Implement RFC 3631: add rustdoc doc_cfg features

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -173,7 +173,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 gate_doc!(
                     "experimental" {
                         cfg => doc_cfg
-                        cfg_hide => doc_cfg_hide
                         masked => doc_masked
                         notable_trait => doc_notable_trait
                     }

compiler/rustc_passes/messages.ftl

@@ -182,8 +182,17 @@ passes_doc_alias_start_end =
 passes_doc_attr_not_crate_level =
     `#![doc({$attr_name} = "...")]` isn't allowed as a crate-level attribute
 
-passes_doc_cfg_hide_takes_list =
-    `#[doc(cfg_hide(...))]` takes a list of attributes
+passes_doc_auto_cfg_expects_hide_or_show =
+    `only "hide" or "show" are allowed in "#[doc(auto_cfg(...))]"`
+
+passes_doc_auto_cfg_hide_show_expects_list =
+    `#![doc(auto_cfg({$attr_name}(...)))]` only expects a list of items
+
+passes_doc_auto_cfg_hide_show_unexpected_item =
+    `#![doc(auto_cfg({$attr_name}(...)))]` only accepts identifiers or key/values items
+
+passes_doc_auto_cfg_wrong_literal =
+    `expected boolean for #[doc(auto_cfg = ...)]`
 
 passes_doc_expect_str =
     doc {$attr_name} attribute expects a string: #[doc({$attr_name} = "a")]

compiler/rustc_passes/src/check_attr.rs

@@ -1303,16 +1303,56 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Check that the `#![doc(cfg_hide(...))]` attribute only contains a list of attributes.
-    ///
-    fn check_doc_cfg_hide(&self, meta: &MetaItemInner, hir_id: HirId) {
-        if meta.meta_item_list().is_none() {
-            self.tcx.emit_node_span_lint(
-                INVALID_DOC_ATTRIBUTES,
-                hir_id,
-                meta.span(),
-                errors::DocCfgHideTakesList,
-            );
+    /// Check that the `#![doc(auto_cfg(..))]` attribute has expected input.
+    fn check_doc_auto_cfg(&self, meta: &MetaItemInner, hir_id: HirId) {
+        let MetaItemInner::MetaItem(meta) = meta else {
+            unreachable!();
+        };
+        match &meta.kind {
+            MetaItemKind::Word => {}
+            MetaItemKind::NameValue(lit) => {
+                if !matches!(lit.kind, LitKind::Bool(_)) {
+                    self.tcx.emit_node_span_lint(
+                        INVALID_DOC_ATTRIBUTES,
+                        hir_id,
+                        meta.span,
+                        errors::DocAutoCfgWrongLiteral,
+                    );
+                }
+            }
+            MetaItemKind::List(list) => {
+                for item in list {
+                    let Some(attr_name) = item.name() else { continue };
+                    if attr_name != sym::hide && attr_name != sym::show {
+                        self.tcx.emit_node_span_lint(
+                            INVALID_DOC_ATTRIBUTES,
+                            hir_id,
+                            meta.span,
+                            errors::DocAutoCfgExpectsHideOrShow,
+                        );
+                    } else if let Some(list) = item.meta_item_list() {
+                        for item in list {
+                            if item.meta_item_list().is_some() {
+                                self.tcx.emit_node_span_lint(
+                                    INVALID_DOC_ATTRIBUTES,
+                                    hir_id,
+                                    item.span(),
+                                    errors::DocAutoCfgHideShowUnexpectedItem {
+                                        attr_name: attr_name.as_str(),
+                                    },
+                                );
+                            }
+                        }
+                    } else {
+                        self.tcx.emit_node_span_lint(
+                            INVALID_DOC_ATTRIBUTES,
+                            hir_id,
+                            meta.span,
+                            errors::DocAutoCfgHideShowExpectsList { attr_name: attr_name.as_str() },
+                        );
+                    }
+                }
+            }
         }
     }
 
@@ -1375,10 +1415,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             self.check_attr_crate_level(attr, meta, hir_id);
                         }
 
-                        Some(sym::cfg_hide) => {
-                            if self.check_attr_crate_level(attr, meta, hir_id) {
-                                self.check_doc_cfg_hide(meta, hir_id);
-                            }
+                        Some(sym::auto_cfg) => {
+                            self.check_doc_auto_cfg(meta, hir_id);
                         }
 
                         Some(sym::inline | sym::no_inline) => {

compiler/rustc_passes/src/errors.rs

@@ -333,8 +333,24 @@ pub(crate) struct DocTestLiteral;
 pub(crate) struct DocTestTakesList;
 
 #[derive(LintDiagnostic)]
-#[diag(passes_doc_cfg_hide_takes_list)]
-pub(crate) struct DocCfgHideTakesList;
+#[diag(passes_doc_auto_cfg_wrong_literal)]
+pub(crate) struct DocAutoCfgWrongLiteral;
+
+#[derive(LintDiagnostic)]
+#[diag(passes_doc_auto_cfg_expects_hide_or_show)]
+pub(crate) struct DocAutoCfgExpectsHideOrShow;
+
+#[derive(LintDiagnostic)]
+#[diag(passes_doc_auto_cfg_hide_show_expects_list)]
+pub(crate) struct DocAutoCfgHideShowExpectsList<'a> {
+    pub attr_name: &'a str,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(passes_doc_auto_cfg_hide_show_unexpected_item)]
+pub(crate) struct DocAutoCfgHideShowUnexpectedItem<'a> {
+    pub attr_name: &'a str,
+}
 
