Fix 4.9 compat issues

Sebastian Silbermann · Sebastian Silbermann · commit d823c700844a · 2023-11-06T21:16:51.000+01:00
Fixes ``` Error: /home/runner/work/DefinitelyTyped/DefinitelyTyped/types/react-dom/test/canary-tests.tsx:158:9 ERROR: 158:9 expect TypeScript@4.9 expected type to be: number got: 0 ERROR: 158:22 expect Compile error in typescript@4.9 but not in typescript@5.0. Fix by adding '"minimumTypeScriptVersion": "5.0"' to package.json. No overload matches this call. Overload 1 of 2, '(action: (state: number) => number | Promise<number>, initialState: number, permalink?: string | undefined): [state: number, dispatch: () => void]', gave the following error. Argument of type '(prevState: 0) => Promise<number>' is not assignable to parameter of type '(state: number) => number | Promise<number>'. Types of parameters 'prevState' and 'state' are incompatible. Type 'number' is not assignable to type '0'. Overload 2 of 2, '(action: (state: number, payload: unknown) => number | Promise<number>, initialState: number, permalink?: string | undefined): [state: number, dispatch: (payload: unknown) => void]', gave the following error. Argument of type '(prevState: 0) => Promise<number>' is not assignable to parameter of type '(state: number, payload: unknown) => number | Promise<number>'. Types of parameters 'prevState' and 'state' are incompatible. Type 'number' is not assignable to type '0'. at testTypesVersion (/home/runner/work/DefinitelyTyped/DefinitelyTyped/node_modules/.pnpm/@DefinitelyTyped+dtslint@0.0.190_typescript@5.4.0-dev.20231105/node_modules/@definitelytyped/dtslint/src/index.ts:202:11) at runTests (/home/runner/work/DefinitelyTyped/DefinitelyTyped/node_modules/.pnpm/@DefinitelyTyped+dtslint@0.0.190_typescript@5.4.0-dev.20231105/node_modules/@definitelytyped/dtslint/src/index.ts:170:7) ELIFECYCLE Command failed with exit code 1. ```
diff --git a/types/react-dom/test/canary-tests.tsx b/types/react-dom/test/canary-tests.tsx
@@ -73,7 +73,7 @@ function preloadTest() {
         ReactDOM.prefetchDNS("foo");
         ReactDOM.prefetchDNS(
             "bar", // @ts-expect-error prefetchDNS does not accept any options at the moment
-            {},
+            {}
         );
 
         // @ts-expect-error
@@ -135,32 +135,35 @@ function formTest() {
         ] = useFormState(action, 1);
 
         function actionExpectingPromiseState(state: Promise<number>) {
-            return state.then(s => s + 1);
+            return state.then((s) => s + 1);
         }
 
         useFormState(
             // @ts-expect-error
             actionExpectingPromiseState,
-            Promise.resolve(1),
+            Promise.resolve(1)
         );
         useFormState(
             action,
             // @ts-expect-error
-            Promise.resolve(1),
+            Promise.resolve(1)
         );
         // $ExpectType number
-        useFormState<Promise<number>>(
-            action,
-            1,
-        )[0];
+        useFormState<Promise<number>>(action, 1)[0];
 
-        // $ExpectType number
-        useFormState(async (prevState) => prevState + 1, 0)[0];
+        useFormState(
+            async (
+                prevState: // only needed in TypeScript 4.9
+                // 5.0 infers `number` whereas 4.9 infers `0`
+                number
+            ) => prevState + 1,
+            0
+        )[0];
         // $ExpectType number
         useFormState(
             async (prevState) => prevState + 1,
             // @ts-expect-error
-            Promise.resolve(0),
+            Promise.resolve(0)
         )[0];
 
         return (
