[clang] [lldb] [llvm] [llvm][TargetParser] Return optional from getHostCPUFeatures (PR #97824)

[Alex Langford via llvm-commits]

https://github.com/bulbazord commented:

>From an API standpoint, there doesn't actually seem to be a huge difference between an empty StringMap and an optional with an empty string map in it right? Why not return a map every time?

https://github.com/llvm/llvm-project/pull/97824