Unnecessary hubris. I assure you the original ABI authors were plenty smart and just faced a different set of problems.
> Our forebears are either not interested in a world without the mounting, crushing debt or just prefer not to tackle that mess right now
The article mentions the organizational/social part of this problem, but then goes on to drop this turd.
I can also assure you that our forebears were neither malicious or lazy; but faced the same problem this proposal does.
I don’t like seeing such disrespect for the folks who laid out the groundwork for us.
At that point though, one could claim that they can do it in C as well and implement half of Objective-C
You're taking the idea of respect too far.
The Assembly like abilities have been growing as language extensions in specific compilers, not as part of ISO C.
Going back to K&R C, inline Assembly or intrisics were not even available, all of that required using the Assembler directly.
It's a myth that this is a myth.
Have you ever worked with newbies learning C?
These students split pretty hard into two camps (of course there are oddball exceptions): those who knew assembly and find C easy, and those who didn't and struggle with pointers until they finally get it (some, never do).
Of the mainstream languages, C is the only one where understanding and dealing with direct memory access is a fundamental requirement if you're going to get anything done.
The myth argument is that C code doesn't directly translate into the execution flow on the CPU. No, of course it doesn't. That's not the point.
What people mean when they say C is lower level than most mainstream languages is because it forces you to deal with details most other languages paper over.
Yes, multiple languages have some way of achieving this kind of memory access, but except from C, it is considered an esoteric edge case that mostly nobody needs.
But it is also wrong to reduce a language to what is in the spec.
Apparently reducing the language to what is in the spec is only a thing when talking about C and to some extent C++.
When other languages have compiler specific extensions beyond the spec, it is a failure in their design.
Yet when C and C++ devs have to reach out to compiler specific extensions, it is not a design failure like it is pointed out to others, rather an advantage.
It is also wrong to not apply the same measure when it doesn't suit the message.
The point is in C you have greater control of execution and resources, not that it matches the hardware exactly. It’s a spectrum and C is closer on that spectrum than JavaScript.
So I keep re-educating folks that isn't the case.
Every thread has different people reading it, so there is always a first time for many of them.
And if you move to e.g. C# / Java or similar, if you squint, and you try to be a smart-arse, then you could deny that C is closer to the hardware than C#, because C# probably has everything you need to control it, to the same degree that C allows you to. But if you work in these languages for a while, and look at the code that you ended up producing, then again you will absolutely find that it would be ridiculous to not admit that C gives you better control.
And you could even extend this to Rust, because the language encourages you to use high-level prefabricated components. It discourages you from doing low-level things, at least a little bit I think (I'm not a Rust user).
I think what you are doing all the time, is you are being a smart-arse, nothing else. What interesting low-level performant things have you actually programmed lately?
I disagree somewhat. C gives you better control, and you have to accept that gift to get anything done. The likes of (modern) C# give you better control, but you can reject the gift if you want, and program in higher abstractions. You can also accept it in some places and reject it in others.
With C, you can reject the control, too, but then, you have to use third party libraries (or write them yourselves), and using those, your code looks less nice because it cannot escape C’s syntax (yes, macros help a bit there, but having real syntax beats it)
I have doubts that you can program easily in a C-style way in C# without adding lots of annotations everywhere in many places. But don't know, maybe I'm wrong, I did a search for a simple C-style arena allocator in C#, and it looked acceptable, it was quite close. The most annoying thing was maybe keyword boilerplate.
And then coming with such lengthy ad hominem.
Let make a fun exercise for the audience, given your performance remark.
Paste a random C code that I should replicate in whatever language I feel like.
There is one rule.
If the sample code is pure ISO C, then I will only use what is in the standard of whatever language I pick up.
If the sample code makes use of single language extension not part of ISO C, then I will have the freedom to also pick whatever language extensions I feel like.
Using C++ as your other comparison point when arguing that C isn't low level is by far the most smartass idea in this thread.
