[pjmlp]

The problem is which modern C++ projects?

Android source code is definitely not one of them, and yet Google as ISO C++ contributor should know all about modern C++, right?

Ah, what about Microsoft and their UWP code samples for C++ developers, or the C++/WinRT based libraries?

As advocates from C++ Core Guidelines, surely those samples will be perfect examples from modern C++, right?

Or what about Bloomberg, with heavy contributors like John Lakos?

Maybe they are still in the process of adopting C++11 and C++14, while writing a book about language adoption issues.

I like C++ a lot, but we really need a compiler switch to turn off compiling Vintage C++, it would be marvelous.

[pclmulqdq]

Every single codebase you have just cited here (except for the nebulous "advocates from C++ core guidelines") is older than the Rust language. Look at high frequency trading code or maybe recent game engines for good C++ projects - I don't know if any of these are open source.

I 100% agree with breaking C compatibility, breaking ABI compatibility, and turning off vintage C++.

[pjmlp]

C++/WinRT is from 2015.

C++ Oboe SDK for Android was initially released in 2018.

Android Games Developer SDK was just released last month.

What game engines? Lumberyard , Unreal and Godot certainly not.

Vulkan C++ bindings from Khronos or Dawn for WebGPU? Also not.

The only modern C++ I can find in real life are at CppCon and C++Now talks, and books promoting it.

Even Bjarne Stroustroup has recently on a interview mentioned how he is disappointed how C++ Core Guidelines keep being largely ignored by the community.

There is even, yet again, a paper from him trying to advocate for better C++ on the next C++ mailing.