1 files changed, 29 insertions, 9 deletions

diff --git a/src/librustdoc/clean/utils.rs b/src/librustdoc/clean/utils.rs
index 270321aaa11..3b2f50db8c7 100644
--- a/src/librustdoc/clean/utils.rs
+++ b/src/librustdoc/clean/utils.rs
@@ -8,14 +8,13 @@ use crate::clean::{
 };
 use crate::core::DocContext;
 
-use itertools::Itertools;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
-use rustc_middle::ty::{self, DefIdTree, Ty};
+use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt};
 use rustc_span::symbol::{kw, sym, Symbol};
 use std::mem;
 
@@ -43,7 +42,7 @@ crate fn krate(mut cx: &mut DocContext<'_>) -> Crate {
     let mut module = module.clean(cx);
     let mut masked_crates = FxHashSet::default();
 
-    match module.kind {
+    match *module.kind {
         ItemKind::ModuleItem(ref module) => {
             for it in &module.items {
                 // `compiler_builtins` should be masked too, but we can't apply
@@ -61,7 +60,7 @@ crate fn krate(mut cx: &mut DocContext<'_>) -> Crate {
 
     let ExternalCrate { name, src, primitives, keywords, .. } = LOCAL_CRATE.clean(cx);
     {
-        let m = match module.kind {
+        let m = match *module.kind {
             ItemKind::ModuleItem(ref mut m) => m,
             _ => unreachable!(),
         };
@@ -74,7 +73,7 @@ crate fn krate(mut cx: &mut DocContext<'_>) -> Crate {
             )
         }));
         m.items.extend(keywords.into_iter().map(|(def_id, kw)| {
-            Item::from_def_id_and_parts(def_id, Some(kw.clone()), ItemKind::KeywordItem(kw), cx)
+            Item::from_def_id_and_parts(def_id, Some(kw), ItemKind::KeywordItem(kw), cx)
         }));
     }
 
@@ -180,12 +179,12 @@ crate fn get_real_types(
     if arg.is_full_generic() {
         let arg_s = Symbol::intern(&arg.print().to_string());
         if let Some(where_pred) = generics.where_predicates.iter().find(|g| match g {
-            &WherePredicate::BoundPredicate { ref ty, .. } => ty.def_id() == arg.def_id(),
+            WherePredicate::BoundPredicate { ty, .. } => ty.def_id() == arg.def_id(),
             _ => false,
         }) {
             let bounds = where_pred.get_bounds().unwrap_or_else(|| &[]);
             for bound in bounds.iter() {
-                if let GenericBound::TraitBound(ref poly_trait, _) = *bound {
+                if let GenericBound::TraitBound(poly_trait, _) = bound {
                     for x in poly_trait.generic_params.iter() {
                         if !x.is_type() {
                             continue;
@@ -307,7 +306,7 @@ crate fn strip_path(path: &Path) -> Path {
         .segments
         .iter()
         .map(|s| PathSegment {
-            name: s.name.clone(),
+            name: s.name,
             args: GenericArgs::AngleBracketed { args: vec![], bindings: vec![] },
         })
         .collect();
@@ -338,7 +337,7 @@ crate fn build_deref_target_impls(cx: &DocContext<'_>, items: &[Item], ret: &mut
     let tcx = cx.tcx;
 
     for item in items {
-        let target = match item.kind {
+        let target = match *item.kind {
             ItemKind::TypedefItem(ref t, true) => &t.type_,
             _ => continue,
         };
@@ -624,3 +623,24 @@ where
     *cx.impl_trait_bounds.borrow_mut() = old_bounds;
     r
 }
+
+/// Find the nearest parent module of a [`DefId`].
+///
+/// **Panics if the item it belongs to [is fake][Item::is_fake].**
+crate fn find_nearest_parent_module(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
+    if def_id.is_top_level_module() {
+        // The crate root has no parent. Use it as the root instead.
+        Some(def_id)
+    } else {
+        let mut current = def_id;
+        // The immediate parent might not always be a module.
+        // Find the first parent which is.
+        while let Some(parent) = tcx.parent(current) {
+            if tcx.def_kind(parent) == DefKind::Mod {
+                return Some(parent);
+            }
+            current = parent;
+        }
+        None
+    }
+}