What about you do xxHash? Should be quite basic, not a lot of complicated structures. https://github.com/Cyan4973/xxHash/blob/dev/xxhash.h
Or what about you do an audio or video codec? Or an operating system?
Not going to paste any of my own code, because any non-trivial stuff is hundreds to thousands of lines. But one more example (that I recently did myself): Create a block allocator (power of two blocks) with bookkeeping in shadow memory (administered in individually committed zones representing virtual memory regions of 64 MB (2^26)). Any used memory has bookkeeping support for being sub-allocated at any and all levels up from 64 KB (2^16) to 64 MB (2^26), and even higher (by joining committed regions). Individual blocks are collected (using intrinsic linking, because no memory allocation) in a hierarchy of pools of same-sized chunks that have the same parent, and can be recursively sub-allocated on any smaller chosen power-of-2 level, and finally be consumed in linear fashion (arenas). Blocks are pooled with a moderate retain policy (watermark system) to allow subsystems to almost completely avoid any system calls and avoid inter-thread synchronisation. The memory overhead must be below 1% even though it's totally flexible (as said has metadata for all levels from 64 KB up).
The bookkeeping should function on 32-bit systems (small virtual space, occupancy range from megabytes to 3 GB) as well 64-bit systems (2^48-2^57 bytes of virtual address space, occupancy range from megabytes to hundreds of gigabytes) with reasonable overhead compared to actual usage.
This requires intrusively linked lists, occupancy bitmasks, bit-counting and bit-prefix counting, OS syscall access (virtual memory), pointer arithmetic (alignment needed to address shadow bookkeeping memory) and thread synchronisation. The reference code is >> 95% pure ISO C++11 (could be C99 with few changes), with a little platform code glued in. It works on Windows but it could be ported to Linux in a few hours. It supports a mostly-immediate-mode GUI with hundreds of thousands (maybe millions?) of small variable-sized allocations per second. Allocation has almost completely disappeared from the CPU profile, well below 1% of CPU usage.
This is common with C, when interfacing with hardware.
What are you even arguing right now? (Btw -ansi compiler flag)
> Smart-arse is comparing C versus JavaScript
I chose JavaScript to make the idea of a spectrum clearer using extremes. I can do C++ if you like. The machine doesn’t care about destructors, move, concepts, initializer lists, virtual methods, launder, or inheritance. You are programming against an abstract model further divorced from how x86 CPUs work.
It was already outdated by the time Borland released Turbo C++ 1.0 for MS-DOS, and only got new wind thanks to GNU FOSS and their manifest to prefer C as the main compiled language for GNU projects.
Everywhere else outside UNIX, was going with a mix of C++ for OS frameworks, Apple, Microsoft, IBM, Be, Nokia, Epoch,....
Naturally given the option, between C, C++ and something else I might prefer that something else, however I managed a few interesting positions exactly due to my C++ skills, and interests.
So don't mix my preferences for C and C++ on the same basket.
> So don't mix my preferences for C and C++ on the same basket.
That mistake is mine indeed, I'll remember. Thanks, and I hope "no harm meant" was implicit :)
> and I hope "no harm meant" was implicit :)
Ad hominen then an apology, mixed signals here or I'm missing something. Maybe sarcasm?
I think many of us throughout the years been reading pjmlp's comments which fits a certain "theme". I don't mind though, it's just text after all, but was hard to keep myself from entering the meta-conversation when the opportunity just sat there. I still don't mean no harm by it, we all have our less agreeable ways of writing our comments, I'm surely guilty of it in some way too.
You can express annoyance at someone's pattern of behavior without it being personal. embedding-shape isn't the only person annoyed by pjmlp's repeated disdain and snark towards people who use C (or Zig or WebAssembly or Rust or...).
No, you're usually the initiator. Usually it's with some off-hand quip about how C programmers don't understand C, or how the people designing WebAssembly are ignorant of COM or the JVM, or how Zig is just Modula-2, etc.
Most threads you participate in aren't filled with snark until you enter them.
