Unbalanced parenthesis cause unclear error message

[axic]

contract C {
  function f() {
    require(balanceOf();
  }
}

results in

[error] contracts/A.sol: TypeError: Cannot read property 'length' of undefined
[error]     at ASTBuilder.visitExpression (/node_modules/@solidity-parser/parser/dist/index.cjs.js:36002:26)
[error]     at ASTBuilder.visitExpressionStatement (/node_modules/@solidity-parser/parser/dist/index.cjs.js:35932:24)
[error]     at ExpressionStatementContext.accept (/node_modules/@solidity-parser/parser/dist/index.cjs.js:33418:22)
[error]     at ASTBuilder.visit (/node_modules/@solidity-parser/parser/dist/index.cjs.js:17669:19)
[error]     at ASTBuilder.visitSimpleStatement (/node_modules/@solidity-parser/parser/dist/index.cjs.js:35449:17)
[error]     at SimpleStatementContext.accept (/node_modules/@solidity-parser/parser/dist/index.cjs.js:33590:22)
[error]     at ASTBuilder.visit (/node_modules/@solidity-parser/parser/dist/index.cjs.js:17669:19)
[error]     at ASTBuilder.visitStatement (/node_modules/@solidity-parser/parser/dist/index.cjs.js:35446:17)
[error]     at /node_modules/@solidity-parser/parser/dist/index.cjs.js:35482:51
[error]     at Array.map (<anonymous>)

My reasoning for including this here is the same as in #585, let me know if these reports should not be made here, or if they are not useful.

[mattiaerre]

@axic isn't this an issue that a linter should catch?

[Janther]

Yes, incorrect syntax is not something in the scope of this tool.

[axic]

The main question with these issues is a clear goal/expectation detailed in the README:

1. Is prettier only supposed to work on code the compiler (which version?) is not complaining about? In this case the current non-user-friendly failures are expected.

(Please note that with the compiler has changed syntax numerous times, and most tools try to support the superset of syntax it ever supported.)

2. Is prettier supposed to gracefully work (report an error) on invalid code?

It would be nice to have this decision documented in the README 🙂

Disclaimer: I work on the Solidity compiler.

[fvictorio]

Same comment as here, but I agree with this:

It would be nice to have this decision documented in the README

Clarifying in the README that invalid code (that is, code that cannot be parsed) doesn't work makes sense. Let's keep this one open until we do that.