Linux 5.2 released: list of changes

> The case-insensitive file name lookup feature is supported on a per-directory basis, allowing the user to mix case-insensitive and case-sensitive directories in the same filesystem. It is enabled by flipping the +F inode attribute of an empty directory.

That's nicer than how Darwin handles it in that it doesn't force you to use it for the entire file system, although I'd be willing to bet this exposes some interesting bugs in applications, and I wonder if mixing case sensitivity inside a filesystem doesn't make them even more interesting to deal with.