[clang] [clang-tools-extra] [Clang] Add a builtin that deduplicate types into a pack (PR #106730)

[Ilya Biryukov via cfe-commits]

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@@ -7004,7 +7058,7 @@ class SubstTemplateTypeParmType final
 /// that pack expansion (e.g., when all template parameters have corresponding
 /// arguments), this type will be replaced with the \c SubstTemplateTypeParmType
 /// at the current pack substitution index.
-class SubstTemplateTypeParmPackType : public Type, public llvm::FoldingSetNode {
+class SubstTemplateTypeParmPackType : public SubstPackType {
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ilya-biryukov wrote:

Definitely need to remove it, thanks for mentioning this.
I'll send a commit to remove it.

https://github.com/llvm/llvm-project/pull/106730