Stabilize doc_cfg, auto_doc_cfg and cfg_hide features

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -200,8 +200,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }}
 
                 gate_doc!(
-                    cfg => doc_cfg
-                    cfg_hide => doc_cfg_hide
                     masked => doc_masked
                     notable_trait => doc_notable_trait
                 );

compiler/rustc_error_messages/locales/en-US/passes.ftl

@@ -75,6 +75,15 @@ passes_doc_alias_not_string_literal = `#[doc(alias("a"))]` expects string litera
 passes_doc_alias_malformed =
     doc alias attribute expects a string `#[doc(alias = "a")]` or a list of strings `#[doc(alias("a", "b"))]`
 
+passes_doc_auto_cfg_malformed = `#![doc({$attr_str})]` attribute doesn't expect a value
+
+passes_doc_both_auto_cfg = please don't specify both `doc(auto_cfg)` and `doc(no_auto_cfg)`
+    .label = the other is specified here
+
+passes_doc_no_auto_cfg_enabled_by_default = `doc(no_auto_cfg)` is enabled by default before the 2024 edition
+
+passes_doc_auto_cfg_enabled_by_default = `doc(auto_cfg)` is enabled by default since the 2024 edition
+
 passes_doc_keyword_empty_mod = `#[doc(keyword = "...")]` should be used on empty modules
 
 passes_doc_keyword_not_mod = `#[doc(keyword = "...")]` should be used on modules

compiler/rustc_feature/src/accepted.rs

@@ -132,6 +132,13 @@ declare_features! (
     (accepted, destructuring_assignment, "1.59.0", Some(71126), None),
     /// Allows `#[doc(alias = "...")]`.
     (accepted, doc_alias, "1.48.0", Some(50146), None),
+    /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
+    (accepted, doc_auto_cfg, "1.65.0", Some(43781), None),
+    /// Allows `#[doc(cfg(...))]`. It adds information about under which condition an item is
+    /// available.
+    (accepted, doc_cfg, "1.65.0", Some(43781), None),
+    /// Allows `#[doc(cfg_hide(...))]`.
+    (accepted, doc_cfg_hide, "1.65.0", Some(43781), None),
     /// Allows `..` in tuple (struct) patterns.
     (accepted, dotdot_in_tuple_patterns, "1.14.0", Some(33627), None),
     /// Allows `..=` in patterns (RFC 1192).

compiler/rustc_feature/src/active.rs

@@ -378,12 +378,6 @@ declare_features! (
     (active, deprecated_safe, "1.61.0", Some(94978), None),
     /// Allows having using `suggestion` in the `#[deprecated]` attribute.
     (active, deprecated_suggestion, "1.61.0", Some(94785), None),
-    /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
-    (active, doc_auto_cfg, "1.58.0", Some(43781), None),
-    /// Allows `#[doc(cfg(...))]`.
-    (active, doc_cfg, "1.21.0", Some(43781), None),
-    /// Allows `#[doc(cfg_hide(...))]`.
-    (active, doc_cfg_hide, "1.57.0", Some(43781), None),
     /// Allows `#[doc(masked)]`.
     (active, doc_masked, "1.21.0", Some(44027), None),
     /// Allows `dyn* Trait` objects.

compiler/rustc_passes/src/check_attr.rs

@@ -5,7 +5,7 @@
 //! item.
 
 use crate::errors;
-use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
+use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MetaItem, MetaItemKind, NestedMetaItem};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{fluent, struct_span_err, Applicability, MultiSpan};
 use rustc_expand::base::resolve_path;
@@ -25,6 +25,7 @@ use rustc_session::lint::builtin::{
     CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, UNUSED_ATTRIBUTES,
 };
 use rustc_session::parse::feature_err;
+use rustc_span::edition::Edition;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
@@ -97,6 +98,7 @@ impl CheckAttrVisitor<'_> {
                     target,
                     &mut specified_inline,
                     &mut doc_aliases,
+                    &mut seen,
                 ),
                 sym::no_link => self.check_no_link(hir_id, &attr, span, target),
                 sym::export_name => self.check_export_name(hir_id, &attr, span, target),
@@ -936,6 +938,56 @@ impl CheckAttrVisitor<'_> {
         is_valid
     }
 
