fix: Incorrect scope analysis of class name in extends expression

[lizhihao132]

#112
or
#59

[linux-foundation-easycla]

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[eslint-github-bot]

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[eslint-github-bot]

Hi @lizhihao132!, thanks for the Pull Request

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[eslint-github-bot]

Hi @lizhihao132!, thanks for the Pull Request

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[eslint-github-bot]

Hi @lizhihao132!, thanks for the Pull Request

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[bradzacher]

Suggested change

	let may_ref_classid = node.superClass && node.superClass.type!=='Identifier'
	let mayRefClassid = node.superClass && node.superClass.type!=='Identifier'

The naming convention for the codebase is camelCase.

[mdjermanovic]

Why is extends <Identifer> a special case?

var C = class {};

var C1 = class C extends C {}; // ReferenceError: Cannot access 'C' before initialization

It seems we should just always visit node.superClass after this.scopeManager.__nestClassScope(node)?

[lizhihao132]

No, we must discuss this on a case-by-case basis, as it is different. Before explaining this issue, we need to first understand what the following three function calls do specifically:

• "this.scopeManager.__nestClassScope(node)": Essentially, it creates a child scope s based on the currently used scope p (the node associated with this scope is node, that is: p.block === node), inherits the symbols of p, and sets the "currently used scope" to s.
• "this.close(node)": Assuming the "currently used scope" is m (m.block === node), this function call sets the "currently used scope" to the parent scope of m.
• "this.visit(x)": Traverse the x node based on the "currently used scope".

Now let's answer your question.

The first scenario:
In this piece of code, class A extends B { ... }, if we first call: "this.scopeManager.__nestClassScope(node);", this causes the "currently used scope" to be set to the newly created scope (it is a child scope of the top-scope), and then this.visit(node.superClass), this causes the superClass node, that is, B to be analyzed within this child scope, making it a reference to the child scope instead of the top-scope. This is incorrect. Because under the JS specification, the B above should be a reference to the top-scope.

The second scenario:
when superClass is not an Identifier but a complex node, such as the following code:

var C = 'outside';

var cls = class C extends (
    probeHeritage = function() { return C; },
    setHeritage = function() {  }
  ) {
  method() {
    return C;
  }
};

It is a comma expression wrapped in parentheses, containing two assignment expressions. At this time, the C symbol in the superClass node is no longer the var C in the top-scope, but points to the C in class C (which is the issue we need to resolve). Therefore, the solution is quite obvious: we need to traverse the superClass node when the "currently used scope" is in the class scope, in order to make the resolution of the C symbol correct. Different from the first scenario, when superClass is an Identifier, it needs to be traversed when the "currently used scope" is the top-scope, so "this.visit(node.superClass)" needs to be done before "this.scopeManager.__nestClassScope(node);".

[nzakas]

@lizhihao132 please sign the CLA.

[lizhihao132]

@lizhihao132 please sign the CLA.

ok，done

[lizhihao132]

Can any body tell me how to do the CLA Authorization？i sign more than one times, but no thing change here but："Missing CLA Authorization"

[lizhihao132]

i close this pull-request, and new one：#114