And you need the gazillion things on top of a grammar. Error recovery, IDE, language server, formatter, all the memory bugs, all the semantics that's not described in a formal language (and you can't auto-generate code to check or request it), all the binding generators for other languages and linking conventions... Ugh I wish we had a standard tool for that, like a much much much expanded yacc + interpreter generator + batteries included... There's something with libadalang and its language-agnostic tooling langkit (https://github.com/AdaCore/lang kit) that is very seducing (write once generate much code).
Sorry I'm trying to find out more but the project is a bit confusing. I found http://www.dotgnu.org/treecc_essay.html that looks of historical value (nowadays using java code generation / bytecode engineering quite often with amazing success). And of course libjit, but I'm at a loss finding out about semantic attributes and functions & typechecking and others.
