But no concepts, no const expr, or use of auto at least according to cppreference

It's no wonder. C++ is deeply and irreparably broken, yet instead of fixing anything they just pile up more features in an effort to compete with Rust and Go. Modern C++ is like a 19th century horse carriage with a big subwoofer (but you have to bring a bunch of 9V batteries), huge hot-rod wheels (but no amortization so don't even think about going above 20 kmh) and an airplane engine from Rolls-Royce (which is there for the sake of heating only).

In what way is C++ "deeply" broken? I seem to be using it daily with no problem, as does the rest of the world. I manage to use applications and operating systems where vast portions of it are written in C++ without problems - what problems are you having? Honestly, it's dead easy to criticise but you must be using the product of another language if you feel so strongly about this...?

Tell me, which browser and operating system are you using to write this comment? It must be one written in something other than C++, right? Your browser isn't using WebKit or Blink by any chance is it??

Let's hope the web server or network appliances used to transfer the data to you are not using software written using this "deeply broken" language!

I also use C++ everyday, and find it quite powerful, but I also feel that it is ill designed. The other day I had to work with code that involved a public member function that returns a private type. You can only bind to the return value of this function with auto (because the type is private), but can otherwise do anything with the object. Why this is allowed is beyond me.

You're right that much of the software we use is written in C++, for good reasons, but asking people to "use a product of another language" just because they are critical (in a not so nice way, admitted) of it is going a bit too far. It's like asking someone to move to a different country because they think their system is "broken beyond repair".

Your design above with the private type being returned could possibly be useful. Perhaps outsiders to the class will be prevented from instantiating the nested-type without using the class itself to generate the nested type. This could be contextually useful and certain (interface) functionality could be grouped in a manner that is more convenient to use than by calling methods on the original class.

I like that C++ allows us to express this situation, even if it's a bit of an unusual design pattern.

You can prevent instantiation of the nested type already by using private ctors and friending the wrapper class from this type, while keeping the class itself public. That is a much cleaner expression of intent. I believe that if a class is usable via its interface, it is public any way (in that you will need to go and change all uses of this object should you decide to change the nested type's API, whether it is declared private or not).

And also note that binding to the object at all has been possible only after C++11, while this "feature" works with earlier standards. That rules out the possibility of this being designed into the language with the express goal of achieving what you say (it doesn't matter, but just pointing out).

Visibiliy has always been sabout naming thing. You were always able to bind private types to template arguments (otherwise you would never been able to create an std::vector<PrivateType> or pass MyPrivateContainer to an std algorithm. What's new in C++11 is the ability to also bind locals, but that no more powerful than what you could do before (via a CPS transform).

I use this case quite commonly for implementation encapsulation. You could think of it as a capability.

The type of a lambda is inexpressible so they can only be handled with auto or decltype. I think that’s reasonable.

I am curious how you achieve encapsulation this way, please elaborate (I tried to find uses for this pattern. Even the author of the code I'm talking about, and other much better C++ programmers than myself seemed to call this an oversight rather than intent).

Here's a simple example: I have a table of stageful actions (perhaps part of a UI) that is dynamically constructed and maintained. I could register token which looks up the necessary information in an internal hash table. Of course said internal table would have to stay in sync with the UI's table. Instead I can just return an opaque object (perhaps a virtual object if life is fancy) with all the necessary state; if the UI window is deleted then all the objects will be deleted too at just the right time, with no explicit coordination with the part of code that created them (their destructors could do some bookkeeping if appropriate).

Traditional callbacks can also be used in this case, but what is a callback lambda but private state? And a stateful object rather than a lambda function is easier to manipulate, say by inspecting in the debugger or perhaps by providing a generic function for things like printing the entry.

Another case is where you have some hairball third party or legacy library that you want to be able to use in your modern code; you can often simply make it an opaque private object rather than making a complex visitor for it.

I kind of understand what you describe, but I still don't understand why the type needs to be private. You can return opaque objects of a public type just as well for this job, can't you?

    class Token {
      virtual ~Token();
      protected:
        friend class MyClass;
        ...
        /* all your state */
    };

> what is a callback lambda but private state?

You can (and do) program to the callback's interface -- say you ask for an std::function<void()>, and the user gives you that. What is behind the function (private state or not) is not your concern, you simply perform an public operation (calling it) on a public interface (i.e., via std::function).

What is the difference to you if I pass a private object or a public object all of whose instance variables and methods are private? Either way the point is to say “this is not your object to manipulate”. But making it a type you cannot even express makes that far more explicit.

