CppCon 2026

C++ runs the world’s systems, and with that comes a responsibility for safety and stability. Avoiding AI entirely gives up on incredible potential benefits, but using AI without guardrails poses significant risks to our critical systems. How does AI fit into this world? This talk examines effective and ineffective approaches to using AI in systems that cannot afford “slop.” We will explore several case studies where AI produced significant value in C++, and several where it did not. The pattern that emerges is consistent: AI thrives when it is orchestrating well-defined, deterministic components, translating between them intelligently without being trusted to reason correctly on its own. When AI is asked to be the system rather than connect the system, things fall apart.

Today's world runs on C++. That's because, in domains requiring scale, performance, low latency, and fine-grained control over concurrency, C++ is second to none! Yet in recent years, a growing concern has emerged: C++ programs are often considered unsafe — not because of programmer negligence, but because the language itself provides insufficient mechanisms to prevent or reliably detect undefined behavior (UB).

For those financially and technically invested in C++, its current lack of language safety raises a fundamental question: How can we evolve ISO C++ to be UB-safe without necessarily sacrificing runtime performance, and without breaking backward compatibility with existing, valid C++ code?

In this talk, we begin by motivating an overall approach to UB-safety that starts from a simple but uncompromising premise: each individual potential source of UB must be able to be detected via runtime checking. Crucially, this approach eliminates the notion of "safe" and "unsafe" regions of a program — there is no place where UB can hide, and no need to switch languages, subsets, or tools to achieve comprehensive coverage.

We then examine how the C++26 contracts facility provides the essential foundation for transforming optional runtime checks into the practical, scalable mechanisms to eliminate UB bugs in production software. Contracts give developers fine-grained control over where and when checking occurs, allowing runtime overhead to be spent where it is affordable or most valuable — such as in new, rarely executed, or security-critical code. These decisions naturally evolve over time, as long-running checks that never fire may no longer justify their cost.

Finally, we outline the concrete steps of an incremental journey toward reducing undefined behavior in ISO C++. The result is a model of UB-safety — rooted in C++26 contracts and optional runtime checking — that is competitive with, and in key respects stronger than, approaches taken by other high-performance languages. Most importantly, this model applies not only to new code, but to the vast body of existing C++ software already in the wild.

Working with C++ code can be difficult, and it's made even more difficult when the code isn't your own. Everyone agrees that documentation is necessary when sharing a library. But, as a user of a library, the documentation may not help when you want to know the current state of your program. If you're a veteran C++ programmer then you may easily find your way around memory readouts, putting print statements in exactly the right spots, or reading "between the lines" of the documentation. Some of us are not very experienced, or we aren't able to recompile the code with print statements, or the documentation may not help with the problem.

Hopefully, the author had written a GDB extension to pretty-print their data types. But odds are, they didn't. As library writers, or as people writing classes for others to use and reuse, we can and should be writing debugger visualizers. We can empower our users by lowering the barrier to using the library successfully. Let's make our libraries more accessible. Software is about more than just the source code.

This talk will help you make the most of GDB extensions. After briefly discussing how to get started with GDB assuming zero prior knowledge, we will discuss how to write a GDB pretty-printer, how to set up your system to use the pretty-printer, how to embed it into your compiled binary, and how to distribute it with auto-loading scripts. By the end of the talk, the user will not only know the basics of writing a simple "to_string()", but will also understand how to effectively display containers and how to implement custom debugger-side user-facing extension methods. Let's get excited about debuggers!