Upcoming C++ User Group meetings in June 2026

by Jens Weller

From the article:

In early April of 2023 I've posted the last list of upcoming C++ User Group meetings, as a change in Meetup made this feature not accessible.

I've noticed last week that this has changed now, and so will return to posting this monthly list again. I'm working on also integrating these into the website it self in June.

Its nice to see so many C++ User Groups to still be active!

 

Annotations for C++26 Hashing

by Krystian Piękoś

From the article:

In my recent post, I demonstrated how to use static reflection from C++26 to implement generic hash computation for custom types. Let's review the final implementation. The core of the solution is the calculate_hash() function, which iterates over sub-objects (including both base classes sub-objects and class/struct non-static data members) to compute a combined hash.

template <typename T>
concept Hashable = requires {
  { std::hash<T>{}(std::declval<T>()) } -> std::convertible_to<size_t>;
};

template <typename T>
  requires std::is_class_v<T>
size_t calculate_hash(const T& obj, size_t seed = 0)
{
  constexpr auto ctx = std::meta::access_context::unchecked();

 
  static constexpr auto r_subobjects = std::define_static_array(std::meta::subobjects_of(^^T, ctx));

  template for (constexpr auto r_sub : r_subobjects)
  {
    using Subobject_t = typename[:std::meta::type_of(r_sub):];
    static_assert(Hashable<Subobject_t>, "Subobject must be hashable");
    Utility::hash_combine(seed, obj.[:r_sub:])
  }

  return seed;
}

How ref qualifiers led to deducing this

by Jens Weller

From the article:

Last week I shared an overview on ref qualifiers with you, this is a follow up on this post. Featuring deducing this, a C++23 feature that should be available in your compiler if its been released in 2025 or later.

Lets start with two more things you may want to know about ref qualifiers. First, const is also supported for the rvalue version: m::f()const && exists, though this is mostly not very useful. Thats why you rarely see it covered, as const rvalues are unusual to unvalid. But thats where m::f()const&&=delete comes in, it allows you to turn these object states in to compilation errors.

As ref qualifiers are also often used...

 

Back to Basics: Master C++ Friendship

by Mateusz Pusz

Summary of the talk:

C++ offers a rich set of access specifiers to control the visibility of class members. However, the friend keyword introduces a unique and often misunderstood concept. This talk explores the nuances of friendship, examining its role in code design, testing, and compilation performance optimization.

We'll delve into the intricacies of friendship, exploring its benefits and potential pitfalls. We'll examine how to leverage friendship effectively, discuss best practices, and uncover hidden gems and common misconceptions. We will see how friendship affects name lookup and compile-time error messages. We will discuss best practices for using it effectively and learn how to avoid or resolve compilation problems that may occur when C++ templates are involved.

By the end of this session, you'll have a solid grasp of friendship and be able to use it to write more elegant, efficient, and maintainable C++ code.

C++26: Structured Bindings in Conditions

by Sandor Dargo

From the article:

Structured bindings were introduced in C++17 as an alternative way of declaring variables. They allow you to decompose an object into a set of named variables, where the collection of those bindings conceptually represents the original object as a whole.

// https://godbolt.org/z/97GaMajMP

#include <cassert> #include <string> 
struct MyStruct {
    int num;
    std::string text;

    bool operator==(const MyStruct&) const noexcept = default;
};

MyStruct foo() {
    return {42, "let's go"};
}

int main() {
    const auto& [n, t] = foo();
    MyStruct ms{n, t};
    assert(ms == foo());
    return 0;
}

Could C++ Developers Handle an ABI Break Today?

by Luis Caro Campos

Summary of the talk:

The C++ Evolution Working Group recently reaffirmed its commitment to ABI stability, prioritizing link compatibility with C and older C++. The C++11 libstdc++ ABI updates introduced in gcc 5.1, although not strictly “breaking”, are still in the collective memory of C++ developers and this experience shows us how sensitive the ecosystem is to ABI updates.

This talk challenges the assumption that a future ABI break would be equally problematic, as the landscape has evolved significantly in the last decade.

On the one hand, the C++ standard has evolved in such a way that even if the standards committee and compiler vendors go through great lengths to avoid breaking the ABI of standard library implementations, library authors are not as cautious - so in practice, the ability to link objects built with different C++ standard levels does not hold true for a lot of cases.

On the other hand, tooling has evolved significantly in this time period. For example, both Conan and vcpkg are able to “tag” binaries on some arbitrary ABI version. We can see similar examples in other tools or ecosystems that need to work around ABI complexities.

This talk is not intended to argue about the merits or risks of future ABI changes - but to ask ourselves the question: are we overestimating the pain of a future ABI break?

Let the Compiler Check Your Units

by Wu Yongwei

From the article:

I recently came across a C++ standard proposal P3045 [P3045R7], which aims to add physical units to C++. Curious, I looked into the existing unit libraries and went down quite a rabbit hole.

