In Prague, the C++ committee took a series of polls on whether to break ABI, and decided not to. There was no applause. But I’m not sure we fully understood what we did and the consequences it could have. I do believe none of the consequences will be good. What is ABI ABI is the shared understanding libraries have about how your program is serialized, both in term of layout, calling convention and mangling. Read more

C++20 has shipped! C++ is better and more alive than it has ever been. You might have read on the Internet (rarely a good idea), that C++ grows too fast, too complicated, too big. I do not think this is true. Bjarne Stroustrup reminded us that concepts are mentioned in Design and Evolution of C++, a book written in 1994, before even the first C++ standard. Coroutines and Modules are also old ideas that represent more than a decade of work. Read more

std::move doesn’t move. It casts to an rvalue-reference, which is a type of reference that can be passed to a move constructor or assignment operator, if one exists. template <typename T> decltype(auto) move(T&& a) { return static_cast<std::remove_reference_t<T>&&>(a); } Some expressions will be converted to rvalue-references automatically, when the compiler is certain that the value is expiring (will not be reused). This is the case for temporaries or non-reference objects returned from functions. Read more

This article is the sequel to A Universal Async Abstraction for C++, in which I talk about the Executor proposal targeting C++23. Quite a bit happened since then. SG-11, the study group charged of all things concurrency and parallelism made forward progress and sent the proposal to LEWG - with the hope of landing a future revision in the C++23 draft. This is rather big news given that this work has been brewing for about a decade. Read more

Before we start This blog post features iframes, interactive SVG files, and graphs which may not render properly on handheld devices. Sorry about that. The charts are however interactive, so you can zoom in an see the exact values. If I were a compiler, I would simply put all your bytes in your binary There have been a few interesting and passionate discussions about std::embed lately. std::embed would surely be a great tool to have in one’s toolbox, and I’m sure some version of it will be adopted in time, once a consensus in reach (I have yet to find someone not sold on the usefulness of that proposal). Read more

Unicode Characters have a name, which makes it easier to talk about them without having to know their codepoint. For example, the character λ (U+03BB) is called GREEK SMALL LETTER LAMDA. Given a character name, we want to be able to know its code point. There are a few use cases for that, the main one being to be able to put Unicode characters by name in string literals, a feature offered by Python, Perl and Perl 6 Raku. Read more

Executors - of which P0443R11 is one of the latest iterations - is poised to be the most fundamental library addition to C++23. But what is it about? It is first and foremost a quest to find the most basic building blocks on top of which one could build asynchronous, concurrent and parallel code, whether it be on a small chip or a supercomputer with thousands of CPUs and GPUs. Read more