Two measures two weights, in C versus other systems languages.
I'm not pjmlp but I can explain this for the case of Rust, where this works a bit like C but with a few interesting differences.
Mainly, in Rust there is not a concept of a "memory object" per se in the runtime semantics. Memory is made of allocations and allocations are made of bytes. Unlike C, bytes are guaranteed to be 8 bits in size. Every byte of memory can hold integer values (0x00 to 0xff), pieces of a pointer or be uninitialized. That means there is nothing like strict aliasing, and therefore no need to have special rules for byte-level access. You can alias any type as any other type, so long as you avoid all the other sources of UB (out-of-bounds access, uninitialized memory access etc.).
The way to practically access this is much the same as in C. You can do things like cast pointers between different types and project a pointer to a struct to a pointer to one of its fields. It should be noted that, unlike with major C implementations, structs do not have a stable, well-defined layout, so if you do manual pointer math you need to put #[repr(C)] on the struct to get C layout rules (which might still yield platform-dependent field offsets, e.g. size_t is not the same size everywhere).
Note also that these are the dynamic rules of Rust, you need to follow these when writing unsafe code to avoid UB. The static rules of safe Rust are much more restrictive and don't allow much at all. It is possible to write unsafe code that exposes safe abstractions for this, one example is the "bytemuck" crate. It provides macros that can parse a type definition to check certain properties (e.g. well-defined layout, no padding) and then provide you with safe functions for byte-level access. Since there is no strict aliasing, for certain types you can also get safe functions for access at other granularities. For example:
#[repr(C)] struct Foo {
x: u32,
y: u16,
z: u16
}
#[repr(C)] struct Bar {
x1: u16,
x2: u16,
y: u16,
z: u16
}
BTW: If you use character-pointers, you also do not need to worry about strict-aliasing in C.
Or for something more modern either D or C++ will do.
Examples omitted on request.
Being able to find someone who's made the argument you're rebutting doesn't make it not a straw man. What matters is whether the person you're arguing with is making the argument.
Specifically this:
> When other languages have compiler specific extensions beyond the spec, it is a failure in their design.
Is not a point I've seen anyone here make.
This one of the failures of Linus T. with the linux kernel: he was not able to keep the assembly source code with plain and simple C code you can compile with a small and alternative C compiler (same failure for the glibc devs I think).
I don't blame him, he is already keeping the linux ABI stable, and pulling that off is something.
Each additional compiler supported by a project means variance in functionality and thus additional work for the project. That work could make the codebase more robust. Or it could be a ton of useless work. Or anything in between. Depends on the context of the project.
Which part of that big clause is the part that failed? Because I thought you could still compile Linux with TCC.
With those assembly source files (which do not abuse any pre-processor) and plain and simple C, I could build a modern x86_64 linux kernel with cproc/qbe (which gets 70% of gcc speed in my CPU intensive benchmarks... for a few % of gcc code and in plain and simple C, not brain damaged c++).
But I kind of don't mind since the future is assembly coding on non-IP-locked standard like RISC-V, and the main issue for that future is the abuse of pre-processors (ffmpeg was bitten by it) or code generators which would not be written in assembly themselves (or with a simple high level language with an assembly written interpreter, asmpython?).
Any code that ventures anywhere near that territory is 99% Undefined Behavior. It's almost impossible to write proper C/C++ code that isn't UB while touching byte-level representations.
This is undefined behavior!
const int* magic_intp = (const int*)bytes;
Heck even something trivial like this is UB:
bool bar(char ch) { return isxdigit(ch); }
The only safe thing to do is memcpy, but that's super useless. As soon as you try to interpret or manipulate the byte-level data in any way, there are UB traps everywhere you go.
Saying inline ASM is no different than a function call is like saying standard control structures are no different from function calls. I suppose from a Smalltalk perspective that could be true, but is that the mental model most programmers use?
