feat: add config.keep_names option (#8771)

---------

Co-authored-by: Somhairle MacLeòid <[email protected]>

Author: dario-piotrowicz

.changeset/long-mugs-pull.md

@@ -0,0 +1,20 @@
+---
+"wrangler": minor
+---
+
+feat: add `config.keep_names` option
+
+Adds a new option to Wrangler to allow developers to opt out of esbuild's `keep_names` option (https://esbuild.github.io/api/#keep-names). By default, Wrangler sets this to `true`
+
+This is something developers should not usually need to care about, but sometimes
+`keep_names` can create issues, and in such cases they will be now able to opt-out.
+
+Example `wrangler.jsonc`:
+
+```json
+{
+	"name": "my-worker",
+	"main": "src/worker.ts",
+	"keep_names": false
+}
+```

packages/wrangler/src/__tests__/deploy.test.ts

@@ -6571,6 +6571,84 @@ addEventListener('fetch', event => {});`
 			`);
 			expect(std.err).toMatchInlineSnapshot(`""`);
 		});
+
+		it("should apply esbuild's keep-names functionality by default", async () => {
+			writeWranglerConfig({
+				main: "./index.js",
+				legacy_env: false,
+				env: {
+					testEnv: {},
+				},
+			});
+			fs.writeFileSync(
+				"./index.js",
+				`
+				export
+					default {
+						fetch() {
+							function sayHello() {
+								return "Hello World with keep_names";
+							}
+							return new Response(sayHello());
+					}
+				}
+				`
+			);
+
+			const underscoreUnderscoreNameRegex = /__name\(.*?\)/;
+
+			mockUploadWorkerRequest({
+				env: "testEnv",
+				expectedType: "esm",
+				legacyEnv: false,
+				expectedEntry: (str) => {
+					expect(str).toMatch(underscoreUnderscoreNameRegex);
+				},
+			});
+
+			mockSubDomainRequest();
+			await runWrangler("deploy -e testEnv index.js");
+		});
+
+		it("should apply esbuild's keep-names functionality unless keep_names is set to false", async () => {
+			writeWranglerConfig({
+				main: "./index.js",
+				legacy_env: false,
+				env: {
+					testEnv: {
+						keep_names: false,
+					},
+				},
+			});
+			fs.writeFileSync(
+				"./index.js",
+				`
+				export
+					default {
+						fetch() {
+							function sayHello() {
+								return "Hello World without keep_names";
+							}
+							return new Response(sayHello());
+					}
+				}
+				`
+			);
+
+			const underscoreUnderscoreNameRegex = /__name\(.*?\)/;
+
+			mockUploadWorkerRequest({
+				env: "testEnv",
+				expectedType: "esm",
+				legacyEnv: false,
+				expectedEntry: (str) => {
+					expect(str).not.toMatch(underscoreUnderscoreNameRegex);
+				},
+			});
+
+			mockSubDomainRequest();
+			await runWrangler("deploy -e testEnv index.js");
+		});
 	});
 
 	describe("durable object migrations", () => {

packages/wrangler/src/api/startDevWorker/BundlerController.ts

@@ -117,6 +117,7 @@ export class BundlerController extends Controller<BundlerControllerEventMap> {
 						jsxFragment: config.build.jsxFactory,
 						tsconfig: config.build.tsconfig,
 						minify: config.build.minify,
+						keepNames: config.build.keepNames ?? true,
 						nodejsCompatMode: config.build.nodejsCompatMode,
 						define: config.build.define,
 						checkFetch: shouldCheckFetch(
@@ -246,6 +247,7 @@ export class BundlerController extends Controller<BundlerControllerEventMap> {
 				rules: config.build.moduleRules,
 				tsconfig: config.build?.tsconfig,
 				minify: config.build?.minify,
+				keepNames: config.build?.keepNames ?? true,
 				nodejsCompatMode: config.build.nodejsCompatMode,
 				define: config.build.define,
 				alias: config.build.alias,

packages/wrangler/src/api/startDevWorker/ConfigController.ts

@@ -289,6 +289,7 @@ async function resolveConfig(
 			moduleRules: input.build?.moduleRules ?? getRules(config),
 
 			minify: input.build?.minify ?? config.minify,
+			keepNames: input.build?.keepNames ?? config.keep_names,
 			define: { ...config.define, ...input.build?.define },
 			custom: {
 				command: input.build?.custom?.command ?? config.build?.command,

packages/wrangler/src/api/startDevWorker/types.ts

@@ -108,6 +108,8 @@ export interface StartDevWorkerInput {
 		alias?: Record<string, string>;
 		/** Whether the bundled worker is minified. Only takes effect if bundle: true. */
 		minify?: boolean;
+		/** Whether to keep function names after JavaScript transpilations. */
+		keepNames?: boolean;
 		/** Options controlling a custom build step. */
 		custom?: {
 			/** Custom shell command to run before bundling. Runs even if bundle. */

packages/wrangler/src/config/config.ts

@@ -332,6 +332,7 @@ export const defaultWranglerConfig: Config = {
 	build: { command: undefined, watch_dir: "./src", cwd: undefined },
 	no_bundle: undefined,
 	minify: undefined,
+	keep_names: undefined,
 	dispatch_namespaces: [],
 	first_party_worker: undefined,
 	logfwdr: { bindings: [] },

packages/wrangler/src/config/environment.ts

@@ -306,6 +306,14 @@ interface EnvironmentInheritable {
 	 */
 	minify: boolean | undefined;
 
+	/**
+	 * Keep function names after javascript transpilations.
+	 *
+	 * @default {true}
+	 * @inheritable
+	 */
+	keep_names: boolean | undefined;
+
 	/**
 	 * Designates this Worker as an internal-only "first-party" Worker.
 	 *

packages/wrangler/src/config/validation.ts

@@ -1417,6 +1417,14 @@ function normalizeAndValidateEnvironment(
 			isBoolean,
 			undefined
 		),
+		keep_names: inheritable(
+			diagnostics,
+			topLevelEnv,
+			rawEnv,
+			"keep_names",
+			isBoolean,
+			undefined
+		),
 		first_party_worker: inheritable(
 			diagnostics,
 			topLevelEnv,

packages/wrangler/src/deploy/deploy.ts

@@ -558,6 +558,7 @@ See https://developers.cloudflare.com/workers/platform/compatibility-dates for m
 						jsxFragment,
 						tsconfig: props.tsconfig ?? config.tsconfig,
 						minify,
+						keepNames: config.keep_names ?? true,
 						sourcemap: uploadSourceMaps,
 						nodejsCompatMode,
 						define: { ...config.define, ...props.defines },

packages/wrangler/src/deployment-bundle/bundle.ts

@@ -120,6 +120,7 @@ export type BundleOptions = {
 	watch: boolean | undefined;
 	tsconfig: string | undefined;
 	minify: boolean | undefined;
+	keepNames: boolean;
 	nodejsCompatMode: NodeJSCompatMode | undefined;
 	define: Config["define"];
 	alias: Config["alias"];
@@ -154,6 +155,7 @@ export async function bundleWorker(
 		watch,
 		tsconfig,
 		minify,
+		keepNames,
 		nodejsCompatMode,
 		alias,
 		define,
@@ -353,7 +355,7 @@ export async function bundleWorker(
 		bundle,
 		absWorkingDir: entry.projectRoot,
 		outdir: destination,
-		keepNames: true,
+		keepNames,
 		entryNames: entryName || path.parse(entryFile).name,
 		...(isOutfile
 			? {