Private instance method throws error, Cannot read property 'flags' of undefined

[jperl]

Bug Report

• TSLint version: 3.15.1 and 4.0.0-dev.0
• TypeScript version: 2.0.3
• Running TSLint via: CLI

TypeScript code being linted

 private getQuality = ({ dataKey, rowData: { quality } }) => quality[dataKey];

Actual behavior

/Users/jperl/dev/my-project/node_modules/typescript/lib/typescript.js:49932
            var flags = symbol.flags;
                              ^
TypeError: Cannot read property 'flags' of undefined
    at displayPartKind (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:49932:31)
    at symbolPart (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:49930:34)
    at Object.writeSymbol (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:49917:31)
    at buildBindingElementDisplay (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:18782:28)
    at /Users/jperl/my-project/node_modules/typescript/lib/typescript.js:18763:110
    at buildDisplayForCommaSeparatedList (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:18809:21)
    at buildBindingPatternDisplay (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:18763:21)
    at buildParameterDisplay (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:18747:21)
    at buildDisplayForParametersAndDelimiters (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:18837:21)
    at buildSignatureDisplay (/Users/jperl/my-project/node_modules/typescript/lib/typescript.js:18883:17)

Expected behavior

No error.

[adidahiya]

what does your tslint.json look like? can you track down which rule is throwing this exception? that stack trace doesn't have any reference to tslint in it, which is a bit strange...

[jperl]

tslint.json

{
  "extends": ["tslint:latest", "tslint-react"],
  "rules": {
    "no-console": [false],
    "quotemark": [true, "single"]
  }
}

[jperl]

When I change the code to

  private getQuality = (options) => {
    const { dataKey, rowData: { quality } } = options;
    return quality[dataKey];
  };

it runs fine

[grovesNL]

I just ran into the same issue, i.e.:

function test({ x: { y } }) {
    console.log(y);
}
test({ x: { y: "test" } });

will fail with the var flags = symbol.flags exception.

Here's the complete call stack while linting the above example:

Perhaps it's a TypeScript issue?

[adidahiya]

looks like a duplicate of #1641, see my comment: #1641 (comment)

I recommend disabling the no-unused-variable rule and using the compiler checks instead

[grovesNL]

@adidahiya Thanks, I missed that issue. Will do!

[ghost]

Should be fixed by #2235.