Add FIXMEs relating to caching of projection results

src/librustc/middle/traits/fulfill.rs

@@ -115,6 +115,8 @@ impl<'tcx> FulfillmentContext<'tcx> {
 
         assert!(!trait_ref.has_escaping_regions());
 
+        // FIXME(#20304) -- cache
+
         let ty_var = infcx.next_ty_var();
         let projection =
             ty::Binder(ty::ProjectionPredicate {

src/librustc_trans/trans/monomorphize.rs

@@ -319,7 +319,7 @@ pub fn normalize_associated_type<'tcx,T>(tcx: &ty::ctxt<'tcx>, t: &T) -> T
         return t.clone();
     }
 
-    // TODO cache
+    // FIXME(#20304) -- cache
 
     let infcx = infer::new_infer_ctxt(tcx);
     let param_env = ty::empty_parameter_environment();