+    /// Checks that `doc(auto_cfg)` is valid (i.e. no value) and warn if it's used whereas the
+    /// "equivalent feature" is already enabled.
+    fn check_auto_cfg(&self, meta: &MetaItem, hir_id: HirId, seen: &mut FxHashMap<Symbol, Span>) -> bool {
+        let name = meta.name_or_empty();
+        if !meta.is_word() {
+            self.tcx
+                .sess
+                .emit_err(errors::DocAutoCfgMalformed { span: meta.span, attr_str: name.as_str() });
+            return false;
+        }
+        let mut is_valid = true;
+        let other = if name == sym::no_auto_cfg {
+            if self.tcx.sess.edition() < Edition::Edition2024 {
+                self.tcx.emit_spanned_lint(
+                    UNUSED_ATTRIBUTES,
+                    hir_id,
+                    meta.span,
+                    errors::DocNoAutoCfgEnabledByDefault,
+                );
+                is_valid = false;
+            }
+            sym::auto_cfg
+        } else {
+            if self.tcx.sess.edition() > Edition::Edition2021 {
+                self.tcx.emit_spanned_lint(
+                    UNUSED_ATTRIBUTES,
+                    hir_id,
+                    meta.span,
+                    errors::DocAutoCfgEnabledByDefault,
+                );
+                is_valid = false;
+            }
+            sym::no_auto_cfg
+        };
+
+        match seen.entry(other) {
+            Entry::Occupied(entry) => {
+                self.tcx
+                    .sess
+                    .emit_err(errors::BothDocAutoCfg { span: *entry.get(), attr_span: meta.span });
+                is_valid = false;
+            }
+            Entry::Vacant(entry) => {
+                entry.insert(meta.span);
+            }
+        }
+
+        is_valid
+    }
+
     /// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
     ///
     /// `specified_inline` should be initialized to `None` and kept for the scope
@@ -949,6 +1001,7 @@ impl CheckAttrVisitor<'_> {
         target: Target,
         specified_inline: &mut Option<(bool, Span)>,
         aliases: &mut FxHashMap<String, Span>,
+        seen: &mut FxHashMap<Symbol, Span>,
     ) -> bool {
         let mut is_valid = true;
 
@@ -984,6 +1037,8 @@ impl CheckAttrVisitor<'_> {
                         | sym::html_root_url
                         | sym::html_no_source
                         | sym::test
+                        | sym::auto_cfg
+                        | sym::no_auto_cfg
                             if !self.check_attr_crate_level(attr, meta, hir_id) =>
                         {
                             is_valid = false;
@@ -1001,6 +1056,11 @@ impl CheckAttrVisitor<'_> {
                             is_valid = false;
                         }
 
+                        sym::auto_cfg | sym::no_auto_cfg
+                            if !self.check_auto_cfg(i_meta, hir_id, seen) => {
+                            is_valid = false;
+                        }
+
                         // no_default_passes: deprecated
                         // passes: deprecated
                         // plugins: removed, but rustdoc warns about it itself
@@ -1022,6 +1082,8 @@ impl CheckAttrVisitor<'_> {
                         | sym::notable_trait
                         | sym::passes
                         | sym::plugins
+                        | sym::auto_cfg
+                        | sym::no_auto_cfg
                         | sym::fake_variadic => {}
 
                         sym::test => {

compiler/rustc_passes/src/errors.rs

@@ -189,6 +189,31 @@ pub struct DocAliasMalformed {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(passes::doc_auto_cfg_malformed)]
+pub struct DocAutoCfgMalformed<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub attr_str: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes::doc_both_auto_cfg)]
+pub struct BothDocAutoCfg {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub attr_span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(passes::doc_auto_cfg_enabled_by_default)]
+pub struct DocAutoCfgEnabledByDefault;
+
+#[derive(LintDiagnostic)]
+#[diag(passes::doc_no_auto_cfg_enabled_by_default)]
+pub struct DocNoAutoCfgEnabledByDefault;
+
 #[derive(Diagnostic)]
 #[diag(passes::doc_keyword_empty_mod)]
 pub struct DocKeywordEmptyMod {

compiler/rustc_span/src/symbol.rs

@@ -405,6 +405,7 @@ symbols! {
         attr_literals,
         attributes,
         augmented_assignments,
+        auto_cfg,
         auto_traits,
         automatically_derived,
         avx,
@@ -995,6 +996,7 @@ symbols! {
         next,
         nll,
         no,
+        no_auto_cfg,
         no_builtins,
         no_core,
         no_coverage,

library/alloc/src/lib.rs

@@ -190,8 +190,8 @@
 #![feature(with_negative_coherence)]
 //
 // Rustdoc features:
-#![feature(doc_cfg)]
-#![feature(doc_cfg_hide)]
+#![cfg_attr(bootstrap, feature(doc_cfg))]
+#![cfg_attr(bootstrap, feature(doc_cfg_hide))]
 // Technically, this is a bug in rustdoc: rustdoc sees the documentation on `#[lang = slice_alloc]`
 // blocks is for `&[T]`, which also has documentation using this feature in `core`, and gets mad
 // that the feature-gate isn't enabled. Ideally, it wouldn't check for the feature gate for docs

