Added a help span which informs the user about the escaping of curly braces in a format string if a wrongly escaped one is detected in a string.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/test/parse-fail/wrong-escape-of-curly-braces.rs b/src/test/parse-fail/wrong-escape-of-curly-braces.rs
new file mode 100644
index 00000000000..d86bf726cbd
--- /dev/null
+++ b/src/test/parse-fail/wrong-escape-of-curly-braces.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.
+
+fn f() {
+    let ok = "{{everything fine}}";
+    let bad = "\{it is wrong\}";
+    //~^  ERROR unknown character escape: {
+    //~^^  HELP if used in a formatting string, curly braces are escaped with `{{` and `}}`
+    //~^^^ ERROR unknown character escape: }
+    //~^^^^  HELP if used in a formatting string, curly braces are escaped with `{{` and `}}`
+}