[clang-tools-extra] Adding an initial version of the "Initialized Class Members" checker. (PR #65189)

[Piotr Zegar via cfe-commits]

https://github.com/PiotrZSL requested changes to this pull request.

Do not re-implement thigns that are already covered by other check (cppcoreguidelines-pro-type-member-init).
I don't see curently any point for this check.
If there are some small difrences bettwen this check and cppcoreguidelines-pro-type-member-init, then simply implement them as a part of cppcoreguidelines-pro-type-member-init (under configuration option), or even better as completly separate check that only check for what is not covered by cppcoreguidelines-pro-type-member-init.

https://github.com/llvm/llvm-project/pull/65189