Path: csiph.com!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Tim Rentsch Newsgroups: comp.lang.c Subject: Re: Top 10 most common hard skills listed on resumes... Date: Sat, 31 Aug 2024 15:10:07 -0700 Organization: A noiseless patient Spider Lines: 51 Message-ID: <86seuktkcg.fsf@linuxsc.com> References: <874j75zftu.fsf@bsb.me.uk> <87mskwy9t1.fsf@bsb.me.uk> <875xrkxlgo.fsf@bsb.me.uk> <87o75bwlp8.fsf@bsb.me.uk> <871q27weeh.fsf@bsb.me.uk> <20240829083200.195@kylheku.com> <87v7zjuyd8.fsf@bsb.me.uk> <20240829084851.962@kylheku.com> <87mskvuxe9.fsf@bsb.me.uk> <875xrivrg0.fsf@bsb.me.uk> <20240829191404.887@kylheku.com> <86cylqw2f8.fsf@linuxsc.com> <871q2568vl.fsf@nosuchdomain.example.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Date: Sun, 01 Sep 2024 00:10:07 +0200 (CEST) Injection-Info: dont-email.me; posting-host="1ccc4d5fef9c2c82c9c978d9286151e6"; logging-data="1240558"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19I7476rlyunOr9xmTsMGEVCB79I3Rlxmc=" User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.4 (gnu/linux) Cancel-Lock: sha1:ynVyIKRtDtEiNdf6hx4p2AIJkl8= sha1:4lPCx8fus5KuIrT8+au9MU1iNEY= Xref: csiph.com comp.lang.c:388059 Bart writes: > On 30/08/2024 21:41, Keith Thompson wrote: > >> Tim Rentsch writes: >> >>> Kaz Kylheku <643-408-1753@kylheku.com> writes: >>> >>>> On 2024-08-29, Ben Bacarisse wrote: >>>> >>>>> Bart writes: >>>>> >>>>>> I think that these (with x, y having compatible scalar types): >>>>>> >>>>>> x + 1 = y; >>>>>> (x + 1) = y; // in case above was parsed differently >>>>>> >>>>>> are both valid syntax in C. It will fail for a different reason: >>>>>> an '+' term is not a valid lvalue. >>>>> >>>>> The compiler must tell you that neither is valid C. That's >>>>> because what is required on each side of assignment is not >>>>> exactly the same thing. It's a distraction to argue about why >>>>> each is not valid C as both have errors that require diagnostic >>>>> at compile time. >>>> >>>> Bart is only saying that it's valid syntax, not that it's valid C. >>>> >>>> According to the ISO C syntax (not taking into account contraints, >>>> which are not syntax) that view is justified. >>> >>> The second line is syntactically well-formed. The first line is >>> not. >> >> Right, because the LHS of an assignment is a unary-expression. >> `(x + 1)` can be parsed as a unary-expression, but `x + 1` cannot. > > AFAICT both terms are parsed the same way. > > Given this: > > x + y = z; > (x + y) = z; > > My compiler produces the same AST for the LHS of '=' in both > cases. To understand why they are different, try drawing parse trees rather than abstract syntax trees. https://en.wikipedia.org/wiki/Parse_tree