tools: update ESLint to 6.1.0

Update ESLint to 6.1.0

PR-URL: https://github.com/nodejs/node/pull/28793
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

6 files changed, 311 insertions, 41 deletions

diff --git a/tools/node_modules/eslint/lib/rules/arrow-body-style.js b/tools/node_modules/eslint/lib/rules/arrow-body-style.js
index 6d84c7adfb..8d3b400037 100644
--- a/tools/node_modules/eslint/lib/rules/arrow-body-style.js
+++ b/tools/node_modules/eslint/lib/rules/arrow-body-style.js
@@ -175,10 +175,10 @@ module.exports = {
                             }
 
                             /*
-                             * If the first token of the reutrn value is `{`,
+                             * If the first token of the reutrn value is `{` or the return value is a sequence expression,
                              * enclose the return value by parentheses to avoid syntax error.
                              */
-                            if (astUtils.isOpeningBraceToken(firstValueToken)) {
+                            if (astUtils.isOpeningBraceToken(firstValueToken) || blockBody[0].argument.type === "SequenceExpression") {
                                 fixes.push(
                                     fixer.insertTextBefore(firstValueToken, "("),
                                     fixer.insertTextAfter(lastValueToken, ")")
diff --git a/tools/node_modules/eslint/lib/rules/dot-location.js b/tools/node_modules/eslint/lib/rules/dot-location.js
index b9857ae239..c2e734a1a0 100644
--- a/tools/node_modules/eslint/lib/rules/dot-location.js
+++ b/tools/node_modules/eslint/lib/rules/dot-location.js
@@ -54,29 +54,31 @@ module.exports = {
          */
         function checkDotLocation(obj, prop, node) {
             const dot = sourceCode.getTokenBefore(prop);
-            const textBeforeDot = sourceCode.getText().slice(obj.range[1], dot.range[0]);
+
+            // `obj` expression can be parenthesized, but those paren tokens are not a part of the `obj` node.
+            const tokenBeforeDot = sourceCode.getTokenBefore(dot);
+
+            const textBeforeDot = sourceCode.getText().slice(tokenBeforeDot.range[1], dot.range[0]);
             const textAfterDot = sourceCode.getText().slice(dot.range[1], prop.range[0]);
 
-            if (dot.type === "Punctuator" && dot.value === ".") {
-                if (onObject) {
-                    if (!astUtils.isTokenOnSameLine(obj, dot)) {
-                        const neededTextAfterObj = astUtils.isDecimalInteger(obj) ? " " : "";
-
-                        context.report({
-                            node,
-                            loc: dot.loc.start,
-                            messageId: "expectedDotAfterObject",
-                            fix: fixer => fixer.replaceTextRange([obj.range[1], prop.range[0]], `${neededTextAfterObj}.${textBeforeDot}${textAfterDot}`)
-                        });
-                    }
-                } else if (!astUtils.isTokenOnSameLine(dot, prop)) {
+            if (onObject) {
+                if (!astUtils.isTokenOnSameLine(tokenBeforeDot, dot)) {
+                    const neededTextAfterToken = astUtils.isDecimalIntegerNumericToken(tokenBeforeDot) ? " " : "";
+
                     context.report({
                         node,
                         loc: dot.loc.start,
-                        messageId: "expectedDotBeforeProperty",
-                        fix: fixer => fixer.replaceTextRange([obj.range[1], prop.range[0]], `${textBeforeDot}${textAfterDot}.`)
+                        messageId: "expectedDotAfterObject",
+                        fix: fixer => fixer.replaceTextRange([tokenBeforeDot.range[1], prop.range[0]], `${neededTextAfterToken}.${textBeforeDot}${textAfterDot}`)
                     });
                 }
+            } else if (!astUtils.isTokenOnSameLine(dot, prop)) {
+                context.report({
+                    node,
+                    loc: dot.loc.start,
+                    messageId: "expectedDotBeforeProperty",
+                    fix: fixer => fixer.replaceTextRange([tokenBeforeDot.range[1], prop.range[0]], `${textBeforeDot}${textAfterDot}.`)
+                });
             }
         }
 
