What does Apple use for source control ???. I know Google is all custom and MS uses (???) a modified instance of Perforce.
Microsoft maintains the entire Windows source tree in Git now and has made some really interesting contributions to git where it comes to very large projects, though I don't know about the penetration throughout other dev groups. They also own Github now obviously.
I was just looking at Microsoft's git VFS (https://github.com/microsoft/VFSForGit), which is deprecated and now points to Scalar (https://github.com/microsoft/scalar), which is also deprecated I think? What's Microsoft's story with git for large repos now? Is there still a virtual file system involved at all?