I remember coding together a compiler using flex and bison. It was a nightmare. This definitely is not a short term task. Frankly I don't think the commitment is there from the community. Not yet at least.
Then again, gcc breakage is ridiculously common. It's got to be tackled at some point.
Flex and bison? See, that's a mistake right there! The tools often end up more hassle than coding the lexer and parser directly.
Writing compilers is normally fun, not a nightmare. It does tend towards nightmarish if your implementation language is very low-level, though; particularly if it lacks type safety and garbage collection.
Then again, gcc breakage is ridiculously common. It's got to be tackled at some point.