Refactor how impl self types are stored

In order to avoid a confusing use of the tcache, I added an extra
node ID field to trait refs. Now trait refs have a "ref ID" (the one
that resolve3 resolves) and an "impl ID" (the one that you look up
in the tcache to get the self type).

Closes #2434

4 files changed, 20 insertions, 8 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index f79f6cbcae2..095038f02e3 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -675,10 +675,15 @@ type attribute_ = {style: attr_style, value: meta_item, is_sugared_doc: bool};
 
 /*
   trait_refs appear in both impls and in classes that implement traits.
-  resolve maps each trait_ref's id to its defining trait.
+  resolve maps each trait_ref's ref_id to its defining trait; that's all
+  that the ref_id is for. The impl_id maps to the "self type" of this impl.
+  If this impl is an item_impl, the impl_id is redundant (it could be the
+  same as the impl's node id). If this impl is actually an impl_class, then
+  conceptually, the impl_id stands in for the pair of (this class, this
+  trait)
  */
 #[auto_serialize]
-type trait_ref = {path: @path, id: node_id};
+type trait_ref = {path: @path, ref_id: node_id, impl_id: node_id};
 
 #[auto_serialize]
 enum visibility { public, private }
diff --git a/src/libsyntax/ast_map.rs b/src/libsyntax/ast_map.rs
index 129a03f71aa..a5ae45d54ee 100644
--- a/src/libsyntax/ast_map.rs
+++ b/src/libsyntax/ast_map.rs
@@ -188,7 +188,7 @@ fn map_item(i: @item, cx: ctx, v: vt) {
     let item_path = @/* FIXME (#2543) */ copy cx.path;
     cx.map.insert(i.id, node_item(i, item_path));
     alt i.node {
-      item_impl(_, _, _, ms) {
+      item_impl(_, opt_ir, _, ms) {
         let impl_did = ast_util::local_def(i.id);
         for ms.each |m| {
             map_method(impl_did, extend(cx, i.ident), m,
@@ -218,8 +218,14 @@ fn map_item(i: @item, cx: ctx, v: vt) {
           let (_, ms) = ast_util::split_class_items(items);
           // Map trait refs to their parent classes. This is
           // so we can find the self_ty
-          do vec::iter(traits) |p| { cx.map.insert(p.id,
-                                  node_item(i, item_path)); };
+          do vec::iter(traits) |p| { cx.map.insert(p.ref_id,
+                                  node_item(i, item_path));
+                            // This is so we can look up the right things when
+                            // encoding/decoding
+                            cx.map.insert(p.impl_id,
+                                          node_item(i, item_path));
+
+                           };
           let d_id = ast_util::local_def(i.id);
           let p = extend(cx, i.ident);
            // only need to handle methods
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index 0e16d4bdca8..f5edb96f5e1 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -287,7 +287,8 @@ fn noop_fold_item_underscore(i: item_, fld: ast_fold) -> item_ {
 }
 
 fn fold_trait_ref(&&p: @trait_ref, fld: ast_fold) -> @trait_ref {
-    @{path: fld.fold_path(p.path), id: fld.new_id(p.id)}
+    @{path: fld.fold_path(p.path), ref_id: fld.new_id(p.ref_id),
+     impl_id: fld.new_id(p.impl_id)}
 }
 
 fn noop_fold_method(&&m: @method, fld: ast_fold) -> @method {
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 5a1eb7636ba..7448f246698 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -2189,7 +2189,7 @@ class parser {
             if option::is_none(ident) {
                 ident = some(vec::last(path.idents));
             }
-            some(@{path: path, id: self.get_id()})
+            some(@{path: path, ref_id: self.get_id(), impl_id: self.get_id()})
         } else { none };
         let ident = alt ident {
           some(name) { name }
@@ -2223,7 +2223,7 @@ class parser {
 
     fn parse_trait_ref() -> @trait_ref {
         @{path: self.parse_path_with_tps(false),
-          id: self.get_id()}
+          ref_id: self.get_id(), impl_id: self.get_id()}
     }
 
     fn parse_trait_ref_list() -> ~[@trait_ref] {