CppCon 2026

Software development has now shifted decisively to a distributed, asynchronous paradigm, in which engineers must manage code that may be executing on parallel threads, or on a different machine. Many mainstream programming languages have adapted themselves to this new world. For example, JavaScript has promises and async/await, Python has asyncio, Rust offers zero-cost async/await with compile-time safety, and Go built goroutines and channels as first-class primitives.

C++ developers face the same challenge but have been left without a standard solution. As a result, much production code remains stuck in “callback hell,” where control flow is inverted, error handling is duplicated at every level, and common patterns like "run A and B in parallel, and then combine results" must be hand-rolled every time.

This is not simply a matter of bolting async/await onto C++. Deterministic destruction, zero-overhead abstraction, and precise control over memory and lifetimes, these very properties making C++ powerful dictate that an async framework cannot rely on a garbage collector or managed runtime to paper over complexity. It must earn its place by working with the language's ownership model, not around it.

std::execution is C++’s answer to this problem. Introduced as part of C++ 26, it solves this through composable senders: lazy, type-safe descriptions of work that can be chained, branched, and parallelized before being submitted to an execution context. Like Swift's structured concurrency, std::execution enforces structured lifetimes so that async work cannot silently outlive its scope.

This talk aims to provide application developers with an introduction to the current proposal and give them a grounding in the fundamentals that can be applied in real-world applications. We will walk through several worked examples: from simple chains to parallel fan-out with error propagation, showing side-by-side comparisons with callback-based equivalents to make the advantages more concrete and relatable.

This talk assumes no knowledge of the std::execution framework and no expertise in async programming, though practical, real-world experience will certainly help ground the examples. Attendees will leave with a working understanding of the sender/receiver model, practical patterns they can use, and a clear picture of what structured concurrency means for C++.

Floating point has a reputation for betrayal. Change the thread count, vector width, compiler flags, reduction tree, or target architecture, and the low bits can move. Parallel algorithms make this worse: the standard often specifies the operation, but not the numerical expression whose result must be reproduced. This talk asks a provocative question: what if reproducible numerics did not have to be slow?

We will show reproducible, deterministic implementations of reduce and scan that exhibit better error behavior on hostile floating-point workloads and can match or beat conventional standard-library implementations on realistic workloads. The trick is not to freeze the execution schedule. It is to specify the expression being computed, then let the implementation use SIMD, threading, blocking, tiling, and platform-specific strategies to compute that expression efficiently.

The key idea, developed through C++ standardization work such as P4016R0 and P4229R0, is reproducibility by reproducing the computation. Instead of asking the implementation to promise a particular schedule, we give the calculation a named expression. Once that expression is chosen, changing the thread count, vector width, chunking, or blocking strategy does not silently change the answer.

A reproducible scan makes this harder than reduce because it does not expose only one final value. It exposes every prefix. A reproducible final sum is not enough if the intermediate results still drift. We will show how expression and observation contracts make those prefixes reproducible without forcing the computation back into a slow sequential order.

Then we go below the algorithm layer, to the places where bits usually escape: FMA contraction, denormals, floating-point environment choices, math-library approximations, and vectorized transcendental functions. The goal is not to get the same answer by turning off the hardware. We will show reproducible vectorized primitives, including transcendental functions, running at speeds comparable to established vector math libraries while preserving a cross-platform numerical contract.

Finally, we put the whole stack under stress: a heterogeneous numerical pipeline across x86-64, Apple Silicon, and CUDA. The data is deliberately hostile, with high cancellation rates and fragile intermediate states. The aim is not to pass friendly benchmark cases, but to reproduce the specified computation, including the same intermediate failures, not just the same final answer, bit for bit, across CPUs, GPUs, and toolchains.

C++ templates are one of the language’s most powerful yet often misunderstood features. This talk walks the audience through the entire template landscape, starting with the basic syntax and definition, moving through function and class templates, and culminating in advanced techniques.

Attendees will learn how template argument deduction works, why implicit requirements matter, and how explicit specialization can replace error-prone macro tricks. Real-world examples, including a flexible register abstraction used in production code, show how generic programming can deliver type-safe, high-performance solutions without sacrificing readability and performance (zero cost abstraction).

By the end of the session, participants will feel confident writing their own generic components, understand the trade-offs of different template features, and have a toolbox of best-practice patterns they can apply immediately to their projects.

For thirty years, SIMD has been the preserve of experts. Writing the fastest C++ has meant hand-written intrinsics, locking code to one architecture, and parallel implementations maintained across every instruction set you ship to. Auto-vectorization can help, but optimizers may give up in complex scenarios where iteration independence isn't obvious. C++26 changes that by putting SIMD in the hands of every C++ programmer, bringing portable, expressive data parallelism into the standard library.

For the engineers who have spent decades writing intrinsics in telecoms, finance, HPC, and embedded systems, migration to std::simd is only worthwhile if it preserves the performance they have fought to achieve. Every cycle counts when code runs tens of thousands of times per second, for years on end, and a portable abstraction that costs ten percent is not a win. The bar for adoption is therefore high: the abstraction must be measurably cheap, the generated code must match hand-written intrinsics, and the tricks and techniques those engineers rely on must all be expressible in the library, not lost in translation.

This talk takes the practitioner's view, aimed squarely at the engineers who write real intrinsics code today and need to know whether std::simd can replace it. It starts with what modern SIMD hardware actually offers, grounding std::simd in real silicon. It then works through the main features of C++26's std::simd with worked examples drawn from the patterns that recur in production intrinsics code, accessible to programmers new to the library and detailed enough for intrinsics veterans to map against their own kernels with all their accumulated tricks and techniques. A look under the hood at our implementation shows how careful API design and aggressive use of hardware features make the abstraction as cheap as the target architecture allows, and how the library fills the gaps on weaker targets with implementations that an expert library author can write once on behalf of every user. The talk closes with a preview of the C++29 proposals being written now to close the remaining gaps, so that std::simd becomes a clear win even for the most performance-critical code.

C++ gives us at least four different ways to pass "a thing that can be called" from one piece of code to another: function pointers, function objects, lambdas, and type-erased wrappers like std::function . Modern C++ has added more — generic lambdas, deducing-this lambdas, std::move_only_function , and a healthy ecosystem of concept-constrained callable parameters. Each of these has a job it is good at and several jobs it is bad at, but they are often used interchangeably until something breaks.

We will start with the basics: what a callable actually is, how function pointers, function objects, and lambdas relate to one another, and how the compiler thinks about each of them. We will look at lambda capture rules in detail — by-value, by-reference, init captures, dangling captures, and the cases where well-meaning developers reach for [=] or [&] and ship a bug — and we will see how generic lambdas (C++14) and deducing-this lambdas (C++23) extend the model without giving up clarity.

From there we will turn to the question of how to store and pass callables. We will compare function pointers, std::function , std::move_only_function (C++23), and concept-templated callable parameters along the axes that actually matter: ownership, allocation, move-only support, performance, and what the API tells the reader. Examples will be drawn from issues that have come up writing production code and mentoring developers — including the kind of subtle ABI and lifetime bugs that hide behind a perfectly reasonable-looking std::function<void()> parameter.

We will conclude with recommendations for which tool to reach for in which situation, with reference to the C++ Core Guidelines where useful. Attendees will leave with a clearer mental model of callables in modern C++ and a defensible default for the next time they write a function that takes one.