library/core/src/lib.rs

@@ -181,11 +181,11 @@
 #![feature(const_refs_to_cell)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
-#![feature(doc_cfg)]
+#![cfg_attr(bootstrap, feature(doc_cfg))]
+#![cfg_attr(bootstrap, feature(doc_cfg_hide))]
 #![feature(doc_notable_trait)]
 #![feature(rustdoc_internals)]
 #![feature(exhaustive_patterns)]
-#![feature(doc_cfg_hide)]
 #![feature(extern_types)]
 #![feature(fundamental)]
 #![feature(if_let_guard)]

library/std/src/lib.rs

@@ -245,8 +245,8 @@
 #![feature(const_trait_impl)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
-#![feature(doc_cfg)]
-#![feature(doc_cfg_hide)]
+#![cfg_attr(bootstrap, feature(doc_cfg))]
+#![cfg_attr(bootstrap, feature(doc_cfg_hide))]
 #![feature(doc_masked)]
 #![feature(doc_notable_trait)]
 #![feature(dropck_eyepatch)]

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

@@ -43,88 +43,6 @@ plain text.
 These features operate by extending the `#[doc]` attribute, and thus can be caught by the compiler
 and enabled with a `#![feature(...)]` attribute in your crate.
 
-### `#[doc(cfg)]`: Recording what platforms or features are required for code to be present
-
- * Tracking issue: [#43781](https://github.com/rust-lang/rust/issues/43781)
-
-You can use `#[doc(cfg(...))]` to tell Rustdoc exactly which platform items appear on.
-This has two effects:
-
-1. doctests will only run on the appropriate platforms, and
-2. When Rustdoc renders documentation for that item, it will be accompanied by a banner explaining
-   that the item is only available on certain platforms.
-
-`#[doc(cfg)]` is intended to be used alongside [`#[cfg(doc)]`][cfg-doc].
-For example, `#[cfg(any(windows, doc))]` will preserve the item either on Windows or during the
-documentation process. Then, adding a new attribute `#[doc(cfg(windows))]` will tell Rustdoc that
-the item is supposed to be used on Windows. For example:
-
-```rust
-#![feature(doc_cfg)]
-
-/// Token struct that can only be used on Windows.
-#[cfg(any(windows, doc))]
-#[doc(cfg(windows))]
-pub struct WindowsToken;
-
-/// Token struct that can only be used on Unix.
-#[cfg(any(unix, doc))]
-#[doc(cfg(unix))]
-pub struct UnixToken;
-
-/// Token struct that is only available with the `serde` feature
-#[cfg(feature = "serde")]
-#[doc(cfg(feature = "serde"))]
-#[derive(serde::Deserialize)]
-pub struct SerdeToken;
-```
-
-In this sample, the tokens will only appear on their respective platforms, but they will both appear
-in documentation.
-
-`#[doc(cfg(...))]` was introduced to be used by the standard library and currently requires the
-`#![feature(doc_cfg)]` feature gate. For more information, see [its chapter in the Unstable
-Book][unstable-doc-cfg] and [its tracking issue][issue-doc-cfg].
-
-### `doc_auto_cfg`: Automatically generate `#[doc(cfg)]`
-
- * Tracking issue: [#43781](https://github.com/rust-lang/rust/issues/43781)
-
-`doc_auto_cfg` is an extension to the `#[doc(cfg)]` feature. With it, you don't need to add
-`#[doc(cfg(...)]` anymore unless you want to override the default behaviour. So if we take the
-previous source code:
-
-```rust
-#![feature(doc_auto_cfg)]
-
-/// Token struct that can only be used on Windows.
-#[cfg(any(windows, doc))]
-pub struct WindowsToken;
-
-/// Token struct that can only be used on Unix.
-#[cfg(any(unix, doc))]
-pub struct UnixToken;
-
-/// Token struct that is only available with the `serde` feature
-#[cfg(feature = "serde")]
-#[derive(serde::Deserialize)]
-pub struct SerdeToken;
-```
-
-It'll render almost the same, the difference being that `doc` will also be displayed. To fix this,
-you can use `doc_cfg_hide`:
-
-```rust
-#![feature(doc_cfg_hide)]
-#![doc(cfg_hide(doc))]
-```
-
-And `doc` won't show up anymore!
-
-[cfg-doc]: ./advanced-features.md
-[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 "Notable traits" dialog
 
  * Tracking issue: [#45040](https://github.com/rust-lang/rust/issues/45040)