Subject: Re: [boost] Bug with gcc and array
From: Andreas Klein (klein_at_[hidden])
Date: 2008-11-25 05:45:47
Hello
>
> There is no bug. boost::array does no dynamic memory allocation, so
> you are creating a circa 30 MB array on the stack. This is enough to
> blow the stack size limit on most OSs.
>
>> In contrast a C-array works fine.
>>
>> Since the naturale implementation of the array class is just a wrapper
>> around the C-style array this is very strange.
>
> Sheer luck probably. You have gone beyond an implementation defined
> limit and it is UB. In fact using a C -style array might (or not) have
> blown the stack in the same way.
I guess not. I submitt a minimal example. I found the problem in a big
complicated computaion. With the C array it works fine no crash and gives
the expected result.
> It is not a bug of gcc (although a warning would have been
> appreciated), just a manifestation of UB. It might be that the intel
> compiler sets the stack size limit higher, it disables stack overflow
> checking or simply you are just being lucky (or unlucky, depends on
> how you see it) and UB is not showing up as an hard crash.
>
> Morale: do not stack allocate huge objects.
Do have a reference for me were to find the implementation limits?
Would it a good idea to add a static assert to boost::array that ensures
that the array size is small enough? I think a error message at compile
time is more help full than Segmentation fault at run time.
Best wishes
Andreas Klein