Unify the rhs and lhs types in a send

Closes #662.

One-line fixes are always the best :-D

src/comp/middle/typeck.rs

@@ -1877,6 +1877,7 @@ fn check_expr(&@fn_ctxt fcx, &@ast::expr expr) {
                     fcx.ccx.tcx.sess.span_fatal(expr.span,s);
                 }
             }
+            demand::simple(fcx, expr.span, chan_t, lhs_t);
             write::ty_only_fixup(fcx, id, chan_t);
         }
         case (ast::expr_recv(?lhs, ?rhs)) {

src/test/run-pass/send-type-inference.rs

@@ -0,0 +1,10 @@
+// xfail-stage0
+// tests that ctrl's type gets inferred properly
+type command[K, V] = rec(K key, V val);
+
+fn cache_server[K, V] (chan[chan[command[K,V]]] c) {
+    auto ctrl = port();
+    c <| chan(ctrl);
+}
+fn main() {
+}