Fix tracking of ContextModule (#52795)

When doing dynamic imports like `import(variable)`, Webpack _tries_ to statically analyze it and creates a regex like context module for it (which includes all possible modules). This `ContextModule` doesn't have a resource path so we need to use the identifier to track it.

Tested with @alexkirsz's repro here #50243 (comment) and confirmed that it fixes the problem.

Closes #50243.

packages/next/src/build/webpack/plugins/flight-client-entry-plugin.ts

@@ -586,9 +586,14 @@ export class FlightClientEntryPlugin {
       // We have to always use the resolved request here to make sure the
       // server and client are using the same module path (required by RSC), as
       // the server compiler and client compiler have different resolve configs.
-      const modRequest: string | undefined =
+      let modRequest: string | undefined =
         mod.resourceResolveData?.path + mod.resourceResolveData?.query
 
+      // Context modules don't have a resource path, we use the identifier instead.
+      if (mod.constructor.name === 'ContextModule') {
+        modRequest = (mod as any)._identifier
+      }
+
       if (!modRequest || visited.has(modRequest)) return
       visited.add(modRequest)
 

test/e2e/app-dir/rsc-basic/app/dynamic/_dynamic.js

@@ -0,0 +1,8 @@
+'use client'
+
+import { useState } from 'react'
+
+export default function Dynamic() {
+  const [data] = useState('dynamic data!')
+  return <h1>{data}</h1>
+}

test/e2e/app-dir/rsc-basic/app/dynamic/page.js

@@ -0,0 +1,5 @@
+export default async function Page() {
+  const dynamic = '_dynamic'
+  const { default: Component } = await import(`./${dynamic}.js`)
+  return <Component />
+}

test/e2e/app-dir/rsc-basic/rsc-basic.test.ts

@@ -193,6 +193,11 @@ createNextDescribe(
       expect(content).toMatchInlineSnapshot('"next_streaming_data"')
     })
 
+    it('should track client components in dynamic imports', async () => {
+      const html = await next.render('/dynamic')
+      expect(html).toContain('dynamic data!')
+    })
+
     it('should support next/link in server components', async () => {
       const $ = await next.render$('/next-api/link')
       const linkText = $('body a[href="/root"]').text()