-- intermediate only
        -- NB: as things stand, phaseInputExt (Hsc x) must not evaluate x
        --     because runPipeline uses the StopBefore phase to pick the
        --     output filename.  That could be fixed, but watch out.
phaseInputExt HCc                 = "hc"
phaseInputExt HCc                 = "hc"
phaseInputExt HCc                 = "hc"