[clang] [llvm] [ImmutableSet] Optimize add/remove operations to avoid redundant tree modifications (PR #159845)

[Gábor Horváth via llvm-commits]

Xazax-hun wrote:

Thanks a lot for the thorough investigation! I am glad this did not introduce any regressions for the static analyzer 

https://github.com/llvm/llvm-project/pull/159845