Fix incorrect SSG classification for dynamic pages with generateStaticParams

packages/next/src/build/index.ts

@@ -3286,6 +3286,17 @@ export default async function build(
               }
             }
 
+            // After processing all static prerendered routes, check if any had revalidate: 0
+            // and update the parent page accordingly. This handles the case where
+            // generateStaticParams was used but the routes turned out to be dynamic.
+            if (hasRevalidateZero && pageInfos.get(page)?.isSSG) {
+              pageInfos.set(page, {
+                ...(pageInfos.get(page) as PageInfo),
+                isStatic: false,
+                isSSG: false,
+              })
+            }
+
             if (!hasRevalidateZero && isDynamicRoute(page)) {
               // When PPR fallbacks aren't used, we need to include it here. If
               // they are enabled, then it'll already be included in the

test/production/app-dir/build-output-tree-view/build-output-tree-view.test.ts

@@ -67,13 +67,83 @@ describe('build-output-tree-view', () => {
       `)
     })
   })
+
+  describe('with dynamic access and generateStaticParams', () => {
+    describe.each([true, false])('cache components: %s', (cacheComponents) => {
+      const { next } = nextTestSetup({
+        files: path.join(__dirname, 'fixtures/dynamic-generate-static-params'),
+        env: {
+          __NEXT_PRIVATE_DETERMINISTIC_BUILD_OUTPUT: '1',
+        },
+        // We don't skip start in this test because we want to actually hit the
+        // dynamic pages, and starting again would cause the current API to
+        // re-build the app again.
+        nextConfig: {
+          experimental: {
+            cacheComponents,
+          },
+        },
+      })
+
+      it('should mark routes with connection() as dynamic, not SSG', async () => {
+        if (cacheComponents) {
+          // When cache components are enabled, routes with connection() should be
+          // marked as partial prerendered.
+          expect(getTreeView(next.cliOutput)).toMatchInlineSnapshot(`
+           "Route (app)
+           ┌ ○ /_not-found
+           └ ◐ /dynamic/[slug]
+               ├ /dynamic/[slug]
+               ├ /dynamic/slug-01
+               ├ /dynamic/slug-02
+               └ /dynamic/slug-03
+
+
+           ○  (Static)             prerendered as static content
+           ◐  (Partial Prerender)  prerendered as static HTML with dynamic server-streamed content"
+          `)
+        } else {
+          // Routes with generateStaticParams that use connection() should be marked as dynamic
+          // because connection() makes the page dynamic. This is a regression test for a bug
+          // where pages with generateStaticParams were incorrectly marked as SSG even when
+          // the individual routes used dynamic APIs.
+          expect(getTreeView(next.cliOutput)).toMatchInlineSnapshot(`
+           "Route (app)
+           ┌ ○ /_not-found
+           └ ƒ /dynamic/[slug]
+               ├ /dynamic/slug-01
+               ├ /dynamic/slug-02
+               └ /dynamic/slug-03
+
+
+           ○  (Static)   prerendered as static content
+           ƒ  (Dynamic)  server-rendered on demand"
+          `)
+        }
+      })
+
+      it('should render the dynamic pages correctly', async () => {
+        // Test one of the generated routes. We expect it to render and not
+        // error.
+        const $ = await next.render$('/dynamic/slug-01')
+        expect($('#page').text()).toBe('Page slug-01')
+      })
+    })
+  })
 })
 
 function getTreeView(cliOutput: string): string {
   let foundStart = false
+  let cliHeader = 0
   const lines: string[] = []
 
   for (const line of cliOutput.split('\n')) {
+    // Once we've seen the CLI header twice, we can stop reading the output,
+    // as we've already collected the first command (the `next build` command)
+    // and we can ignore the rest of the output.
+    if (line.includes('▲ Next.js')) cliHeader++
+    if (cliHeader === 2) break
+
     foundStart ||= line.startsWith('Route ')
 
     if (foundStart) {

test/production/app-dir/build-output-tree-view/fixtures/dynamic-generate-static-params/app/dynamic/[slug]/page.tsx

@@ -0,0 +1,16 @@
+import { connection } from 'next/server'
+
+export async function generateStaticParams() {
+  return [{ slug: 'slug-01' }, { slug: 'slug-02' }, { slug: 'slug-03' }]
+}
+
+export default async function Page({
+  params,
+}: {
+  params: Promise<{ slug: string }>
+}) {
+  await connection()
+  const { slug } = await params
+
+  return <div id="page">Page {slug}</div>
+}

test/production/app-dir/build-output-tree-view/fixtures/dynamic-generate-static-params/app/layout.tsx

@@ -0,0 +1,11 @@
+import { ReactNode, Suspense } from 'react'
+
+export default function Root({ children }: { children: ReactNode }) {
+  return (
+    <html>
+      <body>
+        <Suspense>{children}</Suspense>
+      </body>
+    </html>
+  )
+}