fix warning

Author: el-ev

clang/test/Analysis/builtin_assume.cpp

@@ -65,9 +65,11 @@ int using_builtin_assume_has_no_sideeffects(int y) {
 
 template <int ...args>
 bool issue151529() {
-  [[assume((true))]]; // no-crash
-  [[assume(((args >= 0) && ...))]]; // no-crash
-  return ((args >= 0) && ...);
+  // no-crash
+  [[assume((true))]]; 
+  // no-crash
+  [[assume(((args >= 0) && ...))]];  // expected-warning {{pack fold expression is a C++17 extension}}
+  return ((args >= 0) && ...); // expected-warning {{pack fold expression is a C++17 extension}}
 }
 
 void instantiate_issue151529() {