Fix impl stripped in rustdoc HTML whereas it should not be in case the impl is implemented on a type alias

src/librustdoc/passes/stripper.rs

@@ -56,13 +56,10 @@ impl<'a, 'tcx> DocFolder for Stripper<'a, 'tcx> {
             | clean::TraitItem(..)
             | clean::FunctionItem(..)
             | clean::VariantItem(..)
-            | clean::MethodItem(..)
             | clean::ForeignFunctionItem(..)
             | clean::ForeignStaticItem(..)
             | clean::ConstantItem(..)
             | clean::UnionItem(..)
-            | clean::AssocConstItem(..)
-            | clean::AssocTypeItem(..)
             | clean::TraitAliasItem(..)
             | clean::MacroItem(..)
             | clean::ForeignTypeItem => {
@@ -80,6 +77,16 @@ impl<'a, 'tcx> DocFolder for Stripper<'a, 'tcx> {
                 }
             }
 
+            clean::MethodItem(..) | clean::AssocConstItem(..) | clean::AssocTypeItem(..) => {
+                let item_id = i.item_id;
+                if item_id.is_local()
+                    && !self.effective_visibilities.is_reachable(self.tcx, item_id.expect_def_id())
+                {
+                    debug!("Stripper: stripping {:?} {:?}", i.type_(), i.name);
+                    return None;
+                }
+            }
+
             clean::StructFieldItem(..) => {
                 if i.visibility(self.tcx) != Some(Visibility::Public) {
                     return Some(strip_item(i));
@@ -192,16 +199,16 @@ impl<'a> DocFolder for ImplStripper<'a, '_> {
                     && imp.items.iter().all(|i| {
                         let item_id = i.item_id;
                         item_id.is_local()
-                            && !is_item_reachable(
-                                self.tcx,
-                                self.is_json_output,
-                                &self.cache.effective_visibilities,
-                                item_id,
-                            )
+                            && !self
+                                .cache
+                                .effective_visibilities
+                                .is_reachable(self.tcx, item_id.expect_def_id())
                     })
                 {
+                    debug!("ImplStripper: no public item; removing {imp:?}");
                     return None;
                 } else if imp.items.is_empty() && i.doc_value().is_empty() {
+                    debug!("ImplStripper: no item and no doc; removing {imp:?}");
                     return None;
                 }
             }
@@ -212,21 +219,21 @@ impl<'a> DocFolder for ImplStripper<'a, '_> {
                 && !imp.for_.is_assoc_ty()
                 && !self.should_keep_impl(&i, did)
             {
-                debug!("ImplStripper: impl item for stripped type; removing");
+                debug!("ImplStripper: impl item for stripped type; removing {imp:?}");
                 return None;
             }
             if let Some(did) = imp.trait_.as_ref().map(|t| t.def_id())
                 && !self.should_keep_impl(&i, did)
             {
-                debug!("ImplStripper: impl item for stripped trait; removing");
+                debug!("ImplStripper: impl item for stripped trait; removing {imp:?}");
                 return None;
             }
             if let Some(generics) = imp.trait_.as_ref().and_then(|t| t.generics()) {
                 for typaram in generics {
                     if let Some(did) = typaram.def_id(self.cache)
                         && !self.should_keep_impl(&i, did)
                     {
-                        debug!("ImplStripper: stripped item in trait's generics; removing impl");
+                        debug!("ImplStripper: stripped item in trait's generics; removing {imp:?}");
                         return None;
                     }
                 }

