Your Rust Code Compiles, Passes Tests, and Is UB – You Just Don’t Know It

When examining a random crate from crates.io with Miri, the likelihood of encountering undefined behavior in its dependencies approaches certainty. This phenomenon raises important questions about pointer provenance, Stacked Borrows, and Tree Borrows. Additionally, the history of the noalias attribute in LLVM, which has been disabled three times, adds another layer of complexity to understanding Rust's safety guarantees. Developers often assume that their code is safe simply because it compiles and passes tests, but the reality is that subtle issues can lead to unpredictable behavior. This article delves into these concepts, shedding light on how developers can better understand and mitigate the risks associated with undefined behavior in their Rust applications.