Split doc_cfg and doc_auto_cfg features

(cherry picked from commit d50a475)

Author: GuillaumeGomez

compiler/rustc_feature/src/active.rs

@@ -684,6 +684,9 @@ declare_features! (
     /// Allows using the `non_exhaustive_omitted_patterns` lint.
     (active, non_exhaustive_omitted_patterns_lint, "1.57.0", Some(89554), None),
 
+    /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
+    (active, doc_auto_cfg, "1.57.0", Some(43781), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------

compiler/rustc_span/src/symbol.rs

@@ -549,6 +549,7 @@ symbols! {
         div_assign,
         doc,
         doc_alias,
+        doc_auto_cfg,
         doc_cfg,
         doc_cfg_hide,
         doc_keyword,

src/librustdoc/clean/types.rs

@@ -774,6 +774,7 @@ impl AttributesExt for [ast::Attribute] {
     fn cfg(&self, tcx: TyCtxt<'_>, hidden_cfg: &FxHashSet<Cfg>) -> Option<Arc<Cfg>> {
         let sess = tcx.sess;
         let doc_cfg_active = tcx.features().doc_cfg;
+        let doc_auto_cfg_active = tcx.features().doc_auto_cfg;
 
         fn single<T: IntoIterator>(it: T) -> Option<T::Item> {
             let mut iter = it.into_iter();
@@ -784,24 +785,26 @@ impl AttributesExt for [ast::Attribute] {
             Some(item)
         }
 
-        let mut cfg = if doc_cfg_active {
+        let mut cfg = if doc_cfg_active || doc_auto_cfg_active {
             let mut doc_cfg = self
                 .iter()
                 .filter(|attr| attr.has_name(sym::doc))
                 .flat_map(|attr| attr.meta_item_list().unwrap_or_else(Vec::new))
                 .filter(|attr| attr.has_name(sym::cfg))
                 .peekable();
-            if doc_cfg.peek().is_some() {
+            if doc_cfg.peek().is_some() && doc_cfg_active {
                 doc_cfg
                     .filter_map(|attr| Cfg::parse(attr.meta_item()?).ok())
                     .fold(Cfg::True, |cfg, new_cfg| cfg & new_cfg)
-            } else {
+            } else if doc_auto_cfg_active {
                 self.iter()
                     .filter(|attr| attr.has_name(sym::cfg))
                     .filter_map(|attr| single(attr.meta_item_list()?))
                     .filter_map(|attr| Cfg::parse(attr.meta_item()?).ok())
                     .filter(|cfg| !hidden_cfg.contains(cfg))
                     .fold(Cfg::True, |cfg, new_cfg| cfg & new_cfg)
+            } else {
+                Cfg::True
             }
         } else {
             Cfg::True

src/test/rustdoc/doc-auto-cfg.rs

@@ -0,0 +1,8 @@
+#![feature(doc_auto_cfg)]
+
+#![crate_name = "foo"]
+
+// @has foo/fn.foo.html
+// @has - '//*[@class="item-info"]/*[@class="stab portability"]' 'non-test'
+#[cfg(not(test))]
+pub fn foo() {}

src/test/rustdoc/doc-cfg-hide.rs

@@ -1,5 +1,5 @@
 #![crate_name = "oud"]
-#![feature(doc_cfg, doc_cfg_hide)]
+#![feature(doc_auto_cfg, doc_cfg, doc_cfg_hide)]
 
 #![doc(cfg_hide(feature = "solecism"))]
 

src/test/rustdoc/doc-cfg-implicit.rs

@@ -1,5 +1,5 @@
 #![crate_name = "funambulism"]
-#![feature(doc_cfg)]
+#![feature(doc_auto_cfg, doc_cfg)]
 
 // @has 'funambulism/struct.Disorbed.html'
 // @count   - '//*[@class="stab portability"]' 1

src/test/rustdoc/feature-gate-doc_auto_cfg.rs

@@ -0,0 +1,8 @@
+#![feature(doc_cfg)]
+
+#![crate_name = "foo"]
+
+// @has foo/fn.foo.html
+// @count - '//*[@class="item-info"]/*[@class="stab portability"]' 0
+#[cfg(not(test))]
+pub fn foo() {}