Fixing C++ compilation bugs for the MacOS Catalina upgrade

<p dir="auto">I recently updated to macOS Catalina and encountered several issues with programs that use a C/C++ compiler.<br /> If you see any of these errors this post might be helpful for you: <pre><code>/usr/local/Cellar/llvm/7.0.1/include/c++/v1/wchar.h:119:15: fatal error: 'wchar.h' file not found #include_next <wchar.h> ^~~~~~~~~ 1 error generated. <p dir="auto">Or any error indicating that a standard library couldn't be found: <pre><code>ld: library not found for -ldl clang-10: error: linker command failed with exit code 1 (use -v to see invocation) <h2>What's the issue? <p dir="auto">The issue is that macOS Catalina doesn't use the <code>/usr/include and <code>/usr/lib/ directories anymore for all C++ headers and libraries.<br /> A lot of projects rely on these directories to exist, can't find the files and then break.<br /> Instead they are under the xcode path and you need to tell the C/C++ compiler where to find these libraries now. <h2>How to fix it? <ol> <li>Optionally, install a C++ compiler like clang / gcc through <code>brew if one is missing. <li>Install <strong>Xcode through the App store to get access to the developer command-line tools.<br /> This will install the C++ header files and libraries, albeit, in a different directory. They will be installed in <code>/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk or a similar directory. To get the correct path for your system you can run the <code>xcrun --show-sdk-path command. <li>The C++ compiler needs to be told to look at this root path instead of <code>/usr/include. This can be done by setting the <code>CPLUS_INCLUDE_PATH env variable. It's important to also <strong>include LLVM's normal include path because this is where it should search first. <pre><code># adjust your llvm and CLT include paths to match your setup export CPLUS_INCLUDE_PATH=/usr/local/opt/llvm/include/c++/v1:/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include This should fix any <code>fatal error: 'xxx.h' file not found errors. <li>You might still run into linker errors like <code>ld: library not found for -lxxx. The linker also needs to be told to look for libraries in the CommandLineTools/Xcode paths by setting the <code>LIBRARY_PATH env variable. <pre><code>export LIBRARY_PATH=$LIBRARY_PATH:/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/lib <li>Make sure to add these <code>export statements to your <code>.bash_rc, <code>.zshrc, <code>.bash_profile, or whatever shell you use, to make these adjusted environment variables available in all terminals. <h3>Resources <p dir="auto">Thanks a lot to this <a href="https://github.com/imageworks/OpenShadingLanguage/issues/1055#issuecomment-581920327" target="_blank" rel="nofollow noreferrer noopener" title="This link will take you away from hive.blog" class="external_link">GitHub post for helping me figure out what's wrong. <hr /> <p dir="auto">Originally published at <a href="https://cmichel.io/fixing-cpp-compilation-bugs-for-the-mac-os-catalina-upgrade/" target="_blank" rel="nofollow noreferrer noopener" title="This link will take you away from hive.blog" class="external_link">https://cmichel.io/fixing-cpp-compilation-bugs-for-the-mac-os-catalina-upgrade/