Path: csiph.com!news.mixmin.net!eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Tim Rentsch Newsgroups: comp.lang.c Subject: Re: Call to a function Date: Sun, 29 Oct 2023 05:47:14 -0700 Organization: A noiseless patient Spider Lines: 45 Message-ID: <86msw11tpp.fsf@linuxsc.com> References: <20230922081706.858@kylheku.com> <87zg1et4wv.fsf@nosuchdomain.example.com> <86jzs3de3h.fsf@linuxsc.com> <87h6n7tkv4.fsf@nosuchdomain.example.com> <86ttqf2w6p.fsf@linuxsc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: dont-email.me; posting-host="8287b7f320df8d3a443ae94f1f0ba80f"; logging-data="4078521"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18C3/vJ1fDydhwiTNCHdwkF50zUR+WnqYM=" User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.4 (gnu/linux) Cancel-Lock: sha1:7mQmZbnW9k8vUUfg88HJfXAcnEk= sha1:qGpTq28vsV1qNBPh9BGcpuLRjQQ= Xref: csiph.com comp.lang.c:379356 James Kuyper writes: > On 10/24/23 8:54 PM, Tim Rentsch wrote: > >> Keith Thompson writes: >> >>> Tim Rentsch writes: >>> [...] >>> >>>> The point isn't quite the same. The C standard explicitly says >>>> integers may be converted to any pointer type. The C standard >>>> does not say that a pointer to an object type may be converted >>>> to a pointer to function type. Every implementation is within >>>> its rights to reject any program whose static text includes[*] a >>>> cast from a pointer to an object type to a pointer to function >>>> type, regardless of whether the cast has any chance of being >>>> executed. >>>> >>>> [*] meaning, still present as source of any preprocessor >>>> conditionals have been processed, etc. >>> >>> I disagree. (I think we've discussed this before.) >>> >>> Concretely, I believe that this program violates no syntax error >>> or constraint. It includes code whose behavior would be undefined >>> if it were executed, but the `if (0)` prevents that. >>> >>> On what basis do you think a conforming implementation may reject >>> it? >> >> First let me ask a question. Does the C standard allow an >> implementation to reject any program that is not strictly >> conforming? > > [...] > > The standard never talks about rejection. It requires that "A > conforming hosted implementation shall accept any strictly > conforming program.". No such requirement applies to any program > which is not strictly conforming. (4p6) Perhaps I shouldn't have used the word "reject". If the question were phrased "Does the C standard allow an implementation not to accept any program that is not strictly conforming?", does your comment above mean you would say Yes to that question?