@@ -86,7 +88,9 @@ module.exports = {
          * @returns {void}
          */
         function checkNode(node) {
-            checkDotLocation(node.object, node.property, node);
+            if (!node.computed) {
+                checkDotLocation(node.object, node.property, node);
+            }
         }
 
         return {
diff --git a/tools/node_modules/eslint/lib/rules/no-extra-parens.js b/tools/node_modules/eslint/lib/rules/no-extra-parens.js
index 98fc49654c..6c3198b5f0 100644
--- a/tools/node_modules/eslint/lib/rules/no-extra-parens.js
+++ b/tools/node_modules/eslint/lib/rules/no-extra-parens.js
@@ -81,6 +81,8 @@ module.exports = {
         const PRECEDENCE_OF_ASSIGNMENT_EXPR = precedence({ type: "AssignmentExpression" });
         const PRECEDENCE_OF_UPDATE_EXPR = precedence({ type: "UpdateExpression" });
 
+        let reportsBuffer;
+
         /**
          * Determines if this rule should be enforced for a node given the current configuration.
          * @param {ASTNode} node - The node to be checked.
@@ -316,19 +318,33 @@ module.exports = {
                 }
             }
 
-            context.report({
-                node,
-                loc: leftParenToken.loc.start,
-                messageId: "unexpected",
-                fix(fixer) {
-                    const parenthesizedSource = sourceCode.text.slice(leftParenToken.range[1], rightParenToken.range[0]);
+            /**
+             * Finishes reporting
+             * @returns {void}
+             * @private
+             */
+            function finishReport() {
+                context.report({
+                    node,
+                    loc: leftParenToken.loc.start,
+                    messageId: "unexpected",
+                    fix(fixer) {
+                        const parenthesizedSource = sourceCode.text.slice(leftParenToken.range[1], rightParenToken.range[0]);
+
+                        return fixer.replaceTextRange([
+                            leftParenToken.range[0],
+                            rightParenToken.range[1]
+                        ], (requiresLeadingSpace(node) ? " " : "") + parenthesizedSource + (requiresTrailingSpace(node) ? " " : ""));
+                    }
+                });
+            }
 
-                    return fixer.replaceTextRange([
-                        leftParenToken.range[0],
-                        rightParenToken.range[1]
-                    ], (requiresLeadingSpace(node) ? " " : "") + parenthesizedSource + (requiresTrailingSpace(node) ? " " : ""));
-                }
-            });
+            if (reportsBuffer) {
+                reportsBuffer.reports.push({ node, finishReport });
+                return;
+            }
+
+            finishReport();
         }
 
