Re: Analyzer warning about garbage with double return values
Re: Analyzer warning about garbage with double return values
- Subject: Re: Analyzer warning about garbage with double return values
- From: Bjoern Knafla <email@hidden>
- Date: Wed, 2 Sep 2009 10:58:35 +0200
Its hidden in the following info box text from the link http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/ObjectiveC/Articles/ocObjectsClasses.html#//apple_ref/doc/uid/TP30001163-CH11-SW7
:
Note: The behavior of sending messages to nil changed slightly with
Mac OS X v10.5.
On Mac OS X v10.4 and earlier, a message to nil also is valid, as
long as the message returns an object, any pointer type, void, or any
integer scalar of size less than or equal to sizeof(void*); if it
does, a message sent to nil returns nil. If the message sent to nil
returns anything other than the aforementioned value types (for
example, if it returns any struct type, any floating-point type, or
any vector type) the return value is undefined. You should therefore
not rely on the return value of messages sent tonil unless the
method’s return type is an object, any pointer type, or any integer
scalar of size less than or equal to sizeof(void*).
Kind regards,
Bjoern
On 02.09.2009, at 10:50, Jean-Daniel Dupas wrote:
Le 2 sept. 2009 à 10:45, Jonas Maebe a écrit :
On 02 Sep 2009, at 10:07, Markus Spoettl wrote:
I thought it was safe to message nil-objects, the return value
would be 0 or the equivalent for the respective expression return
type. Is this not the case for double return values?
See http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/ObjectiveC/Articles/ocObjectsClasses.html#//apple_ref/doc/uid/TP30001163-CH11-SW7
, in particular the last bullet in that list.
Yes, and it does not concern double as it is in "aforementioned
types". (see second bullet)
If the method returns any pointer type, any integer scalar of size
less than or equal to sizeof(void*), a float, a double, a long
double, or a long long, then a message sent to nil returns 0.
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