Why is std::is_assignable counter-intuitive?

Question

std::is_assignable::value == false in a conforming implementation (e.g. clang/libc++, gcc/libstdc++, but not VS2012).

Intuitively, this

Answer 1

std::is_assignable::value == false means that "an int literal cannot be assigned to an int literal" (among other things).

Your statement int x = 3 is std::is_assignable::value.

For more info: http://en.cppreference.com/w/cpp/types/is_assignable