Linking troubles with boost::program_options on OSX using LLVM - c++

Question

I'm having trouble getting through the linking phase in my C++ program due to problems with Boost 1.49. I have switched to C++ (-std=c++11 -libc=libc++) which works fine for another piece of code (which also uses boost). Boost was installed using homebrew with:
brew install boost --universal --with-mpi --with-icu
The trouble starts with boost::program_options. I get the link errors like this:
"boost::program_options::validate(boost::any&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, int)", referenced from:
... etc. ...
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
This is a little strange, because doing an nm on the library used reveals, that the symbol appears to be there:
nm -U /usr/local/lib/libboost_program_options-mt.dylib | grep validate
0000000000019880 - 01 0000 FUN __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISbIwSt11char_traitsIwESaIwEESaIS7_EEPSsi
0000000000019880 T __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISbIwSt11char_traitsIwESaIwEESaIS7_EEPSsi
00000000000199e0 - 01 0000 FUN __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISbIwSt11char_traitsIwESaIwEESaIS7_EEPbi
00000000000199e0 T __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISbIwSt11char_traitsIwESaIwEESaIS7_EEPbi
0000000000019930 T __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISsSaISsEEPSsi
0000000000019930 - 01 0000 FUN __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISsSaISsEEPSsi
0000000000019c70 - 01 0000 FUN __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISsSaISsEEPbi
0000000000019c70 T __ZN5boost15program_options8validateERNS_3anyERKSt6vectorISsSaISsEEPbi
I have already tried coaxing homebrew to compile boost with clang instead of gcc by setting CXX and CXX_FLAGS accordingly prior to installation. Not sure I succeeded though.
Pointers greatly appreciated.

Answer 1

You will need to recompile boost with clang and std11 flags, the libc++ library is not binary compatible with the installed libstdc++ in OSX (very early version of gcc prior to changing to gpl3). If your version of clang is 3.1 or over then you can use (otherwise change c++11 to c++0x for earlier versions).
./bootstrap.sh
mkdir build
sudo ./bjam toolset=clang cxxflags="-std=c++0x -stdlib=libc++" variant=release link=static threading=multi runtime-link=shared --build-dir=Build --layout=system --without-mpi --without-python install --prefix=/usr/local
You can of course alter any of these as you wish except
toolset=clang cxxflags="-std=c++0x -stdlib=libc++"
This should work for you.

Answer 2

I would like to share my (moderately painful) experience of building Boost 1.54 on Mac OS X 10.8.5 with clang 5.0.0 as supplied by Xcode 5.0 . If you want the C++11 features it is very important to compile and link with clang++, not with clang.
Illustration: take the following simple program:
#include <iostream>
#include <string>
int main(int argc, char *argv[]) {
std::string str = "OK";
std::cout << str << std::endl;
return 0;
}
Can be built with the following command:
clang++ -std=c++11 -stdlib=libc++ clangstr.cc -o clangstr
however, if you try this instead:
clang -std=c++11 -stdlib=libc++ clangstr.cc -o clangstr
then you get linker errors. Note that the clang manpage says that the language is selected by the -std= option, but this is clearly not enough.
The lesson is that we have to tell bjam to explicitly use clang++ when compiling Boost with C++11 support.
Following this very useful post, I put the following into my tools/build/v2/user-config.jam:
using clang : 11
: "/usr/bin/clang++"
: <cxxflags>"-std=c++11 -stdlib=libc++ -ftemplate-depth=512" <linkflags>"-stdlib=libc++"
;
Then I ran ./b2 clean, then I built Boost with the following command:
mkdir -p build/clangstage/
./b2 -j8 --build-dir=build --stagedir=build/clangstage toolset=clang-11 define=BOOST_SYSTEM_NO_DEPRECATED variant=release threading=multi address-model=64 stage
This builds the 64-bit static and dynamic libraries with multithreading support. If you need a different set then change the command above accordingly.