--- /dev/null
+// 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.
+
+// This is a regression test for the ICE from issue #10846.
+//
+// The original issue causing the ICE: the LUB-computations during
+// type inference were encountering late-bound lifetimes, and
+// asserting that such lifetimes should have already been subsituted
+// with a concrete lifetime.
+//
+// However, those encounters were occurring within the lexical scope
+// of the binding for the late-bound lifetime; that is, the late-bound
+// lifetimes were perfectly valid. The core problem was that the type
+// folding code was over-zealously passing back all lifetimes when
+// doing region-folding, when really all clients of the region-folding
+// case only want to see FREE lifetime variables, not bound ones.
+
+pub fn main() {
+ fn explicit() {
+ fn test(_x: Option<|f: <'a> |g: &'a int||>) {}
+ test(Some(|_f: <'a> |g: &'a int|| {}));
+ }
+
+ // The code below is shorthand for the code above (and more likely
+ // to represent what one encounters in practice).
+ fn implicit() {
+ fn test(_x: Option<|f: |g: & int||>) {}
+ test(Some(|_f: |g: & int|| {}));
+ }
+
+ explicit();
+ implicit();
+}