Re: [Boost-bugs] [Boost C++ Libraries] #6898: Compiler warning when using boost::posix_time::from_ftime.

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6898: Compiler warning when using boost::posix_time::from_ftime.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-08-15 13:59:47

#6898: Compiler warning when using boost::posix_time::from_ftime.
---------------------------------------------+------------------------------
  Reporter:  oscar.lara@…                    |       Owner:  az_sw_dude
      Type:  Bugs                            |      Status:  new       
 Milestone:  To Be Determined                |   Component:  date_time 
   Version:  Boost 1.42.0                    |    Severity:  Cosmetic  
Resolution:                                  |    Keywords:            
---------------------------------------------+------------------------------
Description changed by viboes:

Old description:

> VC2005 compiler reports a compilation warning when using from_time
> function.
>
> 1>c:\workspace\boost\boost\date_time\filetime_functions.hpp(146) :
> warning C4244: 'initializing' : conversion from 'boost::uint64_t' to
> 'boost::uint32_t', possible loss of data
> 1>
> c:\workspace\boost\boost\date_time\posix_time\conversion.hpp(81) : see
> reference to function template instantiation 'TimeT
> boost::date_time::time_from_ftime<TimeT,FileTimeT>(const FileTimeT &)'
> being compiled
> 1>        with
> 1>        [
> 1>            TimeT=boost::posix_time::ptime,
> 1>            FileTimeT=FILETIME
> 1>        ]
> 1>        c:\workspace\blah\rainbowkeyimpl.cpp(126) : see reference to
> function template instantiation 'TimeT
> boost::posix_time::from_ftime<boost::posix_time::ptime,FILETIME>(const
> FileTimeT &)' being compiled
> 1>        with
> 1>        [
> 1>            TimeT=boost::posix_time::ptime,
> 1>            FileTimeT=FILETIME
> 1>        ]
>
> Looking the code in the latest Boost version the line that the warning is
> pointing hasn't changed.
>
> uint32_t sub_sec = (caster.as_integer % 10000000UL)
> #if !defined(BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG)
>         / 10; // microseconds since the last second
> #else
>         * 100; // nanoseconds since the last second
> #endif
>
> A quick way to resolve it would be to static_cast<uint32_t> the results.
> The cast shouldn't cause any data loss as the mod is and the
> multiplication are keeping the maximum value within the uint32_t range.

New description:

 VC2005 compiler reports a compilation warning when using from_time
 function.

 1>c:\workspace\boost\boost\date_time\filetime_functions.hpp(146) : warning
 C4244: 'initializing' : conversion from 'boost::uint64_t' to
 'boost::uint32_t', possible loss of data
 1>        c:\workspace\boost\boost\date_time\posix_time\conversion.hpp(81)
 : see reference to function template instantiation 'TimeT
 boost::date_time::time_from_ftime<TimeT,FileTimeT>(const FileTimeT &)'
 being compiled
 1>        with
 1>        [
 1>            TimeT=boost::posix_time::ptime,
 1>            FileTimeT=FILETIME
 1>        ]
 1>        c:\workspace\blah\rainbowkeyimpl.cpp(126) : see reference to
 function template instantiation 'TimeT
 boost::posix_time::from_ftime<boost::posix_time::ptime,FILETIME>(const
 FileTimeT &)' being compiled
 1>        with
 1>        [
 1>            TimeT=boost::posix_time::ptime,
 1>            FileTimeT=FILETIME
 1>        ]

 Looking the code in the latest Boost version the line that the warning is
 pointing hasn't changed.


 {{{
 uint32_t sub_sec = (caster.as_integer % 10000000UL)
 #if !defined(BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG)
         / 10; // microseconds since the last second
 #else
         * 100; // nanoseconds since the last second
 #endif
 }}}


 A quick way to resolve it would be to static_cast<uint32_t> the results.
 The cast shouldn't cause any data loss as the mod is and the
 multiplication are keeping the maximum value within the uint32_t range.

--
-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6898#comment:2>
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