Fix argument order for CFArraySetValueAtIndex. (#1679)

The Swift dispatching of CFArraySetValueAtIndex had the arguments for
value and index switched around. If someone creates a Swift NSArray
which is eventually bridged to CFArray, and some other piece calls
CFArraySetValueAtIndex, CF_SWIFT_FUNCDISPATCHV will delegate to the
Swift method, but will send a pointer where CFIndex is expected, and a
CFIndex where a pointer is expected, probably causing a segmentation
fault.

The test tries to simplify the scenario (not easy to create the right
conditions) and uses unsafeBitCast (which is the same that happens in
the internal _cfObject). The test crashes before the patch is applied.

Author: drodriguez

CoreFoundation/Collections.subproj/CFArray.c

@@ -628,7 +628,7 @@ void CFArrayAppendValue(CFMutableArrayRef array, const void *value) {
 }
 
 void CFArraySetValueAtIndex(CFMutableArrayRef array, CFIndex idx, const void *value) {
-    CF_SWIFT_FUNCDISPATCHV(CFArrayGetTypeID(), void, (CFSwiftRef)array, NSMutableArray.setObject, idx, value);
+    CF_SWIFT_FUNCDISPATCHV(CFArrayGetTypeID(), void, (CFSwiftRef)array, NSMutableArray.setObject, value, idx);
     CF_OBJC_FUNCDISPATCHV(CFArrayGetTypeID(), void, (NSMutableArray *)array, setObject:(id)value atIndex:(NSUInteger)idx);
     __CFGenericValidateType(array, CFArrayGetTypeID());
     CFAssert1(__CFArrayGetType(array) != __kCFArrayImmutable, __kCFLogAssertion, "%s(): array is immutable", __PRETTY_FUNCTION__);

TestFoundation/TestNSArray.swift

@@ -7,6 +7,8 @@
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 
+import CoreFoundation
+
 class TestNSArray : XCTestCase {
 
     static var allTests: [(String, (TestNSArray) -> () throws -> Void)] {
@@ -42,6 +44,7 @@ class TestNSArray : XCTestCase {
             ("test_insertObjectsAtIndexes", test_insertObjectsAtIndexes),
             ("test_replaceObjectsAtIndexesWithObjects", test_replaceObjectsAtIndexesWithObjects),
             ("test_pathsMatchingExtensions", test_pathsMatchingExtensions),
+            ("test_arrayUsedAsCFArrayInvokesArrayMethods", test_arrayUsedAsCFArrayInvokesArrayMethods),
         ]
     }
 
@@ -794,6 +797,14 @@ class TestNSArray : XCTestCase {
         XCTAssertEqual(match5, [])
     }
 
+    func test_arrayUsedAsCFArrayInvokesArrayMethods() {
+        let number = 789 as NSNumber
+        let array = NSMutableArray(array: [123, 456])
+        CFArraySetValueAtIndex(unsafeBitCast(array, to: CFMutableArray.self), 1, UnsafeRawPointer(Unmanaged.passUnretained(number).toOpaque()))
+        XCTAssertEqual(array[0] as! NSNumber, 123 as NSNumber)
+        XCTAssertEqual(array[1] as! NSNumber, 789 as NSNumber)
+    }
+
     private func createTestFile(_ path: String, _contents: Data) -> String? {
         let tempDir = NSTemporaryDirectory() + "TestFoundation_Playground_" + NSUUID().uuidString + "/"
         do {