Why is a class with multiple public access specifiers standard_layout?

Question

I was just playing around with g++, and I found that

#include <type_traits>

class Foo {
public: int x;
public: char y;
public: double z;
};

static_assert(std::is_standard_layout<Foo>::value, "Foo is not standard layout");

int main() {}

Compiles just fine.

According to this answer, data members across access specifiers may be reordered in memory. So there's no gaurantee that x has to actually be the first member of Foo when actually laid out in memory. The way I've defined Foo, y could actually be the first element right?

I thought standard layout meant that you could more or less understand how the bytes are laid out for the given type. Allowing fields in a standard layout type to be reordered in an arbitrary manner seems counterintuitive to me. Why is this allowed?

Answer 1

All members of your structure have the same access specifier: public. The fact that the keyword appears before every class member is immaterial. This is equivalent to the public access specifier appearing once, before all class members.