rdar://127199021, fix compatibility with apps that accidentally do [[[aSwiftArray class] new] mutableCopy] to work

Author: Catfish-Man

stdlib/public/stubs/SwiftNativeNSXXXBase.mm.gyb

@@ -103,6 +103,15 @@ swift_stdlib_connectNSBaseClasses() {
   return true;
 }
 
+@interface __SwiftNativeNSArrayBase ()
+
++ (id) new {
+  // Some apps accidentally do [[[aSwiftArray class] new] mutableCopy]
+  return [objc_lookUpClass("NSArray") new];
+}
+
+@end
+
 #endif
 
 // ${'Local Variables'}:

test/stdlib/ArrayBridge.swift.gyb

@@ -422,6 +422,11 @@ tests.test("testThunks") {
   testBridgeableValue(Thunks())
 }
 
+tests.test("testHKTFilter") {
+  let base = ["hello", "world"]
+  let result = testHKTFilter(base) as Array
+  expectEqual(result, ["hello"])
+}
 
 tests.test("testRoundTrip") {
   class Test : NSObject {

test/stdlib/Inputs/ArrayBridge/ArrayBridge.h

@@ -16,6 +16,7 @@ NSArray* idAsArray(id a);
 
 void testSubclass(id thunks);
 void testBridgeableValue(id thunks);
+id testHKTFilter(id array);
 
 @interface RDar27905230 : NSObject
 + (NSDictionary<NSString *, NSArray<id> *> *)mutableDictionaryOfMutableLists;

test/stdlib/Inputs/ArrayBridge/ArrayBridge.m

@@ -67,6 +67,22 @@ void testBridgeableValue(id thunks) {
   [thunks acceptBridgeableValueArray: toSwiftArr];
 }
 
+static id filter(id<NSFastEnumeration, NSObject> container, BOOL (^predicate)(id)) {
+  id result = [[[container class] new] mutableCopy];
+  for (id object in container) {
+    if (predicate(object)) {
+      [result addObject:object];
+    }
+  }
+  return result;
+}
+
+id testHKTFilter(id array) {
+  return filter(array, ^(id obj) {
+    return [obj isEqual:@"hello"]
+  });
+}
+
 @implementation RDar27905230
 
 + (NSDictionary<NSString *, NSArray<id> *> *)mutableDictionaryOfMutableLists  {