[TS Migration][No QA] Improve routes validation

src/ROUTES.ts

@@ -1,6 +1,7 @@
-import type {IsEqual, ValueOf} from 'type-fest';
+import type {ValueOf} from 'type-fest';
 import type CONST from './CONST';
 import type {IOURequestType} from './libs/actions/IOU';
+import type AssertTypesNotEqual from './types/utils/AssertTypesNotEqual';
 
 // This is a file containing constants for all the routes we want to be able to go to
 
@@ -739,20 +740,18 @@ export default ROUTES;
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 type ExtractRouteName<TRoute> = TRoute extends {getRoute: (...args: any[]) => infer TRouteName} ? TRouteName : TRoute;
 
-type AllRoutes = {
+/**
+ * Represents all routes in the app as a union of literal strings.
+ */
+type Route = {
     [K in keyof typeof ROUTES]: ExtractRouteName<(typeof ROUTES)[K]>;
 }[keyof typeof ROUTES];
 
-type RouteIsPlainString = IsEqual<AllRoutes, string>;
+type RoutesValidationError = 'Error: One or more routes defined within `ROUTES` have not correctly used `as const` in their `getRoute` function return value.';
 
-/**
- * Represents all routes in the app as a union of literal strings.
- *
- * If this type resolves to `never`, it implies that one or more routes defined within `ROUTES` have not correctly used
- * `as const` in their `getRoute` function return value.
- */
-type Route = RouteIsPlainString extends true ? never : AllRoutes;
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+type RouteIsPlainString = AssertTypesNotEqual<string, Route, RoutesValidationError>;
 
 type HybridAppRoute = (typeof HYBRID_APP_ROUTES)[keyof typeof HYBRID_APP_ROUTES];
 
-export type {Route, HybridAppRoute, AllRoutes};
+export type {Route, HybridAppRoute};

src/components/MoneyRequestConfirmationList.tsx

@@ -26,7 +26,7 @@ import * as TransactionUtils from '@libs/TransactionUtils';
 import * as IOU from '@userActions/IOU';
 import CONST from '@src/CONST';
 import ONYXKEYS from '@src/ONYXKEYS';
-import type {AllRoutes} from '@src/ROUTES';
+import type {Route} from '@src/ROUTES';
 import ROUTES from '@src/ROUTES';
 import type * as OnyxTypes from '@src/types/onyx';
 import type {Participant} from '@src/types/onyx/IOU';
@@ -122,7 +122,7 @@ type MoneyRequestConfirmationListProps = MoneyRequestConfirmationListOnyxProps &
     isReadOnly?: boolean;
 
     /** Depending on expense report or personal IOU report, respective bank account route */
-    bankAccountRoute?: AllRoutes;
+    bankAccountRoute?: Route;
 
     /** The policyID of the request */
     policyID?: string;

src/types/utils/AssertTypesNotEqual.ts

@@ -0,0 +1,11 @@
+import type {IsEqual} from 'type-fest';
+
+type MatchError = 'Error: Types do match';
+
+/**
+ * The 'AssertTypesNotEqual' type here enforces that `T1` and `T2` do not match.
+ * If `T1` or `T2` are the same this type will cause a compile-time error.
+ */
+type AssertTypesNotEqual<T1, T2 extends IsEqual<T1, T2> extends false ? T1 : TMatchError, TMatchError = MatchError> = T1 & T2;
+
+export default AssertTypesNotEqual;