Enabling static analysis for partial java programs

Abstract

Software engineering tools often deal with the source code of programs retrieved from the web or source code repositories. Typically, these tools only have access to a subset of a program's source code (one file or a subset of files) which makes it difficult to build a complete and typed intermediate representation (IR). Indeed, for incomplete object-oriented programs, it is not always possible to completely disambiguate the syntactic constructs and to recover the declared type of certain expressions because the declaration of many types and class members are not accessible. We present a framework that performs partial type inference and uses heuristics to recover the declared type of expressions and resolve ambiguities in partial Java programs. Our framework produces a complete and typed IR suitable for further static analysis. We have implemented this framework and used it in an empirical study on four large open source systems which shows that our system recovers most declared types with a low error rate, even when only one class is accessible.