Repository: eslint/eslint (js)

Issue:
no-unused-vars errors with parameters when parameter marked used later
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**Tell us about your environment**

* **ESLint Version:** 5.6.1 
* **Node Version:** v9.4.0
* **npm Version:** 5.6.0

**What parser (default, Babel-ESLint, etc.) are you using?** babel-eslint

**Please show your full configuration:**

<details>
<summary>Configuration</summary>

<!-- Paste your configuration below: -->
```js
{
	"parser": "babel-eslint",
	"plugins": [
		"babel",
		"react"
	],
	"extends": ["plugin:react/recommended"],
	"rules": {
		"no-unused-vars": 1
	}
}
```

</details>

**What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.**

The eslint-plugin-react rule for `jsx-uses-vars` [marks the `Wrapped` parameter as used](https://github.com/yannickcr/eslint-plugin-react/blob/master/lib/rules/jsx-uses-vars.js#L45).  However, `no-unused-vars` doesn't update the status of `config`.  The default for `no-unused-vars` should not warn on parameters before the first used parameter.

<!-- Paste the source code below: -->
```js
import React from 'react';
import foo from 'foo';

export const AccessibilityDecorator = foo((config, Wrapped) => {
	return class t extends React.Component {
		render () {
			return <Wrapped />;
		}
	};
});
```

<!-- Paste the command you used to run ESLint: -->
```bash
eslint .
```

**What did you expect to happen?**

No warnings.

**What actually happened? Please include the actual, raw output from ESLint.**

```
/Users/.../.../test.js
  4:44  warning  'config' is defined but never used  no-unused-vars

✖ 1 problem (0 errors, 1 warning)
```

Linked issue: yannickcr/eslint-plugin-react#2009

Pull request description:
Fix: no-unused-vars false pos. with markVariableAsUsed (fixes #10952)
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**What is the purpose of this pull request? (put an "X" next to item)**

[ ] Documentation update
[x] Bug fix ([template](https://raw.githubusercontent.com/eslint/eslint/master/templates/bug-report.md))
[ ] New rule ([template](https://raw.githubusercontent.com/eslint/eslint/master/templates/rule-proposal.md))
[ ] Changes an existing rule ([template](https://raw.githubusercontent.com/eslint/eslint/master/templates/rule-change-proposal.md))
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

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#10952
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**What changes did you make? (Give an overview)**
Added check to `isAfterLastUsedArg()` to recognize variables used by `context.markVariableAsUsed()`

**Is there anything you'd like reviewers to focus on?**
I did not check other situations for where `context.markVariableAsUsed()` may be ignored.  Also, I was not certain whether `isAfterLastUsedArg()` should just be calling `isUsedVariable()` and that function should be updated to check for `eslintUsed`.

Patch:
diff --git a/lib/rules/no-unused-vars.js b/lib/rules/no-unused-vars.js
index fff3e33d9..6f36813ac 100644
--- a/lib/rules/no-unused-vars.js
+++ b/lib/rules/no-unused-vars.js
@@ -469,7 +469,7 @@ module.exports = {
             const posteriorParams = params.slice(params.indexOf(variable) + 1);
 
             // If any used parameters occur after this parameter, do not report.
-            return !posteriorParams.some(v => v.references.length > 0);
+            return !posteriorParams.some(v => v.references.length > 0 || v.eslintUsed);
         }
 
         /**
diff --git a/lib/rules/one-var.js b/lib/rules/one-var.js
index 15b664d77..3efd0f27f 100644
--- a/lib/rules/one-var.js
+++ b/lib/rules/one-var.js
@@ -314,6 +314,11 @@ module.exports = {
         function splitDeclarations(declaration) {
             return fixer => declaration.declarations.map(declarator => {
                 const tokenAfterDeclarator = sourceCode.getTokenAfter(declarator);
+
+                if (tokenAfterDeclarator === null) {
+                    return null;
+                }
+
                 const afterComma = sourceCode.getTokenAfter(tokenAfterDeclarator, { includeComments: true });
 
                 if (tokenAfterDeclarator.value !== ",") {
diff --git a/lib/rules/space-infix-ops.js b/lib/rules/space-infix-ops.js
index 49b64658d..17b49cc11 100644
--- a/lib/rules/space-infix-ops.js
+++ b/lib/rules/space-infix-ops.js
@@ -34,37 +34,25 @@ module.exports = {
 
     create(context) {
         const int32Hint = context.options[0] ? context.options[0].int32Hint === true : false;
-
-        const OPERATORS = [
-            "*", "/", "%", "+", "-", "<<", ">>", ">>>", "<", "<=", ">", ">=", "in",
-            "instanceof", "==", "!=", "===", "!==", "&", "^", "|", "&&", "||", "=",
-            "+=", "-=", "*=", "/=", "%=", "<<=", ">>=", ">>>=", "&=", "^=", "|=",
-            "?", ":", ",", "**"
-        ];
-
         const sourceCode = context.getSourceCode();
 
