[clang] [Clang] Reapply CWG2369 "Ordering between constraints and substitution" (PR #122423)

[via cfe-commits]

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@@ -13372,6 +13376,17 @@ class Sema final : public SemaBase {
       bool SkipForSpecialization = false,
       bool ForDefaultArgumentSubstitution = false);
 
+  /// Apart from storing the result to \p Result, this behaves the same as
+  /// another overload.
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cor3ntin wrote:

It would be cleaner to put the documentation on this overload, declare it first, and then say that the other overload creates a new MultiLevelTemplateArgumentList and call getTemplateInstantiationArgs with it as the first param) 

https://github.com/llvm/llvm-project/pull/122423