Rollup merge of #111642 - GuillaumeGomez:only-impl-from-bodies, r=notriddle

[rustdoc] Only keep impl blocks from bodies

Fixes https://github.com/rust-lang/rust/issues/111415.

The problem was that we kept everything inside bodies whereas only impl blocks are actually accessible from outside bodies.

r? `@notriddle`

src/librustdoc/visit_ast.rs

@@ -5,7 +5,7 @@ use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId, LocalDefIdSet};
-use rustc_hir::intravisit::{walk_item, Visitor};
+use rustc_hir::intravisit::{walk_body, walk_item, Visitor};
 use rustc_hir::{Node, CRATE_HIR_ID};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::TyCtxt;
@@ -106,6 +106,7 @@ pub(crate) struct RustdocVisitor<'a, 'tcx> {
     exact_paths: DefIdMap<Vec<Symbol>>,
     modules: Vec<Module<'tcx>>,
     is_importable_from_parent: bool,
+    inside_body: bool,
 }
 
 impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
@@ -129,6 +130,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
             exact_paths: Default::default(),
             modules: vec![om],
             is_importable_from_parent: true,
+            inside_body: false,
         }
     }
 
@@ -368,6 +370,26 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
         import_id: Option<LocalDefId>,
     ) {
         debug!("visiting item {:?}", item);
+        if self.inside_body {
+            // Only impls can be "seen" outside a body. For example:
+            //
+            // ```
+            // struct Bar;
+            //
+            // fn foo() {
+            //     impl Bar { fn bar() {} }
+            // }
+            // Bar::bar();
+            // ```
+            if let hir::ItemKind::Impl(impl_) = item.kind &&
+                // Don't duplicate impls when inlining or if it's implementing a trait, we'll pick
+                // them up regardless of where they're located.
+                impl_.of_trait.is_none()
+            {
+                self.add_to_current_mod(item, None, None);
+            }
+            return;
+        }
         let name = renamed.unwrap_or(item.ident.name);
         let tcx = self.cx.tcx;
 
@@ -564,4 +586,10 @@ impl<'a, 'tcx> Visitor<'tcx> for RustdocVisitor<'a, 'tcx> {
     fn visit_lifetime(&mut self, _: &hir::Lifetime) {
         // Unneeded.
     }
+
+    fn visit_body(&mut self, b: &'tcx hir::Body<'tcx>) {
+        let prev = mem::replace(&mut self.inside_body, true);
+        walk_body(self, b);
+        self.inside_body = prev;
+    }
 }

tests/rustdoc/nested-items-issue-111415.rs

@@ -0,0 +1,36 @@
+// Regression test for <https://github.com/rust-lang/rust/issues/111415>.
+// This test ensures that only impl blocks are documented in bodies.
+
+#![crate_name = "foo"]
+
+// @has 'foo/index.html'
+// Checking there are only three sections.
+// @count - '//*[@id="main-content"]/*[@class="small-section-header"]' 3
+// @has - '//*[@id="main-content"]/*[@class="small-section-header"]' 'Structs'
+// @has - '//*[@id="main-content"]/*[@class="small-section-header"]' 'Functions'
+// @has - '//*[@id="main-content"]/*[@class="small-section-header"]' 'Traits'
+// Checking that there are only three items.
+// @count - '//*[@id="main-content"]//*[@class="item-name"]' 3
+// @has - '//*[@id="main-content"]//a[@href="struct.Bar.html"]' 'Bar'
+// @has - '//*[@id="main-content"]//a[@href="fn.foo.html"]' 'foo'
+// @has - '//*[@id="main-content"]//a[@href="trait.Foo.html"]' 'Foo'
+
+// Now checking that the `foo` method is visible in `Bar` page.
+// @has 'foo/struct.Bar.html'
+// @has - '//*[@id="method.foo"]/*[@class="code-header"]' 'pub fn foo()'
+// @has - '//*[@id="method.bar"]/*[@class="code-header"]' 'fn bar()'
+pub struct Bar;
+
+pub trait Foo {
+    fn bar() {}
+}
+
+pub fn foo() {
+    pub mod inaccessible {}
+    pub fn inner() {}
+    pub const BAR: u32 = 0;
+    impl Bar {
+        pub fn foo() {}
+    }
+    impl Foo for Bar {}
+}