@nergal neither VS nor MsBuild are compilers. Msb if I remember correctly either calls or replaces nmake. VS is an ide that calls either nmake or MsBuild and depending on your language uses the compilers that are in the SDKs such as ccl or whatever the c# one is called. But take a peek at SharpDevelop instead whose full source is available and presumably calls all the same compilers and so forth.