Re: [boost] [1.35][functional]gcc-4.2:dereferencingtype-punnedpointer will breakstrict-aliasing rules

From: Bo Persson (bop_at_[hidden])
Date: 2008-04-19 14:38:10

Giovanni Piero Deretta wrote:
> On Sat, Apr 19, 2008 at 5:30 PM, Bo Persson <bop_at_[hidden]> wrote:
>>
>> Giovanni Piero Deretta wrote:
>>  > On Fri, Apr 18, 2008 at 5:34 PM, Matt Doyle <mdoyle_at_[hidden]>
>>  > wrote:
>>  >>> [mailto:boost-bounces_at_[hidden]] On Behalf Of Giovanni
>>  >>  > Piero Deretta
>>  >>  >
>>  >>  > Changing:
>>  >>  >
>>  >>  >        inline std::size_t float_hash_impl(float v)
>>  >>  >        {
>>  >>  >             boost::uint32_t* ptr = (boost::uint32_t*)&v;
>>  >>  >             std::size_t seed = *ptr;
>>  >>  >             return seed;
>>  >>  >        }
>>  >>  >
>>  >>  > to
>>  >>  >
>>  >>  >      inline std::size_t float_hash_impl(float v)
>>  >>  >      {
>>  >>  >             std::size_t seed;
>>  >>  >             std::memcpy(&x, &v, sizeof(x));
>>  >>  >             return seed;
>>  >>  >      }
>>  >>  >
>>  >>
>>  >>  /x/seed/ ??
>>  >>
>>  >
>>  > Yes, of course :)
>>
>>
>>  And also assuming that sizeof(seed) ==sizeof(float)  ?
>>
> Yes, but, as the code is only compiled in when under X86, you can
> safely assume that.

Ok, I though it was used for x86_64 as well, but I might be wrong.

Bo Persson