Type safety and user-defined literals

Before exploring these libraries, I was already somewhat familiar with the idea of ‘type safety’. I was also aware that user-defined literals (UDLs) [CppReference-1] allow creating literals of specific types with ease. Typical uses in the standard library include string/string_view literals and the chrono library [CppReference-2], which make code both convenient and safe.

Figure 1 shows some simple examples.

auto msg = "Hello "s + user_name;
auto t1 = chrono::steady_clock::now();
this_thread::sleep_for(500ms);
auto t2 = chrono::steady_clock::now();
auto duration = t2 - t1;
auto what = t1 + t2;      // Can't compile
cout << duration / 1.0ms; // To double, in ms

How To Build Robust C++ Inter-Process Queues

by Jody Hagins

Summary of the talk:

This talk will offer design and implementation details of a queue intended to be used between multiple processes.

The C++ standard was written with a single-process worldview, mentioning processes only once—in a note stating that lock-free atomic operations work across process boundaries. This has led to widespread but incorrect advice about using std::atomic in shared memory. When moving queue implementations from threads to processes, seemingly rock-solid code can induce undefined behavior.

In addition, traditional queue interfaces are fundamentally insufficient for cross-process communication. A properly designed inter-process queue API must enforce role separation, ensuring that a process can only perform operations appropriate to its designated role. For example, a producer process should not be able to consume messages or manage the queue itself, and the API should prevent multiple processes from accidentally assuming the same role in a single-producer design.

By the end of this talk, you will understand the fundamental differences between thread process synchronization, how to design proper interfaces for interprocess queues that enforce correct usage across process boundaries, and practical techniques to ensure your cross-process code works reliably in production environments.

Oh yeah, and you will have a full implementation that you can use and improve upon.

Exploring ref qualifiers in C++

by Jens Weller

From the article:

Ref qualifiers are today an old C++11 feature, and recently I wanted to know more about them. Especially their potential use cases.

Thats a particular point with this feature, I've seen examples - but often without a compelling use case. This feature is a great way to achieve very specific things in C++...

 

The road to 'import boost': a library developer's journey into C++20 modules

Rubén Pérez Hidalgo

Watch now:

Concept-based Generic Programming

by Bjarne Stroustrup

Summary of the talk:

This talk presents programming techniques to illustrate the facilities and principles of C++ generic programming using concepts. Concepts are C++’s way to express constraints on generic code. As an initial example, it provides a simple type system that eliminate narrowing conversions and provides range checking.

Concepts are used throughout to provide user-defined extensions to the type system. The aim is to show their utility and the fundamental ideas behind them, rather than to provide a detailed or complete explanation of C++’s language support for generic programming or the extensive support provided by the standard library.

The final sections briefly present design rationales and origins for key parts of the concept design, including use patterns, the relationship to Object-Oriented Programming, value arguments, syntax, concept type-matching, and definition checking. They also mention static reflection, a C++26 improvements in the support of general programming.

Meeting C++ 2026: Call for Sponsors

by Jens Weller

from the article:

Have you thought about the possibilty that you could have your employer sponsor Meeting C++ 2026?

Maybe your employer is interested in being present as a sponsor at this years Meeting C++ conference? With the call for talks closing on June 4th, now is the ideal time to talk about sponsorships for Meeting C++!

The 15th Meeting C++ conference is looking for sponsors! Come to Berlin in late November and be part of a large gathering of the C++ community!

 

In today's post, I will explain one of C++'s biggest pitfalls: reinterpret_cast. Another title for this post could be: This is not the cast you're looking for!

What reinterpret_cast doesn't do

Andreas Fertig

From the article:

My motivation for this blog post comes from multiple training classes I thought over the past several months and a couple of talks I gave. Since C++23, you have a new facility in the Standard Library: std::start_lifetime_as. When teaching class with a focus on embedded environments or presenting talks with such a focus, I started to add std::start_lifetime_as to the material. With an interesting outcome.

The feedback I get is roughly:

• why do I need std::start_lifetime_as, I already have reinterpret_cast?
• why can I use reinterpret_cast?

If you never heard of start_lifetime_as please consider reading my post, The correct way to do type punning in C++ - The second act.

What Happens When a Destructor Throws

by Sandor Dargo

From the article:

Recently I wrote about the importance of finding joy in our jobs on The Dev Ladder. Mastery and deep understanding are key elements in finding that joy, especially now that generating code is cheap and increasingly done better by AI than by us.

Then a memory surfaced. I frequently ask during interviews — as part of a code review exercise — what happens when a destructor throws. Way too many candidates, even those interviewing for senior positions, cannot answer the question. Most say it’s bad practice, but cannot explain why. Some say the program might terminate. Getting an elaborate answer is rare.

I’m not saying it’s a dealbreaker, but it definitely doesn’t help.

Let’s see what actually happens.

