ns_consumed should work with void* pointers.

[llvmbot]

Bugzilla Link	9075
Resolution	WONTFIX
Resolved on	Jun 16, 2011 23:44
Version	unspecified
OS	All
Attachments	Test case
Reporter	LLVM Bugzilla Contributor
CC	@tkremenek

Extended Description

Many C libraries allow clients to store void * pointers with arbitrary data or pass them through to callbacks. It would be helpful if attribute((ns_consumed)) worked in such cases. However, it has no effect on void * pointers in checker-254.

I posted an example of such a case here: http://stackoverflow.com/questions/4822178/telling-clang-static-analyzer-about-third-party-libraries-owning-references/ . Ted Kremeneck assumed that ns_consumed would work in this case, but in fact it does not; however, it works in the analogous case using id pointers.

The attached test case includes a model of the pattern, once with a void * pointer, once with an id pointer. The checker complains about the void * case, but not the id case.

[llvmbot]

assigned to @tkremenek

[tkremenek]

cloned to rdar://problem/8926822

[tkremenek]

We're evaluating what to do here, as this could possibly be used with attribute((NSObject)).

This does work (as expected) with cf_consumed.

[llvmbot]

Oddly, while switch to cf_consumed works in the test case, it makes no difference in my real code. It’s not clear what the significant difference is. My actual code doesn’t call retain directly, but rather a method marked attribute((ns_returns_retained)), but this doesn’t make a difference in the test case.

[tkremenek]

We went back and forth on this. We decided we only want to support ns_consumed for values the compiler can tell are Objective-C object references.