// If the super-classes method is override-able by a default method we need to keep
// track of it since though it is override-able it is not guaranteed to be 'overridden'.
// If it turns out not to be overridden and we did not keep track of it we might add it
- // to the vtable twice, causing corruption in this class and possibly any subclasses.
+ // to the vtable twice, causing corruption (vtable entries having inconsistent and
+ // illegal states, incorrect vtable size, and incorrect or inconsistent iftable entries)
+ // in this class and any subclasses.
DCHECK(vtable_impl == nullptr || vtable_impl == supers_method)
<< "vtable_impl was " << PrettyMethod(vtable_impl) << " and not 'nullptr' or "
<< PrettyMethod(supers_method) << " as expected. IFTable appears to be corrupt!";