tests/rustdoc/async-fn.rs

@@ -48,6 +48,8 @@ impl Foo {
 
 pub trait Pattern<'a> {}
 
+impl Pattern<'_> for () {}
+
 pub trait Trait<const N: usize> {}
 // @has async_fn/fn.const_generics.html
 // @has - '//pre[@class="rust item-decl"]' 'pub async fn const_generics<const N: usize>(_: impl Trait<N>)'
@@ -57,18 +59,18 @@ pub async fn const_generics<const N: usize>(_: impl Trait<N>) {}
 // regression test for #63037
 // @has async_fn/fn.elided.html
 // @has - '//pre[@class="rust item-decl"]' 'pub async fn elided(foo: &str) -> &str'
-pub async fn elided(foo: &str) -> &str {}
+pub async fn elided(foo: &str) -> &str { "" }
 // This should really be shown as written, but for implementation reasons it's difficult.
 // See `impl Clean for TyKind::Ref`.
 // @has async_fn/fn.user_elided.html
 // @has - '//pre[@class="rust item-decl"]' 'pub async fn user_elided(foo: &str) -> &str'
-pub async fn user_elided(foo: &'_ str) -> &str {}
+pub async fn user_elided(foo: &'_ str) -> &str { "" }
 // @has async_fn/fn.static_trait.html
 // @has - '//pre[@class="rust item-decl"]' 'pub async fn static_trait(foo: &str) -> Box<dyn Bar>'
-pub async fn static_trait(foo: &str) -> Box<dyn Bar> {}
+pub async fn static_trait(foo: &str) -> Box<dyn Bar> { Box::new(()) }
 // @has async_fn/fn.lifetime_for_trait.html
 // @has - '//pre[@class="rust item-decl"]' "pub async fn lifetime_for_trait(foo: &str) -> Box<dyn Bar + '_>"
-pub async fn lifetime_for_trait(foo: &str) -> Box<dyn Bar + '_> {}
+pub async fn lifetime_for_trait(foo: &str) -> Box<dyn Bar + '_> { Box::new(()) }
 // @has async_fn/fn.elided_in_input_trait.html
 // @has - '//pre[@class="rust item-decl"]' "pub async fn elided_in_input_trait(t: impl Pattern<'_>)"
 pub async fn elided_in_input_trait(t: impl Pattern<'_>) {}
@@ -78,18 +80,20 @@ struct AsyncFdReadyGuard<'a, T> { x: &'a T }
 impl Foo {
     // @has async_fn/struct.Foo.html
     // @has - '//*[@class="method"]' 'pub async fn complicated_lifetimes( &self, context: &impl Bar ) -> impl Iterator<Item = &usize>'
-    pub async fn complicated_lifetimes(&self, context: &impl Bar) -> impl Iterator<Item = &usize> {}
+    pub async fn complicated_lifetimes(&self, context: &impl Bar) -> impl Iterator<Item = &usize> {
+        [0].iter()
+    }
     // taken from `tokio` as an example of a method that was particularly bad before
     // @has - '//*[@class="method"]' "pub async fn readable<T>(&self) -> Result<AsyncFdReadyGuard<'_, T>, ()>"
-    pub async fn readable<T>(&self) -> Result<AsyncFdReadyGuard<'_, T>, ()> {}
+    pub async fn readable<T>(&self) -> Result<AsyncFdReadyGuard<'_, T>, ()> { Err(()) }
     // @has - '//*[@class="method"]' "pub async fn mut_self(&mut self)"
     pub async fn mut_self(&mut self) {}
 }
 
 // test named lifetimes, just in case
 // @has async_fn/fn.named.html
 // @has - '//pre[@class="rust item-decl"]' "pub async fn named<'a, 'b>(foo: &'a str) -> &'b str"
-pub async fn named<'a, 'b>(foo: &'a str) -> &'b str {}
+pub async fn named<'a, 'b>(foo: &'a str) -> &'b str { "" }
 // @has async_fn/fn.named_trait.html
 // @has - '//pre[@class="rust item-decl"]' "pub async fn named_trait<'a, 'b>(foo: impl Pattern<'a>) -> impl Pattern<'b>"
 pub async fn named_trait<'a, 'b>(foo: impl Pattern<'a>) -> impl Pattern<'b> {}

tests/rustdoc/impl-on-ty-alias-issue-119015.rs

@@ -0,0 +1,27 @@
+#![crate_name = "foo"]
+
+// @has 'foo/index.html'
+// There should be only `type A`.
+// @count - '//*[@class="item-table"]//*[@class="item-name"]' 1
+// @has - '//*[@class="item-name"]/a[@href="type.A.html"]' 'A'
+
+mod foo {
+    pub struct S;
+}
+
+use foo::S;
+
+pub type A = S;
+
+// @has 'foo/type.A.html'
+// @has - '//*[@id="method.default"]/h4' 'fn default() -> Self'
+impl Default for A {
+    fn default() -> Self {
+        S
+    }
+}
+
+// @has - '//*[@id="method.a"]/h4' 'pub fn a(&self)'
+impl A {
+    pub fn a(&self) {}
+}