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Re: www.gnu.org/software/gcc/bugs/#nonbugs_c (with ++ / --)
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: Fabian Cenedese <Cenedese at indel dot ch>
- Cc: gcc-help <gcc-help at gcc dot gnu dot org>
- Date: Fri, 4 Jul 2014 09:14:10 +0100
- Subject: Re: www.gnu.org/software/gcc/bugs/#nonbugs_c (with ++ / --)
- Authentication-results: sourceware.org; auth=none
- References: <201407031041 dot 56843 at ----Apocryphe----> <CAH6eHdSv6PmfM7BMfDMeZRPa6qWQALBV1=fZv=4EN4Fh9va02A at mail dot gmail dot com> <20140704073257 dot 5A6FA1E8DD6E at macserver dot private>
On 4 July 2014 08:33, Fabian Cenedese wrote:
>
>>> Nothing defined
>>> implementation of the passage of a function settings. But it turns out that
>>> in the case of gcc, they are pushed onto the stack from right to left.
>>
>>I think it depends on the hardware architecture.
>>
>>> As it
>>> has been since the dawn of time in Savannah, it is definitely impossible to
>>> change this state of affairs in gnou. Thus be it!
>>>
>>> So my question is: reverse the order of parameters (shock me, but) make
>>> functional! What about you? Portability?
>>
>>I don't understand the question.
>
> He probably means that if he reverses the argument order (like a+=1, b, a) then
> he'd get the desired result. But as you mentioned it probably depends on the
> hardware and compiler so it is not portable.
>
> I'd say this is undefined behaviour and could be solved like
> c=a;
> foo(c, b, a+=1); // order of evaluation not important
Agreed, that is a safe and portable way to do it.