c++assertalignas

assert that struct type is declared with alignas()

As the title states, I need some way to assert that a type has been declared with alignas as such:

struct alignas(16) MyStruct {
    ...
};

It is meant to be used for a template parameter where the template class needs to make sure that the type it is templated on is 16 byte aligned.

Solution

  • There is alignof that you can use to make sure the type you get is aligned to the correct size. You would use it in your function like

    template <typename T>
void foo(const T& bar)
{
    static_assert(alignof(T) == 16, "T must have an alignment of 16");
    // rest of function
}

    If using this in a class you'd have

    template <typename T>
class foo
{
    static_assert(alignof(T) == 16, "T must have an alignment of 16");
    // rest of class
};