api.markVariableAsUsed does not check Node.js scope

[yannickcr]

The Node.js scope is not checked by the api.markVariableAsUsed function making these variables impossible to mark as used.

"use strict";

var eslint = require("./lib/api.js").linter;

var code = "var a = 1, b = 2;";

eslint.reset();
eslint.on("Program:exit", function() {
    eslint.markVariableAsUsed("a"); // return false, the variable was not found in the scope
});

eslint.verify(code, { env: { node: true }}, "test.js", true);

[nzakas]

I'm not sure I'd call this a bug with the method, it seems more a bug with how it's being used. The method searches from the current scope up to the global scope. If you're calling it in "Program", then you're saying "only search the global scope".

However, in almost all cases you should not be calling markVariableAsUsed() in the global scope, you should be calling it where the identifier is actually used.

Can you show me how you're using it?

[nzakas]

Okay, I saw your other bug and I get it now. While I'd still recommend not using markVariableAsUsed() in the global scope, rather use it in the appropriate JSX element context, I can see how this would be confusing.

[yannickcr]

I'm using it to mark as used the variables in the JSX code.

You can see the rule here: https://github.com/yannickcr/eslint-plugin-react/blob/master/lib/rules/jsx-uses-vars.js

[nzakas]

That looks like it should work (since you're not in the global scope). Are you still seeing an error?

[yannickcr]

Yes, there is an error when the variable is used in the global scope.

You can see some example of problematic code here and here

[nzakas]

Hmm, I'm I'm looking at this correctly, I'm not sure markVariableAsUsed() is the problem. Because it searches from the current scope up to the global scope, it should still find any variable that was defined in the Node.js scope. It seems more likely the problem is in no-undef and no-unused-vars not checking the Node.js scope.

[yannickcr]

Sorry but I do not see the relation with no-undef or no-unused-vars

To retake the above example:

"use strict";

var eslint = require("./lib/api.js").linter;

var code = "var a = 1, b = 2;";

eslint.reset();
eslint.on("Program:exit", function() {
    eslint.markVariableAsUsed("a"); // return false, the variable was not found in the scope
});

eslint.verify(code, { env: { node: true }}, "test.js", true);

But if we are not in the the Node.js environment:

"use strict";

var eslint = require("./lib/api.js").linter;

var code = "var a = 1, b = 2;";

eslint.reset();
eslint.on("Program:exit", function() {
    eslint.markVariableAsUsed("a"); // return true, the variable was found in the scope
});

eslint.verify(code, {}, "test.js", true);

When in a Node.js scope, the variable a and b cannot be found in scope.variables but are in scope.childScopes[0].variables which is not currently checked in the actual markVariableAsUsed(). Seems to be a bug with markVariableAsUsed() to me :)

Pull request #2090 should fix this.

[nzakas]

What I meant was the original issue you reported had nothing to do with this. This is a separate issue.

[nzakas]

Working on this.