[Boost-build] Building fat libraries on OSX

Subject: [Boost-build] Building fat libraries on OSX
From: Raffi Enficiaud (raffi.enficiaud_at_[hidden])
Date: 2016-11-22 04:57:41

Hi all,

Building fat libraries (i386, x64) on OSX does not seem to work as 
expected with b2. I am using XCode 8 / Clang8.

./b2 toolset=clang address-model=32_64 architecture=x86 cxxflags="-arch 
x86_64 -arch i386 -std=c++11 -stdlib=libc++" linkflags="-stdlib=libc++" 
--prefix=`pwd`/../${build_folder}  --without-log --layout=versioned install

- address-model=32_64 has no effect, I need to add "-arch x86_64 -arch i386"

- static libraries are fine:
   $ lipo -info boost_1_62_0/lib/libboost_thread-clang-darwin42-mt-1_62.a
   Architectures in the fat file: lib/libboost_thread-
clang-darwin42-mt-1_62.a are: x86_64 i386

- shared libraries are not:
   $ lipo -info 
boost_1_62_0/lib/libboost_thread-clang-darwin42-mt-1_62.dylib
   Architectures in the fat file: lib/libboost_thread-
clang-darwin42-mt-1_62.dylib are: x86_64

Does anyone has experience with this? I have the feeling that setting 
"cxxflags" removes the effect of "address-model=32_64", can anyone confirm?
how can I build boost with clang and C++11 mode?

Thanks in advance,
Raffi