https://github.com/rust-lang/rust/issues/45040
 
 ### Exclude certain dependencies from documentation
 

src/doc/unstable-book/src/language-features/doc-notable-trait.md

@@ -0,0 +1,33 @@
+# `doc_notable_trait`
+
+The tracking issue for this feature is: [#45040]
+
+The `doc_notable_trait` feature allows the use of the `#[doc(notable_trait)]`
+attribute, which will display the trait in a "Notable traits" dialog for
+functions returning types that implement the trait. For example, this attribute
+is applied to the `Iterator`, `Future`, `io::Read`, and `io::Write` traits in
+the standard library.
+
+You can do this on your own traits like so:
+
+```
+#![feature(doc_notable_trait)]
+
+#[doc(notable_trait)]
+pub trait MyTrait {}
+
+pub struct MyStruct;
+impl MyTrait for MyStruct {}
+
+/// The docs for this function will have a button that displays a dialog about
+/// `MyStruct` implementing `MyTrait`.
+pub fn my_fn() -> MyStruct { MyStruct }
+```
+
+This feature was originally implemented in PR [#45039].
+
+See also its documentation in [the rustdoc book][rustdoc-book-notable_trait].
+
+[#45040]: https://github.com/rust-lang/rust/issues/45040
+[#45039]: https://github.com/rust-lang/rust/pull/45039
+[rustdoc-book-notable_trait]: ../../rustdoc/unstable-features.html#adding-your-trait-to-the-notable-traits-dialog

src/doc/unstable-book/src/language-features/doc-spotlight.md

@@ -628,7 +628,7 @@ crate fn record_extern_trait(cx: &mut DocContext<'_>, did: DefId) {
 
     let trait_ = clean::TraitWithExtraInfo {
         trait_,
-        is_spotlight: clean::utils::has_doc_flag(cx.tcx.get_attrs(did), sym::spotlight),
+        is_spotlight: clean::utils::has_doc_flag(cx.tcx.get_attrs(did), sym::notable_trait),
     };
     cx.external_traits.borrow_mut().insert(did, trait_);
     cx.active_extern_traits.remove(&did);

src/librustdoc/clean/inline.rs

@@ -229,7 +229,7 @@ impl<'a, 'tcx> DocFolder for CacheBuilder<'a, 'tcx> {
         if let clean::TraitItem(ref t) = *item.kind {
             self.cache.traits.entry(item.def_id).or_insert_with(|| clean::TraitWithExtraInfo {
                 trait_: t.clone(),
-                is_spotlight: item.attrs.has_doc_flag(sym::spotlight),
+                is_spotlight: item.attrs.has_doc_flag(sym::notable_trait),
             });
         }
 

src/librustdoc/formats/cache.rs

@@ -0,0 +1,10 @@
+// ignore-tidy-linelength
+// check-pass
+// run-rustfix
+
+#![feature(doc_notable_trait)]
+
+#[doc(notable_trait)]
+//~^ WARN unknown `doc` attribute `spotlight`
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+trait MyTrait {}

src/test/rustdoc-ui/doc-spotlight.fixed

@@ -0,0 +1,10 @@
+// ignore-tidy-linelength
+// check-pass
+// run-rustfix
+
+#![feature(doc_notable_trait)]
+
+#[doc(spotlight)]
+//~^ WARN unknown `doc` attribute `spotlight`
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+trait MyTrait {}

src/test/rustdoc-ui/doc-spotlight.rs

@@ -0,0 +1,14 @@
+warning: unknown `doc` attribute `spotlight`
+  --> $DIR/doc-spotlight.rs:7:7
+   |
+LL | #[doc(spotlight)]
+   |       ^^^^^^^^^ help: use `notable_trait` instead
+   |
+   = note: `#[warn(invalid_doc_attributes)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #82730 <https://github.com/rust-lang/rust/issues/82730>
+   = note: `doc(spotlight)` was renamed to `doc(notable_trait)`
+   = note: `doc(spotlight)` is now a no-op
+
+warning: 1 warning emitted
+

src/test/rustdoc-ui/doc-spotlight.stderr

@@ -1,14 +1,14 @@
-#![feature(doc_spotlight)]
+#![feature(doc_notable_trait)]
 
 pub struct Wrapper<T> {
     inner: T,
 }
 
 impl<T: SomeTrait> SomeTrait for Wrapper<T> {}
 
-#[doc(spotlight)]
+#[doc(notable_trait)]
 pub trait SomeTrait {
-    // @has doc_spotlight/trait.SomeTrait.html
+    // @has doc_notable_trait/trait.SomeTrait.html
     // @has - '//code[@class="content"]' 'impl<T: SomeTrait> SomeTrait for Wrapper<T>'
     fn wrap_me(self) -> Wrapper<Self> where Self: Sized {
         Wrapper {
@@ -21,15 +21,15 @@ pub struct SomeStruct;
 impl SomeTrait for SomeStruct {}
 
 impl SomeStruct {
-    // @has doc_spotlight/struct.SomeStruct.html
+    // @has doc_notable_trait/struct.SomeStruct.html
     // @has - '//code[@class="content"]' 'impl SomeTrait for SomeStruct'
     // @has - '//code[@class="content"]' 'impl<T: SomeTrait> SomeTrait for Wrapper<T>'
     pub fn new() -> SomeStruct {
         SomeStruct
     }
 }
 
-// @has doc_spotlight/fn.bare_fn.html
+// @has doc_notable_trait/fn.bare_fn.html
 // @has - '//code[@class="content"]' 'impl SomeTrait for SomeStruct'
 pub fn bare_fn() -> SomeStruct {
     SomeStruct

src/test/rustdoc/doc-spotlight.rs renamed to src/test/rustdoc/doc-notable_trait.rs

@@ -0,0 +1,4 @@
+#[doc(notable_trait)] //~ ERROR: `#[doc(notable_trait)]` is experimental
+trait SomeTrait {}
+
+fn main() {}

src/test/ui/feature-gates/feature-gate-doc_notable_trait.rs

@@ -0,0 +1,12 @@
+error[E0658]: `#[doc(notable_trait)]` is experimental
+  --> $DIR/feature-gate-doc_notable_trait.rs:1:1
+   |
+LL | #[doc(notable_trait)]
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #45040 <https://github.com/rust-lang/rust/issues/45040> for more information
+   = help: add `#![feature(doc_notable_trait)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.