Denotes the first subtype of the incomplete class-wide type rooted at
T. The completion of T shall declare a tagged type. Such
an attribute reference shall occur in the same library unit as the incomplete_type_declaration.
Reason: {AI95-00326-01}
This must occur in the same unit to prevent children from imposing requirements
on their ancestor library units for deferred incomplete types.
{AI95-00326-01}
This clause is new. This feature was moved here because the tagged incomplete
type provides a better way to provide this capability (it doesn't put
requirements on the completion based on uses that could be anywhere).
Pity we didn't think of it in 1994.
Sponsored by Ada-Europe