> The problem with yacc/bison-style LALR parser generators is that you end up with an LALR parser. Which works great on syntactically correct code, but trying to get a reasonable error message out of one is about as much fun as repeatedly poking yourself in the eye with a sharp stick.

The standard ways of getting error messages from LR parsers are pretty bad, but there is a long line of work that's tried to make it better. If you'll forgive the immodesty on my part, I've been working on updating and fixing that work. There's a draft paper at https://arxiv.org/abs/1804.07133 and a beta-ish implementation at https://github.com/softdevteam/grmtools/, so you can see what you think!

[EDIT: fixed formatting]