Domain Restricted Types for Improved Code Correctness

Abstract

ReDi is a new static analysis tool for improving code correctness. It targets the C# language and is a .NET Roslyn live analyzer providing live analysis feedback to the developers using it. ReDi uses principles from formal specification and symbolic execution to implement methods for performing domain restriction on variables, parameters, and return values. A domain restriction is an invariant implemented as a check function, that can be applied to variables utilizing an annotation referring to the check method.

ReDi can also help to prevent runtime exceptions caused by null pointers. ReDi can prevent null exceptions by integrating nullability into the domain of the variables, making it feasible for ReDi to statically keep track of null, and detecting variables that may be null when used. ReDi shows promising results with finding inconsistencies and faults in some programming projects, the open source CoreWiki project by Jeff Fritz and several web service API projects for services offered by Innovation Norway. Three main types of faults where found, input validation, internal API validation, and nullability faults.