Dealing with compiler-dependent source code

This recipe is similar to the previous one in the sense that we will use CMake to accommodate the compilation of conditional source code that is dependent on the environment: in this case, it will be dependent on the chosen compiler. Again, for the sake of portability, this is a situation that we try to avoid when writing new code, but it is also a situation that we are almost guaranteed to meet sooner or later, especially when using legacy code or when dealing with compiler-dependent tooling, such as sanitizers. From the recipes of this and the previous chapter, we have all the ingredients to achieve this. Nevertheless, it will be useful to discuss the problem of dealing with compiler-dependent source code since we will have the chance to introduce some new aspects of CMake.