rules/no-use-before-define.js: TypeError: Cannot read property '1' of undefined

Tell us about your environment

• ESLint Version: 3.19.0

• Node Version: v7.10.0

• npm Version: 4.5.0

What parser (default, Babel-ESLint, etc.) are you using? Babel-ESLint

Please show your full configuration:

FILE: .eslintrc.json

{
  "parser": "babel-eslint",
  "extends": "standard"
}

What did you do? Please include the actual source code causing the issue.

// @flow
type FieldOptions<T> = {| defaultValue: T |}
type DateFieldOptions = {| ...FieldOptions<Date> |}

What did you expect to happen?

What actually happened? Please include the actual, raw output from ESLint.

[eslintbug]$ node_modules/.bin/eslint fields.js 
Cannot read property '1' of undefined
TypeError: Cannot read property '1' of undefined
    at scope.references.forEach.reference (/tmp/eslintbug/node_modules/eslint/lib/rules/no-use-before-define.js:206:83)
    at Array.forEach (native)
    at findVariablesInScope (/tmp/eslintbug/node_modules/eslint/lib/rules/no-use-before-define.js:194:30)
    at EventEmitter.Program:exit (/tmp/eslintbug/node_modules/eslint/lib/rules/no-use-before-define.js:242:21)
    at emitOne (events.js:101:20)
    at EventEmitter.emit (events.js:191:7)
    at NodeEventGenerator.applySelector (/tmp/eslintbug/node_modules/eslint/lib/util/node-event-generator.js:265:26)
    at NodeEventGenerator.applySelectors (/tmp/eslintbug/node_modules/eslint/lib/util/node-event-generator.js:294:22)
    at NodeEventGenerator.leaveNode (/tmp/eslintbug/node_modules/eslint/lib/util/node-event-generator.js:317:14)
    at CodePathAnalyzer.leaveNode (/tmp/eslintbug/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:622:23)

[platinumazure]

Nice find, @mysticatea, knew it was something like that. Honestly I’d much prefer that babel-eslint fix this if possible, so I’m not 100% sure I actually want to submit this patch.

I’ll open an issue over there later today. Thanks!

[ilyavolodin]

Closing this issue, as it’s a problem with babel-eslint.