Resolve type vars when inferring borrow kinds for upvars

src/librustc_typeck/check/mod.rs

@@ -1635,14 +1635,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     {
         let raw_ty = self.expr_ty(expr);
         let raw_ty = self.infcx().shallow_resolve(raw_ty);
+        let resolve_ty = |&: ty: Ty<'tcx>| self.infcx().resolve_type_vars_if_possible(&ty);
         ty::adjust_ty(self.tcx(),
                       expr.span,
                       expr.id,
                       raw_ty,
                       adjustment,
                       |method_call| self.inh.method_map.borrow()
                                                        .get(&method_call)
-                                                       .map(|method| method.ty))
+                                                       .map(|method| resolve_ty(method.ty)))
     }
 
     pub fn node_ty(&self, id: ast::NodeId) -> Ty<'tcx> {

src/librustc_typeck/check/upvar.rs

@@ -121,13 +121,8 @@ impl<'a,'tcx> SeedBorrowKind<'a,'tcx> {
                      capture_clause: ast::CaptureClause,
                      _body: &ast::Block)
     {
-        let is_old_skool_closure = match self.fcx.expr_ty(expr).sty {
-            _ => false,
-        };
-
         match capture_clause {
-            ast::CaptureByValue if !is_old_skool_closure => {
-            }
+            ast::CaptureByValue => {}
             _ => {
                 ty::with_freevars(self.tcx(), expr.id, |freevars| {
                     for freevar in freevars.iter() {

src/test/run-pass/issue-21306.rs

@@ -0,0 +1,17 @@
+// Copyright 2015 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.
+
+use std::sync::Arc;
+
+fn main() {
+    let x = 5us;
+    let command = Arc::new(Box::new(|&:| { x*2 }));
+    assert_eq!(command(), 10);
+}