Rollup merge of #22884 - japaric:obsolete, r=alexcrichton

 This is leftover from #21843

If you still have `|&:| {}` closures in your code, simply remove the `&:` part.

[breaking-change]

1 files changed, 18 insertions, 0 deletions

diff --git a/src/test/parse-fail/obsolete-closure-kind.rs b/src/test/parse-fail/obsolete-closure-kind.rs
new file mode 100644
index 00000000000..89134e806a7
--- /dev/null
+++ b/src/test/parse-fail/obsolete-closure-kind.rs
@@ -0,0 +1,18 @@
+// 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.
+
+// Test that we generate obsolete syntax errors around usages of closure kinds: `|:|`, `|&:|` and
+// `|&mut:|`.
+
+fn main() {
+    let a = |:| {};  //~ ERROR obsolete syntax: `:`, `&mut:`, or `&:`
+    let a = |&:| {};  //~ ERROR obsolete syntax: `:`, `&mut:`, or `&:`
+    let a = |&mut:| {};  //~ ERROR obsolete syntax: `:`, `&mut:`, or `&:`
+}