[clang] [clang] Adds a RecursiveASTEnterExitVisitor data type (PR #136136)

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Sirraide wrote:

Moreover, this functionality is already available for `Stmt`s in `(Dynamic)RecursiveASTVisitor` in the form of `dataTraverseStmtPre()`/`dataTraverseStmtPost()`.

https://github.com/llvm/llvm-project/pull/136136