|
|
|
/*
|
|
|
|
* Copyright (c) 2014 - present Facebook, Inc.
|
|
|
|
* All rights reserved.
|
|
|
|
*
|
|
|
|
* This source code is licensed under the BSD style license found in the
|
|
|
|
* LICENSE file in the root directory of this source tree. An additional grant
|
|
|
|
* of patent rights can be found in the PATENTS file in the same directory.
|
|
|
|
*/
|
|
|
|
|
|
|
|
#import <Foundation/Foundation.h>
|
|
|
|
|
|
|
|
@interface A : NSObject
|
|
|
|
|
|
|
|
@property int x;
|
|
|
|
|
|
|
|
+ (instancetype)sharedInstance;
|
|
|
|
|
|
|
|
@end
|
|
|
|
|
|
|
|
@implementation A {
|
|
|
|
}
|
|
|
|
|
|
|
|
+ (instancetype)sharedInstance {
|
|
|
|
static dispatch_once_t once;
|
|
|
|
static id sharedInstance;
|
|
|
|
dispatch_once(&once, ^{
|
|
|
|
sharedInstance = [[self alloc] init];
|
|
|
|
});
|
|
|
|
return sharedInstance;
|
|
|
|
}
|
|
|
|
|
|
|
|
+ (instancetype)trans {
|
|
|
|
static id sharedInstance;
|
|
|
|
void (^dummy_block)() = ^{
|
|
|
|
sharedInstance = [[self alloc] init];
|
|
|
|
};
|
|
|
|
dummy_block();
|
|
|
|
return sharedInstance;
|
|
|
|
}
|
|
|
|
|
|
|
|
+ (instancetype)dispatch_a_block_variable {
|
|
|
|
static __typeof__([self new]) static_storage__;
|
|
|
|
void (^initialization_block__)() = ^{
|
|
|
|
static_storage__ = ([self new]);
|
|
|
|
};
|
|
|
|
static dispatch_once_t once_token__;
|
|
|
|
_dispatch_once(&once_token__, initialization_block__);
|
|
|
|
return static_storage__;
|
|
|
|
}
|
|
|
|
|
|
|
|
@end
|
|
|
|
|
|
|
|
int main() {
|
|
|
|
A* b = [A sharedInstance];
|
|
|
|
int* p = 0;
|
|
|
|
if (b == 0)
|
|
|
|
return *p;
|
|
|
|
else
|
|
|
|
return 0;
|
|
|
|
}
|