ld: library not found for -lboost_python on MacOS

Question

On Mac, I want to build the example Boost.Python code

hello.cpp

#include <boost/python.hpp>

char const* greet()
{
    return "hello, world";
}

BOOST_PYTHON_MODULE(hello_ext)
{
    using namespace boost::python;
    def("greet", greet);
}

I installed the Boost.Python with brew install boost-python --with-python3

And I compiled the hello.cpp by

g++ -fpic -c -L/usr/local/Cellar/boost/1.67.0_1/lib `python3.6m-config --includes --libs  --ldflags`  hello.cpp  

There is a hello.o file generated. And generate .so file by

g++ -shared -L/usr/lib -L/usr/local/Cellar/boost/1.67.0_1/lib -L/usr/local/Cellar/boost-python3/1.67.0_1/lib/  `python3.6m-config --libs --ldflags` -lboost_python3 -o hello_ext.so hello.o

But it returned

ld: library not found for -lboost_python3
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Or more detailed output with -v.

g++ -shared -L/usr/lib -L/usr/local/Cellar/boost/1.67.0_1/lib -L/usr/local/Cellar/boost-python3/1.67.0_1/lib/  `python3.6m-config --libs --ldflags`  -lboost_python3 -o hello_ext.so hello.o -v
Apple LLVM version 9.0.0 (clang-900.0.38)
Target: x86_64-apple-darwin17.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
 "/Library/Developer/CommandLineTools/usr/bin/ld" -demangle -lto_library /Library/Developer/CommandLineTools/usr/lib/libLTO.dylib -dynamic -dylib -arch x86_64 -macosx_version_min 10.13.0 -o hello_ext.so -L/usr/lib -L/usr/local/Cellar/boost/1.67.0_1/lib -L/usr/local/Cellar/boost-python3/1.67.0_1/lib/ -L/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/config-3.6m-darwin -lpython3.6m -ldl -framework CoreFoundation -lpython3.6m -ldl -framework CoreFoundation -lboost_python3 hello.o -lc++ -lSystem /Library/Developer/CommandLineTools/usr/lib/clang/9.0.0/lib/darwin/libclang_rt.osx.a
ld: library not found for -lboost_python3
clang: error: linker command failed with exit code 1 (use -v to see invocation)

How can I fix it?

Answer 1

Finally, I found there is no such libboost_python37.dylib in boost-python lib path

$ ls /usr/local/Cellar/boost-python3/1.67.0_1/lib
libboost_numpy37-mt.a      libboost_numpy37.a         libboost_python37-mt.dylib libboost_python37.dylib
libboost_numpy37-mt.dylib  libboost_numpy37.dylib     libboost_python37-mt.a     libboost_python37.a

So I created a soft link

$ sudo ln -s libboost_python37.dylib libboost_python3.dylib

I can compile my code now.