https://issues.dlang.org/show_bug.cgi?id=21075

          Issue ID: 21075
           Summary: Finalize lowering a < b for class and interface
                    objects to .object.__cmp
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: andrei@erdani.com

Currently https://github.com/dlang/dmd/pull/9629 and https://github.com/dlang/druntime/pull/2562 are not finished. This means class objects are compared for ordering using __cmp when part of arrays, and with opCmp when not. Looks like some compiler finesse is needed on the dmd side.

--