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

From: Teemu Torma (teemu_at_[hidden])
Date: 2008-04-18 17:45:00

On Friday 18 April 2008, Giovanni Piero Deretta wrote:
> Â  Â  Â inline std::size_t float_hash_impl(float v)
> Â  Â  Â {
> Â  Â  Â  Â  Â  Â  std::size_t seed;
> Â  Â  Â  Â  Â  Â  std::memcpy(&x, &v, sizeof(x));
> Â  Â  Â  Â  Â  Â  return seed;
> Â  Â  Â }
>
> should work and should produce optimal code, at least with a recent
> gcc.

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;
       }

Teemu