Re: [boost] [PATCH] [exception] Replace C cast with reinterpret_cast for Metrowerks C++

Subject: Re: [boost] [PATCH] [exception] Replace C cast with reinterpret_cast for Metrowerks C++
From: Christopher Jefferson (chris_at_[hidden])
Date: 2011-03-05 05:07:42

On 5 Mar 2011, at 09:48, Joshua Juran wrote:

> Metrowerks C++ 2.4.1 thinks the type of (T*)0 is T, rather than T*.  But reinterpret_cast works fine.

That is an incredibly strange bug.

This also introduced a bug. (T*)0 is the expected way to get a null pointer of type T*. A reinterpret_cast is incorrect (although in practice likely to work on most machines / compiles)

Does static_cast work? That would be fine instead of the C-style cast.

Chris

> 
> ---
> 
> This patch doesn't affect the compilation of g++ 4.0.1.
> 
> diff --git boost/exception/exception.hpp boost/exception/exception.hpp
> index fd516dd..87063af 100644
> --- boost/exception/exception.hpp
> +++ boost/exception/exception.hpp
> @@ -334,7 +334,7 @@ boost
>         struct
>         enable_error_info_return_type
>             {
> -            typedef typename enable_error_info_helper<T,sizeof(exception_detail::dispatch_boost_exception((T*)0))>::type type;
> +            typedef typename enable_error_info_helper<T,sizeof(exception_detail::dispatch_boost_exception(reinterpret_cast<T*>(0)))>::type type;
>             };
>         }
> 
> 
> 
> <reinterpret_cast-for-MWC.patch>
> 
> 
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