Target Boost:: already has an imported location + link errors

Question

I\'m using Homebrew to install LLVM, Boost, and CMake on MacOS Mojave. After upgrading my LLVM to version 9.0.0 and Boost to 1.71.0, CMake (v3.15.3) started complaining about va

Answer 1

I asked about the CMake warning on Slack. As explained by Peter Dimov:

this is because homebrew installs both multithreaded and single-threaded boost

in addition, due to an issue in boost 1.71's cmake support, Boost_USE_MULTITHREADED is not respected

I've fixed this for the next release

you can define Boost_NO_BOOST_CMAKE=ON to get around it

See https://github.com/boostorg/boost_install/issues/13, it should be fixed in the next release.

January 22, 2020: Updating boost through brew upgrade boost to 1.72 and adding set(Boost_USE_MULTITHREADED TRUE) to my CMakeLists.txt has fixed this problem for me.