https://issues.dlang.org/show_bug.cgi?id=12624
--- Comment #2 from Jonathan M Davis <issues.dl...@jmdavisprog.com> --- Well, this is a finicky one. I'd tried to reduce the failing code to something more manageable in the past and failed, but I thought that I'd take another stab at it, and simply copying the entire std.datetime module to a module separate from Phobos (and changing the module declaration of course) and then doing Rebindable!(immutable TimeZone) _timezone = UTC(); works instead of failing like it does when that line is changed inside of Phobos. It wouldn't surprise me if this problem simply went away when I finally split of std.datetime (which I think that I'm going to take another stab at getting done shortly) simply due to how specific the failure is - which just means that the compiler bug would then be hidden away again rather than anything truly having been fixed (which certainly isn't good), but if it went away like that, at least it wouldn't be blocking improvements to SysTime anymore. --