Use the same implementation for different situations.
Always have been worried about banned functions in your project? Create a new project and use the same code for different situations.
Using ConditionalCompiler, you can create projects (executables or libraries) with different implementations of the same functions based on the configuration of the project.
For instance, let's assume that you created a library using the time function. You can have a project who is using the part of your libary using the time function. But you can also have another project who is using the same part of your library, but without the time function (because it is banned in the project). You'll then need to remove the time function from your library and create a new project using the same part of your library, but without the time function.
With ConditionalCompiler, you could have two implementations of the same function in your library, one using the time function and the other one without the time function. Then, you could create two projects, one using the implementation with the time function and the other one using the implementation without the time function.