Public Comment Number PC-UK0086

ISO/IEC CD 9899 (SC22N2620) Public Comment

=========================================== 

Date: 1998-02-25
Author: N.M Maclaren
Author Affiliation: Self
Postal Address:
    University of Cambridge,
    Computer Laboratory,
    New Museums Site,
    Pembroke Street,
    Cambridge CB3 3QG,
    United Kingdom
E-mail Address: <nmm1@cam.ac.uk>
Telephone Number: +44 1223 334761
Fax Number:       +44 1223 334679
Number of individual comments: 1


Comment 1. 

Category: Request for information/clarification

Committee Draft subsection: 6.8.1

Title: Invalid but skipped pre-processor directives


Detailed description:

Programs of the following form currently cause serious arguments, and I 
cannot see that the ambiguity has been resolved:

    #if 0 == 1
    #axolotl
    #endif

Is this permitted or is it not?  I.e. is the undefined pre-processing
directive "#axolotl" an error?  Most compilers assume that it should be
quietly ignored, but a few reject the above program fragment.  Assuming 
that it should be ignored, I suggest a footnote in 6.8.1 Conditional
inclusion after "the other preprocessing tokens in the group." along the
lines of:

    124a Thus unrecognised preprocessing directives in a group that is
    skipped are ignored and do not cause an error.

Alternatively, if it should be an error, there should be some rewording to
indicate that.