Don't call `item` on modules for json renderer

Closes #80664

src/librustdoc/formats/renderer.rs

@@ -13,6 +13,11 @@
     /// Gives a description of the renderer. Used for performance profiling.
     fn descr() -> &'static str;
 
+    /// Whether to call `item` recursivly for modules
+    ///
+    /// This is true for html, and false for json. See #80664
+    const RUN_ON_MODULE: bool;
+
     /// Sets up any state required for the renderer. When this is called the cache has already been
     /// populated.
     fn init(
@@ -68,7 +73,7 @@ fn after_krate(
 
     let unknown = Symbol::intern("<unknown item>");
     while let Some((mut cx, item)) = work.pop() {
-        if item.is_mod() {
+        if item.is_mod() && T::RUN_ON_MODULE {
             // modules are special because they add a namespace. We also need to
             // recurse into the items of the module as well.
             let name = item.name.as_ref().unwrap().to_string();

src/librustdoc/html/render/context.rs

@@ -290,6 +290,8 @@ fn descr() -> &'static str {
         "html"
     }
 
+    const RUN_ON_MODULE: bool = true;
+
     fn init(
         mut krate: clean::Crate,
         options: RenderOptions,

src/librustdoc/json/conversions.rs

@@ -179,7 +179,8 @@ fn from_clean_item_kind(item: clean::ItemKind, tcx: TyCtxt<'_>, name: &Option<Sy
             bounds: g.into_iter().map(Into::into).collect(),
             default: t.map(Into::into),
         },
-        StrippedItem(inner) => from_clean_item_kind(*inner, tcx, name),
+        // `convert_item` early returns `None` for striped items
+        StrippedItem(_) => unreachable!(),
         PrimitiveItem(_) | KeywordItem(_) => {
             panic!("{:?} is not supported for JSON output", item)
         }

src/librustdoc/json/mod.rs

@@ -129,6 +129,8 @@ fn descr() -> &'static str {
         "json"
     }
 
+    const RUN_ON_MODULE: bool = false;
+
     fn init(
         krate: clean::Crate,
         options: RenderOptions,
@@ -169,8 +171,10 @@ fn item(&mut self, item: clean::Item) -> Result<(), Error> {
                 e.impls = self.get_impls(id)
             }
             let removed = self.index.borrow_mut().insert(from_def_id(id), new_item.clone());
+
             // FIXME(adotinthevoid): Currently, the index is duplicated. This is a sanity check
-            // to make sure the items are unique.
+            // to make sure the items are unique. The main place this happens is when an item, is
+            // reexported in more than one place. See `rustdoc-json/reexport/in_root_and_mod`
             if let Some(old_item) = removed {
                 assert_eq!(old_item, new_item);
             }

src/test/rustdoc-json/reexport/in_root_and_mod.rs

+#![feature(no_core)]
+#![no_core]
+
+mod foo {
+    // @set foo_id = in_root_and_mod.json "$.index[*][?(@.name=='Foo')].id"
+    pub struct Foo;
+}
+
+// @has - "$.index[*][?(@.name=='in_root_and_mod')].inner.items[*]" $foo_id
+pub use foo::Foo;
+
+pub mod bar {
+    // @has - "$.index[*][?(@.name=='bar')].inner.items[*]" $foo_id
+    pub use crate::foo::Foo;
+}

src/test/rustdoc-json/reexport/in_root_and_mod_pub.rs

+#![feature(no_core)]
+#![no_core]
+
+pub mod foo {
+    // @set bar_id = in_root_and_mod_pub.json "$.index[*][?(@.name=='Bar')].id"
+    // @has - "$.index[*][?(@.name=='foo')].inner.items[*]" $bar_id
+    pub struct Bar;
+}
+
+// @set root_import_id = - "$.index[*][?(@.inner.span=='foo::Bar')].id"
+// @is - "$.index[*][?(@.inner.span=='foo::Bar')].inner.id" $bar_id
+// @has - "$.index[*][?(@.name=='in_root_and_mod_pub')].inner.items[*]" $root_import_id
+pub use foo::Bar;
+
+pub mod baz {
+    // @set baz_import_id = - "$.index[*][?(@.inner.span=='crate::foo::Bar')].id"
+    // @is - "$.index[*][?(@.inner.span=='crate::foo::Bar')].inner.id" $bar_id
+    // @has - "$.index[*][?(@.name=='baz')].inner.items[*]" $baz_import_id
+    pub use crate::foo::Bar;
+}

src/test/rustdoc-json/reexport/rename_private.rs

+// edition:2018
+
+#![no_core]
+#![feature(no_core)]
+// @!has rename_private.json "$.index[*][?(@.name=='inner')]"
+mod inner {
+    // @!has - "$.index[*][?(@.name=='Public')]"
+    pub struct Public;
+}
+
+// @set newname_id = - "$.index[*][?(@.name=='NewName')].id"
+// @is - "$.index[*][?(@.name=='NewName')].kind" \"struct\"
+// @has - "$.index[*][?(@.name=='rename_private')].inner.items[*]" $newname_id
+pub use inner::Public as NewName;