llvm-project

866879f8 - [clang] Don't silently inherit the VFS from `FileManager` (#164323)

[clang] Don't silently inherit the VFS from `FileManager` (#164323) Since https://github.com/llvm/llvm-project/pull/158381 the `CompilerInstance` is aware of the VFS and co-owns it. To reduce scope of that PR, the VFS was being inherited from the `FileManager` during `setFileManager()` if it wasn't configured before. However, the implementation of that setter was buggy. This PR fixes the bug, and moves us closer to the long-term goal of `CompilerInstance` requiring the VFS to be configured explicitly and owned by the instance.