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

[Donát Nagy via cfe-commits]

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@@ -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;
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NagyDonat wrote:

Why is this `using` required in this context? Is there a name collision with something else?

Note that I'm planning to merge my CheckerFamily PR #139256 very soon and it will refactor this area -- will you be able to rebase your commit to that revision?

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