I’ve been working with C++ lately, particularly the compilers that support the latest C++ standards such as C++11, C++14, C++17, and C++2a (the upcoming C++20 which should be finally published sometime in February). Rather than install gcc/g++ via Brew on my Mac, I’ve been endeavoring to learn how to compile against those standards using Apple’s clang/clang++ compilers.

The unfortunate part for me (at first) was what command line switches needed to be passed to clang to enable the ability to compile a given standard’s code. I was able to determine what those switches were by deliberately mangling a switch in a makefile and then running make. For my troubles I got the following helpful list:

note: use 'c++98' or 'c++03' for 'ISO C++ 1998 with amendments' standardnote: use 'gnu++98' or 'gnu++03' for 'ISO C++ 1998 with amendments and GNU extensions' standardnote: use 'c++11' for 'ISO C++ 2011 with amendments' standardnote: use 'gnu++11' for 'ISO C++ 2011 with amendments and GNU extensions' standardnote: use 'c++14' for 'ISO C++ 2014 with amendments' standardnote: use 'gnu++14' for 'ISO C++ 2014 with amendments and GNU extensions' standardnote: use 'c++17' for 'ISO C++ 2017 with amendments' standardnote: use 'gnu++17' for 'ISO C++ 2017 with amendments and GNU extensions' standardnote: use 'c++2a' for 'Working draft for ISO C++ 2020' standardnote: use 'gnu++2a' for 'Working draft for ISO C++ 2020 with GNU extensions' standard

For example, to compile against C++17, you would use

clang++ --std=c++17 ...

to enable compilation of source code that uses features from C++17 on back. This keeps the tool clutter down on my Mac, which was getting a bit out of hand with the various GCC compilers via Brew. The GCC tools are all very good, but I would rather use clang since it’s delivered by Apple and is a part of the Xcode tool suite available to every Apple user. As of this point in time the Xcode version is 12.1.2 and clang’s version is 11.0.0. One final note, gcc is linked to clang and g++ is linked to clang++.