rustdoc: Use impl_id and for_ DefId's for Blanket item id

Author: Stupremee

src/librustdoc/clean/blanket_impl.rs

@@ -96,7 +96,7 @@ impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
                     name: None,
                     attrs: Default::default(),
                     visibility: Inherited,
-                    def_id: ItemId::Blanket { trait_: trait_def_id, for_: item_def_id },
+                    def_id: ItemId::Blanket { impl_id: impl_def_id, for_: item_def_id },
                     kind: box ImplItem(Impl {
                         span: self.cx.tcx.def_span(impl_def_id).clean(self.cx),
                         unsafety: hir::Unsafety::Normal,

src/librustdoc/clean/types.rs

@@ -57,7 +57,7 @@ crate enum ItemId {
     /// Identifier that is used for auto traits.
     Auto { trait_: DefId, for_: DefId },
     /// Identifier that is used for blanket implementations.
-    Blanket { trait_: DefId, for_: DefId },
+    Blanket { impl_id: DefId, for_: DefId },
     /// Identifier for primitive types.
     Primitive(PrimitiveType, CrateNum),
 }

src/librustdoc/json/conversions.rs

@@ -182,8 +182,8 @@ crate fn from_item_id(did: ItemId) -> Id {
 
     match did {
         ItemId::DefId(did) => Id(format!("{}", DisplayDefId(did))),
-        ItemId::Blanket { for_, trait_ } => {
-            Id(format!("b:{}-{}", DisplayDefId(trait_), DisplayDefId(for_)))
+        ItemId::Blanket { for_, impl_id } => {
+            Id(format!("b:{}-{}", DisplayDefId(impl_id), DisplayDefId(for_)))
         }
         ItemId::Auto { for_, trait_ } => {
             Id(format!("a:{}-{}", DisplayDefId(trait_), DisplayDefId(for_)))