can't tell if compiler bug or undefined behavior

horror.cpp

DynArray<TypeMember> clone(const DynArray<TypeMember> &memberset)
{
    DynArray<TypeMember> result = dynarray_init<TypeMember>(memberset.count);

    for (u32 i = 0; i < memberset.count; ++i)
    {

        TypeMember *dest_member = append(&result);
        ZERO_PTR(dest_member);
        NameRef newname = src_member->name;
        
        printf_ln("[%i] 2 Members count... %i, srcdata address %px  destdata address %px memberset address %px"
                  "\n    dest_member == memberset ? %i",
                  i, memberset.count, memberset.data, result.data, &memberset,
                  (char *)dest_member == (char *)&memberset);
                  
        dest_member->name = newname;
        
        printf_ln("[%i] 3 Members count... %i, srcdata address %px  destdata address %px memberset address %px"
                  "\n    dest_member == memberset ? %i"
                  "\n--------------",
                  i, memberset.count, memberset.data, result.data, &memberset,
                  (char *)dest_member == (char *)&memberset);
    }

    return result;
}