Merge pull request #2123 from septs/ro-map

Author: jdeniau

type-definitions/immutable.d.ts

@@ -617,7 +617,7 @@ declare namespace Immutable {
    * but since Immutable Map keys can be of any type the argument to `get()` is
    * not altered.
    */
-  function Map<K, V>(collection?: Iterable<[K, V]>): Map<K, V>;
+  function Map<K, V>(collection?: Iterable<readonly [K, V]>): Map<K, V>;
   function Map<R extends { [key in PropertyKey]: unknown }>(obj: R): MapOf<R>;
   function Map<V>(obj: { [key: string]: V }): Map<string, V>;
   function Map<K extends string | symbol, V>(obj: { [P in K]?: V }): Map<K, V>;

type-definitions/ts-tests/map.ts

@@ -10,6 +10,10 @@ test('#constructor', () => {
 
   expect(Map([['a', 'a']])).type.toBe<Map<string, string>>();
 
+  expect(Map([] as ReadonlyArray<readonly [number, string]>)).type.toBe<
+    Map<number, string>
+  >();
+
   expect(Map(List<[number, string]>([[1, 'a']]))).type.toBe<
     Map<number, string>
   >();