[Boost-bugs] [Boost C++ Libraries] #11380: Container library std forward declarations incorrect in std_fwd.hpp on libc++ with gcc

Subject: [Boost-bugs] [Boost C++ Libraries] #11380: Container library std forward declarations incorrect in std_fwd.hpp on libc++ with gcc
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-06-08 06:36:56

#11380: Container library std forward declarations incorrect in std_fwd.hpp on
libc++ with gcc
-------------------------------------+------------------------
 Reporter:  tsniatowski@…            |      Owner:  igaztanaga
     Type:  Bugs                     |     Status:  new
Milestone:  To Be Determined         |  Component:  container
  Version:  Boost Development Trunk  |   Severity:  Problem
 Keywords:                           |
-------------------------------------+------------------------
 std_fwd.hpp contains code to detect libc++ and try to forward declare some
 types there appropriately. However, the ifdef logic assumes that libc++ is
 only ever used on Clang, which is incorrect. It is possible to use libc++
 with GCC, for example on Android where you generally choose the compiler
 and C++ library separately.

 Currently, "#if defined(__clang__) && defined(_LIBCPP_VERSION)" is used to
 trigger libc++-specific style of forward declarations. Only
 _LIBCPP_VERSION should be checked, with a secondary __clang__ check to
 disable a warning.

 As a side note, shouldn't there be a build-time setting to disable this
 std:: forwarding altogether? It feels fragile, and borderline UB. It
 sacrifices portability for some potential build speed improvement, which
 might not be the best choice for everyone.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11380>
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