From 291114726449a7fc0ffe2ac1c979d557b49196d2 Mon Sep 17 00:00:00 2001
From: Sebastian Markbage <sebastian@calyptus.eu>
Date: Tue, 15 Apr 2025 11:47:57 -0400
Subject: [PATCH] Warn if you pass a hidden prop to Activity

---
 .../src/ReactFiberBeginWork.js                | 16 +++++++++++
 .../src/__tests__/Activity-test.js            | 28 +++++++++++++++++--
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiberBeginWork.js b/packages/react-reconciler/src/ReactFiberBeginWork.js
index fc5019b2ff850..fd8451a3ef1be 100644
--- a/packages/react-reconciler/src/ReactFiberBeginWork.js
+++ b/packages/react-reconciler/src/ReactFiberBeginWork.js
@@ -873,6 +873,22 @@ function updateActivityComponent(
   renderLanes: Lanes,
 ) {
   const nextProps: ActivityProps = workInProgress.pendingProps;
+  if (__DEV__) {
+    const hiddenProp = (nextProps: any).hidden;
+    if (hiddenProp !== undefined) {
+      console.error(
+        '<Activity> doesn\'t accept a hidden prop. Use mode="hidden" instead.\n' +
+          '- <Activity %s>\n' +
+          '+ <Activity %s>',
+        hiddenProp === true
+          ? 'hidden'
+          : hiddenProp === false
+            ? 'hidden={false}'
+            : 'hidden={...}',
+        hiddenProp ? 'mode="hidden"' : 'mode="visible"',
+      );
+    }
+  }
   const nextChildren = nextProps.children;
   const nextMode = nextProps.mode;
   const mode = workInProgress.mode;
diff --git a/packages/react-reconciler/src/__tests__/Activity-test.js b/packages/react-reconciler/src/__tests__/Activity-test.js
index 4655d4917d6a3..d514bb4e0b0f0 100644
--- a/packages/react-reconciler/src/__tests__/Activity-test.js
+++ b/packages/react-reconciler/src/__tests__/Activity-test.js
@@ -732,7 +732,7 @@ describe('Activity', () => {
 
     const root = ReactNoop.createRoot();
     await act(() => {
-      root.render(<Activity hidden={false} />);
+      root.render(<Activity />);
     });
     assertLog([]);
     expect(root).toMatchRenderedOutput(null);
@@ -741,7 +741,7 @@ describe('Activity', () => {
       // Partially render a component
       startTransition(() => {
         root.render(
-          <Activity hidden={false}>
+          <Activity>
             <Child />
             <Text text="Sibling" />
           </Activity>,
@@ -1480,4 +1480,28 @@ describe('Activity', () => {
     assertLog([]);
     expect(root).toMatchRenderedOutput(<span prop={2} />);
   });
+
+  // @gate enableActivity
+  it('warns if you pass a hidden prop', async () => {
+    function App() {
+      return (
+        // eslint-disable-next-line react/jsx-boolean-value
+        <Activity hidden>
+          <div />
+        </Activity>
+      );
+    }
+
+    const root = ReactNoop.createRoot();
+    await act(() => {
+      root.render(<App show={true} step={1} />);
+    });
+    assertConsoleErrorDev([
+      '<Activity> doesn\'t accept a hidden prop. Use mode="hidden" instead.\n' +
+        '- <Activity hidden>\n' +
+        '+ <Activity mode="hidden">\n' +
+        '    in Activity (at **)\n' +
+        '    in App (at **)',
+    ]);
+  });
 });