The role of a destructor

A destructor is the key to implementing the RAII idiom. RAII matters because after you acquire a resource, things might go south. A function might need to return early, or it might throw. Making sure resources are released is cumbersome, and the cleanest way to achieve it is to wrap both acquisition and release in an object that handles this automatically.

But what if the release itself is not successful?

Destructors have no return value, so error reporting is limited. Typical options include logging, storing error state, or (discouraged) throwing.

Why did I mark throwing an exception discouraged?

The trailer premieres today at 19:00 UTC. Click Notify me on the YouTube Premiere page to get a reminder when it goes live.

The film will have its world premiere on May 28 at a special live event in New York City’s Financial District, followed by a panel discussion that will be recorded for later release. C++: The Documentary will be released worldwide on YouTube on June 4, with the panel recording following a few days later.

Crafting the Code You Don’t Write: Sculpting Software in an AI World

by Daisy Hollman

Summary of the talk:

It’s shockingly uncontroversial to say that the fields of developer experience and developer productivity have changed more in the past six months than in the 25 years before that.

As part of the Claude Code team at Anthropic, I’ve had the privilege of witnessing the evolution of agentic coding from proof-of-concept experiments to nearly autonomous software engineers in just six months. In this keynote, I’ll share some of my experiences and learnings from that journey, talk about how LLMs work more generally, attempt some live demonstrations of the latest functionality, explore the future of agentic programming, and tie all of this back to what it means for your workflow as a software engineer.

When I agreed to give this talk earlier this year, there was some portion of the narrative that involved “why you should be using agents to accelerate your development process.” Since then, the world of software engineering has evolved such that the interesting question is no longer “why” but “how.” Like sculptors facing the invention of power tools, or painters around the invention of photography, we now live in a world where vast quantities of rough-draft code can be generated with a very low barrier to entry. How does the role of a software engineer evolve when AI can autonomously implement features from requirements? How do we build safety features into the power tools we’re chiseling away at our codebases with? What aspects of software craftsmanship become more important, not less, in an age of abundant code generation? And critically for the C++ community: how do we leverage these tools where correctness and performance are non-negotiable? The future isn’t about AI replacing programmers, but about a fundamental shift in how we think about software creation. And surprisingly, you might not miss the old way of doing things.

Evolving a Translation System with Reflection in C++

By GitHub user: friedkeenan
 

From the post:

Lately, I’ve been using C++26 reflection to create some crazy and cursed stuff. But even though I quite enjoy that work, it is as well quite far from the norm of what reflection is going to offer us in our everyday code.

Reflection is definitely not just that craziness, and so I want to present reflection in a more grounded environment, and in a way that will probably land as more typical usage as our codebases gradually come into contact with it.

So then, in this blogpost, I will be exploring a spectrum of options for how reflection can upgrade a translation system that I already use in one of my projects. We’ll look at where it’s at now without reflection, identify places in which reflection could plausibly help, and then explore a series of modifications we could make to soothe those problem points.

The purpose of looking at each of these options will not be to declare that one is clearly the best option or the one that makes the most sense, but rather to get a better feel for what could make sense to do, and whether some things are really worth the effort. We’re trying to gauge the benefits that reflection can bring to our code.

And who knows, even if one option is less appealing for this particular situation, maybe in a different situation it could be the perfect fit.

Reflection: C++’s Decade-Defining Rocket Engine

by Herb Sutter

Summary of the talk:

In June 2025, C++ crossed a Rubicon: it handed us the keys to its own machinery. For the first time, C++ can describe itself—and generate more. The first compile-time reflection features in draft C++26 mark the most transformative turning point in our language’s history by giving us the most powerful new engine for expressing efficient abstractions that C++ has ever had, and we’ll need the next decade to discover what this rocket can do.

This session is a high-velocity tour through what reflection enables today in C++26, and what it will enable next. We’ll start with live compiler demos (Godbolt, of course) to show how much the initial C++26 feature set can already do. Then we’ll jump a few years ahead, using Dan Katz’s Clang extensions and my own cppfront reflection implementation to preview future capabilities that could reshape not just C++, but the way we think about programming itself.

We’ll see how reflection can simplify C++’s future evolution by reducing the need for as many bespoke new language features, since many can now be expressed as reusable compile-time libraries—faster to design, easier to test, and portable from day one. We’ll even glimpse how it might solve a problem that has long eluded the entire software industry, in a way that benefits every language.

The point of this talk isn’t to immediately grok any given technique or example. The takeaway is bigger: to leave all of us dizzy from the sheer volume of different examples, asking again and again, “Wait, we can do that now?!”—to fire up our imaginations to discover and develop this enormous new frontier together, and chart the strange new worlds C++ reflection has just opened for us to explore.

Reflection has arrived, more is coming, and the frontier is open. Let’s go.

