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Re: C++ Standard Question

On 1/22/2015 3:44 PM, Marc Glisse wrote:
> On Thu, 22 Jan 2015, Joel Sherrill wrote:
>> I think this is a glibc issue but since this method is defined in the C++
>> standards, I thought there were plenty of language lawyers here. :)
> s/glibc/libstdc++/ and they have their own ML.
  Thank you.
>> <strstream>
> That's deprecated, isn't it?
Yes. There is also a warning about that coming from the test code.
I don't know how long it has been deprecated since even with
-std=c++03, the warning is present.
>>   class strstreambuf : public basic_streambuf<char, char_traits<char> >
>>   ISSUE ====> int pcount() const;   <===== ISSUE
>> My reading of the C++03 and draft C++14 says that the int pcount() method
>> in this class is not const. glibc has it const in the glibc shipped with
>> Fedora 20
>> and CentOS 6.
>> This is a simple test case:
>>    #include <strstream>
>>    int main() {
>>        int (std::strstreambuf::*dummy)() = &std::strstreambuf::pcount;
>> /*-- pcount is conformant --*/
>>        return 0;
>>    }
>> What's the consensus?
> The exact signature of member functions is not mandated by the standard, 
> implementations are allowed to make the function const if that works (or 
> provide both a const and a non-const version). Your code is not guaranteed 
> to work. Lambdas usually provide a fine workaround.
This code is actually from the Open Group FACE Conformance Test Suite.
It uses code like this to check the presence of methods from the C Standard
Library, POSIX APIs, and the C++ Standard Library. It would be really
if you could cite the place in the C++ standard so I can provide that as
to the authors of the test suite.

On a positive note, the test suite isn't flagging much using this
technique. This
may be the only method. But I would like to provide the correct feedback to
them so no one else deals with this.


Joel Sherrill, Ph.D.             Director of Research & Development        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985

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