Javarifier: Inferring Reference Immutability for Java 6.883: Program Analysis Course Project

Reference immutability constraints restrict certain references in a program from modifying objects. These constraints, such as those provided by the Javari programming language, have been shown to increase the expressiveness of a language and to prevent and detect errors. Unfortunately, annotating existing code, including libraries, with reference immutabil­ ity constraints is a tedious and error prone task. We propose an algorithm for inferring the references in a pro­ gram that can be declared as read­only (or romaybe). Addi­ tionally, to gain additional precision, we introduce heuristics that suggest assignable and mutable fields. To evaluate our algorithm, we have implemented a tool, Javarifier, to aid programmers in converting Java programs to Javari. We also demonstrate the practicality of our algo­ rithm by using Javarifier to annotate an existing program.