J.11 The Class Attribute of Untagged Incomplete Types

danger

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Static Semantics

1/2

For the first subtype S of a type T declared by an incomplete_type_declaration that is not tagged, the following attribute is defined:

2/2

S'Class

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.

2.a/2

reason

This must occur in the same unit to prevent children from imposing requirements on their ancestor library units for deferred incomplete types.

Wording Changes from Ada 95

2.b/3

This subclause 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.