fix(pnp): suppress experimental ESM loader warning

.yarn/versions/53017d46.yml

@@ -0,0 +1,28 @@
+releases:
+  "@yarnpkg/cli": patch
+  "@yarnpkg/plugin-pnp": patch
+  "@yarnpkg/pnp": patch
+
+declined:
+  - "@yarnpkg/esbuild-plugin-pnp"
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/core"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/nm"
+  - "@yarnpkg/pnpify"
+  - "@yarnpkg/sdks"

packages/yarnpkg-pnp/sources/loader/applyPatch.ts

@@ -411,20 +411,27 @@ export function applyPatch(pnpapi: PnpApi, opts: ApplyPatchOptions) {
     originalExtensionJSFunction.call(this, module, filename);
   };
 
-  // When using the ESM loader Node.js prints the following warning
+  // When using the ESM loader Node.js prints either of the following warnings
   //
-  // (node:14632) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
-  // (Use `node --trace-warnings ...` to show where the warning was created)
+  // - ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
+  // - ExperimentalWarning: Custom ESM Loaders is an experimental feature. This feature could change at any time
   //
   // Having this warning show up once is "fine" but it's also printed
   // for each Worker that is created so it ends up spamming stderr.
   // Since that doesn't provide any value we suppress the warning.
-  const originalEmitWarning = process.emitWarning;
-  process.emitWarning = function (warning: string | Error, name?: string | undefined, ctor?: Function | undefined) {
-    if (name === `ExperimentalWarning` && typeof warning === `string` && warning.includes(`--experimental-loader`))
-      return;
+  const originalEmit = process.emit;
+  // @ts-expect-error - TS complains about the return type of originalEmit.apply
+  process.emit = function (name, data, ...args) {
+    if (
+      name === `warning` &&
+      typeof data === `object` &&
+      data.name === `ExperimentalWarning` &&
+      (data.message.includes(`--experimental-loader`) ||
+        data.message.includes(`Custom ESM Loaders is an experimental feature`))
+    )
+      return false;
 
-    originalEmitWarning.apply(process, arguments as any);
+    return originalEmit.apply(process, arguments as unknown as Parameters<typeof process.emit>);
   };
 
   patchFs(fs, new PosixFS(opts.fakeFs));