No dependencies are detected in files using optional chaining

[haggholm]

Bug Description

If a file contains the optional chaining proposal object?.optionalProperty, parsing appears to fail and no dependencies are detected in the file.

Code snippets

Where the dependency is used:

import _ from 'lodash';

export default function foo(ob) {
    return _.identity(ob?.x);
}

Where the dependency is listed in package.json:

The dependency is not listed in package.json (in my sample scenario, it doesn’t contain any dependencies at all).

Expected outcome:

Missing dependencies
* lodash

Actual outcome: No output/nothing detected.

Versions

• node -v: v10.4.0
• npm -v: 6.1.0
• depcheck -v: No output, it doesn’t seem to recognise the -v flag. However, the version is 0.6.11.

Extra info

depcheck --json

{
  "dependencies": [],
  "devDependencies": [],
  "missing": {},
  "using": {},
  "invalidFiles": {
    "/client/tmp/test.jsx": "SyntaxError: Unexpected token (4:25)\n    at Parser.pp$5.raise (/client/tmp/node_modules/babylon/lib/index.js:4454:13)\n    at Parser.pp.unexpected (/client/tmp/node_modules/babylon/lib/index.js:1761:8)\n    at Parser.pp$3.parseExprAtom (/client/tmp/node_modules/babylon/lib/index.js:3750:12)\n    at Parser.parseExprAtom (/client/tmp/node_modules/babylon/lib/index.js:7238:22)\n    at Parser.pp$3.parseExprSubscripts (/client/tmp/node_modules/babylon/lib/index.js:3494:19)\n    at Parser.pp$3.parseMaybeUnary (/client/tmp/node_modules/babylon/lib/index.js:3474:19)\n    at Parser.pp$3.parseExprOps (/client/tmp/node_modules/babylon/lib/index.js:3404:19)\n    at Parser.pp$3.parseMaybeConditional (/client/tmp/node_modules/babylon/lib/index.js:3381:19)\n    at Parser.pp$3.parseMaybeAssign (/client/tmp/node_modules/babylon/lib/index.js:3344:19)\n    at Parser.parseMaybeAssign (/client/tmp/node_modules/babylon/lib/index.js:6474:20)"
  },
  "invalidDirs": {}
}

I tried to add 'optionalChaining' to the list of plugins in depcheck/dist/jsx.js', but this appeared to have no effect.

[mnkhouri]

Thanks for the report @haggholm. I did a bit of digging around that plugin:

Our current parser is Babylon@6.1.21, which does not support the 'optionalChaining' plugin per the documentation for 6.26.3 (so it's definitely not in our 6.1.21)

As of Babel@7, Babylon was renamed to @babel/parser, which does support the optionalChaining plugin, according to documention for @babel/parser@7.1.0

So the solution is for us to update babylon to @babel/parser. I'll try to get to this this weekend, but if anyone else feels like tackling it in the meantime, a PR would be greatly appreciated! I would guess it's a drop-in replacement, or minimal changes

[LinusU]

So the solution is for us to update babylon to @babel/parser

Would be awesome to get this in 👏

[haggholm]

@mnkhouri If there weren’t so many things broken all over the place by the Babel transition—and if the Babel 7 transition weren’t compelled by React Native—I’d at least like to think of myself that I’d whip up a PR. But in actual reality, there’s no realistic chance by the weekend. :P

[rumpl]

Fixed by #307