ANTLR grammar in the Solidity repository

[axic]

Since the Solidity repository maintains the ANTLR grammar which originated from here and it is kept up to date with the language, perhaps it would make sense considering to use that?

See ethereum/solidity#8482

[fvictorio]

@axic I'm maintaining a fork of this project that is used by many tools in the ecosystem (buidler, solhint, solidity-coverage, eth-gas-reporter, prettier-solidity, and probably others). There's nothing that I would love more than stop maintaining the grammar (fork), because I don't know nearly enough about ANTLR and grammars to do it properly and I'm playing it by ear, plus it takes time and energy.

That being said, I don't think I could use the current grammar soon. Here's why:

• First, it seems like a lot was changed, so adapting the wrapper will be hard.
• Second, if I'm understanding correctly, the goal is for the official grammar to be correct for 0.7.x. Right now, as you know, the grammar used by the js parser is very forgiving and it basically accepts a lot. You mentioned in the PR that that doesn't make sense to you, but it does. For example, some tools only need to parse imports, and so the incompatibilities between versions don't matter much. Others, like prettier, work at a local node level and don't care about versions either.
  That doesn't mean that a middle ground can't be found: maybe the parser could make a first pass just to get the pragmas, and then use the proper version of the grammar from what it found. Of course, this is also a lot of work and it means the solidity team should also create and maintain grammars for 0.4, 0.5 and 0.6, assuming you want to do that and have the bandwidth.

My short-term plan is to continue to maintain the grammar and the parser as I've been doing it so far: kind of patching it so that it continues to work with the new features and hoping for the best. This is unsustainable, but it's the only option I see right now. Probably a sustainable, long-term plan would imply some collaboration with the Solidity team. If you are interested, please open an issue in my fork or talk to me on Telegram (@fvictorio).