Re: [Boost-users] Reverse for loop with boost::adaptors::reverse crashes

Subject: Re: [Boost-users] Reverse for loop with boost::adaptors::reverse crashes
From: Filip Konvička (filip.konvicka_at_[hidden])
Date: 2014-11-25 17:40:39

>> Is this related to the issue I reported here?
>> https://svn.boost.org/trac/boost/ticket/10789
>
> Looking more into this issue, I found this bug report from 2 years ago
> that describes what I think is the underlying problem:
> https://svn.boost.org/trac/boost/ticket/7630
>
> Given that the issue (bug?) involves a use case as simple as the one
> described by OP, many people might be bothered by it. Not everyone will
> know to ask on this list. Worse still, some might invest time in
> uselessly reporting the same issue all over again. For these reasons, I
> strongly agree with OP in suggesting that a *big warning sign* should be
> included in the Boost Range 2.0 documentation about this issue:
>
>     "Thou shalt not use boost range adaptors on rvalue containers in
>     C++11 range-based for loops."
>
> If the note is already there, then it is not prominent enough.
>
> Regarding solutions or workarounds, the last post by neilgroves in the
> bug report is from 9 months ago, suggesting he has a solution. Are
> there any updates on that?

Thanks for the links.  As Neil said earlier in this thread, there is 
currently no good solution; I guess we've got to live with that.

To be honest, I still think that the design of the range-based for loop 
is strange.  This problem applies also to other use cases than those 
involving Boost.Range.  I understand why the temporaries get destroyed, 
but is there a rationale for that from the language design perspective? 
  Isn't it more intuitive to let the temporaries live until the loop 
finishes?  Maybe this is a question that I should ask somewhere else.

By the way, does anyone have a link to Eric's proposal?

Thanks,
Filip