Implement RFC 3631

5 files changed, 64 insertions, 18 deletions

diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
index 9ab5b0b3547..fe9cc8e61ed 100644
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -182,8 +182,6 @@ 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
                     }
diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
index 870e0a90b54..19014f37c66 100644
--- a/compiler/rustc_passes/messages.ftl
+++ b/compiler/rustc_passes/messages.ftl
@@ -143,6 +143,15 @@ passes_doc_attribute_not_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({$attr_name}(...)))]` only expects a list of items
+
+passes_doc_auto_cfg_wrong_literal =
+    `expected boolean for #[doc(auto_cfg = ...)]`
+
 passes_doc_expect_str =
     doc {$attr_name} attribute expects a string: #[doc({$attr_name} = "a")]
 
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 007353f136d..3dc232a35ec 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -1160,16 +1160,43 @@ 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 item.meta_item_list().is_none() {
+                        self.tcx.emit_node_span_lint(
+                            INVALID_DOC_ATTRIBUTES,
+                            hir_id,
+                            meta.span,
+                            errors::DocAutoCfgHideShowExpectsList { attr_name: attr_name.as_str() },
+                        );
+                    }
+                }
+            }
         }
     }
 
@@ -1245,10 +1272,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             self.check_attr_crate_level(attr, style, meta, hir_id);
                         }
 
-                        Some(sym::cfg_hide) => {
-                            if self.check_attr_crate_level(attr, style, 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) => {
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index cfd6b9e6dff..6cc0bd6ce48 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -309,8 +309,18 @@ 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_test_unknown_any)]
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index faf32523baa..e80a98994db 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -545,6 +545,7 @@ symbols! {
         attributes,
         audit_that,
         augmented_assignments,
+        auto_cfg,
         auto_traits,
         autodiff,
         autodiff_forward,
@@ -1149,6 +1150,8 @@ symbols! {
         hashset_iter_ty,
         hexagon_target_feature,
         hidden,
+        hidden_cfg,
+        hide,
         hint,
         homogeneous_aggregate,
         host,
@@ -1987,6 +1990,7 @@ symbols! {
         shl_assign,
         shorter_tail_lifetimes,
         should_panic,
+        show,
         shr,
         shr_assign,
         sig_dfl,