I see, I guess then that's where we disagree. It is very confusing for people from my limited experience, for little gain. Plus you make it harder to do things like put these tokens in e.g., a vector without resorting to decltype.

Going back to the original point i was making with this example, I still think this was probably not a capability consciously designed in the language.

I agree this is weird, but isn't it pretty similar to the old c pattern of returning an opaque handle? I'm assuming you can't do anything with the object, since you don't know its layout and its member functions would be inaccessible. it sounds like you just get to hold onto it and pass it to any accessible functions that take it as an argument. am I misunderstanding how this works? I can't find any resources that directly explain this situation.

You can do member access into the object! That breaks encapsulation or whatever was the reason to keep the type private. Passing it around usefully isn't possible except to friend or member functions of the same class (since you can't write a function taking a type T that is private to your scope). In fact the only reason I could think of for doing something like this is to prevent people from including this type in their APIs, while still allowing to work with the object. But there are better ways to do that, including just exposing what the little object would expose via direct method calls on the enclosing class.

This isn't similar to C handles. There is usually a public API around the kind of the handle (e.g., the file oriented syscalls that works with file descriptor integers). In such cases, C handles are more like "this" pointers with an associated API.

Also, it cannot be the intent of allowing this pattern to implement opaque handles, as you can bind to them only after C++11 (auto), while such malformed code still compiles (including member access into the returned temporary) with -std=c++98.

ah okay, looks like I was mistaken. it's pretty hard to see how this could possibly be useful.

With bricks you can build a useless house with no doors, but bricks are pretty great.

I mostly agree with you, but operating systems and web servers are generally written in C and not C++. For example Linux, (the vast majority of) GNU, Apache, and Nginx are all C.

(Though I expect your parent has similarly negative views on C?)

To balance with what you say:

Windows is mainly C for the kernel, and C++ for the rest https://en.wikipedia.org/wiki/Windows_NT#Programming_languag.... That's around 90% of the desktop/laptop market.

IIS, Microsoft's web server, is C++ https://en.wikipedia.org/wiki/Internet_Information_Services. I think it is still the 3rd most popular web server in the worldwide.

A significant portion of the C++ code in Windows uses very few C++ features or idioms and is basically C with classes or one or two useful features.

That's impossible. According to half of the comments in every c++ thread on HN, any usage of C++ will immediately converge to using all features!!

/s obviously.

Which is still C++.

It is, but I do wonder if a large part of the problem with regard to using C++ features on Windows is the poor support for it in the ancient COFF linker and binary format they support. Lots of stuff like template export is possible with ELF which is impossible or dangerous on Windows.

I can also attest that lots of “modern C++” code exists in Windows.

There is code in Windows that was written yesterday and code in Windows that was written over three decades ago.

COM/UWP is the proper way to use C++ features on Windows in a inter-language way.

While not ideal exporting templates has been possible since Windows 3.1 days, as long as one sticks to a specific compiler.

Absolutely, but that kind of code doesn’t really speak to complaints about modern C++ and all it’s become. I just wanted to chime in with that extra information. I don’t really have a dog in the fight, other than having a lot of love for C and good C code.

You are correct, thanks. My comment comes across as very irritated, but it's the same argument that will continue to the end of time I guess - "this tried, tested and widely used language is broken because it is not language $x and because it lacks this edge-case invented usage scenario even though it works adequately for 99.9% of all other scenarios as demonstrated by decades of use". It's wearying. Sure, C++ is complicated but so is English!

I thought nginx was C++?

I also thought large portions of Windows are C++? Everybody loves COM!

Nginx is C, and the authors really don't like C++.

(I used to work on ngx_pagespeed, which was a C++ server module that plugged into Nginx to rewrite pages so they would load faster.)

Thanks for the info!

Did they approve of your module?

They liked that we were building something cool for their server, but our approach was so different from theirs (in ways that went way beyond the language) that our module wasn't ever going to become officially part of Nginx or anything.

No my terrible grasp of English even as a native speaker is the cause of this confusion. What I meant was: “No I meant that from cppreference using coroutines means you can’t use the features I mentioned not that those features don’t exist in c++20“

There's no reason that any of those couldn't be written in c++ by good coders. It's just a historical thing.

