[Patch] libstdc++/36338

[Paolo Carlini]

Hi Chris,
> I might be going mad but:
>
>   
>>       while (__last - __first > 1)
>> -       std::pop_heap(__first, _RandomAccessIterator(__last--));
>> +       {
>> +         --__last;
>> +         std::__pop_heap(__first, __last, __last);
>> +       }
>>     }
>>     
> Seeing as the original was a post-increment, shouldn't the --__last come after?
>   
Well, first I think we would see that when running the testsuite ;) 
Second, more seriously, I don't think so: because the original sort_heap 
was passing __last to pop_heap, which, in turn, was passing __last - 1 
to __pop_heap. Eventually, in the sort_heap loop __last was decremented .

In the new version, __last is decremented immediately, because this is 
what __pop_heap wants, and we are done with it, the sort_heap iteration 
is complete in the same way, __last decremented.

I think the two are completely equivalent.

Paolo.