Back to Basics: Move Semantics

by Ben Saks

Summary of the talk:

While many C++ programmers are familiar with the broad idea of move semantics, even experienced C++ programmers often struggle with the fine details. For example, many programmers are unclear on exactly when an object is considered implicitly movable and when std::move() is required to make the object movable. This is especially unfortunate because using std::move() when it's unnecessary sometimes degrades performance.

This session starts by explaining how move semantics can substantially improve performance for certain types. It then shows how to implement a type with move semantics, and explores some important design issues in creating these types. After that, it explains how types like std::vector＜T＞ can operate much more efficiently on objects of types that support move semantics.

You'll leave this session with a clearer understanding of:

• how to implement move-semantic types,
• how to take maximum advantage of move-semantic types, and
• how move semantics are related to other language features like return-value optimization.

The 2026 Schedule is Here!

by ACCU

From the article:

Four days, five tracks, and a lineup that spans the full breadth of what ACCU on Sea is about: deep C++ content, broader software craft, and the kind of talks that make you rethink something you thought you understood.

JSON and C++26 compile-time reflection: a talk

by Daniel Lemire

Watch now:

Beyond Sequential Consistency: Unlocking Hidden Performance Gains

by Christopher Fretz

Summary of the talk:

In 2011, C++ introduced a formally defined memory model, providing a foundation for portable, multi-threaded code with well-defined correctness guarantees. This was a major milestone, enabling expressive threading primitives and safe concurrency patterns while allowing low-level optimizations for performance.

By default, C++ atomics enforce sequential consistency, which ensures intuitive, predictable behavior. However, these strong guarantees often exceed what’s necessary for correctness and come with a performance cost.

This talk delves into weaker memory orderings, particularly acquire/release and relaxed semantics, using a ring buffer as a practical example of how they can be used. We’ll also examine how the C++ memory model maps to real hardware, focusing on x86’s native guarantees, and comparing against less coherent platforms like ARM. We'll explore how strategic use of weaker synchronization can unlock significant performance gains without sacrificing correctness.

At its core, assert() exists to validate runtime conditions. If the given expression evaluates to false, the program aborts. I’m almost certain you’ve used it before — at work, in personal projects, or at the very least in examples and code snippets.

So what’s the problem?

C++26: A User-Friendly assert() macro

by Sandor Dargo

From the article:

assert() is a macro — and a slightly sneaky one at that. Its name is written in lowercase, so it doesn’t follow the usual SCREAMING_SNAKE_CASE convention we associate with macros. There’s a good chance you’ve been using it for years without ever thinking about its macro nature.

Macros, of course, aren’t particularly popular among modern C++ developers. But the issue here isn’t the usual - but valid - “macros are evil” argument. The real problem is more specific:

The preprocessor only understands parentheses for grouping. It does not understand other C++ syntax such as template angle brackets or brace-initialization.

As a result, several otherwise perfectly valid-looking assertions fail to compile:

// https://godbolt.org/z/9sqM7PvWh using Int = int; int x = 1, y = 2; assert(std::is_same<int, Int>::value); assert([x, y]() { return x < y; }() == 1); assert(std::vector<int>{1, 2, 3}.size() == 3);

 

CppDevSurvey-2026-summary.pdf

A 145-page version of this report that also includes all individual write-in responses has now been forwarded to the C++ standards committee and C++ product vendors, to help inform C++ evolution and tooling.

Your feedback is valuable, and appreciated.

In this article, we'll build a macro-base alternative that's more suitable for game development in ~200 lines of C++.

Stackless coroutines for gamedev in ~200 lines of C++

by Vittorio Romeo

From the article:

For a game I want a coroutine that is part of an object’s data. When the object dies, the coroutine dies with it. When I serialize the object to a save buffer, the coroutine’s state goes with it. When the optimizer is off, there is no extra cost compared to the equivalent state machine. C++20 coroutines do not provide any of these guarantees out of the box.

Let’s build something that does.

GCC 16 Release Series: Changes, New Features, and Fixes

From the announcement:

• C++20 by default: [...] N.B. C++20 modules support is still experimental and must be enabled by -fmodules.

• Several C++26 features have been implemented:
  • P2996R13, Reflection (PR120775, enabled by -std=c++26 -freflection)
  • P3394R4, Annotations for Reflection
  • P3293R3, Splicing a base class subobject
  • P3096R12, Function Parameter Reflection
  • P3491R3, define_static_{string,object,array} (PR120783)
  • P3560R2, Error Handling in Reflection
  • P1306R5, Expansion statements (PR120776)
  • P2900R14, Contracts (PR119061)
  • P2795R5, Erroneous behavior for uninitialized reads (PR114457)
  • [...]

• Improved experimental C++20 modules support:
  • New command line option --compile-std-module that conveniently builds the <bits/stdc++.h> header unit and the std and std.compat modules before compiling any source files explicitly specified on the command line.
  • Whenever the <bits/stdc++.h> header unit has been built, GCC now transparently translates an #include of any importable standard library header into an import of <bits/stdc++.h>.
  • Many reported bugs have been fixed, thanks to Nathaniel Shead.
  • [...]

