I'm not at all familiar with the Mac, but I had always heard/understood that it used 0x0d as the underlying OS-mumble-nix file system newline delimiter. No? (But that is separate and apart from the code experiments that have been done in this thread, since I suspect the delimiter is always 0x0a for Perl internally.)
Mac has been a BSD / NeXTSTEP Unix variant called Darwin under the hood starting c 2000. I suspect some of its files/dev-UI may still use or default to legacy encoding schemes but so far I have been mercifully spared from needing to know.