fixes #35621

Author: TrejGun

lib/lib.es2015.core.d.ts

@@ -283,7 +283,7 @@ interface ObjectConstructor {
      * @param target The target object to copy to.
      * @param source The source object from which to copy properties.
      */
-    assign<T, U>(target: T, source: U): T & U;
+    assign<T extends {}, U>(target: T, source: U): T & U;
 
     /**
      * Copy the values of all of the enumerable own properties from one or more source objects to a
@@ -292,7 +292,7 @@ interface ObjectConstructor {
      * @param source1 The first source object from which to copy properties.
      * @param source2 The second source object from which to copy properties.
      */
-    assign<T, U, V>(target: T, source1: U, source2: V): T & U & V;
+    assign<T extends {}, U, V>(target: T, source1: U, source2: V): T & U & V;
 
     /**
      * Copy the values of all of the enumerable own properties from one or more source objects to a
@@ -302,7 +302,7 @@ interface ObjectConstructor {
      * @param source2 The second source object from which to copy properties.
      * @param source3 The third source object from which to copy properties.
      */
-    assign<T, U, V, W>(target: T, source1: U, source2: V, source3: W): T & U & V & W;
+    assign<T extends {}, U, V, W>(target: T, source1: U, source2: V, source3: W): T & U & V & W;
 
     /**
      * Copy the values of all of the enumerable own properties from one or more source objects to a

src/lib/es2015.core.d.ts

@@ -263,7 +263,7 @@ interface ObjectConstructor {
      * @param target The target object to copy to.
      * @param source The source object from which to copy properties.
      */
-    assign<T, U>(target: T, source: U): T & U;
+    assign<T extends {}, U>(target: T, source: U): T & U;
 
     /**
      * Copy the values of all of the enumerable own properties from one or more source objects to a
@@ -272,7 +272,7 @@ interface ObjectConstructor {
      * @param source1 The first source object from which to copy properties.
      * @param source2 The second source object from which to copy properties.
      */
-    assign<T, U, V>(target: T, source1: U, source2: V): T & U & V;
+    assign<T extends {}, U, V>(target: T, source1: U, source2: V): T & U & V;
 
     /**
      * Copy the values of all of the enumerable own properties from one or more source objects to a
@@ -282,7 +282,7 @@ interface ObjectConstructor {
      * @param source2 The second source object from which to copy properties.
      * @param source3 The third source object from which to copy properties.
      */
-    assign<T, U, V, W>(target: T, source1: U, source2: V, source3: W): T & U & V & W;
+    assign<T extends {}, U, V, W>(target: T, source1: U, source2: V, source3: W): T & U & V & W;
 
     /**
      * Copy the values of all of the enumerable own properties from one or more source objects to a