[Issue 12747] New: std.regex bug in the parser allows reference to open groups.

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=12747

          Issue ID: 12747
           Summary: std.regex bug in the parser allows reference to open
                    groups.
           Product: D
           Version: unspecified
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Phobos
          Assignee: nobody at puremagic.com
          Reporter: dmitry.olsh at gmail.com

Should cause an exception:

auto re = regex(`^x(\1)`);

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