fix(typescript): Setter<T> being assignable to any Setter

closes #1818
solidjs · Jul 26, 2023 · 91db2a5 · 91db2a5
1 parent 039cf60
commit 91db2a5
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Showing 2 changed files with 13 additions and 4 deletions.
diff --git a/packages/solid/src/reactive/signal.ts b/packages/solid/src/reactive/signal.ts
@@ -174,10 +174,11 @@ export function createRoot<T>(fn: RootFunction<T>, detachedOwner?: typeof Owner)
 
 export type Accessor<T> = () => T;
 
-export type Setter<T> = (undefined extends T ? () => undefined : {}) &
-  (<U extends T>(value: (prev: T) => U) => U) &
-  (<U extends T>(value: Exclude<U, Function>) => U) &
-  (<U extends T>(value: Exclude<U, Function> | ((prev: T) => U)) => U);
+export type Setter<T> = (undefined extends T ? () => undefined : {}) & {
+  <U extends T>(value: (prev: T) => U): U;
+  <U extends T>(value: Exclude<U, Function>): U;
+  <U extends T>(value: Exclude<U, Function> | ((prev: T) => U)): U;
+};
 
 export type Signal<T> = [get: Accessor<T>, set: Setter<T>];
 

diff --git a/packages/solid/test/signals.type-tests.ts b/packages/solid/test/signals.type-tests.ts
@@ -1051,3 +1051,11 @@ createEffect<number>((v: number | string) => 123, "asd");
 createComputed<number>((v: number | string) => 123, "asd");
 // @ts-expect-error second generic is not inferred and remains as number
 createRenderEffect<number>((v: number | string) => 123, "asd");
+
+
+//////////////////////////////////////////////////////////////////////////
+// test setter invariance ////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////
+declare const s1: Setter<number>;
+// @ts-expect-error should be invariant
+const s2: Setter<bigint> = s1;