Real-time Safety — Guaranteed by the Compiler! - Anders Schau Knatten - NDC TechTown 2025

This talk was recorded at NDC TechTown in Kongsberg, Norway. #ndctechtown #ndcconferences #developer #softwaredeveloper

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Clang 20 introduced Function Effect Analysis (FEA), which enables real-time safety guarantees at compile-time. Mark your functions as non-throwing, non-allocating, or non-blocking — and have the compiler enforce it! For instance, a function marked non-allocating is not allowed to call malloc or new, and can only call other functions if they are also marked non-allocating (or if the compiler can deduce that they won't allocate).

In this talk, we will demonstrate function effect analysis and explain how it works. We will also see why it can be hard to enable FEA in the presence of third-party libraries, and what can be done about it.

At Squarehead, we've used FEA almost since its official release to refactor our soft real-time pipeline towards harder real-time. We will present our experience and lessons learned from this process, and the talk will be packed with useful real-life tips, tricks, and practices to set you up for success.

If time permits, we will also demonstrate the brand-new RealtimeSanitizer, the run-time companion to FEA.

After this talk, you'll know how and why to use Function Effect Analysis and RealtimeSanitizer and be aware of real-life tips, tricks, and practices for using them in your own projects.