fix: turbopack RSC detection (#6405)

packages/payload/src/utilities/isReactComponent.ts

@@ -2,6 +2,22 @@ import type React from 'react'
 
 import { isPlainObject } from './isPlainObject.js'
 
+/*
+For reference: console.log output of [ClientComponent, RSC] array, tested in Turbo and Webpack (14.3.0-canary.37)
+
+Both component functions async:
+
+Turbo: [ [Function (anonymous)], [AsyncFunction: ExampleServer] ]
+Webpack: [ {}, [AsyncFunction: ExampleServer] ]
+
+
+Both component functions non-async:
+
+Turbo:  [ [Function (anonymous)], [Function: ExampleServer] ]
+Webpack:  [ {}, [Function: ExampleServer] ]
+
+ */
+
 export function isReactServerComponentOrFunction<T extends any>(
   component: React.ComponentType | any,
 ): component is T {
@@ -13,14 +29,19 @@ export function isReactServerComponentOrFunction<T extends any>(
   const isFunctionalComponent =
     typeof component === 'function' && (!component.prototype || !component.prototype.render)
 
-  return isClassComponent || isFunctionalComponent
+  // Anonymous functions are Client Components in Turbopack. RSCs should have a name
+  const isAnonymousFunction = component.name === ''
+
+  return (isClassComponent || isFunctionalComponent) && !isAnonymousFunction
 }
 
 export function isReactClientComponent<T extends any>(
   component: React.ComponentType | any,
 ): component is T {
-  // Do this to test for client components (`use client` directive) bc they import as empty objects
-  return typeof component === 'object' && !isPlainObject(component)
+  const isClientComponentWebpack = typeof component === 'object' && !isPlainObject(component) // In Webpack, client components are {}
+  const isClientComponentTurbo = typeof component === 'function' && component.name === '' // Anonymous functions are Client Components in Turbopack
+
+  return isClientComponentWebpack || isClientComponentTurbo
 }
 
 export function isReactComponentOrFunction<T extends any>(