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Subject: Re: [Boost-cmake] placement_new test failure under VC++8
From: Mike Jackson (mike.jackson_at_[hidden])
Date: 2009-05-17 18:08:16

On Sat, May 16, 2009 at 7:25 PM, David Wolfe <dwolfe_at_[hidden]> wrote:
>> Debug Error!
>>  File
>>  c:\projects\boost\libs\numeric\ublas\placement_new.cpp
>>  Line: 63
>>  Run-Time Check Failure #2 - Stack around the variable 'a' was
>>  corrupted.
> On 5/16/2009 7:59 AM, Mike Jackson wrote:
>> So I am going to assume that there is an actual bug in the code. Is it
>> possible to debug the program with a debugger and get the line of code
>> that VS is bombing on?
> It's definitely the creation of the 1-element UDT array at the same
> address as the scalar instance that's causing the runtime check to
> trigger:
>    udt a;
>    udt* ap = &a;
>    // Capture placement new offsets for a udt
>    new (ap) udt;
>    int new_offset = int (udt::base_pointer - ap);
>    new (ap) udt [1];
>    int array_new_offset = int (udt::base_pointer - ap);
> If I comment out the line that reads 'new (ap) udt[1]', the assertion
> doesn't trigger.

I don't know the udt api but if you really are creating a 1 element
array then trying to access element at index=1 is an error. Trying to
access element at index=0 would be valid. So commenting out the line
obviously gets rid of the error.

I don't know what the intent of the test is but if you replace the [1]
with [0] and try does it succeed?

Try contacting the author of the test/code or ask on the normal boost
mailing list.

Mike Jackson

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