false positive due to not analyzing value dependencies

[llvmbot]

Bugzilla Link	8689
Resolution	INVALID
Resolved on	Nov 29, 2010 17:19
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@tkremenek

Extended Description

Static analyzer for the attached file reports that:

/tmp/test.c:17:28: warning: Access to field 'a' results in a dereference of a null pointer (loaded from variable 'X')
return error ? NULL : X->a;
~ ^

But clearly when X is dereferenced it cannot be NULL.

[llvmbot]

assigned to @tkremenek

[llvmbot]

Hm? This clearly shows 'error' being tested then 'X' being dereferenced. Without a full source example, there's no reason to think that 'error' and 'X' have correlated values.

[llvmbot]

test case

[llvmbot]

Hm? This clearly shows 'error' being tested then 'X' being dereferenced.
Without a full source example, there's no reason to think that 'error' and 'X'
have correlated values.

Sorry somehow I didn't attach the test case, guess I forgot to add description

[llvmbot]

Static analyzer for the attached file reports that:

/tmp/test.c:17:28: warning: Access to field 'a' results in a dereference of a
null pointer (loaded from variable 'X')
return error ? NULL : X->a;
~ ^

But clearly when X is dereferenced it cannot be NULL.

Nick is right, X can be null if the allocation fails. In fact, I see no correlation between X and error in the example.

[tkremenek]

This looks like a completely legit warning from the analyzer. Why is this a false positive?

[llvmbot]

This looks like a completely legit warning from the analyzer. Why is this a
false positive?

I misunderstood one thing. Sorry for the trouble.