Runtime Library (libstdc++)

• [...]
• Improved experimental support for [...]
  • std::mdspan, thanks to Luc Grosheintz.
  • [...]
  • std::simd.
  • std::inplace_vector.
  • [...]

Glaze 7.2 - C++26 Reflection | YAML, CBOR, MessagePack, TOML and more

From the article:

Glaze now supports C++26 reflection with experimental GCC and Clang compilers. GCC 16 will soon be released with this support. When enabled, Glaze replaces the traditional __PRETTY_FUNCTION__ parsing and structured binding tricks with proper compile-time reflection primitives (std::meta).

The API doesn't change at all. You just get much more powerful automatic reflection that still works with Glaze overrides! Glaze was designed with automatic reflection in mind and still lets you customize reflection metadata using glz::meta on top of what std::meta provides via defaults.

The Wonderful World of Designing a USB Stack Using Modern C++

by Madeline Schneider

Summary of the talk:

Have you ever wondered how to design a library to abstract and manage complex communication protocols like USB? Have you ever wondered which parts of a protocol need to be hardware abstractions and which parts are hardware agnostic? Well you’re in luck, my mentor and I have designed a USB stack from the ground up in modern C++! We found that the public offerings did not meet our needs. Our requirements are:

• Resource efficient
• Portable
• Modular
• Convenient to use
• Distributable via single pre-built binary using conan
• Without allocations after initialization

In this talk you’ll learn the basics of how USB works at the lowest level from a software perspective. You’ll learn why malleability and freedom are so important for USB device development and how C++ makes such a library design easy to implement. Embark with me on a deep-dive into shaping a library where complexity runs wild. This talk will have lessons on library and API design in situations where the degrees of freedom are vast and all parts must magically fit together. By the end, you’ll carry away practical patterns for taming vast design spaces—skills that apply to any ambitious library, far beyond USB.

Can Standard C++ Replace CUDA for GPU Acceleration?

by Elmar Westphal

Summary of the talk:

On top of the woes of multi-threaded programming itself, coding for GPUs used to be about dealing with kernels, separate memory domains, warps, blocks and other strange things. Later, life became easier and you could sprinkle in a bunch of pragmas, hoping that your favorite language extension would deal with all of this for you, and better memory model abstractions came up that were less painful to deal with. In recent years, new drivers (seemingly) levelled the boundaries between memory domains and new compilers allow us to deploy code to the GPU using standard C++ execution policies. The performance of the generated code is often similar to that of its CUDA-C++ counterpart. Of course there is no magic bullet to shoot at your (legacy) code and there are caveats, but come and see how using standard parallelism (also) for programming GPUs makes it a lot easier to write portable and more future-proof high-performance C++ code.

Behold the power of meta::substitute

by Barry Revzin

From the article:

Over winter break, I started working on proposal for string interpolation. It was a lot of fun to work through implementing, basically an hour a day during my daughter’s nap time. The design itself is motivated by wanting to have a lot more functionality other than just formatting — and one of the examples in the paper was implementing an algorithm that does highlighting of the interpolations, such that:

 

 

 

would print this:

x=5 and y=*10* and z=hello!

without doing any additional parsing work. I got the example from Vittorio Romeo’s original paper.

Now, when I wrote the paper, I considered this to be a simple example demonstrating something that was possible with the design I was proposing that was not possible with the other design. I thought that because obviously you need the format string as a compile-time constant in order to parse it at compile time to get the information that you need.

The annual global C++ developer survey is now open:

2026 Annual C++ Developer Survey "Lite"

Please share your feedback in this annual 10-minute survey to help inform C++ standardization and C++ tool vendors. This is the biggest opportunity we all have each year to make our voices heard and help improve our industry and community!

A summary of the results, including aggregated highlights of common answers in the write-in responses, will be posted publicly here on isocpp.org and shared with the C++ standardization committee participants and C++ tool vendors to help inform C++ evolution and tooling.

The survey closes in one week.

Thank you for participating and helping to inform our committee and community.

C++: Some Assembly Required

by Matt Godbolt

Summary of the talk:

Join Matt in exploring how the C++ ecosystem has evolved through the interplay of intentional design and emergent collaboration. Standards committees craft language features and compiler teams implement them, but something amazing happens in the spaces between: tools appear, communities form, and solutions emerge that nobody quite planned for. What started as individual developers solving their own problems has grown into an interconnected ecosystem that shapes how we all write C++.

From documentation to testing, from build systems to package managers, we'll examine how the C++ community has assembled itself around shared pain points and accidental standards. Using examples and perhaps too many rainforest metaphors, this talk celebrates not just the language we've built, but the organic ecosystem that's grown up around it. Come discover why C++'s greatest strength might be that it's always required some assembly.

