Make istreambuf_iterator::_M_sbuf immutable and add debug checks

[François Dumont]

Hi

 Â Â Â  Any final decision regarding this patch ?

François


On 23/10/2017 21:08, François Dumont wrote:
> Hi
>
> Â Â Â Â  I completed execution of all tests and found one test impacted by 
> this patch.
>
> Â Â Â Â  It is a good example of the impact of the patch. Users won't be 
> able to build a istreambuf_iterator at a point where the underlying 
> streambuf is at end-of-stream and then put some data in the streambuf 
> and then use the iterator. This is similar to what Petr was proposing, 
> some eof iterator becoming valid again through an operation on the 
> streambuf. I would prefer we forbid it completely or we accept it 
> completely but current middle way situation is strange.
>
> Â Â Â Â  The fix is easy, let the compiler build the streambuf_iterator 
> when needed. Even if patch is not accepted I think we should keep the 
> change on the test which is fragile.
>
> François
>
>
> On 13/10/2017 19:14, François Dumont wrote:
>> Hi
>>
>> Â Â Â Â  Here is the last patch I will propose for istreambuf_iterator. 
>> This is mostly to remove the mutable keyword on _M_sbuf.
>>
>> Â Â Â Â  To do so I had to reset _M_sbuf in valid places that is to say 
>> constructors and increment operators. Despite that we might still 
>> have eof iterators with _M_sbuf not null when you have for instance 
>> several iterator instance but only increment one. It seems fine to me 
>> because even in this case iterator will still be considered as eof 
>> and using several istreambuf_iterator to go through a given streambuf 
>> is not usual.
>>
>> Â Â Â Â  As _M_sbuf is immutable I have been able to restore the simple 
>> call to _M_at_eof() in the increment operators debug check.
>>
>> Ok to commit after successful tests ?
>>
>> François
>>
>>
>>
>
>