 #[derive(LintDiagnostic)]
 #[diag(passes_doc_test_unknown_any)]

compiler/rustc_span/src/symbol.rs

@@ -527,6 +527,7 @@ symbols! {
         attributes,
         audit_that,
         augmented_assignments,
+        auto_cfg,
         auto_traits,
         autodiff,
         automatically_derived,
@@ -1100,6 +1101,8 @@ symbols! {
         hashset_iter_ty,
         hexagon_target_feature,
         hidden,
+        hidden_cfg,
+        hide,
         hint,
         homogeneous_aggregate,
         host,
@@ -1896,6 +1899,7 @@ symbols! {
         shl_assign,
         shorter_tail_lifetimes,
         should_panic,
+        show,
         shr,
         shr_assign,
         sig_dfl,

library/alloc/src/lib.rs

@@ -64,15 +64,29 @@
     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
     test(no_crate_inject, attr(allow(unused_variables), deny(warnings)))
 )]
-#![doc(cfg_hide(
-    not(test),
-    not(any(test, bootstrap)),
-    no_global_oom_handling,
-    not(no_global_oom_handling),
-    not(no_rc),
-    not(no_sync),
-    target_has_atomic = "ptr"
-))]
+#![cfg_attr(
+    bootstrap,
+    doc(cfg_hide(
+        not(test),
+        not(any(test, bootstrap)),
+        no_global_oom_handling,
+        not(no_global_oom_handling),
+        not(no_rc),
+        not(no_sync),
+        target_has_atomic = "ptr"
+    ))
+)]
+#![cfg_attr(
+    not(bootstrap),
+    doc(auto_cfg(hide(
+        bootstrap,
+        no_global_oom_handling,
+        no_global_oom_handling,
+        no_rc,
+        no_sync,
+        target_has_atomic = "ptr"
+    )))
+)]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
 #![no_std]

library/core/src/lib.rs

@@ -51,27 +51,54 @@
     test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
 )]
 #![doc(rust_logo)]
-#![doc(cfg_hide(
-    no_fp_fmt_parse,
-    target_pointer_width = "16",
-    target_pointer_width = "32",
-    target_pointer_width = "64",
-    target_has_atomic = "8",
-    target_has_atomic = "16",
-    target_has_atomic = "32",
-    target_has_atomic = "64",
-    target_has_atomic = "ptr",
-    target_has_atomic_equal_alignment = "8",
-    target_has_atomic_equal_alignment = "16",
-    target_has_atomic_equal_alignment = "32",
-    target_has_atomic_equal_alignment = "64",
-    target_has_atomic_equal_alignment = "ptr",
-    target_has_atomic_load_store = "8",
-    target_has_atomic_load_store = "16",
-    target_has_atomic_load_store = "32",
-    target_has_atomic_load_store = "64",
-    target_has_atomic_load_store = "ptr",
-))]
+#![cfg_attr(
+    bootstrap,
+    doc(cfg_hide(
+        no_fp_fmt_parse,
+        target_pointer_width = "16",
+        target_pointer_width = "32",
+        target_pointer_width = "64",
+        target_has_atomic = "8",
+        target_has_atomic = "16",
+        target_has_atomic = "32",
+        target_has_atomic = "64",
+        target_has_atomic = "ptr",
+        target_has_atomic_equal_alignment = "8",
+        target_has_atomic_equal_alignment = "16",
+        target_has_atomic_equal_alignment = "32",
+        target_has_atomic_equal_alignment = "64",
+        target_has_atomic_equal_alignment = "ptr",
+        target_has_atomic_load_store = "8",
+        target_has_atomic_load_store = "16",
+        target_has_atomic_load_store = "32",
+        target_has_atomic_load_store = "64",
+        target_has_atomic_load_store = "ptr",
+    ))
+)]
+#![cfg_attr(
+    not(bootstrap),
+    doc(auto_cfg(hide(
+        no_fp_fmt_parse,
+        target_pointer_width = "16",
+        target_pointer_width = "32",
+        target_pointer_width = "64",
+        target_has_atomic = "8",
+        target_has_atomic = "16",
+        target_has_atomic = "32",
+        target_has_atomic = "64",
+        target_has_atomic = "ptr",
+        target_has_atomic_equal_alignment = "8",
+        target_has_atomic_equal_alignment = "16",
+        target_has_atomic_equal_alignment = "32",
+        target_has_atomic_equal_alignment = "64",
+        target_has_atomic_equal_alignment = "ptr",
+        target_has_atomic_load_store = "8",
+        target_has_atomic_load_store = "16",
+        target_has_atomic_load_store = "32",
+        target_has_atomic_load_store = "64",
+        target_has_atomic_load_store = "ptr",
+    )))
+)]
 #![no_core]
 #![rustc_coherence_is_core]
 #![rustc_preserve_ub_checks]

library/std/src/lib.rs

@@ -235,12 +235,16 @@
     test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
 )]
 #![doc(rust_logo)]
-#![doc(cfg_hide(
-    not(test),
-    not(any(test, bootstrap)),
-    no_global_oom_handling,
-    not(no_global_oom_handling)
-))]
+#![cfg_attr(
+    bootstrap,
+    doc(cfg_hide(
+        not(test),
+        not(any(test, bootstrap)),
+        no_global_oom_handling,
+        not(no_global_oom_handling)
+    ))
+)]
+#![cfg_attr(not(bootstrap), doc(auto_cfg(hide(bootstrap, no_global_oom_handling,))))]
 // Don't link to std. We are std.
 #![no_std]
 // Tell the compiler to link to either panic_abort or panic_unwind