[Boost-bugs] [Boost C++ Libraries] #8941: Detection of availability of 128-bit integers should be left on Boost.Config

Subject: [Boost-bugs] [Boost C++ Libraries] #8941: Detection of availability of 128-bit integers should be left on Boost.Config
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-07-30 17:45:36

#8941: Detection of availability of 128-bit integers should be left on
Boost.Config
---------------------------------------+--------------------------
 Reporter:  Petr Machata <pmachata@…>  |      Owner:  apolukhin
     Type:  Bugs                       |     Status:  new
Milestone:  To Be Determined           |  Component:  lexical_cast
  Version:  Boost 1.54.0               |   Severity:  Problem
 Keywords:                             |
---------------------------------------+--------------------------
 The following code in lexical_cast.hpp appears wrong:

 {{{
 #if (defined(BOOST_LCAST_HAS_INT128) && !defined(__GNUC__)) || GCC_VERSION
 > 40700
 #define BOOST_LCAST_HAS_INT128
 #endif
 }}}

 I'm uncertain whether BOOST_LCAST_HAS_INT128 serves some purpose such as
 per-library configuration.  It seems to me it would be best to simply
 defer this logic to config.hpp, drop this piece of code, and later on
 dispatch on BOOST_HAS_INT128.  I'm attaching a patch to this effect.

 Note that this logic currently breaks on i386, where GCC doesn't support
 128-bit data types even though it otherwise satisfies the above condition.

 If you wish to have this configured specifically for lexical cast, I can
 work in some logic that overrides BOOST_HAS_INT128 in favor of whatever
 BOOST_LCAST_HAS_INT128 setting came from the "outside" (if any).

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8941>
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