Static error detection using semantic inconsistency inference

Inconsistency checking is a method for detecting software errors that relies only on examining multiple uses of a value. We propose that inconsistency inference is best understood as a variant of the older and better understood problem of type inference. Using this insight, we describe a precise and formal framework for discovering inconsistency errors. Unlike previous approaches to the problem, our technique for finding inconsistency errors is purely semantic and can deal with complex aliasing and path-sensitive conditions. We have built a nullde reference analysis of C programs based on semantic inconsistency inference and have used it to find hundreds of previously unknown null dereference errors in widely used C programs.