solidity grammar: add a new rule usingAliases for usingDirective

[jeasonstudio]

Thank you very much for providing the perfect solidity antlr4 grammar in the official repository, I encountered some problems when using it to build the solidity-antlr4 project (ast parser). This Pull-Request fixes the issue.

In the original grammar definition, usingDirective is hard to parse by the parser runtime:

solidity/docs/grammar/SolidityParser.g4

Lines 336 to 340 in ec563a1

	/**
	* Using directive to attach library functions and free functions to types.
	* Can occur within contracts and libraries and at the file level.
	*/
	usingDirective: Using (identifierPath | (LBrace identifierPath (As userDefinableOperator)? (Comma identifierPath (As userDefinableOperator)?)* RBrace)) For (Mul | typeName) Global? Semicolon;

For example, my code is like this:

using { A, B as + } for uint;

Here is how my parser handles it (using antlr4 typescript as an example):

const visitUsingDirective = (ctx: UsingDirectiveContext) => {
  const isUsingAlias = !!ctx.LBrace() && !!ctx.RBrace(); // not good.
  if (!isUsingAlias) {
    const name = ctx.identifierPath(0); // shouldn't be an array.
  } else {
    const names = ctx.identifierPath(); // symbols.
    const alias = ctx.userDefinableOperator(); // aliases(operators), but it can't correspond with symbol one by one.
  }
};

So I added a new rule usingAliases to solve this problem, and the rule designed refer to the definition of importDirective:

usingDirective:
  Using (
    identifierPath
    | (LBrace usingAliases (Comma usingAliases)* RBrace)
  ) For (Mul | typeName) Global? Semicolon;

usingAliases: identifierPath (As userDefinableOperator)?;

Hope it can be processed soon, thanks.

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[r0qs]

Hi @jeasonstudio thanks for the contribution. LGTM, could you please rebase it?

[jeasonstudio]

Hi @jeasonstudio thanks for the contribution. LGTM, could you please rebase it?

I have rebased this branch, but ci reported an error, and I don‘t think it has anything to do with my pr.

Thank you for your review. @r0qs

[r0qs]

Thanks! Yes, it is indeed unrelated (I did a workaround here: #14833). So I'm approving this anyway. But you may need to rebase it again if we merge the other PR first ;)

[jeasonstudio]

Thanks! Yes, it is indeed unrelated (I did a workaround here: #14833). So I'm approving this anyway. But you may need to rebase it again if we merge the other PR first ;)

done