libcore: De-mode str

1 files changed, 3 insertions, 3 deletions

diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 561e2ecd0b4..e99e35b596c 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -2093,13 +2093,13 @@ fn fn_header_info_to_str(opt_sty: Option<ast::self_ty_>,
     match opt_purity {
       Some(ast::impure_fn) => { }
       Some(purity) => {
-        str::push_str(s, purity_to_str(purity));
-        str::push_char(s, ' ');
+        str::push_str(&mut s, purity_to_str(purity));
+        str::push_char(&mut s, ' ');
       }
       None => {}
     }
 
-    str::push_str(s, opt_proto_to_str(opt_p));
+    str::push_str(&mut s, opt_proto_to_str(opt_p));
 
     return s;
 }