Moving logic from the source code into the compiler invocation is a mixed blessing. In general as the list of -I directories needed to build the thing gets more

Moving logic from the source code into the compiler invocation is a mixed blessing. In general as the list of -I directories needed to build the thing gets more complicated the ease of building it from something other than the provided build scripts goes down. Much like working things out in the preprocessor is ugly but works with other build systems and over-elaborate configure script style stuff makes for prettier source by moving complexity elsewhere.