Jscs chokes on es6 classes with constructor which calls super with "disallowUnusedParams" option set to true

[danny-andrews]

Every time I run jscs against a file which has an es6 with a constructor that calls super, it chokes. .jscsrc:

{
  "disallowUnusedParams": true
}

src/example.js:

import Parent from './parent';

export default class extends Parent {
  constructor() {
    super('hi parent');
  }
}

Example error message

Error running rule disallowUnusedParams: This is an issue with JSCS and not your codebase.
Please file an issue (with the stack trace below) at: https://github.com/jscs-dev/node-jscs/issues/new
RangeError: Maximum call stack size exceeded
    at Function.isArray (native)
    at Referencer.Visitor.visitChildren (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/node_modules/esrecurse/esrecurse.js:84:27)
    at Referencer.CallExpression (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/lib/referencer.js:480:22)
    at Referencer.Visitor.visit (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/node_modules/esrecurse/esrecurse.js:109:34)
    at Referencer.Visitor.visitChildren (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/node_modules/esrecurse/esrecurse.js:93:26)
    at Referencer.Visitor.visit (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/node_modules/esrecurse/esrecurse.js:112:14)
    at Referencer.Visitor.visitChildren (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/node_modules/esrecurse/esrecurse.js:93:26)
    at Referencer.CallExpression (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/lib/referencer.js:480:22)
    at Referencer.Visitor.visit (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/node_modules/esrecurse/esrecurse.js:109:34)
    at Referencer.Visitor.visitChildren (example_project/node_modules/grunt-jscs/node_modules/jscs/node_modules/escope/node_modules/esrecurse/esrecurse.js:93:26) at src/example.js :
     1 |import Parent from './parent';
--------^
     2 |
     3 |export default class extends Parent {

Note, if I comment out the call to super in the constructor, everything works as expected.

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[markelog]

Yeah, all because of the escope package which can't work with babel AST :/

[danny-andrews]

Ah, bummer. So this is a known issue then?

[markelog]

Yeah, bunch of issues with inability of escope to work with circular structures :/

[hzoo]

I think its related to multiple version of escope/estraverse (the same issue in eslint/babel-eslint). https://github.com/babel/babel-eslint/pull/209, https://github.com/eslint/eslint/issues/4485, some others? I haven't updated babel-jscs at all so need to port over babel-eslint changes

[markelog]

Basically, if parser generates AST with circular refs escope will go down, but the sad part is, no one of the maintainers of that package is interesting in fixing it :/

[gibson042]

parser generates AST with circular refs

• abstract syntax tree (AST): "a tree representation of the abstract syntactic structure of source code"
• tree: "an undirected graph in which any two vertices are connected by exactly one path. In other words, any connected graph without simple cycles is a tree."

https://github.com/estree/estree is cycle-free for good reason.

[hzoo]

There are underscored properties like _paths which could do that (info on scopes, parent/child, etc)

[markelog]

@gibson042 sure, but we don't parse ourselves @hzoo underscore is meaningless :/

[markelog]

At this point only major and CST related bugs will be fixed.