Anonymous 'stringstream' sample (compiles, but only for some compilers)

anonymous-stringstream.cpp

// try this in compiler explorer with
//    -std=c++11 -Wall -Wextra
// works for some compilers but not for others (add list here)
// (Oct, 2019)

#include <iostream>
#include <sstream>
#include <string>

int main()
{
   using namespace std;
   cout << ((stringstream() << "hola").str()) << endl ;
}

makefile

.PHONY: x

x: a.out
	./a.out

a.out: a.cpp
	g++ -std=c++11 -Wall -Wextra a.cpp