rustdoc: skip stability inheritance for some item kinds

src/librustdoc/passes/propagate_stability.rs

@@ -9,7 +9,7 @@
 use rustc_attr::{Stability, StabilityLevel};
 use rustc_hir::def_id::CRATE_DEF_ID;
 
-use crate::clean::{Crate, Item, ItemId};
+use crate::clean::{Crate, Item, ItemId, ItemKind};
 use crate::core::DocContext;
 use crate::fold::DocFolder;
 use crate::passes::Pass;
@@ -38,22 +38,45 @@ fn fold_item(&mut self, mut item: Item) -> Option<Item> {
             ItemId::DefId(def_id) => {
                 let own_stability = self.cx.tcx.lookup_stability(def_id);
 
-                // If any of the item's parents was stabilized later or is still unstable,
+                let (ItemKind::StrippedItem(box kind) | kind) = &item.kind;
-                // then use the parent's stability instead.
+                match kind {
-                if let Some(own_stab) = own_stability
+                    ItemKind::ExternCrateItem { .. }
-                    && let StabilityLevel::Stable {
+                    | ItemKind::ImportItem(..)
-                        since: own_since,
+                    | ItemKind::StructItem(..)
-                        allowed_through_unstable_modules: false,
+                    | ItemKind::UnionItem(..)
-                    } = own_stab.level
+                    | ItemKind::EnumItem(..)
-                    && let Some(parent_stab) = parent_stability
+                    | ItemKind::FunctionItem(..)
-                    && (parent_stab.is_unstable()
+                    | ItemKind::ModuleItem(..)
-                        || parent_stab
+                    | ItemKind::TypeAliasItem(..)
-                            .stable_since()
+                    | ItemKind::StaticItem(..)
-                            .is_some_and(|parent_since| parent_since > own_since))
+                    | ItemKind::TraitItem(..)
-                {
+                    | ItemKind::TraitAliasItem(..)
-                    parent_stability
+                    | ItemKind::StructFieldItem(..)
-                } else {
+                    | ItemKind::VariantItem(..)
-                    own_stability
+                    | ItemKind::ForeignFunctionItem(..)
+                    | ItemKind::ForeignStaticItem(..)
+                    | ItemKind::ForeignTypeItem
+                    | ItemKind::MacroItem(..)
+                    | ItemKind::ProcMacroItem(..)
+                    | ItemKind::ConstantItem(..) => {
+                        // If any of the item's parents was stabilized later or is still unstable,
+                        // then use the parent's stability instead.
+                        merge_stability(own_stability, parent_stability)
+                    }
+
+                    // Don't inherit the parent's stability for these items, because they
+                    // are potentially accessible even if the parent is more unstable.
+                    ItemKind::ImplItem(..)
+                    | ItemKind::TyMethodItem(..)
+                    | ItemKind::MethodItem(..)
+                    | ItemKind::TyAssocConstItem(..)
+                    | ItemKind::AssocConstItem(..)
+                    | ItemKind::TyAssocTypeItem(..)
+                    | ItemKind::AssocTypeItem(..)
+                    | ItemKind::PrimitiveItem(..)
+                    | ItemKind::KeywordItem => own_stability,
+
+                    ItemKind::StrippedItem(..) => unreachable!(),
                 }
             }
             ItemId::Auto { .. } | ItemId::Blanket { .. } => {
@@ -70,3 +93,20 @@ fn fold_item(&mut self, mut item: Item) -> Option<Item> {
         Some(item)
     }
 }
+
+fn merge_stability(
+    own_stability: Option<Stability>,
+    parent_stability: Option<Stability>,
+) -> Option<Stability> {
+    if let Some(own_stab) = own_stability
+        && let StabilityLevel::Stable { since: own_since, allowed_through_unstable_modules: false } =
+            own_stab.level
+        && let Some(parent_stab) = parent_stability
+        && (parent_stab.is_unstable()
+            || parent_stab.stable_since().is_some_and(|parent_since| parent_since > own_since))
+    {
+        parent_stability
+    } else {
+        own_stability
+    }
+}

tests/rustdoc/stability.rs

@@ -1,6 +1,8 @@
 #![feature(staged_api)]
+#![feature(rustc_attrs)]
+#![feature(rustdoc_internals)]
 
-#![stable(feature = "rust1", since = "1.0.0")]
+#![stable(feature = "core", since = "1.6.0")]
 
 //@ has stability/index.html
 //@ has - '//ul[@class="item-table"]/li[1]//a' AaStable
@@ -26,7 +28,7 @@ pub struct Unstable {
 #[unstable(feature = "unstable", issue = "none")]
 pub mod unstable {
     //@ !hasraw stability/unstable/struct.StableInUnstable.html \
-    //      '//span[@class="since"]'
+    //      '//div[@class="main-heading"]//span[@class="since"]'
     //@ has - '//div[@class="stab unstable"]' 'experimental'
     #[stable(feature = "rust1", since = "1.0.0")]
     pub struct StableInUnstable;
@@ -34,52 +36,136 @@ pub mod unstable {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub mod stable_in_unstable {
         //@ !hasraw stability/unstable/stable_in_unstable/struct.Inner.html \
-        //      '//span[@class="since"]'
+        //      '//div[@class="main-heading"]//span[@class="since"]'
         //@ has - '//div[@class="stab unstable"]' 'experimental'
         #[stable(feature = "rust1", since = "1.0.0")]
         pub struct Inner;
     }
+
+    //@ has stability/struct.AaStable.html \
+    //      '//*[@id="method.foo"]//span[@class="since"]' '2.2.2'
+    impl super::AaStable {
+        #[stable(feature = "rust2", since = "2.2.2")]
+        pub fn foo() {}
+    }
+
+    //@ has stability/unstable/struct.StableInUnstable.html \
+    //      '//*[@id="method.foo"]//span[@class="since"]' '1.0.0'
+    impl StableInUnstable {
+        #[stable(feature = "rust1", since = "1.0.0")]
+        pub fn foo() {}
+    }
+}
+
+#[unstable(feature = "unstable", issue = "none")]
+#[doc(hidden)]
+pub mod unstable_stripped {
+    //@ has stability/struct.AaStable.html \
+    //      '//*[@id="method.foo"]//span[@class="since"]' '2.2.2'
+    impl super::AaStable {
+        #[stable(feature = "rust2", since = "2.2.2")]
+        pub fn foo() {}
+    }
 }
 