I work on a system from the 90s with custom instructions. GNU-as was patched to understand the instructions. They’re used through macros that ultimately expand to inline ASM. Without this, you’d need function inlining, which may or may not be possible with a linked object (it certainly wasn’t standard in the 90s). So now a single instruction turns into stack management, a jump, more stack management and a return. At that point any benefit to a specialized instruction may be erased, or in the case I’m dealing with talking to external hardware becomes unreasonably expensive.
lets say I really want to use popcnt in my inner loop. with inline assembly I can just shove it in there. external linkage forces a function call overhead that can't be inlined, which obviates any benefit I might have had from using the specialized instruction.
its also true that when I unwrap my new spin with fancy new instructions its unlikely to have a robust set of instrinsics around them.
inline asm is a real mess, I always regret tussling with it, but its kind of pragmatically necessary if you're actually working at the metal in a high performance or embedded context unless you're doing the whole thing in assembly.
C exists in a nether world of being neither assembly nor high-level language.
People only call it high level because in the 1970s, having blocks, loops, and functions was high level, compared to the SoTa machines available in the day, which were either programmed with assembler or some bespoke thing the manufacturer came up with.
C only exists instead of the alternatives, because according to Dennis Ritchie himself it was more fun to create C than using something else, and I quote:
"Although we entertained occasional thoughts about implementing one of the major languages of the time like Fortran, PL/I, or Algol 68, such a project seemed hopelessly large for our resources: much simpler and smaller tools were called for. All these languages influenced our work, but it was more fun to do things on our own."
From https://www.nokia.com/bell-labs/about/dennis-m-ritchie/chist...
"All these languages influenced our work, but it was more fun to do things on our own"
ABIs are defined by CPU and operating system vendors. Those ABIs usually happen to be quite 'C friendly', but that's not a requirement (for instance the AmigaOS ABI was primarily meant to be used from handwritten assembly code, and Amiga C compilers had to adapt to those ABI rules or they wouldn't be able to call into the operating system DLLs).
If they want to find something really obsolete, they better have a look at executable/dynamic lib file formats (PE+, ELF64). In other words, they better look at that first: I am using my own, which is beyond simple (a little RFC would suffice), no loader of any kind, basically userland syscalls. And I do embbed exes in an ELF64 capsule to run them transparently on linux systems (writting a internal linux exe loader would be copying ELF loading code while trashing 90% of its code). (hopefully in some not too far future, I'll try to build a mesa AMD vulkan driver for this very simple format and for that the main issue is.. c++ with its runtime, as always...).
Personal pet theory: C is portable as in "you can retarget the compiler to any machine" moreso than "your code will run on any machine".
This is actually how c grew up. This is also one of the reasons why the spec is quite ambiguous in certain locations. C is made to be easily portable not a universal codebase for all platforms (though you can get quite close with some tricks like macros). Remember the spec allows C to run on a Unisys 1100/2200 just as well as on a pdp-11.
I may be to embedded for this but if you want your code to handle long long as int64_t use <stdint.h>. I am of the opinion that you should always use fixed width types as portable types are a huge footgun and kind off redundant.
Especially when you start doing a little more complex things expecting them to work exactly the same, like 128bit values on a 64bit platform.
But then a lot of software assuming that int means 32 bit got written and even 64 bit ABIs have kept int as 32 bits.
One may say, that shared libraries can save some space for both disk storage and RAM. But such savings aren't that huge and in some cases are even negative - if a library is linked-in, it's possible to discard unused functionality and even inline many library functions.
- 2023-06-10, 64 points, 16 comments: (https://news.ycombinator.com/item?id=36249253)
- 2022-03-13, 175 points, 129 comments: (https://news.ycombinator.com/item?id=30660528)
I think defining a constant function pointer should work. As long the compiler doesn't store this pointer in the result executable and optimizes-out all calls via it into calls to the source function.
> at least we’ll finally have the chance to have that discussion [about breaking ABI] with our communities, rather than just being outright denied the opportunity before Day 0.
