Objective-C init method with return type id unable to return parent object type pointer

[llvmbot]

Bugzilla Link	11293
Resolution	INVALID
Resolved on	Nov 02, 2011 13:46
Version	unspecified
OS	All
Attachments	Objective-C example showing that the init method with return type id is unable to return parent object type pointer
Reporter	LLVM Bugzilla Contributor
CC	@efriedma-quic

Extended Description

Objective-C init method with return type id unable to return parent object type pointer

id type can represent the pointer to any object

When an init method (with a return type "id") of a subclass returns a parent class pointer, the compiler throws a warning / error.

However when another method without the prefix "init" does the same no compilation error / warning is thrown.

Actual Behavior

When an init method (with a return type "id") of a subclass returns a parent class pointer, the compiler throws a warning / error

Expected Behavior

When an init method (with a return type "id") of a subclass returns a parent class pointer, the compiler should not throw a warning / error

Example (Sample Objective-C program explaining the problem)

Pls see the attached Objective-C program that explains the problem

Reference:

The Objective‐C Programming Language (Page 14)

Quoted from the document:

"In Objective-C, object identifiers are of a distinct data type: id. This type is the general type for any kind of object regardless of class and can be used for instances of a class and for class objects themselves."

[efriedma-quic]

This is working as intended; see http://clang.llvm.org/docs/LanguageExtensions.html#objc_instancetype .