[clang] [Clang] support friend declarations with a dependent nested-name-specifier (PR #191268)

[Matheus Izvekov via cfe-commits]

================
@@ -2769,6 +2798,25 @@ bool StructuralEquivalenceContext::CheckCommonEquivalence(Decl *D1, Decl *D2) {
   return true;
 }
 
+bool StructuralEquivalenceContext::IsEquivalent(TemplateParameterList *TPL1,
+                                                TemplateParameterList *TPL2) {
+  if (TPL1 == TPL2)
+    return true;
+
+  if (!TPL1 || !TPL2)
+    return false;
+
+  if (TPL1->size() != TPL2->size())
+    return false;
+
+  for (unsigned I = 0, N = TPL1->size(); I != N; ++I) {
+    if (!IsEquivalent(TPL1->getParam(I), TPL2->getParam(I)))
+      return false;
+  }
+
+  return true;
+}
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mizvekov wrote:

AFAIR there is a requires clause that is part of the template parameter list as well.

https://github.com/llvm/llvm-project/pull/191268