Either that or you could inspect every line of OS source code before compiling and then inspect every machine code of compiler executable to make sure compiler is not infected.
Instead of inspector your normal compiler's machine code, you can create a small special purpose compiler to begin bootstrapping your main compiler from source. Most compilers (including GCC I believe) are specifically designed so that they can be bootstrapped from a relatively small subset of the language. Additionally, you do not need to worry about producing an efficient executable because you will only ever run the resulting program once.
However, there is also the risk that your host OS is compromised, in which case it may simply lie to you and do whatever it wants.