How C++ Finally Beats Rust at JSON Serialization

by Daniel Lemire & Francisco Geiman Thiesen

Summary of the talk:

JSON, or JavaScript Object Notation, has become a cornerstone for storing and exchanging data. Its appeal lies in its simplicity—human-readable text that elegantly captures structured data through attribute-value pairs and arrays: {"age": 5, "name": "Daniel", "toys": ["wooden dog", "little car"]}. JSON is intuitive yet powerful. But ingesting and producing JSON can turn into a performance choke point. In C++, it can be a tedious, error-prone task. Programmers wrestle with unexpected content, manually mapping data to and from native structures, all while striving for speed and safety.

With languages like Java, C#, Zig, Rust, or Python, JSON serialization and deserialization typically requires far less work. In particular, Rust's serde library blends convenience with high speed. We wish for a C++ library to automatically handle JSON production and consumption, seamlessly tied to native data structures. It is not merely to simplify life for developers; it is also about crafting code that is both fast and solid, generated at compile time by a battle-tested library.

Thankfully, C++ might soon be getting reflective metaprogramming (  PR2996  ). Leveraging the  experimental Bloomberg LLVM fork  with reflective metaprogramming, we have built a full-fledged implementation—complete with tests, benchmarks, and documentation. Our goal is to have production-ready code the moment mainstream compilers catch up. The results speak for themselves: we are parsing JSON directly into C++ structures at gigabytes per second, outpacing even mature heavyweights like Rust's serde. Better yet, the conversion between C++ data structures and JSON is fully automated, thanks to metaprogramming. It has the potential to be a leap forward for C++ in the data-driven age. Unfortunately, there are still problems and limitations: we present them and provide some solutions.

Devirtualization and Static Polymorphism

by David Álvarez Rosa

From the article:

Ever wondered why your “clean” polymorphic design underperforms in benchmarks? Virtual dispatch enables polymorphism, but it comes with hidden overhead: pointer indirection, larger object layouts, and fewer inlining opportunities.

Compilers do their best to devirtualize these calls, but it isn’t always possible. On latency-sensitive paths, it’s beneficial to manually replace dynamic dispatch with static polymorphism, so calls are resolved at compile time and the abstraction has effectively zero runtime cost.

Why Every C++ Game Developer Should Learn SDL 3 Now

by Mike Shah

Summary of the talk:

The C++ programming language does not have a standard graphics library, However, there exists many popular graphics frameworks for cross-platform graphics. In this talk, I will provide an introduction to the Simple Directmedia Layer (SDL) library, which has at the start of 2025 released version 3. This library for several decades has been a standard in the games and graphics industry. Throughout this talk, I will show how to get started with the library, some more advanced examples (including compiling graphics applications to web), and then talk about what a standard graphics library could look like in C++, or if it is even necessary. I will also talk about the 3D GPU library in SDL3. Attendees will leave this talk ready to build multimedia / game applications and with an understanding on if SDL3 is the right tool for them.

Like all software, the site requires maintenance. It has been in read-only mode for some time while Nate has been leading the work to migrate it to MediaWiki. Because the Standard C++ Foundation's web wizard, James Riordon, recently migrated the ISO C++ committee wiki (now also maintained by the Foundation) to MediaWiki, I asked Nate whether the Foundation and James could help. Nate accepted our offer, and thanks to Nate and James's work, cppreference is now almost ready to return to normal read-write operation.

To help keep the site running smoothly going forward, the Foundation plans to continue providing hosting and administrative support for the site's infrastructure, including future MediaWiki and related updates. That should let Nate stay focused on leading the site's content and coordinating the volunteer editors who keep cppreference current.

We expect the refreshed site, including support for all languages, to return to read-write mode later this month. Fingers crossed. My thanks again to Nate, James, and everyone who has helped make cppreference the indispensable reference it is today, and to everyone for their patience while this necessary maintenance has been underway.

Cheers,

Herb

Implementing Your Own C++ Atomics

by Ben Saks

Summary of the talk:

Atomic objects are extremely useful for concurrent programming. Unfortunately, some embedded toolchains like AVR-GCC omit portions of the C++ Standard Library, including headers like ＜atomic＞ .This makes it much harder to program concurrent software on these platforms, since many tutorials and open-source libraries assume Standard Library support. For example, these talks from past CppCons present lock-free data structures and algorithms that rely strongly on lock-free instantiations of std::atomic＜T＞:

Single Producer Single Consumer Lock-free FIFO From the Ground Up – Charles Frasch – CppCon 2023
Introduction to Wait-free Algorithms in C++ Programming – Daniel Anderson – CppCon 2024
User API & C++ Implementation of a Multi Producer, Multi Consumer, Lock Free, Atomic Queue – Erez Strauss – CppCon 2024

This session will show you how to implement your own atomic types in the absence of library support. These atomic types can greatly expand the number of tutorials and open-source libraries available for you to use. A clear understanding of how atomic types are implemented will also help you use objects of those types more effectively on platforms that do provide native support.

