src/util/extend.ts

@@ -22,30 +22,30 @@ import { CommonKeys } from "."
 
 // TODO: use OverrideProperties from type-fest?
 export type Extend<T extends readonly object[]> = (
-    T extends [
+    T extends readonly [
         infer Super,
         infer Self,
         ...infer Rest extends readonly object[],
     ]
         ? Pick<Self, CommonKeys<Self, Super>> extends Pick<Super, CommonKeys<Self, Super>>
-            ? Extend<[
+            ? Extend<readonly [
                 Omit<Super, CommonKeys<Self, Super>> & Self,
                 ...Rest,
             ]>
             : never
-        : T extends [infer Self]
+        : T extends readonly [infer Self]
             ? Self
             : {}
 )
 
 export type Extendable<T extends readonly object[]> = (
-    T extends [
+    T extends readonly [
         infer Super,
         infer Self,
         ...infer Rest extends readonly object[],
     ]
         ? Pick<Self, CommonKeys<Self, Super>> extends Pick<Super, CommonKeys<Self, Super>>
-            ? Extendable<[
+            ? Extendable<readonly [
                 Omit<Super, CommonKeys<Self, Super>> & Self,
                 ...Rest,
             ]>
@@ -54,7 +54,7 @@ export type Extendable<T extends readonly object[]> = (
 )
 
 export type NonExtendableKeys<T extends readonly object[]> = (
-    T extends [
+    T extends readonly [
         infer Super   extends object,
         infer Self    extends object,
         ...infer Rest extends readonly object[],
@@ -63,7 +63,7 @@ export type NonExtendableKeys<T extends readonly object[]> = (
             ? never
             : K
         }[keyof Super & keyof Self]
-        | NonExtendableKeys<[
+        | NonExtendableKeys<readonly [
             Super & Self,
             ...Rest,
         ]>