Re: [boost] [1.35][functional] gcc-4.2:dereferencing type-punned pointer will break strict-aliasing rules

From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2008-04-18 19:04:01

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On Friday 18 April 2008 17:45 pm, Teemu Torma wrote:
>
> Wouldn't casting using union be safe and efficient in all cases?
> Something like:
>
>        inline std::size_t float_hash_impl(float v)
>        {
>               union { float v; std::size_t seed; } u;
>               u.v = v;
>               return u.seed;
>        }

It's safe with gcc, but that is a gnu extension.  The standard only allows 
aliasing through char*.

- -- 
Frank
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