         /**
@@ -498,6 +514,126 @@ module.exports = {
             }
         }
 
+        /**
+         * Finds the path from the given node to the specified ancestor.
+         * @param {ASTNode} node First node in the path.
+         * @param {ASTNode} ancestor Last node in the path.
+         * @returns {ASTNode[]} Path, including both nodes.
+         * @throws {Error} If the given node does not have the specified ancestor.
+         */
+        function pathToAncestor(node, ancestor) {
+            const path = [node];
+            let currentNode = node;
+
+            while (currentNode !== ancestor) {
+
+                currentNode = currentNode.parent;
+
+                /* istanbul ignore if */
+                if (currentNode === null) {
+                    throw new Error("Nodes are not in the ancestor-descendant relationship.");
+                }
+
+                path.push(currentNode);
+            }
+
+            return path;
+        }
+
+        /**
+         * Finds the path from the given node to the specified descendant.
+         * @param {ASTNode} node First node in the path.
+         * @param {ASTNode} descendant Last node in the path.
+         * @returns {ASTNode[]} Path, including both nodes.
+         * @throws {Error} If the given node does not have the specified descendant.
+         */
+        function pathToDescendant(node, descendant) {
+            return pathToAncestor(descendant, node).reverse();
+        }
+
+        /**
+         * Checks whether the syntax of the given ancestor of an 'in' expression inside a for-loop initializer
+         * is preventing the 'in' keyword from being interpreted as a part of an ill-formed for-in loop.
+         *
+         * @param {ASTNode} node Ancestor of an 'in' expression.
+         * @param {ASTNode} child Child of the node, ancestor of the same 'in' expression or the 'in' expression itself.
+         * @returns {boolean} True if the keyword 'in' would be interpreted as the 'in' operator, without any parenthesis.
+         */
+        function isSafelyEnclosingInExpression(node, child) {
+            switch (node.type) {
+                case "ArrayExpression":
+                case "ArrayPattern":
+                case "BlockStatement":
+                case "ObjectExpression":
+                case "ObjectPattern":
+                case "TemplateLiteral":
+                    return true;
+                case "ArrowFunctionExpression":
+                case "FunctionExpression":
+                    return node.params.includes(child);
+                case "CallExpression":
+                case "NewExpression":
+                    return node.arguments.includes(child);
+                case "MemberExpression":
+                    return node.computed && node.property === child;
+                case "ConditionalExpression":
+                    return node.consequent === child;
+                default:
+                    return false;
+            }
+        }
+
+        /**
+         * Starts a new reports buffering. Warnings will be stored in a buffer instead of being reported immediately.
+         * An additional logic that requires multiple nodes (e.g. a whole subtree) may dismiss some of the stored warnings.
+         *
+         * @returns {void}
+         */
+        function startNewReportsBuffering() {
+            reportsBuffer = {
+                upper: reportsBuffer,
+                inExpressionNodes: [],
+                reports: []
+            };
+        }
+
+        /**
+         * Ends the current reports buffering.
+         * @returns {void}
+         */
+        function endCurrentReportsBuffering() {
+            const { upper, inExpressionNodes, reports } = reportsBuffer;
+
+            if (upper) {
+                upper.inExpressionNodes.push(...inExpressionNodes);
+                upper.reports.push(...reports);
+            } else {
+
+                // flush remaining reports
+                reports.forEach(({ finishReport }) => finishReport());
+            }
+
+            reportsBuffer = upper;
+        }
+
+        /**
+         * Checks whether the given node is in the current reports buffer.
+         * @param {ASTNode} node Node to check.
+         * @returns {boolean} True if the node is in the current buffer, false otherwise.
+         */
+        function isInCurrentReportsBuffer(node) {
+            return reportsBuffer.reports.some(r => r.node === node);
+        }
+
+        /**
+         * Removes the given node from the current reports buffer.
+         * @param {ASTNode} node Node to remove.
+         * @returns {void}
+         */
+        function removeFromCurrentReportsBuffer(node) {
+            reportsBuffer.reports = reportsBuffer.reports.filter(r => r.node !== node);
+        }
+
         return {
             ArrayExpression(node) {
                 node.elements
@@ -540,7 +676,14 @@ module.exports = {
                 }
             },
 
-            BinaryExpression: checkBinaryLogical,
+            BinaryExpression(node) {
+                if (reportsBuffer && node.operator === "in") {
+                    reportsBuffer.inExpressionNodes.push(node);
+                }
+
+                checkBinaryLogical(node);
+            },
+
             CallExpression: checkCallNew,
 
             ConditionalExpression(node) {
@@ -602,10 +745,6 @@ module.exports = {
             },
 
