https://issues.dlang.org/show_bug.cgi?id=21430

          Issue ID: 21430
           Summary: Add `const` to front, save, & length properties of
                    range returned by std.bitmanip.bitsSet
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: n8sh.secondary@hotmail.com

--