[cfe-commits] [libcxx] r139933 - in /libcxx/trunk: include/__debug include/iterator src/debug.cpp

[Howard Hinnant]

On Sep 16, 2011, at 4:59 PM, David Blaikie wrote:

> 
> 
>> On Fri, Sep 16, 2011 at 1:48 PM, Howard Hinnant <hhinnant at apple.com> wrote:
>> On Sep 16, 2011, at 4:43 PM, Steven Watanabe wrote:
>> 
>> > AMDG
>> >
>> > On 09/16/2011 12:52 PM, Howard Hinnant wrote:
>> >> Author: hhinnant
>> >> Date: Fri Sep 16 14:52:23 2011
>> >> New Revision: 139933
>> >>
>> >> URL: http://llvm.org/viewvc/llvm-project?rev=139933&view=rev
>> >> Log:
>> >> Doug Gregor pointed out some problems with debug mode enabled in one TU and not another.  This patch helps detect those situations and offers improved error messages to help get debug mode enabled in more TU's when it is absolutely necessary to do so.  Thanks Doug.
>> >>
>> >
>> > Okay, so this handles cases where the container/iterator is
>> > constructed without debug information, and used with it.
>> > What about when a container is constructed with debug
>> > information, and destroyed without it?  Will the dangling
>> > pointer in the database cause any problems other than the
>> > obvious memory leak?
>> 
>> If another container gets constructed at the same address, then there will be a collision in the database.  I could probably put some checks in to detect that situation.  Maybe just silently reuse the database entry in that case.
>> 
> You could potentially flag any outstanding iterators as invalid, though that would presumably require extra state tracking you don't already have (increasing the memory footprint of the database).

Actually that state is in there.  And yes, that could be part of the process of recycling the database entry.

Howard