The clang driver is particularly bad at this. There is a frequent 'just add one more thing here!' in every section of the driver. Additionally, it is large, so

The clang driver is particularly bad at this. There is a frequent 'just add one more thing here!' in every section of the driver. Additionally, it is large, somewhat complex, and not very exciting, so those refactors/simplifications don't happen nearly as often as other parts of the clang code base. The tablegen/macro-gen stuff DID get added at one point fortunately, but before that it was pretty rough as well.