[clang] [Sema] Preserve ContainsUnexpandedParameterPack in TransformLambdaExpr (PR #86265)

[via cfe-commits]

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@@ -14037,6 +14037,15 @@ class Sema final : public SemaBase {
       TemplateArgument Arg,
       SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
+  /// Collect the set of unexpanded parameter packs within the given
+  /// template argument.
+  ///
+  /// \param Arg The template argument that will be traversed to find
+  /// unexpanded parameter packs.
+  void collectUnexpandedParameterPacksForFoldExprs(
+      Expr *E, SmallVectorImpl<UnexpandedParameterPack> &Unexpanded,
+      SmallVectorImpl<UnexpandedParameterPack> &UnexpandedFromConstraints);
+
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cor3ntin wrote:

The comment is wrong, and i don't understand why we need `collectUnexpandedParameterPacks` specifically for fold expressions. - We already should handle fold expressions correctly

https://github.com/llvm/llvm-project/pull/86265