The Windows situation is more complicated than I realised
# Ignore Windows and Apple
-# This does not work in its current form on Windows or Apple APFS due
-# to their filesystems requiring paths to be valid Unicode.
+# This does not work in its current form on windows, possibly due to
+# gcc bugs or something about valid Windows paths. See issue #29151
+# for more information.
ifndef IS_WINDOWS
+
+# This also does not work on Apple APFS due to the filesystem requiring
+# valid UTF-u paths.
ifneq ($(shell uname),Darwin)
# The zzz it to allow humans to tab complete or glob this thing.