Restrict return type further

Author: acdlite

packages/react-debug-tools/src/ReactDebugHooks.js

@@ -147,7 +147,7 @@ function useRef<T>(initialValue: T): {current: T} {
 }
 
 function useLayoutEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   inputs: Array<mixed> | void | null,
 ): void {
   nextHook();
@@ -159,7 +159,7 @@ function useLayoutEffect(
 }
 
 function useEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   inputs: Array<mixed> | void | null,
 ): void {
   nextHook();

packages/react-dom/src/server/ReactPartialRendererHooks.js

@@ -375,8 +375,8 @@ function useRef<T>(initialValue: T): {current: T} {
 }
 
 export function useLayoutEffect(
-  create: () => mixed,
-  deps: Array<mixed> | void | null,
+  create: () => (() => void) | void,
+  inputs: Array<mixed> | void | null,
 ) {
   if (__DEV__) {
     currentHookNameInDev = 'useLayoutEffect';

packages/react-reconciler/src/ReactFiberHooks.js

@@ -59,8 +59,14 @@ export type Dispatcher = {
     observedBits: void | number | boolean,
   ): T,
   useRef<T>(initialValue: T): {current: T},
-  useEffect(create: () => mixed, deps: Array<mixed> | void | null): void,
-  useLayoutEffect(create: () => mixed, deps: Array<mixed> | void | null): void,
+  useEffect(
+    create: () => (() => void) | void,
+    deps: Array<mixed> | void | null,
+  ): void,
+  useLayoutEffect(
+    create: () => (() => void) | void,
+    deps: Array<mixed> | void | null,
+  ): void,
   useCallback<T>(callback: T, deps: Array<mixed> | void | null): T,
   useMemo<T>(nextCreate: () => T, deps: Array<mixed> | void | null): T,
   useImperativeHandle<T>(
@@ -119,8 +125,8 @@ type HookDev = Hook & {
 
 type Effect = {
   tag: HookEffectTag,
-  create: () => mixed,
-  destroy: (() => mixed) | null,
+  create: () => (() => void) | void,
+  destroy: (() => void) | null,
   deps: Array<mixed> | null,
   next: Effect,
 };
@@ -805,7 +811,7 @@ function updateEffectImpl(fiberEffectTag, hookEffectTag, create, deps): void {
 }
 
 function mountEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   deps: Array<mixed> | void | null,
 ): void {
   return mountEffectImpl(
@@ -817,7 +823,7 @@ function mountEffect(
 }
 
 function updateEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   deps: Array<mixed> | void | null,
 ): void {
   return updateEffectImpl(
@@ -829,7 +835,7 @@ function updateEffect(
 }
 
 function mountLayoutEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   deps: Array<mixed> | void | null,
 ): void {
   return mountEffectImpl(
@@ -841,7 +847,7 @@ function mountLayoutEffect(
 }
 
 function updateLayoutEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   deps: Array<mixed> | void | null,
 ): void {
   return updateEffectImpl(
@@ -860,7 +866,9 @@ function imperativeHandleEffect<T>(
     const refCallback = ref;
     const inst = create();
     refCallback(inst);
-    return () => refCallback(null);
+    return () => {
+      refCallback(null);
+    };
   } else if (ref !== null && ref !== undefined) {
     const refObject = ref;
     if (__DEV__) {
@@ -1205,7 +1213,10 @@ if (__DEV__) {
       currentHookNameInDev = 'useContext';
       return mountContext(context, observedBits);
     },
-    useEffect(create: () => mixed, deps: Array<mixed> | void | null): void {
+    useEffect(
+      create: () => (() => void) | void,
+      deps: Array<mixed> | void | null,
+    ): void {
       currentHookNameInDev = 'useEffect';
       return mountEffect(create, deps);
     },
@@ -1218,7 +1229,7 @@ if (__DEV__) {
       return mountImperativeHandle(ref, create, deps);
     },
     useLayoutEffect(
-      create: () => mixed,
+      create: () => (() => void) | void,
       deps: Array<mixed> | void | null,
     ): void {
       currentHookNameInDev = 'useLayoutEffect';
@@ -1289,7 +1300,10 @@ if (__DEV__) {
       currentHookNameInDev = 'useContext';
       return updateContext(context, observedBits);
     },
-    useEffect(create: () => mixed, deps: Array<mixed> | void | null): void {
+    useEffect(
+      create: () => (() => void) | void,
+      deps: Array<mixed> | void | null,
+    ): void {
       currentHookNameInDev = 'useEffect';
       return updateEffect(create, deps);
     },
@@ -1302,7 +1316,7 @@ if (__DEV__) {
       return updateImperativeHandle(ref, create, deps);
     },
     useLayoutEffect(
-      create: () => mixed,
+      create: () => (() => void) | void,
       deps: Array<mixed> | void | null,
     ): void {
       currentHookNameInDev = 'useLayoutEffect';
@@ -1376,7 +1390,10 @@ if (__DEV__) {
       warnInvalidHookAccess();
       return mountContext(context, observedBits);
     },
-    useEffect(create: () => mixed, deps: Array<mixed> | void | null): void {
+    useEffect(
+      create: () => (() => void) | void,
+      deps: Array<mixed> | void | null,
+    ): void {
       currentHookNameInDev = 'useEffect';
       warnInvalidHookAccess();
       return mountEffect(create, deps);
@@ -1391,7 +1408,7 @@ if (__DEV__) {
       return mountImperativeHandle(ref, create, deps);
     },
     useLayoutEffect(
-      create: () => mixed,
+      create: () => (() => void) | void,
       deps: Array<mixed> | void | null,
     ): void {
       currentHookNameInDev = 'useLayoutEffect';
@@ -1471,7 +1488,10 @@ if (__DEV__) {
       warnInvalidHookAccess();
       return updateContext(context, observedBits);
     },
-    useEffect(create: () => mixed, deps: Array<mixed> | void | null): void {
+    useEffect(
+      create: () => (() => void) | void,
+      deps: Array<mixed> | void | null,
+    ): void {
       currentHookNameInDev = 'useEffect';
       warnInvalidHookAccess();
       return updateEffect(create, deps);
@@ -1486,7 +1506,7 @@ if (__DEV__) {
       return updateImperativeHandle(ref, create, deps);
     },
     useLayoutEffect(
-      create: () => mixed,
+      create: () => (() => void) | void,
       deps: Array<mixed> | void | null,
     ): void {
       currentHookNameInDev = 'useLayoutEffect';

packages/react/src/ReactHooks.js

@@ -71,15 +71,15 @@ export function useRef<T>(initialValue: T): {current: T} {
 }
 
 export function useEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   inputs: Array<mixed> | void | null,
 ) {
   const dispatcher = resolveDispatcher();
   return dispatcher.useEffect(create, inputs);
 }
 
 export function useLayoutEffect(
-  create: () => mixed,
+  create: () => (() => void) | void,
   inputs: Array<mixed> | void | null,
 ) {
   const dispatcher = resolveDispatcher();