[clang] Reland [Clang] skip default argument instantiation for non-defining friend declarations to meet [dcl.fct.default] p4 (PR #115487)

[Oleksandr T. via cfe-commits]

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@@ -12,6 +12,31 @@ void g() {
 }
 }
 
+namespace GH113324 {
+struct S1 {
+  friend void f1(S1, int = 42) {}
+};
+
+template <bool, class> using __enable_if_t = int;
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a-tarasyuk wrote:

@zyn0217 I've removed unnecessary tests. thanks

https://github.com/llvm/llvm-project/pull/115487