C++ coroutines: What does it mean when I declare my coroutine as noexcept?

by Raymond Chen

Suppose you want a coroutine that terminates on unhandled exceptions, or equivalently (looking at it from the consumer side) a coroutine that never throws an exception when awaited. For regular functions, the way to say this is to put the noexcept exception specification on your function declaration...

C++ coroutines: Associating multiple task types with the same promise type

by Raymond Chen

We created two very similiar promises for hot-start and cold-start coroutines. It turns out that we can unify them...

C++ coroutines: Improving cold-start coroutines which complete synchronously

by Raymond Chen

Last time, we learned that the naïve implementation of cold-start coroutines is susceptible to stack build-up. What we want is for await_suspend to return false if the coroutine completed synchronously. This is tricky because that reintroduces a race condition where the coroutine runs asynchronously and completes at the same time we try to transition from synchronous to asynchronous behavior in the awaiter...

C++ coroutines: Cold-start coroutines

by Raymond Chen

So far, our coroutine promise has implemented a so-called hot-start coroutine, which is one that begins running as soon as it is created. Another model for coroutines is the so-called cold-start coroutine, which is one that doesn’t start running until it is awaited...

C++ coroutines: Getting rid of our atomic variant discriminator

by Raymond Chen

We continue the refinement of our coroutine implementation by removing the atomic variable used as the discriminant of our result holder variant...

Pure Virtual C++ 2021 Schedule Available

by Sy Brand

The schedule for Pure Virtual C++ 2021 is now live on the event website. Remember to sign up to be the first to access our extra on-demand C++ demos and get more virtual surprises...

Five Awesome C++ Papers for the Q1 2021 and C++23 Status

by Bartlomiej Filipek

Between 2018 and 2020, I released several articles with top 5 proposals just around a new ISO C++ meeting happened. Since March 2020, this pattern broke as the meeting went online. Why not restart the series? We can look at the recent papers from a whole Quarter.

Let’s start!

C++ coroutines: Allowing the awaiter to be destroyed while suspended

by Raymond Chen

One issue that we dealt with when we created our co_await awaitable signal was the case of the awaiter being destroyed while suspended. We had been ignoring that problem in our coroutine promise, but we can’t keep our head in the sand forever. Let’s take a look around and see where we are.

Clang 12.0.0 is released

This document contains the release notes for the Clang C/C++/Objective-C frontend, part of the LLVM Compiler Infrastructure, release 12.0.0. Here we describe the status of Clang in some detail, including major improvements from the previous release and new feature work. For the general LLVM release notes, see the LLVM documentation. All LLVM releases may be downloaded from the LLVM releases web site.

For more information about Clang or LLVM, including information about the latest release, please see the Clang Web Site or the LLVM Web Site.

Note that if you are reading this file from a Git checkout or the main Clang web page, this document applies to the next release, not the current one. To see the release notes for a specific release, please see the releases page...

Pros and Cons of Alternative Function Syntax in C++

by Petr Zemek

C++11 introduced an alternative syntax for writing function declarations. Instead of putting the return type before the name of the function (e.g. int func()), the new syntax allows us to write it after the parameters (e.g. auto func() -> int). This leads to a couple of questions: Why was such an alternative syntax added? Is it meant to be a replacement for the original syntax? To help you with these questions, the present blog post tries to summarize the advantages and disadvantages of this newly added syntax...