[cfe-dev] Obj-C false positive warning with deprecation and instancetype?

[Douglas Gregor]

On Jan 11, 2012, at 8:10 AM, Sean McBride wrote:

> Hi all,
> 
> Using clang r147866 on Mac OS X 10.7, the code below causes this warning:
> 
> $ clang -fsyntax-only test.m 
> test.m:18:11: warning: 'initWithContentsOfURL:' is deprecated [-Wdeprecated-declarations]
>        return [[[self alloc] initWithContentsOfURL:inURL] autorelease];
>                 ^
> 
> NSString has a deprecated method initWithContentsOfURL:, but in my own class it's not deprecated.  I would have thought that between my own use of instancetype and clang's special casing of alloc that this should not warn.  Is it a false positive bug?
> 
> -----------
> #import <Foundation/Foundation.h>
> 
> @interface Awesome : NSObject { }
> - (instancetype)initWithContentsOfURL:(NSURL*)inURL; // designated initializer
> + (instancetype)awsomeWithContentsOfURL:(NSURL*)inURL;
> @end
> 
> @implementation Awesome
> 
> - (instancetype)initWithContentsOfURL:(NSURL*)inURL
> {
> 	self = [super init];
> 	return self;
> }
> 
> + (instancetype)awsomeWithContentsOfURL:(NSURL*)inURL
> {
> 	return [[[self alloc] initWithContentsOfURL:inURL] autorelease];
> }
> 
> @end
> 
> int main (int argc, char *argv[])
> {
>    (void)argc; (void)argv;
>    return 0;
> }
> -----------

IIRC, we've seen this bug before, and the issue is that the related result type inference for message sends to 'self' within class methods is not working properly. Definitely looks like a Clang bug.

	- Doug