https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118997
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
You don't even need the 'two' member to get the same effect:
typedef struct _test {
_Alignas(long double) void* one;
} _test;
If the structure has to be aligned, then you will get padding after the 'one'
member. This is not a property of the zero-sized array extension, it's just
that a zero-sized array or flexible array member is one of several ways to
force alignment of the entire struct.
