> 2.1. Stable language and library ABI
> 2.2. Backwards or forwards compatibility
> 2.3. Legacy compiled libraries without source code or ability to rebuild
For fucks sake, C has been stable for decades but somehow C++ just can't manage?
This is such an obnoxious attitude. At least let us automatically generate a set of C-style functions that take an opaque void* representing a C++ class instance if you can't be bothered to do the work.
The authors are (mostly) at Google. They build their binaries from scratch from a monolithic source repo with a reproducible build system every time they want to deploy software. Their use case is unusual and they recognize that. The document lays out their justification for what they prioritize and why, for example, they would happily sacrifice backwards compatibility or nonstandard architecture support for more performance.
Concurrency and parallelism without debugging hell is huge.
While I have your attention, I see your comments here in C++ threads quite often. You seem to like the language and at the same time you have some experience with simpler languages like Oberon. My experience with C++ has been that people happily go on to create giant inheritance hierarchies, with no restraint for multiple inheritance to the point that it's so unmanagable that nobody knows where things go and what actually happens. With all that inheritance, they lose track that the same thing has actually been copied tens of times between different classes and now these tens of classes have code that is basically copy-pasted and who knows what benefit anyone has from all this inheritance. Google engineers are one of the offenders when it comes to overuse of inheritance. Then, modern C++ allegedly fixes some warts, but IME it introduces more of them. E.g. the initialization fiasco (I honestly can't say with 100% confidence what braces do when you initialize std::vector). Then there is this thing that when you create a lambda like so:
[&] { ... }
std::function<void()> create_lambda(args...) {
return [&] { ... };
}
Don't you experience the same fatigue as I do?
EDIT: Oh, I just remembered another thing: at a previous job we discovered that MinGW's implementation of std::random_device just returned 0 every time. It is major facepalm for MinGW, but also for the C++ standard for making this behaviour allowed (yes, it's actually compliant with the standard). And even after it was fixed, there are still systematic issues with this whole randomness API. E.g. you can't actually seed it properly[1].
[1]: https://codingnest.com/generating-random-numbers-using-c-sta...
Fun fact, due to continuous ranting regarding C++ support from game developers, not only did Google announce at GDC 2020 that they are upping their game regarding C++ tooling on Studio, they will also provide Android plugins for Visual Studio.
When people discuss Oberon, they tend to focus on Oberon (1992) or the minimalist approach that Niklaus Wirth has pursued later with Oberon-07.
When I talk about Oberon, I think beyond my early experiences with Native Oberon, and also include Oberon-2, Component Pascal, Zonnon and Active Oberon into the mix. The Oberon language linage, not all of them done directly by Wirth.
In that sense, for me Oberon is what EHTZ nowadays uses as Oberon, namely Active Oberon.
http://cas.inf.ethz.ch/projects/a2/repository/raw/trunk/Lang...
You will find out that minimalist Oberon is long gone and the language in a certain sense compares to C#, D in complexity, with support for generics, untraced references, exceptions, linkage models, inline Assembly.
Because that is the problem with minimalist languages, library boilerplate just grows to emulate what should have been in the language to start with. In Oberon's case, Active Oberon is the result of many years of research and student thesis doing OS implementations in Oberon, while noticing that stuff like generics, untraced references, inline Assembly are quite useful.
As for C++, while I still enjoy using it, nowadays it is mostly a tool for OS integration libraries and GPU shaders (HLSL/Metal/CUDA), I rather write the main code in .NET languages, Java or some other managed language.
Generics is something I can't live without, to be honest. But I don't like C++'s implementation of generics. The error messages they generate and the whole SFINAE business make for a horrible programmer experience. Rust has the best implementation that I know of currently. Inline assembly sure is useful.
Anyway, thanks for the extensive answer. I think I understand your point of view better now.
it doesn't copy the stack pointer, but it enumerates all variables you use and captures a reference to it (I think the &, as used in address-of and references kind of gives it away). [=] {} unsurprisingly captures by value.
Some compilers do warn when you return lambdas capturing local vars by reference, but it is not super reliable.
#include <functional>
#include <iostream>
std::function<void()> create_lambda(const int& x, const int& y) {
return [&] {
std::cout << "x: " << x << "\n";
std::cout << "y: " << y << "\n";
};
}
int main() {
int x = 5;
int y = 7;
const auto f = create_lambda(x, y);
f();
}
this has been 'fixed' with jthread. FWIW I think it is a mistake, blocking in a destructor is can easily lead to deadlocks (I have first hand experience, it is not just a theoretical issue). Detaching is not an option either.
I feel like this is consistent with the "pay for what you use" design. Why capture all variables in scope by copies when you can just capture them all as references (which might go out of scope)? If you truly need to capture other stuff, you can do so using more syntax. If "[&]" did what you describe then "wtf, why is it saying I have a deleted copy constructor for some value I'm not using" or "wtf, why is my code so slow because of unnecessary copies of large objects" would be all sorts of fun.
There is plenty of libraries in C++ that haves you concurrency and parallelism without debugging hell.
Hell in concurrent code comes when you have shared state, and that is valid for both Go and C++. Using shared Golang Map in multi-threaded code is a very good example of deathtrap, even if it's in Go.
Even Arduino like boards use C++ nowadays.
Unity and Godot have their graphics engine written in C++.
Rust, Swift are dependent on LLVM, written in C++.
