1 files changed, 22 insertions, 1 deletions
diff --git a/tools/node_modules/eslint/lib/rules/operator-assignment.js b/tools/node_modules/eslint/lib/rules/operator-assignment.js
index 63982cf392..e294668b42 100644
--- a/tools/node_modules/eslint/lib/rules/operator-assignment.js
+++ b/tools/node_modules/eslint/lib/rules/operator-assignment.js
@@ -150,6 +150,11 @@ module.exports = {
                                 const leftText = sourceCode.getText().slice(node.range[0], equalsToken.range[0]);
                                 const rightText = sourceCode.getText().slice(operatorToken.range[1], node.right.range[1]);
 
+                                // Check for comments that would be removed.
+                                if (sourceCode.commentsExistBetween(equalsToken, operatorToken)) {
+                                    return null;
+                                }
+
                                 return fixer.replaceText(node, `${leftText}${expr.operator}=${rightText}`);
                             }
                             return null;
@@ -182,11 +187,17 @@ module.exports = {
                     messageId: "unexpected",
                     fix(fixer) {
                         if (canBeFixed(node.left)) {
+                            const firstToken = sourceCode.getFirstToken(node);
                             const operatorToken = getOperatorToken(node);
                             const leftText = sourceCode.getText().slice(node.range[0], operatorToken.range[0]);
                             const newOperator = node.operator.slice(0, -1);
                             let rightText;
 
+                            // Check for comments that would be duplicated.
+                            if (sourceCode.commentsExistBetween(firstToken, operatorToken)) {
+                                return null;
+                            }
+
                             // If this change would modify precedence (e.g. `foo *= bar + 1` => `foo = foo * (bar + 1)`), parenthesize the right side.
                             if (
                                 astUtils.getPrecedence(node.right) <= astUtils.getPrecedence({ type: "BinaryExpression", operator: newOperator }) &&
@@ -194,7 +205,17 @@ module.exports = {
                             ) {
                                 rightText = `${sourceCode.text.slice(operatorToken.range[1], node.right.range[0])}(${sourceCode.getText(node.right)})`;
                             } else {
-                                rightText = sourceCode.text.slice(operatorToken.range[1], node.range[1]);
+                                const firstRightToken = sourceCode.getFirstToken(node.right);
+                                let rightTextPrefix = "";
+
+                                if (
+                                    operatorToken.range[1] === firstRightToken.range[0] &&
+                                    !astUtils.canTokensBeAdjacent(newOperator, firstRightToken)
+                                ) {
+                                    rightTextPrefix = " "; // foo+=+bar -> foo= foo+ +bar
+                                }
+
+                                rightText = `${rightTextPrefix}${sourceCode.text.slice(operatorToken.range[1], node.range[1])}`;
                             }
 
                             return fixer.replaceText(node, `${leftText}= ${leftText}${newOperator}${rightText}`);