add cout args

single_file_tests/hello_main.cc

@@ -3,5 +3,8 @@
 // compile: c++ --std=c++17 hello_main.cc
 auto main(int argc, char** argv) -> int {
   std::cout << "hello, have: " << argc << " args" << std::endl;
+  for (int i = 0; i < argc; i++) {
+    std::cout << " - " << argv[i] << std::endl;
+  }
 }