             ForStatement(node) {
-                if (node.init && hasExcessParens(node.init)) {
-                    report(node.init);
-                }
-
                 if (node.test && hasExcessParens(node.test) && !isCondAssignException(node)) {
                     report(node.test);
                 }
@@ -613,6 +752,81 @@ module.exports = {
                 if (node.update && hasExcessParens(node.update)) {
                     report(node.update);
                 }
+
+                if (node.init) {
+                    startNewReportsBuffering();
+
+                    if (hasExcessParens(node.init)) {
+                        report(node.init);
+                    }
+                }
+            },
+
+            "ForStatement > *.init:exit"(node) {
+
+                /*
+                 * Removing parentheses around `in` expressions might change semantics and cause errors.
+                 *
+                 * For example, this valid for loop:
+                 *      for (let a = (b in c); ;);
+                 * after removing parentheses would be treated as an invalid for-in loop:
+                 *      for (let a = b in c; ;);
+                 */
+
+                if (reportsBuffer.reports.length) {
+                    reportsBuffer.inExpressionNodes.forEach(inExpressionNode => {
+                        const path = pathToDescendant(node, inExpressionNode);
+                        let nodeToExclude;
+
+                        for (let i = 0; i < path.length; i++) {
+                            const pathNode = path[i];
+
+                            if (i < path.length - 1) {
+                                const nextPathNode = path[i + 1];
+
+                                if (isSafelyEnclosingInExpression(pathNode, nextPathNode)) {
+
+                                    // The 'in' expression in safely enclosed by the syntax of its ancestor nodes (e.g. by '{}' or '[]').
+                                    return;
+                                }
+                            }
+
+                            if (isParenthesised(pathNode)) {
+                                if (isInCurrentReportsBuffer(pathNode)) {
+
+                                    // This node was supposed to be reported, but parentheses might be necessary.
+
+                                    if (isParenthesisedTwice(pathNode)) {
+
+                                        /*
+                                         * This node is parenthesised twice, it certainly has at least one pair of `extra` parentheses.
+                                         * If the --fix option is on, the current fixing iteration will remove only one pair of parentheses.
+                                         * The remaining pair is safely enclosing the 'in' expression.
+                                         */
+                                        return;
+                                    }
+
+                                    // Exclude the outermost node only.
+                                    if (!nodeToExclude) {
+                                        nodeToExclude = pathNode;
+                                    }
+
+                                    // Don't break the loop here, there might be some safe nodes or parentheses that will stay inside.
+
+                                } else {
+
+                                    // This node will stay parenthesised, the 'in' expression in safely enclosed by '()'.
+                                    return;
+                                }
+                            }
+                        }
+
+                        // Exclude the node from the list (i.e. treat parentheses as necessary)
+                        removeFromCurrentReportsBuffer(nodeToExclude);
+                    });
+                }
+
+                endCurrentReportsBuffering();
             },
 
             IfStatement(node) {
@@ -664,6 +878,16 @@ module.exports = {
                     }).forEach(property => report(property.value));
             },
 
+            Property(node) {
+                if (node.computed) {
+                    const { key } = node;
+
+                    if (key && hasExcessParens(key) && precedence(key) >= PRECEDENCE_OF_ASSIGNMENT_EXPR) {
+                        report(key);
+                    }
+                }
+            },
+
             ReturnStatement(node) {
                 const returnToken = sourceCode.getFirstToken(node);
 
diff --git a/tools/node_modules/eslint/lib/rules/no-param-reassign.js b/tools/node_modules/eslint/lib/rules/no-param-reassign.js
index 880ff93cb5..9b8c828d2c 100644
--- a/tools/node_modules/eslint/lib/rules/no-param-reassign.js
+++ b/tools/node_modules/eslint/lib/rules/no-param-reassign.js
@@ -67,7 +67,8 @@ module.exports = {
             let node = reference.identifier;
             let parent = node.parent;
 
-            while (parent && !stopNodePattern.test(parent.type)) {
+            while (parent && (!stopNodePattern.test(parent.type) ||
+                    parent.type === "ForInStatement" || parent.type === "ForOfStatement")) {
                 switch (parent.type) {
 
                     // e.g. foo.a = 0;
@@ -85,6 +86,16 @@ module.exports = {
                         }
                         break;
 
+                    // e.g. for (foo.a in b) {}
+                    case "ForInStatement":
+                    case "ForOfStatement":
+                        if (parent.left === node) {
+                            return true;
+                        }
+
+                        // this is a stop node for parent.right and parent.body
+                        return false;
+
                     // EXCLUDES: e.g. cache.get(foo.a).b = 0;
                     case "CallExpression":
                         if (parent.callee !== node) {
diff --git a/tools/node_modules/eslint/lib/rules/prefer-const.js b/tools/node_modules/eslint/lib/rules/prefer-const.js
index 68c07da4ed..854da310e4 100644
--- a/tools/node_modules/eslint/lib/rules/prefer-const.js
+++ b/tools/node_modules/eslint/lib/rules/prefer-const.js
@@ -420,8 +420,9 @@ module.exports = {
 
                 let shouldFix = varDeclParent &&
 
-                    // Don't do a fix unless the variable is initialized (or it's in a for-in or for-of loop)
-                    (varDeclParent.parent.type === "ForInStatement" || varDeclParent.parent.type === "ForOfStatement" || varDeclParent.declarations[0].init) &&
+                    // Don't do a fix unless all variables in the declarations are initialized (or it's in a for-in or for-of loop)
+                    (varDeclParent.parent.type === "ForInStatement" || varDeclParent.parent.type === "ForOfStatement" ||
+                        varDeclParent.declarations.every(declaration => declaration.init)) &&
 
