[clang] [Clang] Do not consider a variadic function ellipsis part of a default arg (PR #153496)

[Mariya Podchishchaeva via cfe-commits]

================
@@ -6,3 +6,15 @@ void f(...) {
 }
 
 void h(int n..., int m); // expected-error {{expected ')'}} expected-note {{to match}}
+
+
+namespace GH153445 {
+void f(int = {}...);
+
+struct S {
+  void f(int = {}...);
+  void g(int...);
+};
+
+void S::g(int = {}...) {}
----------------
Fznamznon wrote:

Does something like this
```
template <typename ...T>
constexpr int a() {return 1;}

struct S {
  template <typename ...Ts>
  void f(int = a<Ts...>()...);   
};
```
work too?

https://github.com/llvm/llvm-project/pull/153496