experimental

2018 San Diego ISO C++ Committee Trip Report

The report is here!

2018 San Diego ISO C++ Committee Trip Report

From the article:

The ISO C++ Committee met in San Diego, California ���� last week to continue work on the next International Standard (IS), C++20. This meeting was the last meeting to consider new proposals for C++20, but existing proposals like modules (on track) and coroutines (questions remain) that are in flight but not merged can still make C++20. We’ll make our final decisions about major language features at the next meeting.

Use the official range-v3 with MSVC 2017 version 15.9—CoderCasey

Everything is in the title.

Use the official range-v3 with MSVC 2017 version 15.9

by CoderCasey

From the article:

We’re happy to announce that the ongoing conformance work in the MSVC compiler has reached a new milestone: support for Eric Niebler’s range-v3 library. It’s no longer necessary to use the range-v3-vs2015 fork that was introduced for MSVC 2015 Update 3 support; true upstream range-v3 is now usable directly with MSVC 2017.

Modules Are Not Precompiled Headers—Guillaume Racicot

Interesting talk about modules.

Modules Are Not Precompiled Headers

by Guillaume Racicot

From the article:

Modules have been the subject of many controversies in the C++ community in the recent past and there seem to be some misconception floating around recently about modules. Important decisions will soon be made, and I wanted to clear some of the facts and raise potentially good questions about modules and the path to their adoption.

I do not want to argue about how modules should have been and what should have not been. Instead I want to talk tabout modules as they are today, in the merged proposal.

Five Awesome C++ Papers for San Diego—Bartlomiej Filipek

What do you think?

Five Awesome C++ Papers for San Diego

By Bartlomiej Filipek

From the article:

In two weeks there will be a next C++ Committee meeting. This time the group of C++ experts will travel to San Diego, and they will discuss the shape of the upcoming C++ Standards. As far as I know, the meeting will hold a record in the number of submissions (276 proposals!) So it seems that the session will be quite exhausting smile

Here’s my list of five exciting papers that will be discussed during the meeting. I tried to pick something less popular, and usually smaller than significant features like modules, concepts or ranges...

Mathematics behind Comparison #4: Three-Way Comparison—Jonathan Müller

Everything you need to know!

Mathematics behind Comparison #4: Three-Way Comparison

by Jonathan Müller

From the article:

In order to sort a collection of elements you need to provide a sorting predicate that determines when one element is less than the other. This predicate must “induce a strict total ordering on the equivalence classes” according to cppreference. Wait, what?

The upcoming C++ spaceship operator implements a three-way comparison, i.e. it is a single function that can return the results of <, == and > combined. But related to it are terms like “strong equality” and “weak ordering” which are somewhat confusing if you don’t have the mathematical background.

So let’s untangle it: This series will explain both the mathematics behind equality and ordering, as well as give concrete guidelines for implementing the comparison operators and the spaceship operator.

Now that we’ve covered both equivalence and ordering relations we can finally talk about the spaceship operator and three-way comparisons...

Spaceship Operator—Simon Brand

The future?

Spaceship Operator

by Simon Brand

From the article:

You write a class. It has a bunch of member data. At some point, you realise that you need to be able to compare objects of this type. You sigh and resign yourself to writing six operator overloads for every type of comparison you need to make. Afterwards your fingers ache and your previously clean code is lost in a sea of functions which do essentially the same thing. If this sounds familiar, then C++20’s spaceship operator is for you. This post will look at how the spaceship operator allows you to describe the strength of relations, write your own overloads, have them be automatically generated, and how correct, efficient two-way comparisons are automatically rewritten to use them...

CppCon 2017: Building C++ Modules—Boris Kolpackov

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

Building C++ Modules

by Boris Kolpackov

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

C++ Modules TS is now implemented (to various degrees) by GCC, Clang, and MSVC. The aim of this talk is to provide practical information on the mechanics of creating and consuming modules with these compilers. It is based on our experience adding modules support to the build2 toolchain and then modularizing some of its components.

We start with a brief introduction to C++ modules, why we need them, and how they relate to other physical design mechanisms, namely headers, namespaces, and libraries.

Next we explore the kind of integration modules will require from a C++ build system. Specifically, when and where a module binary interface is built? How can a build system discover which modules are needed? What are the implications for parallel and distributed builds? Can we finally get rid of the preprocessor? And what happens to header-only libraries in this brave new modularized world?

With a firm understanding of the implications C++ modules have on the build process, we can try to answer some of the module design questions: What is an appropriate module granularity? Should we have separate module interface and implementation units? Can we have a dual header/module interface for legacy support? Are module-only libraries to become all the rage?

Announcing “trivially relocatable”—Arthur O’Dwyer

Do you want this?

Announcing “trivially relocatable”

by Arthur O’Dwyer

From the article:

Frequent users of Compiler Explorer, a.k.a. godbolt.org, may have noticed that a few days ago a new compiler appeared in its dropdown menu. “x86-64 clang (experimental P1144)” is a branch of Clang which I have patched to support the concept of “trivially relocatable types,” as described in my C++Now 2018 talk and as proposed for standardization in my upcoming paper P1144 “Object relocation in terms of move plus destroy” (coauthored with Mingxin Wang)...