 #[stable(feature = "rust2", since = "2.2.2")]
 pub mod stable_later {
     //@ has stability/stable_later/struct.StableInLater.html \
-    //      '//span[@class="since"]' '2.2.2'
+    //      '//div[@class="main-heading"]//span[@class="since"]' '2.2.2'
     #[stable(feature = "rust1", since = "1.0.0")]
     pub struct StableInLater;
 
     #[stable(feature = "rust1", since = "1.0.0")]
     pub mod stable_in_later {
         //@ has stability/stable_later/stable_in_later/struct.Inner.html \
-        //      '//span[@class="since"]' '2.2.2'
+        //      '//div[@class="main-heading"]//span[@class="since"]' '2.2.2'
         #[stable(feature = "rust1", since = "1.0.0")]
         pub struct Inner;
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-pub mod stable_earlier {
+#[rustc_allowed_through_unstable_modules]
-    //@ has stability/stable_earlier/struct.StableInUnstable.html \
+pub mod stable_earlier1 {
-    //      '//span[@class="since"]' '1.0.0'
+    //@ has stability/stable_earlier1/struct.StableInUnstable.html \
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.0.0'
+    //@ has - '//*[@id="method.foo"]//span[@class="since"]' '1.0.0'
     #[doc(inline)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub use crate::unstable::StableInUnstable;
 
-    //@ has stability/stable_earlier/stable_in_unstable/struct.Inner.html \
+    //@ has stability/stable_earlier1/stable_in_unstable/struct.Inner.html \
-    //      '//span[@class="since"]' '1.0.0'
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.0.0'
     #[doc(inline)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub use crate::unstable::stable_in_unstable;
 
-    //@ has stability/stable_earlier/struct.StableInLater.html \
+    //@ has stability/stable_earlier1/struct.StableInLater.html \
-    //      '//span[@class="since"]' '1.0.0'
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.0.0'
     #[doc(inline)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub use crate::stable_later::StableInLater;
 
-    //@ has stability/stable_earlier/stable_in_later/struct.Inner.html \
+    //@ has stability/stable_earlier1/stable_in_later/struct.Inner.html \
-    //      '//span[@class="since"]' '1.0.0'
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.0.0'
     #[doc(inline)]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub use crate::stable_later::stable_in_later;
 }
+
+/// These will inherit the crate stability.
+#[stable(feature = "rust1", since = "1.0.0")]
+pub mod stable_earlier2 {
+    //@ has stability/stable_earlier2/struct.StableInUnstable.html \
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.6.0'
+    //@ has - '//*[@id="method.foo"]//span[@class="since"]' '1.0.0'
+    #[doc(inline)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub use crate::unstable::StableInUnstable;
+
+    //@ has stability/stable_earlier2/stable_in_unstable/struct.Inner.html \
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.6.0'
+    #[doc(inline)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub use crate::unstable::stable_in_unstable;
+
+    //@ has stability/stable_earlier2/struct.StableInLater.html \
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.6.0'
+    #[doc(inline)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub use crate::stable_later::StableInLater;
+
+    //@ has stability/stable_earlier2/stable_in_later/struct.Inner.html \
+    //      '//div[@class="main-heading"]//span[@class="since"]' '1.6.0'
+    #[doc(inline)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub use crate::stable_later::stable_in_later;
+}
+
+//@ !hasraw stability/trait.UnstableTraitWithStableMethod.html \
+//      '//div[@class="main-heading"]//span[@class="since"]'
+//@ has - '//*[@id="tymethod.foo"]//span[@class="since"]' '1.0.0'
+//@ has - '//*[@id="method.bar"]//span[@class="since"]' '1.0.0'
+#[unstable(feature = "unstable", issue = "none")]
+pub trait UnstableTraitWithStableMethod {
+    #[stable(feature = "rust1", since = "1.0.0")]
+    fn foo();
+    #[stable(feature = "rust1", since = "1.0.0")]
+    fn bar() {}
+}
+
+//@ has stability/primitive.i32.html \
+//      '//div[@class="main-heading"]//span[@class="since"]' '1.0.0'
+#[rustc_doc_primitive = "i32"]
+//
+/// `i32` is always stable in 1.0, even if you look at it from core.
+#[stable(feature = "rust1", since = "1.0.0")]
+mod prim_i32 {}
+
+//@ has stability/keyword.if.html \
+//      '//div[@class="main-heading"]//span[@class="since"]' '1.0.0'
+#[doc(keyword = "if")]
+//
+/// We currently don't document stability for keywords, but let's test it anyway.
+#[stable(feature = "rust1", since = "1.0.0")]
+mod if_keyword {}