WIP fix librustc_driver test

Author: nikomatsakis

src/librustc_driver/test.rs

@@ -18,7 +18,7 @@ use rustc_lint;
 use rustc_resolve::MakeGlobMap;
 use rustc::middle::region;
 use rustc::ty::subst::{Kind, Subst};
-use rustc::traits::{ObligationCause, Reveal};
+use rustc::traits::ObligationCause;
 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
 use rustc::ty::maps::OnDiskCache;
 use rustc::infer::{self, InferOk, InferResult};
@@ -153,7 +153,7 @@ fn test_env<F>(source_string: &str,
                              |tcx| {
         tcx.infer_ctxt().enter(|infcx| {
             let mut region_scope_tree = region::ScopeTree::default();
-            let param_env = ty::ParamEnv::empty());
+            let param_env = ty::ParamEnv::empty();
             body(Env {
                 infcx: &infcx,
                 region_scope_tree: &mut region_scope_tree,