http://bugs.winehq.org/show_bug.cgi?id=58155
--- Comment #6 from ToastyBug cemer99797@isorax.com --- (In reply to Ken Sharp from comment #4)
CoW has been available for years. This seems like a waste of developer time.
In Linux, you can just use duperemove on a BTRFS system (as well as compression). Can't you do that on Apple?
yes CoW on APFS has been available for years, but the app has to implement it correctly by using `cp` with the `-c` flag to take advantage of it.
There are also two paid apps on macOS (Hyperspace, https://hypercritical.co/hyperspace/ & diskDedupe, https://diskdedupe.softwar.io/) which will do this, but most users won't know about them, and you would have to scan your whole drive and wait for the app to compare SHA-256 checksums of every file with the same filesize to determine if it's an identical match, then the app has to delete the duplicate files and replace them with the CoW'ed versions of those files. It's not an elegant solution for something that should just be taken care of by the original app (meaning Wine)
Take a look at the Wikipedia article (https://en.wikipedia.org/wiki/Apple_File_System#Clones):
Clones allow the operating system to make efficient file copies on the same volume without occupying additional storage space. Changes to a cloned file are saved as delta extents, reducing storage space required for document revisions and copies.[10] There is, however, no interface to mark two copies of the same file as clones of the other, or for other types of data deduplication.
The feature is automatically available when you copy any files using the Finder application, which is macOS's default file manager, but not when using the cp command.[16] To do that on the command-line, the cp utility on macOS has a -c parameter that allows it to use the clonefile system call.[17]