Power of C++26 Reflection: Strong (opaque) type definitions 

From the article:

With reflection, you can easily create "opaque" type definitions, i.e "strong types". It works by having an inner value stored, and wrapping over all public member functions.

Note: I am using queue_injection { ... } with the EDG experimental reflection, which afaik wasn't actually integrated into the C++26 standard, but without it you would simply need two build stages for codegen. This is also just a proof of concept, some features aren't fully developed (e.g aggregate initialization)

struct Item { /* ... */ }; // name, price as methods

struct FoodItem;
struct BookItem;
struct MovieItem;

consteval { 
    make_strong_typedef(^^FoodItem, ^^Item); 
    make_strong_typedef(^^BookItem, ^^Item); 
    make_strong_typedef(^^MovieItem, ^^Item); 
}

// Fully distinct types
void display(FoodItem &i) {
    std::cout << "Food: " << i.name() << ", " << i.price() << std::endl;
}
void display(BookItem &i) {
    std::cout << "Book: " << i.name() << ", " << i.price() << std::endl;
}

int main() {
    FoodItem fi("apple", 10); // works if Item constructor isn't marked explicit
    FoodItem fi_conversion(Item{"chocolate", 5}); // otherwise
    BookItem bi("the art of war", 20);
    MovieItem mi("interstellar", 25);

    display(fi);
    display(bi);
    // display(Item{"hello", 1}); // incorrect, missing display(Item&) function
    // display(mi); // incorrect, missing display(MovieItem&) function
}

Back to Basics: Custom Allocators Explained - From Basics to Advanced

by Kevin Carpenter

Summary of the talk:

Effective memory management is crucial for building efficient and reliable C++ applications. Custom memory allocators provide a powerful tool for optimizing memory usage, reducing fragmentation, and improving performance. This talk will explore the intricacies of memory allocation in C++, from the basics of dynamic memory management to the implementation of custom allocators. Attendees will gain insights into the standard allocator model, techniques for designing custom allocators, and practical examples of their use in real-world applications.

Join us to unlock the full potential of memory management in your C++ projects.

Cache Me Maybe: The Performance Secret Every C++ Developer Needs

by Michelle D'Souza

Summary of the talk:

Calling all code detectives! Grab your trench coats and magnifying glasses ... it's time to crack the case of sluggish C++ performance. In this thrilling investigation, we'll uncover the hidden world of your computer's built-in cache and how to harness it to turbocharge your code.

We'll comb through the fundamentals of caches like seasoned sleuths, uncover clues on optimizing access patterns, and interrogate suspects like false sharing and cache unfriendly data structures. We will also examine benchmark evidence based on real-world production code, exposing how each technique delivers the goods.

By the end of this mission, you'll be armed with a detective's toolkit of cache savvy strategies, ready to solve cross-platform performance mysteries and bring blazing fast code to justice. Cache you at this session, maybe!

std::vector — Four Mechanisms Behind Every push_back()

by Gracjan Olbinski

From the article:

"You call push_back() a thousand times. The vector reallocates about ten. Behind that simple interface, four mechanisms are working together — each one invisible during normal use, each one shaping your performance in ways that push_back() will never tell you about."

Matrix Multiplication Deep Dive || Cache Blocking, SIMD & Parallelization

by Aliaksei Sala

Summary of the talk:

Matrix multiplication is a fundamental operation in scientific computing, game development, AI, and numerous high-performance applications. While its mathematical definition is simple, achieving optimal performance in C++ is far from trivial.

In this talk, we will explore different optimization techniques for matrix multiplication, from naive implementations to highly tuned versions leveraging modern hardware features. We will cover key performance-enhancing strategies such as loop unrolling, cache blocking, SIMD vectorization, parallelization using threads and more. Through benchmarking and profiling, we will measure the real impact of these optimizations.

By the end of this session, attendees will gain insights into two critical questions:

How hard is it to implement an optimized matrix multiplication in C++? How effective is C++ for achieving peak performance in this task?

This talk is suitable for developers interested in performance optimization, computational efficiency, and modern C++ techniques for numerical computing.

In this article, we'll perform some early compilation time benchmarks of one of the most awaited C++26 features.

The hidden compile-time cost of C++26 reflection

by Vittorio Romeo

From the article:

Fast compilation times are extremely valuable to keep iteration times low, productivity and motivation high, and to quickly see the impact of your changes.

I would love to see a world where C++26 reflection is as close as possible to a lightweight language feature [...]

So, I decided to take some early measurements.

Stop Choosing: Get C++ Performance in Python Algos with C++26

by Richard Hickling

From the article:

The “religious war” between Python and C++ in algorithmic trading usually boils down to a single trade-off: Python is faster for getting ideas to market, while C++ is faster for getting orders into the book.

But why choose? With the advent of C++26 Reflection, you can now have the flexibility of a Python-based strategy without the performance penalty of slow loops.

