Change the way NSInvocation retains its arguments

This is closer to what Apple's vresion does, and it also allows us to store
additional objects in the container, which will be useful for pointer argument
pointees later.

This requires a small corresponding change in Foundation (NSInvocation.h)

NSInvocation.m

@@ -49,40 +49,40 @@
 // NSData rather than to the original string.
 - (void)_retainArgument:(NSUInteger)idx
 {
-    NSMethodType *argInfo= [_signature _argInfo:idx];
+    NSMethodType *argInfo = [_signature _argInfo: idx];
     const char *type = stripQualifiersAndComments(argInfo->type);
-    void **arg = [self _idxToArg:idx];
+    void **arg = [self _idxToArg: idx];
 
-    id object = nil;
-
-    switch (*type)
+    if (type[0] == _C_ID)
     {
-        case _C_ID:
-            object = *arg;
-            break;
-        case _C_CHARPTR:
+        id object = (id) *arg;
+        if (object != nil)
         {
-            NSUInteger length = strlen(*arg) + 1;
-            char *copy = malloc(length);
-            strlcpy(copy, *arg, length);
-            *arg = copy;
-
-            object = [NSData dataWithBytesNoCopy:copy length:length freeWhenDone:YES];
-
-            break;
+            [_container addObject: (id) *arg];
         }
-        // In all other cases, store nothing.
-        default:
-            break;
     }
-
-    if (object != _container[idx])
+    else if (type[0] == _C_CHARPTR)
     {
-        [_container[idx] release];
-        _container[idx] = [object retain];
+        char *str = (char *) *arg;
+        if (str != NULL)
+        {
+            NSUInteger length = strlen(str) + 1;
+            NSData *data = [NSData dataWithBytes: str length: length];
+            *arg = [data bytes];
+            [_container addObject: data];
+        }
     }
 }
 
+- (void) _addAttachedObject: (id) object
+{
+    if (_container == nil)
+    {
+        _container = [[NSMutableArray alloc] init];
+    }
+    [_container addObject: object];
+}
+
 - (instancetype)initWithMethodSignature:(NSMethodSignature *)sig
 {
     if (sig == nil)
@@ -110,9 +110,6 @@
             void **ret = _frame;
             *ret = _retdata;
         }
-
-        _container = NULL;
-        _retainedArgs = NO;
     }
 
     return self;
@@ -126,23 +123,7 @@
 
 - (void)dealloc
 {
-    if (_container)
-    {
-        int len = [_signature numberOfArguments] + 1;
-
-        for (int i = 0; i < len; i++)
-        {
-            if (_container[i])
-            {
-                [_container[i] release];
-                _container[i] = nil;
-            }
-        }
-
-        free(_container);
-        _container = NULL;
-    }
-
+    [_container release];
     [_signature release];
     free(_retdata);
     [super dealloc];
@@ -164,10 +145,13 @@
     {
         return;
     }
+    _retainedArgs = YES;
 
     NSUInteger capacity = [_signature numberOfArguments] + 1; // Add one for return value.
-    _container = (id *)calloc(sizeof(id), capacity);
-    _retainedArgs = YES;
+    if (_container == nil)
+    {
+        _container = [[NSMutableArray alloc] initWithCapacity: capacity];
+    }
 
     for (NSUInteger idx = 0; idx < capacity; idx++)
     {
@@ -309,6 +293,7 @@
 
     if (_retainedArgs)
     {
+        // Retain the return value.
         [self _retainArgument:0];
     }
 }