When utilizing the g++ command on the terminal, the Mac OS defaults to employing the clang++ compiler.

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However, it is possible to install the GNU compiler collection (GCC) and use g++ with that compiler instead. This can be done by installing GCC using Homebrew or MacPorts, and then specifying the path to the GCC version of g++ when compiling your code.

For example, if you have installed GCC using Homebrew, you can use the following command to compile your code with g++:

/usr/local/bin/g++ yourfile.cpp

If you want to make sure that you are using the GCC version of g++ by default, you can create an alias in your shell profile:

alias g++="/usr/local/bin/g++"

This will make the system use the GCC version of g++ whenever you type g++ in the terminal.