This isn't so much a bug in Lua as it is a problem in Windows. You
could work around this by forcing stdout to be binary _setmode... but
that's pretty ugly and platform specific.
My point is, today "-o -" is not usable on win32. That the questionable design decision was taken by MS and not Lua is true but irrelevant: the option should either be usable on win32, or disabled for that platform.