🐛 fix getStringIfConstant to handle literals correctly

src/get-string-if-constant.js

@@ -7,6 +7,16 @@ import { getStaticValue } from "./get-static-value"
  * @returns {string|null} The value of the node, or `null`.
  */
 export function getStringIfConstant(node, initialScope = null) {
+    // Handle the literals that the platform doesn't support natively.
+    if (node.type === "Literal" && node.value === null) {
+        if (node.regex) {
+            return `/${node.regex.pattern}/${node.regex.flags}`
+        }
+        if (node.bigint) {
+            return node.bigint
+        }
+    }
+
     const evaluated = getStaticValue(node, initialScope)
     return evaluated && String(evaluated.value)
 }

test/get-string-if-constant.js

@@ -19,6 +19,7 @@ describe("The 'getStringIfConstant' function", () => {
         { code: "`aaa${id}bbb`", expected: null }, //eslint-disable-line no-template-curly-in-string
         { code: "1 + 2", expected: "3" },
         { code: "'a' + 'b'", expected: "ab" },
+        { code: "/(?<a>\\w+)\\k<a>/gu", expected: "/(?<a>\\w+)\\k<a>/gu" },
     ]) {
         it(`should return ${JSON.stringify(expected)} from ${code}`, () => {
             const linter = new eslint.Linter()