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

Subject: Re: [Boost-users] Reverse for loop with boost::adaptors::reverse crashes
From: Lee Clagett (forum_at_[hidden])
Date: 2014-11-25 18:19:01

On Tue, Nov 25, 2014 at 5:40 PM, Filip Konvička <filip.konvicka_at_[hidden]>
wrote:

> 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

I think [ http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4128.html
] is the latest proposal.

Lee