Unexpected character '#'

[coreybutler]

I know it's probably not the intended use, but I was trying to parse a node file with this and received this error. The node script is designed to be a command line tool, and espree is complaining about the shebang (#!/usr/bin/env node).

Stack Trace:

SyntaxError: Unexpected character '#'
    at Parser.instance.raise.instance.raiseRecoverable (node_modules/espree/espree.js:390:19)
    at Parser.pp.getTokenFromCode (node_modules/acorn/dist/acorn.js:2831:8)
    at Parser.pp.readToken (node_modules/acorn/dist/acorn.js:2526:15)
    at Parser.pp.nextToken (node_modules/acorn/dist/acorn.js:2518:71)
    at Parser.parse (node_modules/acorn/dist/acorn.js:1631:10)
    at Object.parse (node_modules/acorn/dist/acorn.js:885:44)
    at Object.parse (node_modules/espree/espree.js:715:21)

This is pretty easily fixed by stripping the first line out, but it requires an extra pre-processing step. It'd be nice to either throw a warning or ignore these (or both) without crashing the process.

[nzakas]

It's invalid JavaScript, so you have to strip that comment before parsing (that's what ESLint does).

[coreybutler]

@nzakas - yeah, that's exactly what I stated. It would still be nice to not have to have a pre-process to do that.

[walshie4]

FWIW it looks like acorn supports skipping this. You'll just need to make sure this option gets passed in - https://github.com/acornjs/acorn/blob/dfcdbe4014cee1996129a8275bae28380cccd20c/acorn/src/state.js#L78

[platinumazure]

@eslint/eslint-team What do you think about this comment? On the one hand it doesn't seem critical to implement, but on the other hand, we could dogfood it in ESLint and get rid of some special logic.

[not-an-aardvark]

It seems like we probably need the special logic anyway for parsers that don't support the option.

[silverwind]

There is a stage 3 proposal to support hashbangs in the language, should this issue be re-opened?

[silverwind]

Proposal reached stage 4, so it will eventually be in acorn (acornjs/acorn#1134).

[mdjermanovic]

This is now supported in espree v9.4.0 with ecmaVersion: 2023.