What is the size of an empty struct in C?

Question

According to me, it is zero but there seems to be bit confusion here

I have tested it with gcc compiler and it gives me zero as output. I know that in C++, size of an

Answer 1

In C99: "If the struct-declaration-list contains no named members, the behavior is undefined."

The syntax doesn't really allow it anyway, though I don't see anything that says a diagnostic is required, which puts it pretty much back in the "undefined behavior" camp.