fix ForAll print

Author: lcnr

src/librustc_middle/ty/mod.rs

@@ -1066,7 +1066,7 @@ impl<'tcx> Predicate<'tcx> {
     ) -> Predicate<'tcx> {
         if self.has_escaping_bound_vars() {
             let qualified = qualifier(Binder::bind(self)).to_predicate(tcx);
-            debug_assert!(!qualified.has_escaping_bound_vars());
+            debug_assert!(!qualified.has_escaping_bound_vars(), "qualified: {:?}", qualified);
             qualified
         } else {
             self

src/librustc_middle/ty/print/pretty.rs

@@ -2062,7 +2062,7 @@ define_print_and_forward_display! {
                    write("`"))
             }
             ty::PredicateKind::ForAll(binder) => {
-                p!(write("forall "), print(binder))
+                p!(print(binder))
             }
         }
     }