For all path_traits convert() and dispatch() functions provide two overloads, one with a "const codecvt_type&" argument, and one without. The overload without a codecvt argument calls path::codecvt() iff a conversion actually needs to be performed. Change all uses of path_traits convert() and dispatch() functions call the appropriate overload, rather than calling with path::codecvt() as a default. This limits the impact of locale("") initialization failures on Linux and other non-BSD POSIX systems to programs that actually depend on locale(""). It further ensures that exceptions thrown as a result of such failures occur after main() has started, and so can be caught.