ISO/ IEC JTC1/SC22/WG14 N672

                    Document Number:  WG14 N672/X3J11 97-035

                        C9X Revision Proposal

Title: reorder subclauses 6.1 and 6.2
Author: Clive D.W. Feather
Author Affiliation: Demon Internet Ltd
Postal Address: 322 Regents Park Road, London N3 2QQ, UK
E-mail Address:
Telephone Number: +44 181 371 1138
Fax Number: +44 181 371 1037
Date: 1997-03-03
Sponsor: BSI/WG14
Proposal Category:
   XX Editorial change/non-normative contribution
   XX Correction
   __ New feature
   __ Addition to obsolescent feature list
   __ Addition to Future Directions
   __ Other (please specify)  ______________________________
Area of Standard Affected:
   __ Environment
   XX Language
   __ Preprocessor
   __ Library
      __ Macro/typedef/tag name
      __ Function
      __ Header
   __ Other (please specify)  ______________________________
Prior Art: n/a
Target Audience: all

Related Documents (if any): none

Proposal Attached: Yes

Subclauses 6.1 and 6.2 are badly organised, and the former contains a
number of ambiguities and inconsistencies. This proposal is a general

This proposal was prepared with the assistance of Mark Brader, Jutta
Degener, Ron Guilmette, and a person whose employment conditions require

Subclauses 6.1 and 6.2 are badly organised, and the former contains a
number of ambiguities and inconsistencies. This proposal is a general

The author believes that no strictly-conforming program is affected by this

The following changes have been made.

(1) The important concepts of scope, linkage, namespaces, storage durations,
and types have been separated out from a subclause of a lexical concept to
a major element of their own. To minimize impact on numbering, the text on
conversions (6.2) is merged with this to become the new 6.1. The remainder
of 6.1, which is actually the lexical elements, becomes 6.2.

Alternatively, the conversions material could remain as 6.2 and the
remainder of 6.1 would become 6.3. This would require renumbering the whole
of subclause 6.

The changes aid the reader of the Standard, in particular by reducing the
need for forward references. It does not alter the language defined. See the
basic proposal and the specific changes marked (D), (F), and (G).

(2) The current standard attempts to treat both operators and punctuators
as syntactic elements. This means that several tokens (including the
keyword "sizeof" occur twice. Instead, punctuator is made a syntactic
concept, and operator a semantic one. The effect is to eliminate some
minor syntactic ambiguities (various tokens have multiple derivations) and
make the concepts clearer. It does not alter the language defined. See the
specific changes marked (A) and (F).

(3) The header name changes of TC1 have been further amended for clarity.
It does not alter the language defined. See the specific change marked (B).

(4) Various nugatory constraints are eliminated. Any program which violates
these constraints also violates one or more syntax rules. It does not alter
the language defined. See the specific changes marked (C) and (F).

(5) It is made clear that '\z' is a syntax error for all escape sequences
other than those listed (footnote 32 and the text that refers to it
contradict the syntax). See the specific change marked (E).

Detailed proposal
Restructure subclauses 6.1 and 6.2 according to the following table, and
alter cross-references throughout the Standard accordingly.

  New number   Title                                Old number
  6.1          Concepts                             none
  6.1.1        Scopes of identifiers      
  6.1.2        Linkages of identifiers    
  6.1.3        Name spaces of identifiers 
  6.1.4        Storage durations of objects
  6.1.5        Types                      
  6.1.6        Compatible type and composite type
  6.1.7        Conversions                          6.2      Characters and integers          Signed and unsigned integers      Real floating and integral       Real floating types              Complex types                    Real and complex                 Usual arithmetic conversions      Lvalues and function designators      void                            Pointers                   
  6.2          Lexical elements                     6.1
  6.2.1        Keywords                             6.1.1
  6.2.2        Identifiers                          6.1.2
  6.2.3        Constants                            6.1.3      Floating constants               Integer constants                Enumeration constants            Character constants        
  6.2.4        String literals                      6.1.4
  6.2.5        Punctuators                          none
  6.2.6        Header names                         6.1.7
  6.2.7        Preprocessing numbers                6.1.8
  6.2.8        Comments                             6.1.9

Delete the old subclauses 6.1.5 and 6.1.6; the new subclause 6.2.5 is given
below. Insert and remove forward references as necessary.

Additionally, make the following specific changes.


(A) In subclause 6.2 (formerly 6.1) syntax, remove the alternative
"operator" from both "token" and "preprocessing-token". In the constraints,
remove "an operator,". In the semantics, remove "operators," (twice).

(B) In subclause 6.2 (formerly 6.1) semantic, combine the last two
paragraphs into one, replacing:

    A header name

at the start of the last paragraph, with

  There is one exception to this rule: a header name

(C) In subclause 6.2.2 (formerly 6.1.2), delete the constraints.

(D) In subclause 6.2.2 (formerly 6.1.2) paragraph 4 (the first paragraph of
the semantics), replace:

  that will be described later:


  described in subclause 6.1.1:

(E) In subclause (formerly description, delete the

  If any other escape sequence is encountered, the behaviour is

Delete footnote 32. Add the following text at the end of footnote 31:

  If any other character follows a backslash, the result is not a
  token and a diagnostic is required. See ``future language
  directions'' (6.9.2).

(F) Insert a new subclause 6.2.5 (replacing the old 6.1.5 and 6.1.6):


          punctuator: one of
                  [  ]  (  )  {  }  .  ->
                  ++  --  &  *  +  -  ~  !
                  /  %  <<  >>  <  >  <=  >=  ==  !=  ^  |  &&  ||
                  ?  :  ;  ...
                  =  *=  /=  %=  +=  -=  <<=  >>=  &=  ^=  |=
                  ,  #  ##  <:  :>  <%  %>  %:  %:%:


  A punctuator is a symbol that has independent syntactic
  and semantic significance. Depending on context, it may specify
  an operation to be performed (which in turn may yield a value
  or a designator, or produce a side effect, or some combination)
  in which case it is known as an *operator* (other forms of
  operator also exist in some contexts). An *operand* is an entity
  on which an operator acts.

  In all aspects of the language, these six tokens

          <:  :>  <%  %>  %:  %:%:

  behave, respectively, the same as these six tokens

          [   ]   {   }   #   ##

  except for their spelling.[34]

  [34] Thus [ and <:  behave  differently  when  ``stringized''
  (see subclause, but can otherwise be freely interchanged.

  Forward references:  expressions (6.3), declarations  (6.5),
  preprocessing directives (6.8), statements (6.6).

(G) In subclause 6.3.17, replace the first sentence of the example with:

       As indicated by the syntax, the comma operator (as described in
  this subclause) cannot appear in contexts where a comma is used to
  separate items in a list (such as arguments to functions or lists
  of initializers).

Clive D.W. Feather    | Associate Director  | Director
Tel: +44 181 371 1138 | Demon Internet Ltd. | CityScape Internet Services Ltd.
Fax: +44 181 371 1150 | <>   | <>
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