[clang] [Clang] Fix various bugs in alias CTAD transform (PR #132061)

[Younan Zhang via cfe-commits]

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@@ -1348,6 +1348,16 @@ std::optional<TemplateDeductionInfo *> Sema::isSFINAEContext() const {
   return std::nullopt;
 }
 
+static TemplateArgument
+getPackSubstitutedTemplateArgument(Sema &S, TemplateArgument Arg) {
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zyn0217 wrote:

This is pre-existing - do I have to rename that?

https://github.com/llvm/llvm-project/pull/132061