Are anonymous structures/unions compatible with their "flattened" form in C17?

The intent of the standard cannot be to make a structure compatible with its flattened form because that would break the language. Consider these structures:

struct s { char x; char y; int z; };
struct s { char x; struct { char y; int z; }; };

In a typical C implementation with four-byte int with four-byte alignment requirement, there would be two bytes of padding in the first structure between y and z, putting z at offset 4. In the second structure, the internal structure needs to have four-byte alignment so that its int can be properly aligned, and it has three bytes of padding between its y and z. Then the outer structure has three bytes of padding between x and the internal structure, putting z at offset 8. Treating these two structures as compatible would not work.