https://issues.dlang.org/show_bug.cgi?id=19266
--- Comment #3 from github-bugzi...@puremagic.com --- Commit pushed to master at https://github.com/dlang/dmd https://github.com/dlang/dmd/commit/ac9272cd42a3a2c10639217abf98b166f9b12baf fix issue 19266 - Some source files names are no longer accepted only add the \\?\ prefix if the filename is actually long and does not start with \\ already. --