Re: [boost] [serialization] Massive failures in develop?

Subject: Re: [boost] [serialization] Massive failures in develop?
From: Robert Ramey (ramey_at_[hidden])
Date: 2015-10-17 16:15:27

On 10/17/15 11:07 AM, John Maddock wrote:
>
>> a) refinement of codecvt facet lifetime issue.
>>
>
> I think this is the issue, you:
>
> * Create the facet as a data member of the archive.
> * Imbue it in a locale and then install that locale in the iostream.
>
> Now on destruction:
>
> * The archive is destroyed first, this destructs the locale facet
> *that's still in the iostream*.
> * The iostream then calls the destructor on an object that's already
> been destroyed.
>
> Depending on the virtual function / destructor implementation, you may
> or may not see this as an error at runtime.
>
> So I think you need to back up the iostream's locale and restore it in
> the archive destructor if you want to go this way.
>
> Apologies if I've misread your code,

This sound correct  - as far as it goes.

Previously, I used stream_buffer_saver - which is now not in there. 
This saved the current locale when created and restored upon termination 
of the archive.  The motivation was to permit a user to have his ostream 
settings unchanged if the serization i/o was introduced in the middle of 
the stream.

This worked as advertised - accept on some gcc configurations.  I 
tracked the problem (in my mind anyway) to the standard system where by 
one creates a new codecvt facet on the heap and passes it to the 
streambuffer that manages the life time of this object.  I spent a lot 
of time trying to make this work but couldn't get to the bottom of it. 
Thinking about it, I built the facet into the archive class so that the 
lifetime managements issues would be resolved.  In the course of making 
this work, I dropped the streambuffer_saver.  My intention is to put 
that back in now that I think I've got everything else sorted out.

It's sounds simple now - but the original problem I was trying solve 
only appeared when using the utf8_codecvt facet to convert strings with 
russian characters in it.  Somewhere it seems there is a coupling that 
is hard to discern.  But anyway, I think I've got it almost where I want 
it to be.

>
> HTH, John.
>
> Update: I think I have a fix, testing now...

Thanks, I'll take a look at it.

Robert Ramey
>
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