To: J3                                                     J3/25-198
From: Malcolm Cohen
Subject: US14 Scoped enumerator access, edits
Date: 2025-October-24
Reference: 23-197, 25-180, 25-007r1.


1. Introduction

This paper contains the edits for US14
    "Provide scoped access to enumeration enumerators".
The formal requirements, specifications, and syntax, are in 25-180.


2. Edits to 25-007r1

[xv] Introduction, Data declaration bullet, insert sentences
   "The accessibility of an enum-type-name can be specified in its
    enum-def-stmt.
    The accessibility of an enumerator in an enum-def or
    enumeration-type-def can be specified in its enumerator-def-stmt or
    enumeration-enumerator-stmt, respectively.".

[xv] Introduction, Data usage and computation bullet, insert sentence
   "The value of an enumerator of an enum type or an enumeration type can
    be accessed via the name of the type, as if it were a component.".

[102:16] 7.6.1 Interoperable enumerations and enum types,
         In R760 enum-def-stmt, insert new productions
           "or ENUM, BIND(C), access-spec :: enum-type-name
            or ENUM, access-spec, BIND(C) :: enum-type-name".
{We could do a more complicated and more general-looking BNF, but that
 would just be more work. This is simple and effective.}

[102:17] Same subclause,
  Change
   "R761 enumerator-def-stmt is ENUMERATOR [ :: ] enumerator-list"
  to
   "R761 enumerator-def-stmt is ENUMERATOR [ [ , access-spec ] :: ]
                                enumerator-list".

[102:29] Same subclause, p2, append new sentence:
   "The accessibility of an enumerator name is determined as specified in
    \ref{D5:Accessibility attribute}.".
{That is "in 8.5.2" presently.}

[102:30] Same subclause, p3, after "that name." insert new sentence:
   "The accessibility of an enum type name is determined as specified in
    \ref{D5:Accessibility attribute}.".

[104:1-lots] Same subclause, NOTE 6,
             After the definition of type myenum, insert
                "Public :: myenum, one, two, three"
             In the definition of type flags,
             insert ",Public" after "Bind(C)",
             and insert ",Public" after "Enumerator".
{Show both ways of specifying accessibility.}

Note: this makes the specification part of enum_mod look like

    "Enum,Bind(C) :: myenum
       Enumerator :: one=1, two, three
     End Enum
     Public myenum, one, two, three
     Enum,Bind(C).Public :: flags
       Enumerator,Public :: f1 = 1, f2 = 2, f3 = 4
     End Enum"

[105:3] 7.6.2 Enumeration types,
change
   "R769 enumeration-enumerator-stmt is ENUMERATOR [ :: ]
                                        enumerator-name-list"
to
   "R769 enumeration-enumerator-stmt is ENUMERATOR [ [ , access-spec ] :: ]
                                        enumerator-name-list".

[105:7-9] Same subclause, p2, replace entire paragraph
   "The access-spec on an ENUMERATION TYPE statement specifies the
    accessibility of the enumeration-type-name and the default
    accessibility of its enumerators. The accessibility of an enumerator
    may be confirmed or overridden by an access-stmt."
with
   "The accessibility of an enumeration type name and its enumerator names
    is determined as specified in \ref{D5:Accessibility attribute}.".
{Replace redundant specification with reference.}

[113:18] 8.5.2 Accessibility attribute, p2,
         After "derived type name." insert new statements:
   "An access-spec in an enum-def-stmt specifies the accessibility of the
    enum type name.
    An access-spec in an enumerator-def-stmt or enumeration-enumerator-stmt
    specifies the accessibility of the enumerators defined by that
    statement.".

[146:7+] 9.1 Designator, R901 designator,
         insert new production alphabetically,
            "or scoped-enumerator-value".
{I chose "scoped-" because that is what we've been calling it, but some
 other, perhaps more descriptive, prefix could be used. For example,
 "qualified-" would work as the enumerator name is being "qualified" by
 the enum or enumeration type name. Note that both enumeration types and
 enum types have "enumerators", so we only need one production to cover
 both. Unless, of course, we *want* to draw a distinction.}

[150:9-] 9.4 Scalars, just before 9.5 Arrays, insert new subclause
   "9.4.6 Scoped enumerator values

    R916a scoped-enumerator-value is type-name % enumerator-name

    C923a The type-name in a scoped-enumerator-value shall be the name of
          an enum type or an enumeration type.

    C923b The enumerator-name shall be the name of one of the enumerators
          defined in the type's enum-def or enumeration-def.

    A scoped-enumerator-value has the type, type parameters, and value of
    the enumerator. The enumerator name need not be accessible in the
    scoping unit.

    NOTE
    For example, given the module

        Module traffic_signal_m
            Enumeration Type, Public :: traffic_signal
                Enumerator, Private :: off, green, amber, red
            End Enumeration Type
        End Module

    then with

        Use traffic_signal_m, signal => traffic_signal
        Type(signal) light

    enumeration values can be accessed and assigned as follows:

        light = signal%amber".

===END===