Update item_children

Author: Zoxc

src/librustc/query/mod.rs

@@ -786,7 +786,7 @@ rustc_queries! {
             eval_always
             desc { "fetching what a crate is named" }
         }
-        query item_children(_: DefId) -> Lrc<Vec<Export<hir::HirId>>> {}
+        query item_children(_: DefId) -> &'tcx [Export<hir::HirId>] {}
         query extern_mod_stmt_cnum(_: DefId) -> Option<CrateNum> {}
 
         query get_lib_features(_: CrateNum) -> Lrc<LibFeatures> {

src/librustc_metadata/cstore_impl.rs

@@ -223,9 +223,9 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     }
     crate_name => { cdata.name }
     item_children => {
-        let mut result = vec![];
+        let mut result = SmallVec::<[_; 8]>::new();
         cdata.each_child_of_item(def_id.index, |child| result.push(child), tcx.sess);
-        Lrc::new(result)
+        tcx.arena.alloc_slice(&result)
     }
     defined_lib_features => { Lrc::new(cdata.get_lib_features()) }
     defined_lang_items => { Lrc::new(cdata.get_lang_items()) }

src/librustdoc/clean/mod.rs

@@ -4430,7 +4430,7 @@ pub fn path_to_def(tcx: TyCtxt<'_, '_, '_>, path: &[Symbol]) -> Option<DefId> {
         loop {
             let segment = path_it.next()?;
 
-            for item in mem::replace(&mut items, Lrc::new(vec![])).iter() {
+            for item in mem::replace(&mut items, &[]).iter() {
                 if item.ident.name == *segment {
                     if path_it.peek().is_none() {
                         return match item.res {