$ cat 12.cpp
int main()
{
	constexpr int i = 0;
	int j = 20;
	if(i)
		if(j % i)
			/* ... */;
}

$ g++ -std=c++11 12.cpp
12.cpp: In function ‘int main()’:
12.cpp:6:10: warning: division by zero [-Wdiv-by-zero]
   if(j % i)
          ^