Fix loading ESM-style shared config file in Node.js 23 (#16857)

* Return `.default` when Node.js 23 module feature is enabled

* Add changelog

* Add `ERR_REQUIRE_ASYNC_MODULE` to ignored error code

changelog_unreleased/api/16857.md

@@ -0,0 +1,12 @@
+#### Fix loading ESM-style shared config file in Node.js 23 (#16857 by @sosukesuzuki)
+
+In Prettier 3.3, attempting to load an ESM-style [shared config file](https://prettier.io/docs/en/sharing-configurations) in Node.js 23 resulted in the following warnings, preventing the options from being loaded:
+
+```
+[warn] Ignored unknown option { __esModule: true }.
+[warn] Ignored unknown option { default: { trailingComma: "es5", tabWidth: 4, singleQuote: true } }.
+```
+
+This issue was caused by a new module feature in Node.js 23, known as [`require(ESM)`](https://nodejs.org/api/modules.html#loading-ecmascript-modules-using-require). Prettier 3.4 resolves this problem, allowing the options to load correctly.
+
+For more details, please see https://github.com/prettier/prettier/issues/16812.

src/config/prettier-config/load-external-config.js

@@ -5,6 +5,7 @@ const requireErrorCodesShouldBeIgnored = new Set([
   "MODULE_NOT_FOUND",
   "ERR_REQUIRE_ESM",
   "ERR_PACKAGE_PATH_NOT_EXPORTED",
+  "ERR_REQUIRE_ASYNC_MODULE",
 ]);
 async function loadExternalConfig(externalConfig, configFile) {
   /*
@@ -15,7 +16,16 @@ async function loadExternalConfig(externalConfig, configFile) {
   3. is a dirname with index.js inside
   */
   try {
-    return requireFromFile(externalConfig, configFile);
+    const required = requireFromFile(externalConfig, configFile);
+    // Since Node.js v23 onwards, it is possible to load ESM using require.
+    // If that feature is enabled, it is necessary to return the default.
+    // https://github.com/prettier/prettier/issues/16812
+    // FIXME: We want to add tests but https://github.com/jestjs/jest/issues/15363 blocks
+    // @ts-expect-error
+    if (process.features.require_module && required.__esModule) {
+      return required.default;
+    }
+    return required;
   } catch (/** @type {any} */ error) {
     if (!requireErrorCodesShouldBeIgnored.has(error?.code)) {
       throw error;