                     /*
                      * If options.destructuring is "all", then this warning will not occur unless
@@ -450,7 +451,12 @@ module.exports = {
                         node,
                         messageId: "useConst",
                         data: node,
-                        fix: shouldFix ? fixer => fixer.replaceText(sourceCode.getFirstToken(varDeclParent), "const") : null
+                        fix: shouldFix
+                            ? fixer => fixer.replaceText(
+                                sourceCode.getFirstToken(varDeclParent, t => t.value === varDeclParent.kind),
+                                "const"
+                            )
+                            : null
                     });
                 });
             }
diff --git a/tools/node_modules/eslint/lib/rules/utils/ast-utils.js b/tools/node_modules/eslint/lib/rules/utils/ast-utils.js
index 1aef4c162d..78ae7bc015 100644
--- a/tools/node_modules/eslint/lib/rules/utils/ast-utils.js
+++ b/tools/node_modules/eslint/lib/rules/utils/ast-utils.js
@@ -37,6 +37,8 @@ const LINEBREAKS = new Set(["\r\n", "\r", "\n", "\u2028", "\u2029"]);
 // A set of node types that can contain a list of statements
 const STATEMENT_LIST_PARENTS = new Set(["Program", "BlockStatement", "SwitchCase"]);
 
+const DECIMAL_INTEGER_PATTERN = /^(0|[1-9]\d*)$/u;
+
 /**
  * Checks reference if is non initializer and writable.
  * @param {Reference} reference - A reference to check.
@@ -284,6 +286,16 @@ function isCommaToken(token) {
 }
 
 /**
+ * Checks if the given token is a dot token or not.
+ *
+ * @param {Token} token - The token to check.
+ * @returns {boolean} `true` if the token is a dot token.
+ */
+function isDotToken(token) {
+    return token.value === "." && token.type === "Punctuator";
+}
+
+/**
  * Checks if the given token is a semicolon token or not.
  *
  * @param {Token} token - The token to check.
@@ -462,12 +474,14 @@ module.exports = {
     isColonToken,
     isCommaToken,
     isCommentToken,
+    isDotToken,
     isKeywordToken,
     isNotClosingBraceToken: negate(isClosingBraceToken),
     isNotClosingBracketToken: negate(isClosingBracketToken),
     isNotClosingParenToken: negate(isClosingParenToken),
     isNotColonToken: negate(isColonToken),
     isNotCommaToken: negate(isCommaToken),
+    isNotDotToken: negate(isDotToken),
     isNotOpeningBraceToken: negate(isOpeningBraceToken),
     isNotOpeningBracketToken: negate(isOpeningBracketToken),
     isNotOpeningParenToken: negate(isOpeningParenToken),
@@ -988,7 +1002,18 @@ module.exports = {
      * '5'     // false
      */
     isDecimalInteger(node) {
-        return node.type === "Literal" && typeof node.value === "number" && /^(0|[1-9]\d*)$/u.test(node.raw);
+        return node.type === "Literal" && typeof node.value === "number" &&
+            DECIMAL_INTEGER_PATTERN.test(node.raw);
+    },
+
+    /**
+     * Determines whether this token is a decimal integer numeric token.
+     * This is similar to isDecimalInteger(), but for tokens.
+     * @param {Token} token - The token to check.
+     * @returns {boolean} `true` if this token is a decimal integer.
+     */
+    isDecimalIntegerNumericToken(token) {
+        return token.type === "Numeric" && DECIMAL_INTEGER_PATTERN.test(token.value);
     },
 
     /**