Pure functions in C++11

Can one in C++11 somehow in gcc mark a function (not a class method) as const telling that it is pure and does not use the global memory but only its arguments?

I've tried gcc's __attribute__((const)) and it is precisely what I want. But it does not produce any compile time error when the global memory is touched in the function.

Edit 1

Please be careful. I mean pure functions. Not constant functions. GCC's attribute is a little bit confusing. Pure functions only use their arguments.