Re: C vs Haskell for XML parsing

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: C vs Haskell for XML parsing
Date	2023-09-03 11:44 -0700
Organization	A noiseless patient Spider
Message-ID	<86il8rqeps.fsf@linuxsc.com> (permalink)
References	(16 earlier) <20230828182115.305@kylheku.com> <uckeel$26q6m$1@dont-email.me> <uckumo$29oe0$1@dont-email.me> <875y4xboly.fsf@nosuchdomain.example.com> <8734zv7cgb.fsf@nosuchdomain.example.com>

Show all headers | View raw

Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>
>> David Brown <david.brown@hesbynett.no> writes:
>> [...]
>>
>>> Being able to accept $ in identifiers is a convenient extension.
>>
>> Quibble: $ in identifiers is not an extension as specified in section 4
>> of the standard.  Starting in C99, the set of characters accepted in
>> identifiers is implementation-defined.  (I'm not sure what difference
>> that makes.)
>
> On further thought, there is a significant difference.
>
> An implementation that supports $ in identifiers via an via the
> "other implementation-defined characters" wording in the syntax
> of an identifier can accept foo$bar as an identifier without
> issuing a diagnostic.  If it's an extension as defined in section 4
> (Conformance) of the standard, it can accept foo$bar but it must
> still issue a diagnostic (presumably a non-fatal warning).

I'm not sure that's right.  Section 5.1.1.3 paragraph 1 says

    A conforming implementation shall produce at least one
    diagnostic message (identified in an implementation-defined
    manner) if a preprocessing translation unit or translation
    unit contains a violation of any syntax rule or constraint,
    even if the behavior is also explicitly specified as
    undefined or implementation-defined.

Note the last clause:  "even if the behavior is also explicitly
specified as undefined or implementation-defined."  This clause
suggests that accepting $ as one of the implementation-defined
characters still warrants a diagnostic.

(And as was pointed out, only if the compiler is invoked in what
is purported to be a conforming mode.)

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Re: C vs Haskell for XML parsing Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-09-03 03:55 -0700
  Re: C vs Haskell for XML parsing Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-03 11:44 -0700
    Re: C vs Haskell for XML parsing Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-09-03 16:20 -0700
      Re: C vs Haskell for XML parsing Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-03 16:47 -0700
        Re: C vs Haskell for XML parsing Richard Damon <Richard@Damon-Family.org> - 2023-09-03 17:24 -0700
        Re: C vs Haskell for XML parsing Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-09-03 17:26 -0700

csiph-web