My parent was arguing "C++ can't be as bad as you say, look at all these things written that use it". Things written in C are not evidence for this, anymore than things written in assembly.

it's obviously possible to make useful things with c++. I too do this every (week)day.

imo, the biggest issue with c++ is the lack of orthogonality. there is usually a "best" way to do something, but you have to read a lot to choose between the many other ways of doing it. the usual "best" way may not be applicable in your case because it is subtly incompatible with some older feature that's already being used.

as an aside, I always get a kick out of standard library functions like std::addressof. you have to use stuff like this in highly generic templated code because you can't be sure that some clown hasn't overridden the `&` operator for some type that will eventually be passed to your function.

> in an effort to compete with Rust and Go

I think that you overestimate how much Go and Rust are used in the wild, and how much of a threat they are to the C++ ecosystem. IMHO C++ is mainly competing with its own past.

I genuinely believe statements like GP’s are a result of living in a cutting-edge tech bubble, not necessarily SV, but online hype and discussion based reality. Sure several large impactful projects use Go and a few companies are dabbling in using Rust. However, the number of these usages is dwarfed into near statistical irrelevance by the amount of C++ code in active production and usage (it is even more irrelevant if you count programs written in C).

That is not to say there is nothing good or beneficial about these languages, devs using them are free to evaluate the features provided and find that they suit their use case and go get to work. But some dev’s pet language, no matter how loudly they scream on Reddit and HN, is not yet threatening C++.

I can't imagine a real world robotic assembly line in 2020 not using c/c++ indefinitely. Doesn't matter how cool the new language is, what people really want is to not have to rewrite that dependency they're still using from 1998.

You can't fix C++ because the only thing there is to fix is to get rid of all the legacy baggage but doing that would break backwards compatibility (including probably compatibility with C) which means that it's not C++ anymore.

"Fixed" C++, per your description, already exists. It's called D. It's called Rust. It's called C#. It's called Go.

Meanwhile there appear to be many people who (I must admit much to my puzzlement) seem to still enjoy writing C++ and want to add even more features and paradigms to it. I wish them good luck and I'll be sure to look at the results from afar and see if I can recognize some bits of the C++ I used to write 15 years ago. Oh! I think I saw an "if"!

> Meanwhile there appear to be many people who (I must admit much to my puzzlement) seem to still enjoy writing C++ and want to add even more features and paradigms to it.

I enjoy C++. My general approach to programming is that you should make a domain-specific language to express your problem, and then solve it in that DSL. C++ is a good tool for that when you also need deterministic performance guarantees. So any "new feature" that allows me to write more expressive DSLs is welcome.

"It's called D. It's called Rust. It's called C#. It's called Go"

All of these languages with the exception of D are completely different. It's like saying you fixed a cupboard by replacing it with a sofa.

D's the most similar, but it's sadly not exactly a hot language or one where there's jobs available.

Was the cupboard being used as a sofa?

* rid of all the legacy baggage * It keeps being repeated over and over but where can I find such a list? There's almost no misfeature in c++. It's issues are just the fact it's too low level / manual.

How is it too manual compared to eg C# where I need to implement IDisposable and wrap use of variables in "using" to really ensure something is cleaned up when I want it cleaned up (without risky memory ballooning relying on the GC)? C++ destructors to clean up your resources are really neat. And deterministic - you know when stuff is going to get cleaned up.

Or was it some other "manual" feature that's too much of a burden? Honestly curious.

Here's a non inclusive list

1. Initialization

    Type foo = Type(FieldType())
    Type foo = Type{FieldType()}
    Type foo = Type { .field = FieldType() } 

2. std::unique_ptr can be null

3. std::shared_ptr does not guarantee atomic reference counting

4. std::variant and std::optional require exception handling.

5. std::map should be the std::unordered_map data structure, while std::ordered_map should be the special case. The unordered_map should also stop being a terrible hashmap implementation on most platforms.

6. std::vector<bool> is not what you think it is under the hood

7. Explicit should mean the opposite when it come to single argument constructors (meaning implicit casting needs to be explicitly enabled in the constructor definition)

8. Although on that point, one could argue that implicit casting should be a different operator overload than constructor definition.

9. There needs to be a mechanism to check the validity of a template argument before the template is expanded (concepts will fix this, iirc)

10. https://codegolf.stackexchange.com/questions/1956/generate-t...

11. It should be trivial to implement an std compliant iterator. It is not: https://stackoverflow.com/questions/8054273/how-to-implement...

> std::unique_ptr can be null

what would be the difference between a never-null unique_ptr and a reference ?

