AndreasFertig.com

Implicit promotion of consteval functions

Andreas Fertig — Tue, 06 Oct 2026 00:00:00 +0000

In today's post, I'll explain a C++23 change when using consteval functions.

Since consteval have been added to C++20 there us a struggle where they can be used. The following code illustrates the typical pitfall:

C++ Insights Episode 78: constexpr lambdas finally FIXED in C++ Insights

Andreas Fertig — Wed, 16 Sep 2026 00:00:00 +0000

I published a new C++ insights episode: constexpr lambdas finally FIXED in C++ Insights.

In this episode, I'll present you one of the latest changes to C++ Insights which makes the lambda transformation close to perfect!

Andreas

Move in C++ without a std::move

Andreas Fertig — Tue, 01 Sep 2026 00:00:00 +0000

In one of my earlier posts, Why you should use std::move only rarely I said that you should use std::move only rarely. In today's post, I would like to show you the benefits of this advice: best performance by default.

Return value optimization

One of the worst enemies …

C++ Insights Episode 77: RVO, NRVO, std::move EXPLAINED

Andreas Fertig — Wed, 19 Aug 2026 00:00:00 +0000

I published a new C++ insights episode: RVO, NRVO, std::move EXPLAINED.

In this episode, I'll answer question from you how return-value optimization works and when to use std::move and when not.

Andreas

More compile-time checks with std::nullptr_t

Andreas Fertig — Tue, 04 Aug 2026 00:00:00 +0000

In today's post, I like to show you the benefit of a often unknown type: std::nullptr_t.

You have that data type in the language since C++11, together with the much more frequently used nullptr. While nullptr is the value, std::nullptr_t is the data type that can hold …

C++ Insights Episode 76: New, better, lambda visualization in C++ Insights

Andreas Fertig — Wed, 15 Jul 2026 00:00:00 +0000

I published a new C++ insights episode: New, better, lambda visualization in C++ Insights.

In this episode, you'll share the latest change in C++ Insights regarding visualizing lambdas.

Andreas

Keep It Tight: Restrict Variadic Templates Using C++20 Concepts

Andreas Fertig — Tue, 07 Jul 2026 00:00:00 +0000

I previously wrote about C++20's Concepts. Today I would like to discuss another aspect of Concepts: how they help you to limit the data type of a variadic type-template parameter to a specific one for all datatypes in the set.

For reference, these are my previous posts about C …

C++ Insights new lambda transformation

Andreas Fertig — Mon, 22 Jun 2026 00:00:00 +0000

Last week I pushed an updated lambda transformation for C++ Insights. Here is a little background on the change.

Since I first published C++ Insights when you transformed a lambda like the following:

int main()
{
   int val{4};

   auto lamb = [&] { return val; };
}

The result …

C++ Insights Episode 75: The Ref-Qualifier That Saves You from Undefined Behavior

Andreas Fertig — Wed, 17 Jun 2026 00:00:00 +0000

I published a new C++ insights episode: The Ref-Qualifier That Saves You from Undefined Behavior.

In this episode, you'll learn how req-qualifers save you from undefined behavior.

Andreas

More C++26 reflection at compile-time

Andreas Fertig — Tue, 02 Jun 2026 00:00:00 +0000

In today's post, I like touch-up on C++26's static reflection. In case you haven't seen, I wrote a first post C++26 reflection at compile-time a while ago.

One of the great things about reflection is that we can already explore the new feature since with Clang there is …

C++ Insights Episode 74: Why move requires noexcept in C++20

Andreas Fertig — Wed, 20 May 2026 00:00:00 +0000

I published a new C++ insights episode: Why move requires noexcept in C++20.

In this episode, you'll learn why noexcept is crucial for move operations of a class.

Andreas

Happy 8th anniversary C++ Insights

Andreas Fertig — Wed, 13 May 2026 00:00:00 +0000

This year, we celebrate the 8th anniversary of C++ Insights!

Thank you all for the wonderful years of support!

The current status

I've been a bit slower in updating C++ Insights to work with the latest Clang version. As a birthday gift I released the latest C++ Insights version which …

From Undefined to Defined: Using std::launder in C++

Andreas Fertig — Tue, 05 May 2026 00:00:00 +0000

In today's post, I will continue with the overall topics of the last two months. Today you'll learn when and where you need to apply C++17's std::launder and where the difference to this utility is to reinterpret_cast or std::start_lifetime_as.

The fields where you can apply today's learning …

C++ Insights Episode 73: Things you can do effortlessly with C++20s concepts

Andreas Fertig — Wed, 15 Apr 2026 00:00:00 +0000

I published a new C++ insights episode: Things you can do effortlessly with C++20s concepts.

In this episode, you'll learn how C++20s concepts help you to write less code that's easier to maintain at the same time.

Andreas

Open-Enrollment classes in 2026

Andreas Fertig — Tue, 14 Apr 2026 00:00:00 +0000

The year 2026 is already four months old. I hope you had a good start to this year. If you're interested in working with me at one of my public classes, here is what you need to know.

I will give a one-day online workshop on Safe and Efficient C …

iX Article: Neue Features in C++26

Andreas Fertig — Thu, 09 Apr 2026 00:00:00 +0000

An article I wrote for the German iX magazine "Neue Features in C++26" is available in issue 2026/04. It is available as a printed edition as well as online.

I hope you find the article both interesting and inspiring.

Andreas

What reinterpret_cast doesn't do

Andreas Fertig — Tue, 07 Apr 2026 00:00:00 +0000

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!

My motivation

My motivation for this blog post comes from multiple training classes I thought over the past several months and a …

C++ Insights Episode 72: Why you should never call a virtual member function in a constructor

Andreas Fertig — Wed, 18 Mar 2026 00:00:00 +0000

I published a new C++ insights episode: Why you should never call a virtual member function in a constructor.

In this episode, you'll learn by example why you should never call a virtual member function from a constructor.

Andreas

Best performance of a C++ singleton

Andreas Fertig — Tue, 03 Mar 2026 00:00:00 +0000

In my Januray post, I focused on implementing a singleton correctly. This time I want to add performance into the mix and show you the best way to implement your singleton... or give you guidance to pick your best way.

Setting the scene

I'm using a display manager as an …

C++ Insights Episode 71: C++23: multidimensional operator[]

Andreas Fertig — Wed, 18 Feb 2026 00:00:00 +0000

I published a new C++ insights episode: C++23: multidimensional operator[].

In this episode, you'll learn about the change to the operator[] in C++23.

Andreas