J3/13-219

To: J3
From: Van Snyder
Subject: procedure designator as procedure pointer target, etc.
Date: 2013 December 20

Title: procedure designator as procedure pointer target, etc.

Submitted by: Van Snyder

Status: For consideration

Basic functionality: Allow all forms of non-generic procedure designator
as a procedure pointer target, actual argument, or specification of an
explicit interface.

Rationale: In addition to the usual reasons for procedure pointers and
procedure arguments, procedure pointers and procedure arguments
facilitate hoisting the decision which procedure to invoke out of a loop
or procedure.  One form of procedure designator, viz. data-ref%binding,
is not allowed.  This would be useful in general, and especially so if
the procedure pointer object is a component of the type of data-ref.
Other procedure designators are already allowed in the requested
contexts.

Estimated impact: Minor

Markham M6 conformance: Remove simple deficiency, inconsistency and
discrepancy.

Detailed specification: Allow <procedure-designator> as a procedure
pointer target, actual argument, or specification of an explicit
interface in a procedure declaration statement.  If
<procedure-designator> is <data-ref>%binding, <data-ref> shall not be
polymorphic.  The designator shall not be generic.

Draft edits: To estimate scope of project

Simplify R740 to

R740 <proc-target> <<is>> <expr>
                   <<or>> <procedure-designator>

Insert a constraint

C729a (R740) If <procedure-designator> is <data-ref>%<binding>,
      <data-ref> shall not be polymorphic, <binding> shall not be
      generic, and <proc-pointer-object> shall have explicit interface.

Replace R1212 with

R1212 <proc-interface> <<is>> <interface-name>
                       <<or>> <procedure-designator>
                       <<or>> <declaration-type-spec>

Insert constraints:

C1222a (R1212) <procedure-designator> shall designate a procedure that
       has explicit interface.

C1222b (R1212) If <procedure-designator> is <data-ref>%<binding>,
       <data-ref> shall not be polymorphic and <binding> shall not be
       generic.

C1222c (R1212) If <procedure-designator> is the <procedure-name> of a
       procedure declared by a <procedure-declaration-stmt>, it shall be
       accessed by use or host association, or be previously declared
       within the same scoping unit.

Insert a paragraph after 12.4.3.6p3

"If <proc-interface> appears and consists of <procedure-designator>, it
specifies an explicit specific interface (12.4.3.2) for the declared
procedures or procedure pointers."

Simplify R1223 to

R1223 <actual-arg> <<is>> <expr>
                   <<or>> <variable>
                   <<or>> <procedure-designator>
                   <<or>> \obs{<alt-return-spec>}

Insert a constraint

C1235a (R1223) If <procedure-designator> is <data-ref>%<binding>,
      <data-ref> shall not be polymorphic and <binding> shall not be
      generic.