Bring in C++ Rapidly: How Reflection Works

The biggest hurdle in hybrid trading systems has always been the “bridge.” Traditionally, if you wrote a complex pricer in C++, you had to manually write “boilerplate” code to tell Python how to talk to it. If you added a new function, you had to update the bridge. It was tedious and error-prone.

Reflection changes the game by allowing the code to “look in the mirror”. Instead of you manually describing your C++ functions to Python, the compiler does it for you. It programmatically inspects your classes and generates the bindings automatically.

Practical Reflection With C++26

by Barry Revzin

Summary of the talk:

With the adoption of Reflection for C++26, the landscape of what is possible has shifted. This talk will focus on implementing Struct-of-Arrays for an arbitrary aggregate, but will also take some detours to cover some techniques that will prove useful for solving a wide range of problems.

A Brief History of Bjarne Stroustrup, the Creator of C++

by CultRepo

Watch now:

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Announcing Meeting C++ 2026

by Jens Weller

From the article:

We'll be meeting from the 26th - 28th November in Berlin! You have the unique chance to spend the 1st advent in Berlin with C++ and Christmas Markets open!

With Mateusz Pusz and Kate Gregory I've chosen two well known speakers for the keynotes this year. Mateusz is well known for his units library, which currently also is proposed for the standard. It is also an important contribution to making C++ more safe and secure, the big topic of last year. Then Kate Gregory will be visiting us in Berlin again, she is known for her ability to create great talks around technical and social aspects in our daily lives as devs. You might remember her from giving a keynote in 2017, or speaking about the aging programmer two years ago.

For the 15th time Meeting C++ will organize a great event for 3 days filled with lots of content about C++, like last year the plan is to host 3 tracks in parallel in Berlin, with an optional 4th track. The 4th track will be unlocked either by sponsorships or ticket sales. You can be a part of this great C++ event by attending onsite and online. There is already great news for onsite attendees: Hudson River Trading is again this years t-shirt sponsor, a great and unique Meeting C++ 2026 t-shirt is an exclusive perk for onsite attendees!

Threads vs Coroutines: Why C++ Has Two Concurrency Models

by Conor Spilsbury

Summary of the talk:

The C++11 standard introduced a powerful set of tools for concurrency such as threads, mutexes, condition variables, and futures. More recently, C++20 introduced another powerful but fundamentally different concurrency abstraction in the form of coroutines. But coroutines are not just an evolution or a replacement for threads. Instead, they each solve different problems in different ways. Choosing the right tool for the job requires understanding how each works under the hood and where they shine. This talk will help build that intuition by looking at how each interacts with the operating system and hardware which will help make better decisions when choosing which to use.

We'll explore how threads and synchronization primitives work at the operating-system and hardware level, from thread creation and scheduling to where context switching and synchronization introduce performance costs. We’ll then contrast this to the coroutine model introduced in C++20 which takes a fundamentally different approach by using a cooperative model based on the suspension and resumption of work.

Given this understanding, we’ll finish by applying this intuition to a set of real-world scenarios to identify whether threads or coroutines are a better fit for the problem at hand.

C++26: std::is_within_lifetime

by Sandor Dargo

From the article:

When I was looking for the next topic for my posts, my eyes stopped on std::is_within_lifetime. Dealing with lifetime issues is a quite common source of bugs, after all. Then I clicked on the link and I read Checking if a union alternative is active. I scratched my head. Is the link correct?

It is — and it totally makes sense.

Let’s get into the details and first check what P2641R4 is about.

What does std::is_within_lifetime do?

C++26 adds bool std::is_within_lifetime(const T* p) to the <type_traits> header. This function checks whether p points to an object that is currently within its lifetime during constant evaluation.

CppCon 2025 More Speed & Simplicity: Practical Data-Oriented Design in C++

by Vittorio Romeo

Summary of the talk:

Data-Oriented Design (DOD) presents a different way of thinking: prioritizing data layout not only unlocks significant performance gains via cache efficiency but can also lead to surprising simplicity in the code that actually processes the data.

This talk is a practical introduction for C++ developers familiar with OOP. Through a step-by-step refactoring of a conventional OOP design, we’ll both cover how data access patterns influence speed and how a data-first approach can clarify intent.

We’ll measure the performance impact with benchmarks and analyze how the refactored code, particularly the data processing loops, can become more direct and conceptually simpler.

Key techniques like Structure-of-Arrays (SoA) vs. Array-of-Structures (AoS) will be explained and benchmarked, considering their effects on both execution time and code clarity. We’ll pragmatically weigh the strengths (performance, simpler data logic) and weaknesses of DOD, highlighting how it can complement, not just replace, OOP.

We’ll also demonstrate that DOD doesn’t necessitate abandoning robust abstractions, showcasing C++ techniques for creating safe, expressive APIs that manage both complexity and performance.

Let’s learn how thinking “data-first” can make your C++ code faster and easier to reason about!