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70 lines
1.2 KiB
70 lines
1.2 KiB
3 years ago
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include <Foundation/Foundation.h>
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@interface Singleton : NSObject
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@property int x;
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@end
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typedef void (^MyBlock)();
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void dispatch(MyBlock block) { block(); }
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@implementation Singleton
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- (int)dispatch_once_no_npe_good {
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static Singleton* a = nil;
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static dispatch_once_t onceToken;
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dispatch_once(&onceToken, ^{
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a = [[Singleton alloc] init];
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});
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return a->_x;
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}
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- (int)dispatch_once_captured_vars_bad {
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static dispatch_once_t onceToken;
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int* x = NULL;
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int val = 5;
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__block int* y = &val;
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dispatch_once(&onceToken, ^{
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y = x;
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});
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return *y;
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}
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- (int)dispatch_no_npe_good {
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static Singleton* a = nil;
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static dispatch_once_t onceToken;
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dispatch(^{
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a = [[Singleton alloc] init];
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a->_x = 5;
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});
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return a->_x;
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}
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@end
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int captured_npe_bad() {
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int* x = NULL;
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int (^my_block)(void) = ^() {
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return *x;
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};
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return my_block();
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}
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int captured_npe_ok(int* y) {
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__block int* x = NULL;
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void (^my_block)(void) = ^() {
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x = y;
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};
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my_block();
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return *x;
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}
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