         /**
          * Returns the first token which violates the rule
          * @param {ASTNode} left - The left node of the main node
          * @param {ASTNode} right - The right node of the main node
+         * @param {string} op - The operator of the main node
          * @returns {Object} The violator token or null
          * @private
          */
-        function getFirstNonSpacedToken(left, right) {
-            const tokens = sourceCode.getTokensBetween(left, right, 1);
-
-            for (let i = 1, l = tokens.length - 1; i < l; ++i) {
-                const op = tokens[i];
-
-                if (
-                    (op.type === "Punctuator" || op.type === "Keyword") &&
-                    OPERATORS.indexOf(op.value) >= 0 &&
-                    (tokens[i - 1].range[1] >= op.range[0] || op.range[1] >= tokens[i + 1].range[0])
-                ) {
-                    return op;
-                }
+        function getFirstNonSpacedToken(left, right, op) {
+            const operator = sourceCode.getFirstTokenBetween(left, right, token => token.value === op);
+            const prev = sourceCode.getTokenBefore(operator);
+            const next = sourceCode.getTokenAfter(operator);
+
+            if (!sourceCode.isSpaceBetweenTokens(prev, operator) || !sourceCode.isSpaceBetweenTokens(operator, next)) {
+                return operator;
             }
+
             return null;
         }
 
@@ -110,7 +98,10 @@ module.exports = {
             const leftNode = (node.left.typeAnnotation) ? node.left.typeAnnotation : node.left;
             const rightNode = node.right;
 
-            const nonSpacedNode = getFirstNonSpacedToken(leftNode, rightNode);
+            // search for = in AssignmentPattern nodes
+            const operator = node.operator || "=";
+
+            const nonSpacedNode = getFirstNonSpacedToken(leftNode, rightNode, operator);
 
             if (nonSpacedNode) {
                 if (!(int32Hint && sourceCode.getText(node).endsWith("|0"))) {
@@ -126,8 +117,8 @@ module.exports = {
          * @private
          */
         function checkConditional(node) {
-            const nonSpacedConsequesntNode = getFirstNonSpacedToken(node.test, node.consequent);
-            const nonSpacedAlternateNode = getFirstNonSpacedToken(node.consequent, node.alternate);
+            const nonSpacedConsequesntNode = getFirstNonSpacedToken(node.test, node.consequent, "?");
+            const nonSpacedAlternateNode = getFirstNonSpacedToken(node.consequent, node.alternate, ":");
 
             if (nonSpacedConsequesntNode) {
                 report(node, nonSpacedConsequesntNode);
@@ -147,7 +138,7 @@ module.exports = {
             const rightNode = node.init;
 
             if (rightNode) {
-                const nonSpacedNode = getFirstNonSpacedToken(leftNode, rightNode);
+                const nonSpacedNode = getFirstNonSpacedToken(leftNode, rightNode, "=");
 
                 if (nonSpacedNode) {
                     report(node, nonSpacedNode);


Test patch:
diff --git a/tests/lib/rules/no-unused-vars.js b/tests/lib/rules/no-unused-vars.js
index f188f8ce3..316df18e0 100644
--- a/tests/lib/rules/no-unused-vars.js
+++ b/tests/lib/rules/no-unused-vars.js
@@ -271,7 +271,11 @@ ruleTester.run("no-unused-vars", rule, {
             code: "(({a, ...rest}) => rest)",
             options: [{ args: "all", ignoreRestSiblings: true }],
             parserOptions: { ecmaVersion: 2018 }
-        }
+        },
+
+        // https://github.com/eslint/eslint/issues/10952
+        "/*eslint use-every-a:1*/ !function(b, a) { return 1 }"
+
     ],
     invalid: [
         { code: "function foox() { return foox(); }", errors: [definedError("foox")] },
diff --git a/tests/lib/rules/one-var.js b/tests/lib/rules/one-var.js
index b628f512a..e5470d2e9 100644
--- a/tests/lib/rules/one-var.js
+++ b/tests/lib/rules/one-var.js
@@ -949,6 +949,17 @@ ruleTester.run("one-var", rule, {
                 column: 1
             }]
         },
+        {
+            code: "var a = 1, b = 2",
+            output: "var a = 1; var b = 2",
+            options: ["never"],
+            errors: [{
+                message: "Split 'var' declarations into multiple statements.",
+                type: "VariableDeclaration",
+                line: 1,
+                column: 1
+            }]
+        },
         {
             code: "var foo = require('foo'), bar;",
             output: null,