fix(rsc): fix custom root

packages/plugin-rsc/e2e/root.test.ts

@@ -0,0 +1,47 @@
+import { test } from '@playwright/test'
+import { setupInlineFixture, useFixture } from './fixture'
+import { defineStarterTest } from './starter'
+import fs from 'node:fs'
+import path from 'node:path'
+
+test.describe(() => {
+  const root = 'examples/e2e/temp/root'
+
+  test.beforeAll(async () => {
+    await setupInlineFixture({
+      src: 'examples/starter',
+      dest: root,
+      files: {
+        'vite.config.base.ts': { cp: 'vite.config.ts' },
+        'vite.config.ts': /* js */ `
+          import baseConfig from './vite.config.base.ts'
+          import path from "node:path";
+          baseConfig.root = "./custom-root";
+          for (const e of Object.values(baseConfig.environments)) {
+            e.build.rollupOptions.input.index = path.resolve(
+              'custom-root',
+              e.build.rollupOptions.input.index,
+          );
+          }
+          export default baseConfig;
+        `,
+      },
+    })
+    fs.mkdirSync(`${root}/custom-root`, { recursive: true })
+    fs.renameSync(`${root}/src`, `${root}/custom-root/src`)
+    fs.renameSync(`${root}/public`, `${root}/custom-root/public`)
+  })
+
+  test.describe('dev-root', () => {
+    const f = useFixture({ root, mode: 'dev' })
+    const oldCreateEditor = f.createEditor
+    f.createEditor = (filePath: string) =>
+      oldCreateEditor(path.resolve(root, 'custom-root', filePath))
+    defineStarterTest(f)
+  })
+
+  test.describe('build-root', () => {
+    const f = useFixture({ root, mode: 'build' })
+    defineStarterTest(f)
+  })
+})

packages/plugin-rsc/src/plugin.ts

@@ -165,6 +165,11 @@ export function vitePluginRscMinimal(
       },
       configResolved(config_) {
         config = config_
+        // ensure outDir is fully resolved to take custom root into account
+        // https://github.com/vitejs/vite/blob/946831f986cb797009b8178659d2b31f570c44ff/packages/vite/src/node/build.ts#L574
+        for (const e of Object.values(config.environments)) {
+          e.build.outDir = path.resolve(config.root, e.build.outDir)
+        }
       },
       configureServer(server_) {
         server = server_