Go, it isn't really in the same league of programmer expressiveness.
Still used lots and lots of places
Then we have Pyston, and the ill fated unladen-swallow.
The Windows kernel is mostly written in C, too. iOS uses Objective C.
Modern C++ isn't bad, but robust classes require an enormous effort together with tests suites that approach the size of test suites required for an untyped Python module.
In practice segfaults are as prevalent in C++ as they are in C. Type errors by implicit conversions are more frequent in C++ than they are in C. Full testing of all conversion rules requires a superhuman effort.
So I think well written C is often safer than well written C++, because one does not have to deal with the case explosions introduced by classes and their implicit rules.
The often quoted safer strings in C++ are just a very tiny part of the equation.
If I had my way, we'd all be writing Ada or Standard ML, but no one listens.
30 years ago no one though commercial UNIXes would be wiped out by a "toy" UNIX clone project.
Windows kernel has been moving into C compiled as C++ since Vista introduced support for kernel mode C++.
iOS uses C++ for its drivers, Metal shaders and compiler toolchain. That Objective-C implementation relies on C++.
Yes, the Trojan horse of C's copy-paste compatibility is also its Achilles heel of security, however in contrast with C's attitude regarding security, C++ provides the library types to actually implement secure code, if one bothers to make use of them.
If I had my way, C would have bounds checking enabled by default, strong typed enums, proper arrays and strings, but no one at WG14 listens.
Like you said, it's not even that far fetched.
It has has one on IBM i and z/OS, as part of the language environments.
I guess when one is bored might try to re-implement ATL, WTL or UWP projections with C macros.
Unfortunately, it is not. C++ is certainly too complicated, that's why it failed at replacing C, and that's why Rust will fail at replacing C as well.
All major C compilers are written in C++ nowadays.
Apple OSes use C++ for device drivers, GPGPU programming and their compiler infrastructure.
Google OSes use legacy C drivers for Linux and everything else is a mix of C++, Java, Rust, using micro-kernel like architecture where each driver gets their own process.
On Windows it has been long considered persona non-grata and everyone advised to either move to C++ or adopt Clang (also provided via VS installer) if they insist in using C. VC++ only supports C to the extent required by ISO C+++ compliance.
One of the reasons OpenCL lost to CUDA was the initial refusal of Khronos to offer similar C++ tooling, making many researches jump to NVidia.
Embedded C++, and the kernel is pure C.
And as of Driver Kit introduction, 100% full C++ is now an option.
In a couple of years from now, when the full transition of kernel extensions to user space modules is complete, the kernel will be the only C piece left.
Which Apple most likely won't bother to rewrite due to the historical baggage of mixing BSD with Mach code that probably no one is willing to re-write.
You say this as if it is the fault of C. I see it the other way around -- Microsoft's refusal to implement C11 is singlehandedly contributing to the decline of C, because they've leveraged their large OS market share to make it impossible to use an update of the language for cross-platform development. They are killing it on purpose, and it's infuriating.
Anyone that wants a C like language with better security has decided that the only path forward is to either ditch it, or impose hardware memory tagging (which Google is imposing on as of Android 11).
Microsoft still supports C in its Checked C variant and just like Google, Oracle and Apple on their platforms, its hardware hardened Azure Sphere Pluton runtime.
C was already on decline in the late 90's, all major desktop and mobile OSes were being written in C++, BeOS, Symbian, Windows with OWL/VCL/MFC, OS/2 with CSet++, Mac OS with MPW/PowerPlant, game developers were moving into C++ with Watcom C++ and PSOne devkit, it was the rise of FOSS UNIX clones with the FSF manifesto to use C as much as possible that changed the wind, thankfully that course has been finally overturned.
The decline of C in an always connected computing world is done by WG14's lack of action.
From what cursory knowledge I have, Rust maintains both a bare bones standard library suitable for embedded work as well as a more fully featured standard library that is built on top of that minimal library.
What features would keep Rust from becoming a new C other than possibly some issues with ABI stability that from my understanding people are working to resolve?
I would argue that C++ needs to increase the pace of change if it wants to remain relevant. Rust, Go, Swift and Kotlin are though competition, while C++20 is still lacking in agility, safety and modularity.
C++ build systems are already worse than all the languages you mentioned in part because there's no module support.
I also disagree that it would hurt performance. If the logic contained in "-D_GLIBCXX_USE_CXX11_ABI=0" was formalized to allow backwards compatibility, libraries would snap together more easily while still preserving inlining better than C ABI exports are able to.
The point of the document is to lay out the goals and priorities of the authors, not to argue that they are universally applicable. The authors compile everything from scratch with the same version of the compiler, down to the OS kernel.
What is the point of fighting to stay relevant by going after use cases that are being served by these other languages? Is it just to win and have more "mind share"? Is it to make the biggest tribe? That seems like a social goal, not a technical one.
C has no strings.
The optimization was considered vital enough for a rare break to actually happen but there are multiple such clear wins that cannot be implemented because of ABI stability. Sometimes it's a major pain to have to keep piling the cruft on.
As a community, we absolutely should reject this proposal and insist that the standards committee continue to support compatibility. Repeating Python3's mistake in C++ would be a nightmare!
the -std=c++03 mode of the compiler is pretty stable... but not many people care about that anymore. If they cared google would be building their next kernel in C, not in C++