[clang] [clang] Propagate definition data to all redecls (PR #170090)

[Jonas Hahnfeld via cfe-commits]

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@@ -2107,8 +2107,8 @@ void ASTDeclMerger::MergeDefinitionData(
     auto *Def = DD.Definition;
     DD = std::move(MergeDD);
     DD.Definition = Def;
-    while ((Def = Def->getPreviousDecl()))
-      cast<CXXRecordDecl>(Def)->DefinitionData = ⅅ
+    for (auto *D : Def->redecls())
+      cast<CXXRecordDecl>(D)->DefinitionData = ⅅ
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hahnjo wrote:

Not really, I consider this a fix of the code introduced in #157019 and I would really like to make progress with #133057...

https://github.com/llvm/llvm-project/pull/170090