[clang] [clang] Implement provisional wording for CWG2398 regarding packs (PR #90820)

[via cfe-commits]

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@@ -2583,8 +2584,11 @@ DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
         return TemplateDeductionResult::MiscellaneousDeductionFailure;
 
       // Perform deduction for this Pi/Ai pair.
-      if (auto Result = DeduceTemplateArguments(S, TemplateParams, P,
-                                                As[ArgIdx], Info, Deduced);
+      TemplateArgument Pi = P, Ai = As[ArgIdx];
+      if (Swapped)
+        std::swap(Pi, Ai);
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cor3ntin wrote:

We might want a comment here too

https://github.com/llvm/llvm-project/pull/90820