From 296777e50a6e1c3fe2dfaadbd25b01cc3071cf7c Mon Sep 17 00:00:00 2001
From: Edward Wang <edward.yu.wang@gmail.com>
Date: Sat, 24 Jan 2015 03:13:26 +0800
Subject: [PATCH] Resolve type vars when inferring borrow kinds for upvars

As part of #20432, upvar checking is now moved out of regionck to its
own pass and before regionck. But regionck has some type resolution of
its own. Without them, now separated upvar checking may be tripped over
by residue `ty_infer`.

Closes #21306
---
 src/librustc_typeck/check/mod.rs   |  3 ++-
 src/librustc_typeck/check/upvar.rs |  7 +------
 src/test/run-pass/issue-21306.rs   | 17 +++++++++++++++++
 3 files changed, 20 insertions(+), 7 deletions(-)
 create mode 100644 src/test/run-pass/issue-21306.rs

diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 5f8ae09b5bd6f..584b6361f35d2 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -1635,6 +1635,7 @@ 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,
@@ -1642,7 +1643,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                       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> {
diff --git a/src/librustc_typeck/check/upvar.rs b/src/librustc_typeck/check/upvar.rs
index ec44d765a8e68..7fc0a83e34ac5 100644
--- a/src/librustc_typeck/check/upvar.rs
+++ b/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() {
diff --git a/src/test/run-pass/issue-21306.rs b/src/test/run-pass/issue-21306.rs
new file mode 100644
index 0000000000000..c75abd8896343
--- /dev/null
+++ b/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);
+}