[prop-types] It crash eslint when using spread operator in a flow type

[lgraziani2712]

Hello! This code crashs eslint:

type RawMazeData = {|
  ...MazeData,
  path: Array<[string, ActivePathBorders]>,
|};

Cannot read property 'type' of undefined
TypeError: Cannot read property 'type' of undefined
    at buildTypeAnnotationDeclarationTypes (C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:452:25)
    at C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:464:54
    at iterateProperties (C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:333:11)
    at buildTypeAnnotationDeclarationTypes (C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:463:11)
    at buildTypeAnnotationDeclarationTypes (C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:455:20)
    at C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:464:54
    at iterateProperties (C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:333:11)
    at buildTypeAnnotationDeclarationTypes (C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:463:11)
    at C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:681:38
    at iterateProperties (C:\dev\repos\codimo\node_modules\eslint-plugin-react\lib\rules\prop-types.js:333:11)

Edit: disabling this rules does not happen.

Thank you!

[AndreyKozlov1984]

I can also say that babel itself could not run that code until the 6.24.1 (or a bit earlier) version of babel-core

[AndreyKozlov1984]

Wow, so fast! Fantastic!

[AndreyKozlov1984]

Sadly I still get that issue:

TypeError: Cannot read property 'type' of undefined
    at buildTypeAnnotationDeclarationTypes (/Users/zeus/Documents/redux_demo/webapp/node_modules/eslint-plugin-react/lib/rules/no-unused-prop-types.js:426:25)
    at /Users/zeus/Documents/redux_demo/webapp/node_modules/eslint-plugin-react/lib/rules/no-unused-prop-types.js:681:25
    at iterateProperties (/Users/zeus/Documents/redux_demo/webapp/node_modules/eslint-plugin-react/lib/rules/no-unused-prop-types.js:287:11)
    at markPropTypesAsDeclared (/Users/zeus/Documents/redux_demo/webapp/node_modules/eslint-plugin-react/lib/rules/no-unused-prop-types.js:680:11)
    at markAnnotatedFunctionArgumentsAsDeclared (/Users/zeus/Documents/redux_demo/webapp/node_modules/eslint-plugin-react/lib/rules/no-unused-prop-types.js:814:7)
    at Object.handleStatelessComponent (/Users/zeus/Documents/redux_demo/webapp/node_modules/eslint-plugin-react/lib/rules/no-unused-prop-types.js:823:7)
    at EventEmitter.updatedRuleInstructions.(anonymous function) (/Users/zeus/Documents/redux_demo/webapp/node_modules/eslint-plugin-react/lib/util/Components.js:624:75)
    at emitOne (events.js:101:20)
    at EventEmitter.emit (events.js:189:7)
    at NodeEventGenerator.applySelector (/Users/zeus/Documents/redux_demo/webapp/node_modules/eslint/lib/util/node-event-generator.js:265:26)

[yannickcr]

Different rule, same issue. I will fix this one too.

[rosskevin]

This should be reopened, still a problem with the same stack on version 7.0.1. I'll see if I can add a test PR that demonstrates it, I suspect it is due to the use of $Exact<> or shorthand {||}.

Cannot read property 'type' of undefined
TypeError: Cannot read property 'type' of undefined
    at buildTypeAnnotationDeclarationTypes (/Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:452:25)
    at /Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:464:54
    at iterateProperties (/Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:333:11)
    at buildTypeAnnotationDeclarationTypes (/Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:463:11)
    at /Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:686:38
    at iterateProperties (/Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:333:11)
    at markPropTypesAsDeclared (/Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:681:11)
    at Object.ClassProperty (/Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/rules/prop-types.js:833:11)
    at Linter.updatedRuleInstructions.(anonymous function) (/Users/kross/projects/ui/node_modules/eslint-plugin-react/lib/util/Components.js:621:75)
    at emitOne (events.js:101:20)
    at Linter.emit (events.js:191:7)
error Command failed with exit code 1.
~/p/ui ❯❯❯ yarn list eslint-plugin-react                                                                                                                                                                                        ⏎ develop ✭ ✱
yarn list v0.24.6
└─ eslint-plugin-react@7.0.1
✨  Done in 1.83s

[rosskevin]

I've pulled master, I see {...data}, {|...data|} are working, I added {...$Exact<data>} and it too works, so my hunch was wrong. I'll keep looking.

EDIT: See below, I can't make tests fail, so...

[rosskevin]

I've reproduced, it is the same thing I've found with flow plugins: I am spreading a type imported from a libdef (like flow-typed) and it is unresolved, therefore there are no children from the imported shape:

[rosskevin]

I've discovered that this problem is not isolated to libdefs, code that is present inside my project is failing to be validated using the object type spread, it appears to be because iterateProperties() makes no attempt to flatten the type, and it calls fn(undefined, undefined) as the key/value.

I think this method will need to check if it is indeed an object type spread and flatten it in-line.

Unfortunately, it doesn't seem to matter what I put in the tests, they all pass, leading me to believe there is a problem in the tests. e.g.:

{
      code: [
        'import type {Data} from \'./Data\'',
        'type Person = {',
        '  ...Data,',
        '  lastname: string',
        '};',
        'class Hello extends React.Component {',
        '  props: Person;',
        '  render () {',
        '    return <div>Hello {this.props.bar}</div>;',
        '  }',
        '}'
      ].join('\n'),
      parser: 'babel-eslint'
    }, {
      code: [
        'import type {Data} from \'some-libdef-like-flow-typed-provides\'',
        'type Person = {',
        '  ...Data,',
        '  lastname: string',
        '};',
        'class Hello extends React.Component {',
        '  props: Person;',
        '  render () {',
        '    return <div>Hello {this.props.bar}</div>;',
        '  }',
        '}'
      ].join('\n'),
      parser: 'babel-eslint'
    }

Both report as passing, and I cannot see how that could be true.

If @yannickcr will reopen this and advise me on the bad tests succeeding, I'm willing to take a shot at this.

[rosskevin]

I finally debugged my case close enough to add a test that breaks the current master. It's a nested spread that breaks this code and proves this should be reopened.

{
      code: [
        'import type {BasePerson} from \'./types\'',
        'type Props = {',
        '  person: {',
        '   ...$Exact<BasePerson>',
        '   lastname: string',
        '  }',
        '};',
        'class Hello extends React.Component {',
        '  props: Props;',
        '  render () {',
        '    return <div>Hello {this.props.person.firstname}</div>;',
        '  }',
        '}'
      ].join('\n'),
      parser: 'babel-eslint'
    }

[ljharb]

@rosskevin would you open a new issue for that, that links back to this one? The OP is fixed; your issue is slightly different :-)