Warning(s):

source_file.cpp:11:10: warning: no previous prototype for function 'make_1' [-Wmissing-prototypes]
Resource make_1() { return Resource(1); }
         ^
source_file.cpp:12:10: warning: no previous prototype for function 'make_2' [-Wmissing-prototypes]
Resource make_2() { throw std::runtime_error("failed"); }
         ^
source_file.cpp:20:6: warning: no previous prototype for function 'process' [-Wmissing-prototypes]
void process(User) {}
     ^
source_file.cpp:25:17: warning: generalized initializer lists are incompatible with C++98 [-Wc++98-compat]
        process({make_1(), make_2()});
                ^
source_file.cpp:28:2: warning: C++98 requires newline at end of file [-Wc++98-compat-pedantic]
}
 ^
5 warnings generated.