Re: [Boost-users] [Boost.Array] gcc 4.1.2 vs. boost alignment

From: Douglas Gregor (doug.gregor_at_[hidden])
Date: 2006-12-18 19:04:38

On Dec 18, 2006, at 5:03 PM, Robert Mecklenburg wrote:

> I've just upgraded my compiler to gcc 4.1.2 and tried the latest
> implementation of tr1 included with gcc.  I've discovered the gcc
> array implementation is not what I expect:
> [snip code]
> That is, the boost array is exactly the size I require 6 bytes, but
> the tr1 array is larger, 16 bytes.  I believe this is due to the
> following declaration in 4.1.2/tr1/array:
>
>       // Support for zero-sized arrays mandatory.
>       value_type _M_instance[_Nm ? _Nm : 1] __attribute__ 
> ((__aligned__));
>
> The boost version is not aligned, but the gcc version is.  Does the
> tr1 implementation require the alignment?  If so, it appears that
> tr1::array is definitely not a suitable wrapper for C-style arrays
> since they aren't the same size!

Ick. I would report this to GCC as a bug.

   Cheers,
   Doug