Date: Fri, 29 Jan 2010 13:45:14 -0500
From: Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: dlclose not calling destructors of static variables.
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On Fri, Jan 29, 2010 at 02:30:48PM +0000, Andrew West wrote:
>On 29/01/2010 13:08, Dave Korn wrote:
>> On 28/01/2010 11:21, Andrew West wrote:
>>>I seem to be having a problem with dlclose not calling the destructors
>>>of statically declared variables.  I've attached a simple test case
>>>which I compile as follows;
>>>
>>Thanks for the report and the STC; this should work.  I'll take a look
>>at it over the weekend or the start of next week if nobody else gets
>>there first.
>>
>Thanks for looking into this, it looks a little more complex than I
>first thought.
>
>I've tried calling __call_exitprocs during dlclose ( after run_dtors
>for the unloading library ) just to see if I was thinking along the
>right lines.  Unfortunately this didn't work as when the destructor is
>registered with atexit it isn't associated with the loaded library but
>with the main executable.
>
>Which brings me on to the bigger problem, the static variables are
>registered with atexit rather than with __cxa_atexit which seems to be
>a violation of the C++ standard (1).
>
>Worse still gcc isn't compiled with cxa_atexit enabled.  So I assume
>the right course of action here is to enable __cxa_atexit in gcc, and
>then make sure __cxa_finalize gets called when the library is unloaded?

I agree with your assessment here.  I've checked in a change which works
around the problem you've uncovered but it is not foolproof.  It should
fix the immediate problem but, in the long run, I agree that gcc should
be emitting code which calls __cxa_atexit.  Of course I have no idea
what the other ramifications of doing that might be.  Hopefully Dave can
enlighten us.

This is in today's snapshot at http://cygwin.com/snapshots/ .

cgf

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