!standard 4.1.5(5.1/4)                                    16-10-06  AI12-0203-1/01
!standard 4.1.5(7/3)
!class presentation 16-10-06
!status work item 16-10-06
!status received 16-09-08
!priority Low
!difficulty Easy
!qualifier Clarification
!subject Overriding a nonoverriddable aspect
!summary

Clarify 4.1.5(7/3).

!question

4.1.5(5.1/4) says:

   The Implicit_Dereference aspect is nonoverridable (see 13.1.1).

while 4.1.5(7/3) starts:

   Given a reference type T, the Implicit_Dereference aspect is
   inherited by descendants of type T if not overridden. 

Since the aspect can't be overridden, why the if not overridden above?

!recommendation

A nonoverridable aspect can have a confirming aspect value specified,
and that is the case that have to be covered by the 4.1.5(7/3) sentence.
A clarification is suggested.

(See Summary.)

!wording

Modify 4.1.5(7/3):

   Given a reference type T, the Implicit_Dereference aspect is inherited
   by descendants of type T if not overridden{ (which is only permitted if
   confirming)}. If a descendant type constrains the value of the reference
   discriminant of T by a new discriminant, that new discriminant is the
   reference discriminant of the descendant. Redundant[If the descendant type
   constrains the value of the reference discriminant of T by an expression
   other than the name of a new discriminant, a generalized_reference that
   identifies an object of the descendant type denotes the object or
   subprogram designated by the value of this constraining expression.]

!discussion

(See !recommendation.)

!ASIS

No ASIS effect.

!ACATS test

No ACATS test needed.

!appendix

The original issue was raised privately by Steve Baird; another AdaCore
person independently raised the issue a few days later. The wording was
suggested by Tucker Taft.

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