This patchset is removing non-DWARF code from `DWARFUnit` as discussed with @labath.
@labath, maybe this is the only patch you did mean? But without the next/further patches D70647 it isn't really useful for DWZ as it still expects `DWARFDIE` itself can reach `DW_AT_language` - which it cannot as it does not contain `DWARFUnit *main_cu`.
I do not plan to check it in yet. I plan to finish it for use by DWZ patchset first (D40474 et al.). Asking whether this is a good way forward.