> std::shared_ptr does not guarantee atomic reference counting

is that a problem in practice ? all implementations do use atomic reference counting. Just because it's not written in the standard does not mean that common sense does not apply.

> std::variant and std::optional require exception handling

exception is the standard way to report errors in C++

> std::map should be the std::unordered_map data structure, while std::ordered_map should be the special case. The unordered_map should also stop being a terrible hashmap implementation on most platforms.

Anyone who has a problem that calls for caring between unordered_map and map will know the difference, and for everyone else, does it matter ?

My opinion on that is that standard library types do not really matter - I use 3 different non-standard map implementations for specific use cases in one of my apps and there is zero friction as maps are almost always an implementation detail, it is nigh uncommon to e.g. have an API that takes / returns maps.

> std::vector<bool> is not what you think it is under the hood

that depends on who you ask :p from past teaching experience, if you ask students to tell you what is vector<bool> they will tell you that it is packed because it feels like the logical thing to do.

> https://codegolf.stackexchange.com/questions/1956/generate-t....

turing-complete language can generate arbitrary things and is not immune to halting problem, news at 11 :p

>what would be the difference between a never-null unique_ptr and a reference ?

Ownership.

> all implementations do use atomic reference counting

They do not.

> exception is the standard way to report errors in C++

Not really, at least in practice. Many C++ developers do not use exceptions at all, with good reason.

>turing-complete language can generate arbitrary things and is not immune to halting problem, news at 11 :p

The point is that a relatively simple syntax error on behalf of the programmer generates an incomprehensible error message. This is just a comical example of that, and a lot of real world code using templates is full of opaque errors at the start. That said, concepts should help eventually.

I don't have a list, but initialisation is quite a mess and the syntax inconsistent. That would be one of the first thing I would fix in C++.

> yet instead of fixing anything they just pile up more features in an effort to compete with Rust and Go

I used to be a C++ diehard, but modern C++ is why I started learning Rust. If I'm going to have to learn a whole bunch of new idioms and rules, I might as well do it with a language that has the new features and safety built-in, rather than bolted on.

I am completely the other way. Coming from Java, I am finding modern C++ pretty amazing tool for design. There are some amazing compile-time API's I can design which is impossible in other languages. Maybe the shiny will wear off after some time but so far I am loving it. I am truly looking forward to C++ 20.

C++ is pretty great in single player mode, you have so much power at your fingertips. It's the epitome of "and the kitchen sink too".

It's when you switch to online multiplayer and end up having to maintain and modify code written by other people who have different opinions on how kitchen sinks should be installed and used that things tend to sour a bit.

This is true for all languages and projects you inherit though. Eg I am trying to use Magento in PHP land and it is truly grotesque.

Magento was grotesque from day one.

> I used to be a C++ diehard, but modern C++ is why I started learning Rust. If I'm going to have to learn a whole bunch of new idioms and rules

You don't. Just because you bump a version number it doesn't mean you are forced to use all the bells and whistles.

That stops working once you're no longer a solo developer, but part of a team, then you need to learn everything any of your fellow developers might use. You might as well focus on learning a new language and having access to new jobs where you don't have to deal with legacy languages.

> That stops working once you're no longer a solo developer

It doesn't. If you have any experience working on C++ projects you will be very aware that deciding which feature is and is not used is the kind of stuff which is defined in the project's coding guidelines docs, along with naming conventions and choice of build system.

With C++ you only have to use a feature introduced after C++11 if you decide you really want to use it. Some projects even in this very day still don't use smart pointers or exceptionsor std::array. Some people still do the old C with classes thing.

Moreover, the world does not come to an end if you arrive at a project and need to learn a feature provided by a programming language.

That's a very optimistic way of looking at things. More than a decade ago (pre-C++11) I used to be a pretty proficient C++ developer. I had a bunch of books about C++ designs, I would use Boost left and right, I knew my design patters, I knew advanced templating tricks etc...

Then I kind of grew frustrated by the complexity and super long build times and for a few years I left C++ on the side, going back to C and other languages. Now I'm a big fan of Rust.

These days when I see a modern C++ codebase using "auto" all over the place, lambdas, the new constructor/initializer syntax, std::move and more, it can be very tricky for me to understand what some code is doing. I feel like I'm reading a new C-based language where I can understand most of it but I feel like some key components are eluding me. Generally I end up figuring it out but I really don't feel comfortable modifying the code because I don't understand all the implications. Very few languages, especially as old and huge as C++, change so drastically and so fast.

