[clang] [clang-repl] Keep earlier declarations alive when an input fails (PR #218149)

[Vassil Vassilev via cfe-commits]

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@@ -25,7 +25,11 @@ class ASTConsumer;
 class CompilerInstance;
 class Parser;
 class Sema;
+class ASTContext;
+class CXXRecordDecl;
+class NamedDecl;
 class TranslationUnitDecl;
+template <typename decl_type> class Redeclarable;
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vgvassilev wrote:

Why do we need these new forward declarations in the header file?

https://github.com/llvm/llvm-project/pull/218149