Most production parsers use their own handwritten recursive descent parsers, not only because of better diagnostics (error handling, language server hinting, etc.), but also for other reasons. One such major reason is that parser generators represent a very unstable dependency. They frequently change their APIs in newer versions, and some are becoming obsolete while new ones are constantly appearing. You don't want to risk the longevity of your parser by basing it on such unstable foundations. Flex/Bison is perhaps the only exception, as it hasn't changed much over time.