Warn for update on different component in render

This warning already exists for class components, but not for functions. It does not apply to render phase updates to the same component, which have special semantics that we do support.
facebook · Oct 15, 2019 · 6b0ffdf · 6b0ffdf
1 parent a8c6a1b
commit 6b0ffdf
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diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.js b/packages/react-reconciler/src/ReactFiberWorkLoop.js
@@ -372,7 +372,7 @@ export function scheduleUpdateOnFiber(
   expirationTime: ExpirationTime,
 ) {
   checkForNestedUpdates();
-  warnAboutInvalidUpdatesOnClassComponentsInDEV(fiber);
+  warnAboutRenderPhaseUpdatesInDEV(fiber);
 
   const root = markUpdateTimeFromFiberToRoot(fiber, expirationTime);
   if (root === null) {
@@ -2663,32 +2663,45 @@ if (__DEV__ && replayFailedUnitOfWorkWithInvokeGuardedCallback) {
 
 let didWarnAboutUpdateInRender = false;
 let didWarnAboutUpdateInGetChildContext = false;
-function warnAboutInvalidUpdatesOnClassComponentsInDEV(fiber) {
-  if (__DEV__) {
-    if (fiber.tag === ClassComponent) {
-      switch (ReactCurrentDebugFiberPhaseInDEV) {
-        case 'getChildContext':
-          if (didWarnAboutUpdateInGetChildContext) {
-            return;
-          }
-          warningWithoutStack(
-            false,
-            'setState(...): Cannot call setState() inside getChildContext()',
-          );
-          didWarnAboutUpdateInGetChildContext = true;
-          break;
-        case 'render':
-          if (didWarnAboutUpdateInRender) {
-            return;
-          }
-          warningWithoutStack(
-            false,
-            'Cannot update during an existing state transition (such as ' +
-              'within `render`). Render methods should be a pure function of ' +
-              'props and state.',
-          );
-          didWarnAboutUpdateInRender = true;
-          break;
+function warnAboutRenderPhaseUpdatesInDEV(fiber) {
+  if (__DEV__ && (executionContext & RenderContext) !== NoContext) {
+    switch (fiber.tag) {
+      case FunctionComponent:
+      case ForwardRef:
+      case SimpleMemoComponent: {
+        warning(
+          false,
+          'Cannot update a component from inside the function body of a ' +
+            'different component.',
+        );
+        break;
+      }
+      case ClassComponent: {
+        switch (ReactCurrentDebugFiberPhaseInDEV) {
+          case 'getChildContext':
+            if (didWarnAboutUpdateInGetChildContext) {
+              return;
+            }
+            warningWithoutStack(
+              false,
+              'setState(...): Cannot call setState() inside getChildContext()',
+            );
+            didWarnAboutUpdateInGetChildContext = true;
+            break;
+          case 'render':
+            if (didWarnAboutUpdateInRender) {
+              return;
+            }
+            warningWithoutStack(
+              false,
+              'Cannot update during an existing state transition (such as ' +
+                'within `render`). Render methods should be a pure function of ' +
+                'props and state.',
+            );
+            didWarnAboutUpdateInRender = true;
+            break;
+        }
+        break;
       }
     }
   }

diff --git a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js
@@ -491,6 +491,50 @@ describe('ReactHooksWithNoopRenderer', () => {
       ]);
       expect(ReactNoop.getChildren()).toEqual([span(22)]);
     });
+
+    it('warns about render phase update on a different component', async () => {
+      let setStep;
+      function Foo() {
+        const [step, _setStep] = useState(0);
+        setStep = _setStep;
+        return <Text text={`Foo [${step}]`} />;
+      }
+
+      function Bar({triggerUpdate}) {
+        if (triggerUpdate) {
+          setStep(1);
+        }
+        return <Text text="Bar" />;
+      }
+
+      const root = ReactNoop.createRoot();
+
+      await ReactNoop.act(async () => {
+        root.render(
+          <>
+            <Foo />
+            <Bar />
+          </>,
+        );
+      });
+      expect(Scheduler).toHaveYielded(['Foo [0]', 'Bar']);
+
+      // Bar will update Foo during its render phase. React should warn.
+      await ReactNoop.act(async () => {
+        root.render(
+          <>
+            <Foo />
+            <Bar triggerUpdate={true} />
+          </>,
+        );
+        expect(() =>
+          expect(Scheduler).toFlushAndYield(['Foo [0]', 'Bar', 'Foo [1]']),
+        ).toWarnDev([
+          'Cannot update a component from inside the function body of a ' +
+            'different component.',
+        ]);
+      });
+    });
   });
 
   describe('useReducer', () => {