Fix: autofix shouldn't produce template literals with \8 or \9

lib/rules/utils/ast-utils.js

@@ -38,7 +38,9 @@ const LINEBREAKS = new Set(["\r\n", "\r", "\n", "\u2028", "\u2029"]);
 const STATEMENT_LIST_PARENTS = new Set(["Program", "BlockStatement", "SwitchCase"]);
 
 const DECIMAL_INTEGER_PATTERN = /^(?:0|0[0-7]*[89]\d*|[1-9](?:_?\d)*)$/u;
-const OCTAL_ESCAPE_PATTERN = /^(?:[^\\]|\\[^0-7]|\\0(?![0-9]))*\\(?:[1-7]|0[0-9])/u;
+
+// Test for presence of at least one LegacyOctalEscapeSequence or NonOctalDecimalEscapeSequence in a raw string
+const OCTAL_OR_NON_OCTAL_DECIMAL_ESCAPE_PATTERN = /^(?:[^\\]|\\.)*\\(?:[1-9]|0[0-9])/su;
 
 const LOGICAL_ASSIGNMENT_OPERATORS = new Set(["&&=", "||=", "??="]);
 
@@ -1766,17 +1768,19 @@ module.exports = {
     },
 
     /**
-     * Determines whether the given raw string contains an octal escape sequence.
+     * Determines whether the given raw string contains an octal escape sequence
+     * or a non-octal decimal escape sequence ("\8", "\9").
      *
-     * "\1", "\2" ... "\7"
-     * "\00", "\01" ... "\09"
+     * "\1", "\2" ... "\7", "\8", "\9"
+     * "\00", "\01" ... "\07", "\08", "\09"
      *
      * "\0", when not followed by a digit, is not an octal escape sequence.
      * @param {string} rawString A string in its raw representation.
-     * @returns {boolean} `true` if the string contains at least one octal escape sequence.
+     * @returns {boolean} `true` if the string contains at least one octal escape sequence
+     * or at least one non-octal decimal escape sequence.
      */
     hasOctalEscapeSequence(rawString) {
-        return OCTAL_ESCAPE_PATTERN.test(rawString);
+        return OCTAL_OR_NON_OCTAL_DECIMAL_ESCAPE_PATTERN.test(rawString);
     },
 
     isLogicalExpression,

tests/lib/rules/prefer-template.js

@@ -194,6 +194,11 @@ ruleTester.run("prefer-template", rule, {
             output: null,
             errors
         },
+        {
+            code: "foo + 'does not autofix non-octal decimal escape sequence' + '\\8'",
+            output: null,
+            errors
+        },
         {
             code: "foo + '\\n other text \\033'",
             output: null,

tests/lib/rules/quotes.js

@@ -614,6 +614,19 @@ ruleTester.run("quotes", rule, {
                     type: "Literal"
                 }
             ]
+        },
+        {
+            code: "var nonOctalDecimalEscape = '\\8'",
+            output: null,
+            options: ["backtick"],
+            parserOptions: { ecmaVersion: 6 },
+            errors: [
+                {
+                    messageId: "wrongQuotes",
+                    data: { description: "backtick" },
+                    type: "Literal"
+                }
+            ]
         }
     ]
 });

tests/lib/rules/utils/ast-utils.js

@@ -1680,27 +1680,31 @@ describe("ast-utils", () => {
             "\\\\\\1": true,
             "\\\\\\01": true,
             "\\\\\\08": true,
+            "\\8": true,
+            "\\9": true,
+            "a\\8a": true,
+            "\\0\\8": true,
+            "\\8\\0": true,
+            "\\80": true,
+            "\\81": true,
+            "\\\\\\8": true,
+            "\\\n\\1": true,
+            "foo\\\nbar\\2baz": true,
+            "\\\n\\8": true,
+            "foo\\\nbar\\9baz": true,
 
             "\\0": false,
-            "\\8": false,
-            "\\9": false,
             " \\0": false,
             "\\0 ": false,
             "a\\0": false,
             "\\0a": false,
-            "a\\8a": false,
-            "\\0\\8": false,
-            "\\8\\0": false,
-            "\\80": false,
-            "\\81": false,
             "\\\\": false,
             "\\\\0": false,
             "\\\\01": false,
             "\\\\08": false,
             "\\\\1": false,
             "\\\\12": false,
             "\\\\\\0": false,
-            "\\\\\\8": false,
             "\\0\\\\": false,
             "0": false,
             "1": false,
@@ -1710,7 +1714,10 @@ describe("ast-utils", () => {
             "80": false,
             "12": false,
             "\\a": false,
-            "\\n": false
+            "\\n": false,
+            "\\\n": false,
+            "foo\\\nbar": false,
+            "128\\\n349": false
         };
         /* eslint-enable quote-props */