Expect pipe symbol after closure parameter lists

src/libsyntax/parse/parser.rs

@@ -4699,7 +4699,7 @@ impl<'a> Parser<'a> {
                     SeqSep::trailing_allowed(token::Comma),
                     |p| p.parse_fn_block_arg()
                 );
-                self.bump();
+                self.expect(&token::BinOp(token::Or))?;
                 args
             }
         };

src/test/compile-fail/issue-44021.rs

@@ -0,0 +1,16 @@
+// 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.
+
+struct MyStruct;
+impl MyStruct {
+    fn f() {|x, y} //~ ERROR expected one of `:`, `@`, or `|`, found `}`
+}
+
+fn main() {}