Bug 298037 – Safer CPP static analyzer erroneously claims the use of `dispatch_get_main_queue()`

• Component: Tools / Tests
• Status: RESOLVED DUPLICATE

[Jean-Yves Avenard [:jya]]

doing something like this
```
[m_synchronizer addPeriodicTimeObserverForInterval:PAL::toCMTime(MediaTime::createWithDouble(3600)) queue:dispatch_get_main_queue() usingBlock:^(CMTime time) { }];
```

will give "Call argument for parameter 'queue' is unretained and unsafe"

the documentation states:
```
 * The main queue is a well known global object that is made automatically on
 * behalf of the main thread during process initialization and is returned by
 * dispatch_get_main_queue(). This object cannot be modified.  Calls to
 * dispatch_suspend(), dispatch_resume(), dispatch_set_context(), etc., will
 * have no effect when used on the main queue.
 */
```

the object returned will never be deleted during a call as shown above, its use can't possibly be unsafe.

An exception should be added. There's currently 377 calls to that method, none wrapping it around a RetainPtr

[Radar WebKit Bug Importer]

<rdar://problem/159361681>

[Ryosuke Niwa]

We added a wrapping function in the bug 298840.

*** This bug has been marked as a duplicate of bug 298840 ***

[Chris Dumez]

Bug 298840 introduced `mainDispatchQueueSingleton()` in wtf/darwin/DispatchExtras.h, which should now be used instead.