fix(core): throw when importing twice

this should make it easier to detect build misconfigurations

Author: wmertens

packages/qwik-router/src/ssg/worker-thread.ts

@@ -14,6 +14,9 @@ import type {
 } from './types';
 
 export async function workerThread(sys: System) {
+  // Special case: we allow importing qwik again in the same process, it's ok because we just needed the serializer
+  // TODO: remove this once we have vite environment API and no longer need the serializer separately
+  delete (globalThis as any).__qwik;
   const ssgOpts = sys.getOptions();
   const pendingPromises = new Set<Promise<any>>();
 
@@ -42,6 +45,9 @@ export async function workerThread(sys: System) {
 }
 
 export async function createSingleThreadWorker(sys: System) {
+  // Special case: we allow importing qwik again in the same process, it's ok because we just needed the serializer
+  // TODO: remove this once we have vite environment API and no longer need the serializer separately
+  delete (globalThis as any).__qwik;
   const ssgOpts = sys.getOptions();
   const pendingPromises = new Set<Promise<any>>();
 

packages/qwik/src/core/index.ts

@@ -1,3 +1,16 @@
+//////////////////////////////////////////////////////////////////////////////////////////
+// Protect against duplicate imports
+//////////////////////////////////////////////////////////////////////////////////////////
+import { version } from './version';
+if ((globalThis as any).__qwik) {
+  console.error(
+    `==============================================\n` +
+      `Qwik version ${(globalThis as any).__qwik} already imported while importing ${version}. Verify external vs bundled imports etc. This can lead to issues due to duplicated shared structures.\n` +
+      `==============================================\n`
+  );
+}
+(globalThis as any).__qwik = version;
+
 //////////////////////////////////////////////////////////////////////////////////////////
 // Developer Core API
 //////////////////////////////////////////////////////////////////////////////////////////

starters/dev-server.ts

@@ -271,7 +271,8 @@ async function routerApp(
   appDir: string,
 ) {
   const ssrPath = join(appDir, "server", `${qwikRouterVirtualEntry}.js`);
-
+  // it's ok in the devserver to import core multiple times
+  (globalThis as any).__qwik = null;
   const mod = await import(file(ssrPath));
   const router: any = mod.router;
   router(req, res, () => {
@@ -289,6 +290,8 @@ async function ssrApp(
   manifest: QwikManifest,
 ) {
   const ssrPath = join(appDir, "server", "entry.ssr.js");
+  // it's ok in the devserver to import core multiple times
+  (globalThis as any).__qwik = null;
   const mod = await import(file(ssrPath));
   const render: Render = mod.default ?? mod.render;