And again, I considered myself an advanced C++ user not so long ago.

>With C++ you only have to use a feature introduced after C++11 if you decide you really want to use it.

If you're the original developer who makes the decisions. If you end up working on a project using a different subset than the one you're used to then you're screwed. That's what the parent is talking about.

> Now I'm a big fan of Rust.

> These days when I see a modern C++ codebase using "auto" all over the place, lambdas, the new constructor/initializer syntax, std::move and more, it can be very tricky for me to understand what some code is doing.

But what if you had spent 1/10th of the time you spent learning Rust looking at these features (frankly looking at the wikipedia pages for each revision is enough most of the time I think :

https://en.wikipedia.org/wiki/C%2B%2B11

https://en.wikipedia.org/wiki/C%2B%2B14

https://en.wikipedia.org/wiki/C%2B%2B17

https://en.wikipedia.org/wiki/C%2B%2B20

)

> But what if you had spent 1/10th of the time you spent learning Rust looking at these features

You can write object-oriented code in C too (e.g. gtk, glib etc). It just involves much more boilerplate, and it doesn't offer the same amount of built-in safety guarantees.

So I know enough Modern C++ to use it, but why would I when there are far better alternatives?

Because those alternatives, while better at syntax + semantics part, are still quite immature at IDE + libraries + eco-system part.

For example, try to use Rust to implement a UWP component callable from .NET, interacting with the Visual Layer, while using mixed mode language debugging inside Visual Studio.

those alternatives don't always offer what C++ has - for instance template<int I> is damn useful in many cases and not many languages have that

> That's a very optimistic way of looking at things.

It's the way a professional software developer who actually works with C++ projects looks at C++.

> More than a decade ago (pre-C++11) I used to be a pretty proficient C++ developer. (...) Then I kind of grew frustrated by the complexity and super long build times

Honestly, that comes out as utter bullshit. It sounds like you tried to find out which were the cliche criticisms and mindlessly repeated them, without noticing none of it makes any sense.

The main "complexity" that C++11 added was smart pointers and threading. It is simply unbelievable how someone who parrots they switched to Rust claims that stuff such as smart pointers and threading is too complex to learn. It's the sort of stuff that any developer quickly picks up with a cursory glance through the docs.

Your whole statement is even less believable if we were to believe your claim that you were somekind of Boost wizard who "considered myself an advanced C++ user", because Boost is the staging ground for whatever was added to the C++ standard.

Quite honestly, I find it hard to believe any of your claims.

> If you have any experience working on C++ projects you will be very aware that deciding which feature is and is not used is the kind of stuff which is defined in the project's coding guidelines

And you will find that you have to learn these features once they are allowed in the guidelines. Some workplaces stick to the old features. Some regularly update with pushes toward use of modern features. When your coding guidelines prefer modern C++, you have to learn it.

The sentiment of dreading having to learn new language features (as in being forced to) does not compute to me. Being a software developer, you should always be learning new things.

The complexity that emerges out of C++ with most/all of its features is immense to the point where it's clearly not worth the investment when there are so many alternatives out there. Nobody should be expected to deal with a language so complex that it takes a decade or more of effort before one can say with confidence he truly understands it.

Which is why C++ is dying and those other alternatives are finding so much appeal with new generations of programmers.

Let's not pretend there are jobs in Rust or whatever you think replaces C++.

True to some extent but education is good and knowing the language you are using can only be a good thing.

The same could be said of English. Would you switch to another language because someone uses a word you have never used before?

> Just because you bump a version number it doesn't mean you are forced to use all the bells and whistles.

But I want to use those features. I want memory safety and a way to say this variable owns the memory, vs that variable which is only borrowing it. I want move semantics in some cases and copy semantics in others. I want lambdas so I don't need to define new functions (or classes) to handle simple visitor patterns (or other cases where passing a 'function' makes sense).

These are good, useful features that I'd like to use to make my code more safe, more performant and more readable, and while C++ can do these things to some degree, there's boiler plate and new rules (rule of 5 vs rule of 3) and gotchas, compared to a language like Rust that has these things built in, with more safety and without compromising performance, and for me it made sense to start using it instead.

I still have projects in C++ that I'll maintain with modernish C++ rather than re-writing them, but for new things where I have a say in the matter, I'll choose Rust.

I see that you have not kept up. Since C++17 it's "rule of zero": you don't need to write any of them, because the compiler does it. As the language gets more capable, the code you write gets simpler.

