[llvm] [ADT] Deprecate the redirection from SmallSet to SmallPtrSet (Take 2) (PR #155078)

[via llvm-commits]

ronlieb wrote:

after this PR, i am seeing ~1800+ messages of the form
llvm/include/llvm/ADT/SmallSet.h:280:43: warning: ‘template<class PointerType, unsigned int N> class llvm::DeprecatedSmallSet’ is deprecated: Use SmallPtrSet instead [-Wdeprecated-declarations]

was this expected ?

https://github.com/llvm/llvm-project/pull/155078