Properly handle reexport of foreign items.

Handles `pub use` of `extern { fn, static, type }`. Also plug in some more
`match` arms where handling `extern type` is reasonable.

Fixed #46098.

src/librustdoc/clean/mod.rs

@@ -2970,6 +2970,7 @@ fn register_def(cx: &DocContext, def: Def) -> DefId {
         Def::Struct(i) => (i, TypeKind::Struct),
         Def::Union(i) => (i, TypeKind::Union),
         Def::Mod(i) => (i, TypeKind::Module),
+        Def::TyForeign(i) => (i, TypeKind::Foreign),
         Def::Static(i, _) => (i, TypeKind::Static),
         Def::Variant(i) => (cx.tcx.parent_def_id(i).unwrap(), TypeKind::Enum),
         Def::SelfTy(Some(def_id), _) => (def_id, TypeKind::Trait),

src/librustdoc/visit_ast.rs

@@ -306,6 +306,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                 Def::Struct(did) |
                 Def::Union(did) |
                 Def::Enum(did) |
+                Def::TyForeign(did) |
                 Def::TyAlias(did) if !self_is_hidden => {
                     self.cx.access_levels.borrow_mut().map.insert(did, AccessLevel::Public);
                 },
@@ -348,6 +349,17 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                 self.inlining = prev;
                 true
             }
+            hir_map::NodeForeignItem(it) if !glob => {
+                // generate a fresh `extern {}` block if we want to inline a foreign item.
+                om.foreigns.push(hir::ForeignMod {
+                    abi: tcx.hir.get_foreign_abi(it.id),
+                    items: vec![hir::ForeignItem {
+                        name: renamed.unwrap_or(it.name),
+                        .. it.clone()
+                    }].into(),
+                });
+                true
+            }
             _ => false,
         };
         self.view_item_stack.remove(&def_node_id);