I don't think that is happening in Rust.

> I see that you have not kept up.

I have not (C++14 onwards was roughly where I started paying less attention), and that was partly my point. C++ has gone through dramatic change, and if I'm going to go through that dramatic change, I might as well do it with a language that has modern features and safety built in, and doesn't require extra boilerplate to do it.

Looking up the rule of zero, it seems there's still some debate about whether it's a good thing or not [0] (don't know if it's been resolved yet), and it still doesn't preclude you from knowing about the rule of 5 and the side-effects of declaring or not declaring certain operators/constructors/destructors.

> As the language gets more capable, the code you write gets simpler.

> I don't think that is happening in Rust.

This happens quite often in Rust, see for example error handling and the evolution of the ? operator, and the recent addition of async/await, and unlike c++, as the language gets more capable the changes required in terms of coding style and updating your mental model of how things work is usually not so dramatic.

0: http://scottmeyers.blogspot.com/2014/03/a-concern-about-rule...

2014 was a long time ago.

Scott has retired. The better alternative to his suggestion was noted right there in the comments. Rules of 3 or 5 concern only designers of a library, and if you are designing a library, you may ignore them now.

Think about it the opposite way: the modern language gives you a much safer and more expressive way to express your algorithms and still gives you access to the large library of existing code.

On the flip side, I learned low-level programming in rust, and am thankful that $bigcorp uses modern c++ so the initial gap was smaller. Rust is still better though.

Do not feed the trolls.

The net number of people adopting C++ in any unit time dwarfs by orders of magnitude the number adopting Rust; and the number already using C++ exceeds that of Rust by many more. That will remain true for a long time. As a consequence, any improvement to C++, either core language or library, has overwhelmingly larger lasting real-world benefit than any corresponding feature in Rust.

Rust pursues benefits by making a class of low-level errors hard to express, at some cost to expressiveness, and at quite substantial cost to adopters who must learn to work around the limitation (which they do). Against such cost it provides some convenient new control flow features, and leaves behind many C and C++ misfeatures that C++ cannot.

C++, instead, pursues benefits by making the language increasingly able to capture semantics in libraries, and thereby deliver thoroughly optimized and tested semantics to users without compromise. The result is that C++ users, by using such libraries, are able to code at a level high above that where the bugs prevented by Rust would manifest, and write less code that could harbor bugs of any kind, overall.

It is not clear whether adoption of high-level coding practices by coders using or switching to C++ will produce more benefit than those adopting Rust, and coding without access to such libraries. I have placed my own bet, and we will see.

But we can say with certainty that every coder who switches to modern, safe C++ from C or C-like C++, or to Rust, is a net win for humanity. And, if Rust in the end fails to grow out of its boutique niche (which is still absolutely possible), everyone later leaving Rust for C++ will bring to it high expectations that will incrementally raise the quality level of new C++ code.

Bad-mouthing of C++ by Rust fans may feel good, but it causes a net harm to humanity by the degree to which it reduces the number of coders who switch to modern C++ from C. The number of C coders who switch to Rust, instead, is far, far too small to compensate for such harm.

So the only defensible, responsible behavior is for C++ and Rust users to promote C++ and Rust (not necessarily in that order) and concentrate on getting coders off C.

You have some strange ideas about why people use C instead of C++ these days. People continue using C not because C++ lacks coroutines or something else (a strange argument for C which has almost no features to speak of), and not because they hate safety. No, people use C dor the sake of portability, for the sake of embedded systems, and for the sake of utter simplicity where that is required. Weaning them off C to C++ is impossible because C++ already doesn't fit their requirements. In fact, Rust is better suited to embedded devices than C++, so there's no real need to proselytize C++ to C programmers. Or to anyone, I would argue, because C++ is a terrible language nearly impossible to write safe software in, as well as an ergonomical, developmental and compilational pain in the ass.

In fact, I believe that in terms of developer time wasted as well user frustration, C++ is the most harmful language in the history of humanity. Someday I'll put together a page listing the dozens of C++'s design daults. Here's just a single article demonstrating how incompatible with simplicity and correctness C++ is: http://www.icu-project.org/docs/papers/cpp_report/the_anatom...

The article is from 1997. Every C++ developer will agree that the area surrounding owning raw pointers is chock-full of footguns, but that area is avoided in modern C++, both in theory and in practice.

