refactor DefPathData variants

In particular, remove the name from the Impl, since that name is
synthesized and is not predictable (it tends to break incr. comp.).

Also rename the variants to be a bit more uniform and remove some
distinctions that we were not really taking advantage of anywhere.

src/librustc/front/map/collector.rs

@@ -133,11 +133,16 @@ impl<'ast> Visitor<'ast> for NodeCollector<'ast> {
         // Pick the def data. This need not be unique, but the more
         // information we encapsulate into
         let def_data = match i.node {
-            ItemDefaultImpl(..) | ItemImpl(..) => DefPathData::Impl(i.name),
-            ItemEnum(..) | ItemStruct(..) | ItemTrait(..) => DefPathData::Type(i.name),
-            ItemExternCrate(..) | ItemMod(..) => DefPathData::Mod(i.name),
-            ItemStatic(..) | ItemConst(..) | ItemFn(..) => DefPathData::Value(i.name),
-            _ => DefPathData::Misc,
+            ItemDefaultImpl(..) | ItemImpl(..) =>
+                DefPathData::Impl,
+            ItemEnum(..) | ItemStruct(..) | ItemTrait(..) |
+            ItemExternCrate(..) | ItemMod(..) | ItemForeignMod(..) |
+            ItemTy(..) =>
+                DefPathData::TypeNs(i.name),
+            ItemStatic(..) | ItemConst(..) | ItemFn(..) =>
+                DefPathData::ValueNs(i.name),
+            ItemUse(..) =>
+                DefPathData::Misc,
         };
 
         self.insert_def(i.id, NodeItem(i), def_data);
@@ -202,7 +207,7 @@ impl<'ast> Visitor<'ast> for NodeCollector<'ast> {
     fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
         self.insert_def(foreign_item.id,
                         NodeForeignItem(foreign_item),
-                        DefPathData::Value(foreign_item.name));
+                        DefPathData::ValueNs(foreign_item.name));
 
         let parent_node = self.parent_node;
         self.parent_node = foreign_item.id;
@@ -222,8 +227,8 @@ impl<'ast> Visitor<'ast> for NodeCollector<'ast> {
 
     fn visit_trait_item(&mut self, ti: &'ast TraitItem) {
         let def_data = match ti.node {
-            MethodTraitItem(..) | ConstTraitItem(..) => DefPathData::Value(ti.name),
-            TypeTraitItem(..) => DefPathData::Type(ti.name),
+            MethodTraitItem(..) | ConstTraitItem(..) => DefPathData::ValueNs(ti.name),
+            TypeTraitItem(..) => DefPathData::TypeNs(ti.name),
         };
 
         self.insert(ti.id, NodeTraitItem(ti));
@@ -246,8 +251,8 @@ impl<'ast> Visitor<'ast> for NodeCollector<'ast> {
 
     fn visit_impl_item(&mut self, ii: &'ast ImplItem) {
         let def_data = match ii.node {
-            ImplItemKind::Method(..) | ImplItemKind::Const(..) => DefPathData::Value(ii.name),
-            ImplItemKind::Type(..) => DefPathData::Type(ii.name),
+            ImplItemKind::Method(..) | ImplItemKind::Const(..) => DefPathData::ValueNs(ii.name),
+            ImplItemKind::Type(..) => DefPathData::TypeNs(ii.name),
         };
 
         self.insert_def(ii.id, NodeImplItem(ii), def_data);

src/librustc/front/map/definitions.rs

@@ -144,10 +144,9 @@ pub enum DefPathData {
     Misc,
 
     // Different kinds of items and item-like things:
-    Impl(ast::Name),
-    Type(ast::Name),
-    Mod(ast::Name),
-    Value(ast::Name),
+    Impl,
+    TypeNs(ast::Name), // something in the type NS
+    ValueNs(ast::Name), // something in the value NS
     MacroDef(ast::Name),
     ClosureExpr,
 
@@ -159,10 +158,6 @@ pub enum DefPathData {
     StructCtor, // implicit ctor for a tuple-like struct
     Initializer, // initializer for a const
     Binding(ast::Name), // pattern binding
-
-    // An external crate that does not have an `extern crate` in this
-    // crate.
-    DetachedCrate(ast::Name),
 }
 
 impl Definitions {
@@ -247,20 +242,21 @@ impl DefPathData {
     pub fn as_interned_str(&self) -> InternedString {
         use self::DefPathData::*;
         match *self {
-            Impl(name) |
-            Type(name) |
-            Mod(name) |
-            Value(name) |
+            TypeNs(name) |
+            ValueNs(name) |
             MacroDef(name) |
             TypeParam(name) |
             LifetimeDef(name) |
             EnumVariant(name) |
-            DetachedCrate(name) |
             Binding(name) |
             Field(name) => {
                 name.as_str()
             }
 
+            Impl => {
+                InternedString::new("{{impl}}")
+            }
+
             // note that this does not show up in user printouts
             CrateRoot => {
                 InternedString::new("{{root}}")