[clang] [Clang] Correctly construct template arguments for file-scope template template parameters (PR #76811)

[Shafik Yaghmour via cfe-commits]

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@@ -345,15 +345,19 @@ MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs(
 
   using namespace TemplateInstArgsHelpers;
   const Decl *CurDecl = ND;
+
+  if (!ND)
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shafik wrote:

Can we also get a comment here why this makes sense to call `Decl::castFromDeclContext(DC)` if `CurrDecl` is not present?

https://github.com/llvm/llvm-project/pull/76811