It is a fact that people still do graduate from C to C++, for a wide variety of reasons. Some discover that their embedded system can be coded with C++ as easily as C. Some learn that C++ is faster than C. Some just gain more confidence and adopt a new feature that is only in C++.

The large number of remaining C coders, and the ease of switching incrementallty, means that the number switching to C++ is always overwhelmingly larger than the number adopting Rust from all starting points.

We may lament that they do not start writing modern, high-level C++ immediately, but the number of CppCon (and similar) talks hosted on Youtube, and rocketing attendance at, and number of, such events, shows that there is great interest in learning good modern C++.

In my experience, the majority of C that is used is actually by people who think they're working in C++, because they were taught to use manual memory management, raw pointers and other such C-like constructs. Some keywords about classes were thrown in towards the end of "C++ 101" or whatever they learned from, and away they go, writing C with classes like the last 30 something years never happened.

That's still C++, just not modern C++.

Technically, in that the C++ spec allows it, yes, it's C++. However, I find such definitions to be of little practical use, although frequently in the workplace I sit and wait while someone satisfies their need to carefully divide the world up into precise, clear, exacting and useless definitions before we can get on with doing something useful - the industry just seems to attract that; often they don't care about trashing all those lines immediately afterwards, so long as everyone acknowledged the lines. That said, the discussion about how many layers there are in a model of networking and what they're named rendered some people unable to do anything for the rest of the day.

Colloquially and practically, I might suggest that it demonstrates that the programmer may be dangerously thinking in C with little lumps of data as their classes. The programmer is thinking and coding in C, with some classes, that they then feed to a C++ compiler.

People were doing it like that back in the nineties, when what we think of as "modern C++" didn't exist.

AFAIK this very problem is addressed with introduction of move semantic and the goodness, which comes with it, such as unique_ptr instead of raw pointers. With that default move assignment operator does the right thing by default. So C++ langauge development actually improves simplicity and correcness as least for this particular example.

> Someday I'll put together a page listing the dozens of C++'s design daults.

It's pretty old and somewhat outdated by now, but you might enjoy the C++ FQA (Frequently Questioned Answers):

https://yosefk.com/c++fqa/

"Here's just a single article demonstrating how incompatible with simplicity and correctness C++ is"

I don't see where is the problem. Perhaps, you could give an example of the equivalent code in your favorite language?

Almost no one is using Rust in embedded. C++ has a much higher uptake among that crowd.

I'm not sure modern C++ has proven to be safer than C (old C++ most certainly has not). Also, I'm not as sure as you that there is an overwhelming number of people adopting modern C++, given the slow speed at which I've seen at least my company being able to move to C++11 and then C++14.

The reality is that C++ is still an extremely unsafe language, where any slight deviation from strict discipline (discipline that itself has only really been ergonomical since C++14 or so) will lead to memory corruption errors. Even with modern C++ features you can get memory corruption: null references, references to moved objects, no way to signal errors from destructors, and there is still no good way to check whether an operation on ints will overflow. Moreover, the insistence on optimizing around undefined behavior, specific to C and C++ I believe, coupled with large reliance on undefined behavior in the standard, leaves C++ in a very poor position as far as guarantees of safety are concerned.

In general, the responsible thing if we want a more secure world would be to discourage the use of manual memory management as much as possible, whether it be in C, C++ or Fortran. That does include trying to get people to use smart pointers if they absolutely have to use C++, but it should also include getting people to use other languages if at all possible (Java, C# or Go would be the more mature ones for large business).

You're saying that switching to "safe" modern C++ is just something you could do at a whim. Learning how to write safe C++ is a hell of a task to undergo, and still you are at the mercy of your program crashing even though you have taken careful approach to memory management etc.

Modern C++ is just not a safe language to program with. It is very easy to produce errors that result in segmentation faults, and it takes great care to produce code that works properly even with shared_ptrs and unique_ptrs and so on.

But you are correct that adoption of C++ is higher than Rust, and will continue to be so until some mission critical framework or for example game engine starts to support Rust in as a first citizen language.

Until then, we have modern C++, with all it's quirks and difficulties and lost developer time in figuring out where the hell was that dangling pointer or why the heck was an object not freed correctly, or why did the array access or vector access go off by some value.

Not saying C++ isn't good, it is, but a lot of time is wasted figuring with C++ currently when a lot safer alternative could be used. Unfortunately that is not very realistic in many scenarios yet, although I carefully evalulated Rust also for my current project, the requirement of supporting a C++ game engine just outweighs easily the hassle of having to figure out bridges and bindings and such.

