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From Alan Conway <acon...@redhat.com>
Subject Re: qpid (cpp) on solaris + Sun Studio 12
Date Tue, 27 May 2008 19:15:32 GMT
Manuel Teira wrote:
> Some new info about this problem.
> 
> I was not able to exactly reproduce the issue with an stanalone and 
> meaninfull source, but have found a way to pass the compilation (other 
> than commenting everything, of course). The problem, I think, is related 
> with the std::lower_bound invocation, as shown before:
> 
> "/opt/SUNWspro/prod/include/CC/stlport4/stl/_algo.h", line 491:
> Information: Instantiating
> std::__lower_bound<qpid::Range<qpid::framing::SequenceNumber>*,
>                                  qpid::framing::SequenceNumber,
>                                  std::less<qpid::framing::SequenceNumber>,
>                                  long>
> (qpid::Range<qpid::framing::SequenceNumber>*,
> qpid::Range<qpid::framing::SequenceNumber>*,
> const qpid::framing::SequenceNumber&,
> std::less<qpid::framing::SequenceNumber>,
> long*).
> 
> All the pain begins (I think) with the fact that the first template type 
> (the iterator) is not valid to travel through the value type. And this 
> is produced (I guess) by the call, in RangeSet<T>::addRange(const 
> Range<T> &r) :
> 
> typename Ranges::iterator i =
>        std::lower_bound(ranges.begin(), ranges.end(), r.begin());
> 
> That way, we are passing two valid Range<T>::iterator types and a T 
> value. changing that with:
> 
> typename Ranges::iterator i = std::lower_bound(ranges.begin(), 
> ranges.end(), r);
> 
> it passes the compilation with the Sun Studio 12.

Hum. Odd. The point of lower_bound(i,j,x) is to evaluate *i < x.
Range<T> has an operator< for T but not for Range<T> so I don't understand
how solaris is satisfying *i < x. when x is a Range<T>

I tried the same thing myself and the GNU compiler didn't choke either so there 
clearly is some conversion sequence that allows the < comparison but it doesn't 
give the right answer because the RangeSet unit tests fail.

HOWEVER: the simple and obvious step of adding:

     bool operator<(const Range<T>& r) const { return end_ < r.begin_; }

to RangeSet makes the whole thing work beautifully so I bet it'll now build for 
you - comitted in revision 660647

> Perhaps the GNU compiler is able to instantiate a whole Range<T> from 
> the r.begin() argument? However, the Range<T>::Range(const T &t) 
> constructor is declared as explicit. So, I don't think that should be 
> the problem
> 
> As an outline, does it make sense to pass to std::lower_bound iterators 
> not compatible with the value argument?

Hah! No it does not. Turns out that one of the requirements on lower_bound is 
that "ForwardIterator's value type is the same type as LessThanComparable."
I was under the mistaken impression that it was only required for *i < x to be a 
valid expression.

So this whole thing is my goof, thanks for sticking with it.

Cheers,
Alan.

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