[clang] [analyzer] Introduce the check::BlockEntrance checker callback (PR #140924)

[Donát Nagy via cfe-commits]

================
@@ -548,6 +564,8 @@ class CheckerProgramPointTag : public SimpleProgramPointTag {
 template <typename CHECK1, typename... CHECKs>
 class Checker : public CHECK1, public CHECKs..., public CheckerBase {
 public:
+  using BlockEntrance = clang::BlockEntrance;
----------------
NagyDonat wrote:

> As I was thinking about this now, I think I'd prefer landing this first.
I'd need to backport this into clang-20, and that would make it (marginally) more complicated.

Sorry, I noticed this comment only when I already merged the checker family commit...

https://github.com/llvm/llvm-project/pull/140924