This is weird, I tested this on MSVC8 at /W4 and it compiled without any warnings or errors:
The MinGW port of g++ 3.4.5 reports a warning with -W.Code:#include <iostream>
#include <vector>
int main()
{
std::vector<int> numbers(10);
std::cout << (-1 < numbers.size() ? "yes" : "no") << std::endl;
}