fix ppaux

Author: arielb1

src/librustc/util/ppaux.rs

@@ -712,6 +712,7 @@ define_print! {
  ty::tls::with(|tcx| {
  // Use a type that can't appear in defaults of type parameters.
  let dummy_self = tcx.mk_infer(ty::FreshTy(0));
+ let mut first = true;
 
  if let Some(principal) = self.principal() {
  let principal = tcx
@@ -724,11 +725,17 @@ define_print! {
  .with_self_ty(tcx, dummy_self)
  }).collect::<Vec<_>>();
  cx.parameterized(f, principal.substs, principal.def_id, &projections)?;
+ first = false;
  }
 
  // Builtin bounds.
  for did in self.auto_traits() {
- write!(f, " + {}", tcx.item_path_str(did))?;
+ if !first {
+ write!(f, " + ")?;
+ }
+ first = false;
+
+ write!(f, "{}", tcx.item_path_str(did))?;
  }
 
  Ok(())