Merge pull request #529 from reduxjs/intersection-GetStateFromSelectors

src/types.ts

@@ -37,15 +37,14 @@ type GetStateFromSelector<S> = S extends Selector<infer State> ? State : never
 export type GetStateFromSelectors<S extends SelectorArray> =
   // handle two elements at once so this type works for up to 30 selectors
   S extends [infer C1, infer C2, ...infer Other]
-    ? Other extends SelectorArray
-      ?
-          | GetStateFromSelector<C1>
-          | GetStateFromSelector<C2>
-          | GetStateFromSelectors<Other>
-      : GetStateFromSelector<C1> | GetStateFromSelector<C2>
+    ? Other extends [any]
+      ? GetStateFromSelector<C1> &
+          GetStateFromSelector<C2> &
+          GetStateFromSelectors<Other>
+      : GetStateFromSelector<C1> & GetStateFromSelector<C2>
     : S extends [infer Current, ...infer Other]
-    ? Other extends SelectorArray
-      ? GetStateFromSelector<Current> | GetStateFromSelectors<Other>
+    ? Other extends [any]
+      ? GetStateFromSelector<Current> & GetStateFromSelectors<Other>
       : GetStateFromSelector<Current>
     : S extends (infer Elem)[]
     ? GetStateFromSelector<Elem>

typescript_test/test.ts

@@ -1060,8 +1060,47 @@ type SelectorArray29 = [
   (_state: StateA) => 29
 ]
 
+// Ensure that input functions with mismatched states raise errors
 type Results = SelectorResultArray<SelectorArray29>
 type State = GetStateFromSelectors<SelectorArray29>
+
+{
+  const selector = createSelector(
+    (state: string) => 1,
+    (state: number) => 2,
+    (...args) => 0
+  )
+  // @ts-expect-error
+  selector('foo')
+  // @ts-expect-error
+  selector(5)
+}
+{
+  const selector = createSelector(
+    (state: { foo: string }) => 1,
+    (state: { bar: string }) => 2,
+    (...args) => 0
+  )
+  selector({ foo: '', bar: '' })
+  // @ts-expect-error
+  selector({ foo: '' })
+  // @ts-expect-error
+  selector({ bar: '' })
+}
+
+{
+  const selector = createSelector(
+    (state: { foo: string }) => 1,
+    (state: { foo: string }) => 2,
+    (...args) => 0
+  )
+  // @ts-expect-error
+  selector({ foo: '', bar: '' })
+  selector({ foo: '' })
+  // @ts-expect-error
+  selector({ bar: '' })
+}
+
 // Issue #526
 function testInputSelectorWithUndefinedReturn() {
   type Input = { field: number | undefined }