save-analysis: fix def_ids for method calls

We were sometime emitting the decl as a def.

Author: nrc

src/librustc/ast_map/mod.rs

@@ -411,6 +411,13 @@ impl<'ast> Map<'ast> {
         }
     }
 
+    pub fn expect_trait_item(&self, id: NodeId) -> &'ast TraitItem {
+        match self.find(id) {
+            Some(NodeTraitItem(item)) => item,
+            _ => panic!("expected trait item, found {}", self.node_to_string(id))
+        }
+    }
+
     pub fn expect_struct(&self, id: NodeId) -> &'ast StructDef {
         match self.find(id) {
             Some(NodeItem(i)) => {

src/librustc_trans/save/mod.rs

@@ -548,13 +548,12 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
                     let ti = self.tcx.impl_or_trait_item(decl_id);
                     match provenence {
                         def::FromTrait(def_id) => {
-                            Some(self.tcx.trait_items(def_id)
-                                    .iter()
-                                    .find(|mr| {
-                                        mr.name() == ti.name()
-                                    })
-                                    .unwrap()
-                                    .def_id())
+                            self.tcx.trait_items(def_id)
+                                .iter()
+                                .find(|mr| {
+                                    mr.name() == ti.name() && self.trait_method_has_body(mr)
+                                })
+                                .map(|mr| mr.def_id())
                         }
                         def::FromImpl(def_id) => {
                             let impl_items = self.tcx.impl_items.borrow();
@@ -594,6 +593,20 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
         }
     }
 
+    fn trait_method_has_body(&self, mr: &ty::ImplOrTraitItem) -> bool {
+        let def_id = mr.def_id();
+        if def_id.krate != ast::LOCAL_CRATE {
+            return false;
+        }
+
+        let trait_item = self.tcx.map.expect_trait_item(def_id.node);
+        if let ast::TraitItem_::MethodTraitItem(_, Some(_)) = trait_item.node {
+            true
+        } else {
+            false
+        }
+    }
+
     pub fn get_field_ref_data(&self,
                               field_ref: &ast::Field,
                               struct_id: DefId,