Borrowing Safe Pointers from Rust in SPARK

Abstract

In the field of deductive software verification, programs with pointers present a major challenge due to pointer aliasing. In this paper, we introduce pointers to SPARK, a well-defined subset of the Ada language, intended for formal verification of mission-critical software. Our solution uses a permission-based static alias analysis method inspired by Rust's borrow-checker and affine types, and enforces the Concurrent Read, Exclusive Write policy. This analysis has been implemented in the GNAT Ada compiler and tested against a number of challenging examples. In the paper, we give a formal presentation of the analysis rules for a miniature version of SPARK and prove their soundness. We discuss the implementation and compare our solution with Rust.