Writing safe modern C++ is much easier, and much less work than the old ways. So it is easy to switch, and easy to tell if you are Doing It Right: if it's not clean, safe, and easy, there is a better way.

"yet instead of fixing anything they just pile up more features in an effort to compete with Rust and Go"

Alternately they're iteratively evolving the language as each generation of features are fleshed out? They've been doing this for several decades now. It's their job. And for those people using C++ tooling, or working on C++ projects: Cool, new stuff to ease some edge conditions.

> an airplane engine from Rolls-Royce

RR makes excellent aircraft engines, for both Boeing and Airbus https://en.wikipedia.org/wiki/Rolls-Royce_Trent

In addition, Rolls-Royce cars are made by BMW now, who also make quite good engines.

Correct. RR doesn't make cars anymore, it's only just a badge. Also, RR is dominating the marine propulsion sector, these engines are some of the largest in the world!

This I did not know, interesting!

As much as I like Rust, progress usually comes in progressive changes, not with big bangs.

Modern C++ is already a large improvement over C, which was already a 19th century carriage, when everyone was moving into steam cars.

Unfortunately, modern C++ still includes (the vast majority of) C, both in theory and in practice in many code bases around the world.

Indeed, and it is its Achilles tendon, once its Trojan horse for adoption, nowadays the source of security headaches.

However, I don't see many companies throwing away their IDEs, game engines, build systems just like that.

It is easier to migrate those teams to static analysis tooling, than throwing it all away and start from scratch in another ecosystem.

Hence why both Microsoft and Google are still two major contributors to ISO C++, in spite of being in the process of adopting Rust.

Can you point out where Google and Microsoft are moving to Rust because I've seen none of that.

“Moving to rust” is too strong; they are both adopting Rust for real, production use cases. I’ll give you one example of each: Google is using Rust in ChromeOS, at the virtualization later, and Microsoft is using ripgrep to power the search for VS: Code. There’s more than just that but those are the two easiest things to point to.

The concepts part I'm not sure about, but the other parts don't look so bad. According to cppreference.com[0]:

> Coroutines cannot use variadic arguments, plain return statements, or placeholder return types (auto or Concept).

> variadic arguments

For the purposes of creating variadic functions, variadic templates are the preferred solution, since variadic arguments have a number of drawbacks (e.g. unavoidable type promotions).

> plain return statements

This is the definition of C++ coroutines, more or less.

> placeholder return types (auto or Concept)

Note that this isn't the typical use of auto (i.e. inferring the type from the right hand side of an assignment), but about return type deduction. From a quick read, it looks like there are multiple, equally valid kind of coroutines (e.g. lazy<int> vs generator<int>) which cannot be deduced from the body of the coroutine. It could be argued that lazy<auto> should work, but I would guess it clashes with all the already existing complexity of template deduction. I agree that this looks like a wart but not a horrible one.

I'm not sure about the concept part, would have to learn more about concepts to comment.

> Constexpr functions, constructors, destructors, and the main function cannot be coroutines.

> Constexpr functions

Constexpr functions are functions whose value can be decided at compile time. Coroutines can call constexpr functions, they just can't be one. I guess it could be useful to determine the full output sequence of a coroutine at compile time. Maybe it could be added in a future language version, if it's worth the added complexity.

> constructors, destructors, and the main function cannot be coroutines

I guess this is just formalism, having those things as coroutines doesn't make logical sense.

0: https://en.cppreference.com/w/cpp/language/coroutines

Thanks for the itemized reply. Your points make sense

> https://gcc.gnu.org/projects/cxx-status.html

seems more up to date than cppreference

No I meant that from cppreference using coroutines means you can’t use the features I mentioned not that those features don’t exist in c++20

C++ is getting more fun to use, every cycle.

C++11 was a huge step up with lambdas, move semantics, atomics, threads, constexpr functions, loops over containers, and loads more. C++14 added generic lambdas and lifted lots of arbitrary restrictions, making everything smoother. C++17 added destructuring, template argument deduction from constructor arguments, and constexpr if. C++20 brings concepts, ranges, modules, coroutines, and automatic comparison opetators.

Each time, more kinds of programming are made natural and easy to write, and more old workarounds become unnecessary. We hardly ever need to write out constructors, copy assignments, or destructors anymore; or even, with '20, comparison operators. Template metaprogramming is mostly unneeded now.

Me too. It's a lot of fun coming.

I am working on a red-green threading on Linux, what interests you?