Add a test case for deduction without separator

Author: spaits

clang/test/SemaTemplate/deduction.cpp

@@ -447,12 +447,18 @@ namespace deduction_after_explicit_pack {
   void call_bar() {
     bar(args_tag<int, int>{}, 4, 8, 1001, 16, 23);
   }
+
   template <typename... Y, typename... T>
   void foo(args_tag<Y...>, args_tag<T...>, type_identity_t<T>..., int mid, type_identity_t<T>...) {}
   void call_foo() {
     foo(args_tag<const int,const int, const int>{}, args_tag<int, int, int>{}, 4, 8, 9, 15, 16, 23, 1);
   }
 
+  template <typename... Y, typename... T> void baz(args_tag<T...>, T..., T...) {}
+  void call_baz() {
+    baz(args_tag<int, int>{}, 1, 2, 3, 4);
+  }
+
   // GCC alarmingly accepts this by deducing T={int} by matching the second
   // parameter against the first argument, then passing the first argument
   // through the first parameter.