---

yaml
---
r: 129791
b: refs/heads/auto
c: fd278a8
h: refs/heads/master
i:
  129789: f6174b9
  129787: c812783
  129783: 7d17af6
  129775: 6a2a927
  129759: 992a5ff
  129727: 6c4ad1e
  129663: d29dd9f
  129535: ffc8fbd
v: v3

Author: huonw

[refs]

@@ -13,7 +13,7 @@ refs/heads/try3: 9387340aab40a73e8424c48fd42f0c521a4875c0
 refs/tags/release-0.3.1: 495bae036dfe5ec6ceafd3312b4dca48741e845b
 refs/tags/release-0.4: e828ea2080499553b97dfe33b3f4d472b4562ad7
 refs/tags/release-0.5: 7e3bcfbf21278251ee936ad53e92e9b719702d73
-refs/heads/auto: 2e4a21c2c2cc0702044dabf11d0839e4ed65a079
+refs/heads/auto: fd278a892a9bb27fbe274d7cb472bc7e4ca0c1b3
 refs/heads/servo: af82457af293e2a842ba6b7759b70288da276167
 refs/tags/release-0.6: b4ebcfa1812664df5e142f0134a5faea3918544c
 refs/tags/0.1: b19db808c2793fe2976759b85a355c3ad8c8b336

branches/auto/src/librustc/middle/typeck/check/mod.rs

@@ -2184,10 +2184,15 @@ fn lookup_method_for_for_loop(fcx: &FnCtxt,
     let method_type = match method {
         Some(ref method) => method.ty,
         None => {
-            fcx.tcx().sess.span_err(iterator_expr.span,
-                                    format!("`for` loop expression has type `{}` which does \
-                                             not implement the `Iterator` trait",
-                                            fcx.infcx().ty_to_string(expr_type)).as_slice());
+            let true_expr_type = fcx.infcx().resolve_type_vars_if_possible(expr_type);
+
+            if !ty::type_is_error(true_expr_type) {
+                let ty_string = fcx.infcx().ty_to_string(true_expr_type);
+                fcx.tcx().sess.span_err(iterator_expr.span,
+                                        format!("`for` loop expression has type `{}` which does \
+                                                 not implement the `Iterator` trait",
+                                                ty_string).as_slice());
+            }
             ty::mk_err()
         }
     };

branches/auto/src/test/compile-fail/for-loop-type-error.rs

@@ -0,0 +1,16 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub fn main() {
+    let x = () + (); //~ ERROR binary operation
+
+    // this shouldn't have a flow-on error:
+    for _ in x {}
+}