[clang] [llvm] [Clang-Repl] Introduce Error Recovery for Clang-Repl. (PR #223305)

[Jared Wyles via cfe-commits]

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@@ -54,6 +54,7 @@
 namespace clang {
 
 class ASTContext;
+class DeclStateReverter;
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jaredwy wrote:

Yes. I share this, I would be extending ASTDeclUnmerger instead of duplicating this.

Then instead of the various casts we do to acces protected members, we could extend the access here and use friends if we need to.  

https://github.com/llvm/llvm-project/pull/223305