3850 - call a method on the argument

package.json

@@ -68,7 +68,7 @@
         "tape": "^5.0.1",
         "ts-jest": "^29.0.5",
         "tsdx": "^0.14.1",
-        "typescript": "^5.0.2"
+        "typescript": "^5.5.0-dev.20240415"
     },
     "husky": {
         "hooks": {

packages/mobx/src/global.d.ts

@@ -1 +1,18 @@
 declare const __DEV__: boolean
+
+// This code is a copy from TS PR#57230
+// Should be removed after it merged
+interface ReadonlySetLike<T> {
+    /**
+     * Despite its name, returns an iterable of the values in the set-like.
+     */
+    keys(): Iterable<T>
+    /**
+     * @returns a boolean indicating whether an element with the specified value exists in the set-like or not.
+     */
+    has(value: T): boolean
+    /**
+     * @returns the number of (unique) elements in the set-like.
+     */
+    readonly size: number
+}

packages/mobx/src/types/observableset.ts

@@ -243,12 +243,20 @@ export class ObservableSet<T = any> implements Set<T>, IInterceptable<ISetWillCh
         } as any)
     }
 
-    intersection(otherSet: Set<T>): IterableIterator<T> {
+    intersection<U>(otherSet: ReadonlySetLike<U>): IterableIterator<T & U> {
         this.atom_.reportObserved()
         const self = this
         let nextIndex = 0
-        const observableValues = Array.from(this.data_.intersection(otherSet))
-        return makeIterable<T>({
+
+        let observableValues
+        if (typeof otherSet.intersection !== "function") {
+            observableValues = Array.from(otherSet.intersection(this.data_))
+        } else {
+            const dehancedSet = new Set(this)
+            observableValues = Array.from(dehancedSet.intersection(otherSet))
+        }
+
+        return makeIterable<T & U>({
             next() {
                 return nextIndex < observableValues.length
                     ? { value: self.dehanceValue_(observableValues[nextIndex++]), done: false }