<html>
    <head>
      <base href="http://llvm.org/bugs/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - Declaring '+(instancetype) alloc __attribute__((unavailable("")));' forbids calling alloc on variables of Class type"
   href="http://llvm.org/bugs/show_bug.cgi?id=20581">20581</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Declaring '+(instancetype) alloc __attribute__((unavailable("")));' forbids calling alloc on variables of Class type
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>new-bugs
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Macintosh
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>MacOS X
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>new bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>rsanchez.saez@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>I have an Objective-C singleton class for which I declare these:

@interface MySingleton : NSObject

+ (instancetype) sharedInstance;
+ (instancetype) alloc __attribute__((unavailable("call sharedInstance
instead")));
- (instancetype) init __attribute__((unavailable("call sharedInstance
instead")));
+ (instancetype) new __attribute__((unavailable("call sharedInstance
instead")));

@end

My implementation is as follows:

@implementation MySingleton

+ (instancetype)sharedInstance
{                                                               
    static dispatch_once_t s_dispatchOnceToken;                 
    static id s_sharedInstance = nil;                           
    dispatch_once(&s_dispatchOnceToken, ^                       
    {                                                           
        s_sharedInstance = [[super alloc] initSharedInstance];  
    });                                                         
    return s_sharedInstance;                                    
}                                                               

- (instancetype)initSharedInstance                              
{                                                               
    return [super init];                                        
}                                                               

@end

All this works as expected.

However, I have a MySingleton instance method like this:

- (void)instanceMethod
{
         Class unrelatedClass = [self getClassWithType:classType]; //classType
is a NSString. This method never returns the MySingleton class
            id activity = [[unrelatedClass alloc] init];
}

which should compile fine, but the compiler wrongly says:

      'alloc' is unavailable: call sharedInstance instead

This issue is present in both CLANG versions included on Xcode 6 Beta 5 and on
5.1.1.</pre>
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