[clang] Reapply "[Clang] Improve diagnostics for expansion length mismatch" (PR #121044)

[via cfe-commits]

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@@ -38,7 +38,7 @@ class CollectUnexpandedParameterPacksVisitor
   unsigned DepthLimit = (unsigned)-1;
 
 #ifndef NDEBUG
-    bool ContainsIntermediatePacks = false;
+  bool ContainsIntermediatePacks = false;
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cor3ntin wrote:

We gain nothing by hiding that behind NDEBUG; we can afford a boolean on the stack

https://github.com/llvm/llvm-project/pull/121044