Mosh is on a mac. I noticed when he compiles it is using xcode. I don’t remember exactly what compiler, debugger, and build tools xcode uses behind the scenes and I’m on a windows machine now.
I saw where some people had issues like getline() and numeric_limits being undefined. If you don’t have any other compilers setup on your system, Clion will default to the bundled MingGw toolchain. See Here
MingGw will require you to explicitly add the correct library for some of these things to work. For example numeric_limits requires including the <limits> library and getline() requires including <string>. If you look up on cppreference.com the examples will show the included library. numeric_limits Also cplusplus.com getline
I have Visual Studio and Cygwin both installed on my system so I can switch toolchains to test. In both of the cases above, if you are using Visual Studio as your toolchain it works like in Mosh examples without having to explicitly include the library.
I suggest doing a lot of research in this course and when the references show including the library I would include it. Having it explicitly included doesn’t seem to cause any issues regardless of the toolchain in use but not including it means it might not compile on other systems.