id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
11380,Container library std forward declarations incorrect in std_fwd.hpp on libc++ with gcc,tsniatowski@…,Ion Gaztañaga,"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.",Bugs,closed,To Be Determined,container,Boost Development Trunk,Problem,fixed,,