rustdoc: render ast::QPath

Fix #18594

src/librustdoc/clean/mod.rs

@@ -1135,6 +1135,11 @@ pub enum Type {
         mutability: Mutability,
         type_: Box<Type>,
     },
+    QPath {
+        name: String,
+        self_type: Box<Type>,
+        trait_: Box<Type>
+    },
     // region, raw, other boxes, mutable
 }
 
@@ -1260,6 +1265,7 @@ fn clean(&self, cx: &DocContext) -> Type {
             TyProc(ref c) => Proc(box c.clean(cx)),
             TyBareFn(ref barefn) => BareFunction(box barefn.clean(cx)),
             TyParen(ref ty) => ty.clean(cx),
+            TyQPath(ref qp) => qp.clean(cx),
             ref x => panic!("Unimplemented type {}", x),
         }
     }
@@ -1362,6 +1368,16 @@ fn clean(&self, cx: &DocContext) -> Type {
     }
 }
 
+impl Clean<Type> for ast::QPath {
+    fn clean(&self, cx: &DocContext) -> Type {
+        Type::QPath {
+            name: self.item_name.clean(cx),
+            self_type: box self.self_type.clean(cx),
+            trait_: box self.trait_ref.clean(cx)
+        }
+    }
+}
+
 #[deriving(Clone, Encodable, Decodable)]
 pub enum StructField {
     HiddenStructField, // inserted later by strip passes

src/librustdoc/html/format.rs

@@ -485,6 +485,9 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                     }
                 }
             }
+            clean::QPath { ref name, ref self_type, ref trait_ } => {
+                write!(f, "<{} as {}>::{}", self_type, trait_, name)
+            }
             clean::Unique(..) => {
                 panic!("should have been cleaned")
             }