https://issues.dlang.org/show_bug.cgi?id=14592
--- Comment #1 from Kenji Hara <[email protected]> --- > I've never come across it, so maybe it's just dead code in DMD. __U is never used for any generated symbols, so it's not necessary to be documented in the spec. But in dmd front-end, it's actually used internally for a *temporary* instance which used on evaluation of template constraint. --