[0]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2901.htm
[1]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3913.htm
Suppose I have a libfoo that has a public function that takes an intmax_t parameter. Or that has a public struct with an intmax_t field. It will be compiled for a particular definition of intmax_t. If you try to link it with a program that uses a different definition, it will fail.
The article's solution with the "MY_LIBC_NEW_CODE" define cannot work because no existing C code knows about "MY_LIBC_NEW_CODE".
The proposed mechanism is somewhat useful to a library that wants to provide multiple incompatible implementations of a function. (But this is mostly only interesting for libc implementations that need to handle historic incompatibilities between all the various Unix specs. Other libraries can just give their new, incompatible function a new name.) It's useless if you want to make an incompatible change to a type definition.
I don't get quite the same impression. The sense I get is more that such a change would basically need to happen "bottom-up":
> Some of [the scenarios that aren't fixed by this proposal] are just the normal dependency management issues. If you build a library on top of something else that uses one of the changed types (such as intmax_t or something else), then you can’t really upgrade until your dependents do.
> <snip>
> For those of us in large ecosystems who have to write plugins or play nice with other applications and system libraries, we’re generally the last to get the benefits.
In which case the benefit of the proposal (as far as I understand) is that such bottom-up changes can occur without forcibly breaking other consumers.
And to be honest, this sort of compiler-specific ABI interoperability is a non-problem that doesn't need solving, it's at most relevant for software developers of closed source libraries who distribute the libraries as precompiled blobs. But those must be stamped out for different target-triples anyway.
Ultimately any ABI discussions need to happen between CPU and OS vendors, compiler toolchains implement whatever comes out of those discussions.
idk, given how ABI impacts the evolution of C I think it's not unreasonable to provide a mechanism by which ABI can be evolved even if it's not specifically for compiler interop.
> Ultimately any ABI discussions need to happen between CPU and OS vendors, compiler toolchains implement whatever comes out of those discussions.
I think part of the article author's reasoning for proposing this feature is that toolchains have implemented something like this feature to try to address ABI issues and that the rest of the ecosystem could benefit from a similar technique.
For areas like application plugins via DLLs it's the OS ABI that matters.
Inter-compiler interop is also in play when the two compilers are the same one at different versions, or even potentially flags.
> Thankfully, we are not particularly concerned about the ability to upgrade this [user-redeclared stdlib] function: users who are declaring Standard Library functions without including the header like this are doing this strictly as experts. They have a strong expectation of what symbol they are getting from their distribution. Transparent aliases are meant to be used for functions which rely on type definitions or structures which may change, prompting the need to provide updated global variables and updated functions without breaking old binaries.
> <snip>
> Therefore, we do not do anything to support or inhibit such declarations. Implementations looking to keep such declarations working from older versions of code should consider leaving those old symbols within their binary artifacts (system tables, shared/static libraries, etc.) to continue supporting such a use case; this proposal is not going to address it or the myriad of other issues around this (such as strong/weak symbols and other attributes/aliasing issues).
To be fair, that section is talking about the stdlib specifically, but nothing jumps out to me as precluding it applying to libraries in general.
[0]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3913.htm#d...
Conceptually intmax_t is a generic type of the form intmax_t<T>. Since C does not have generics, the T is chosen by the compiler during compile time.
But this means that the first time you compile any shared library with an intmax_t parameter or return value in one of its functions, you have permanently baked in the type parameter T to whatever the compiler chose it to be at that moment in time.
You cannot retroactively change intmax_t even if you change the symbols, because intmax_t runs into the same problem any generics system does, you cannot retroactively add instantiations for future types that were not explicitly compiled into the dynamic library.
Even if C gets generics and intmax_t would become obsolete either way, because you don't need intmax_t<T>, you can just have T.
intmax_t is only interesting for choosing the T and even then it is only interesting inside function implementations and never in their signatures.
So my conclusion is that intmax_t was a failed attempt at trying to be "clever" with the idea of introducing generics without introducing generics. This is an idea that is so doomed that anyone trying to rescue it, didn't really understand the problem with intmax_t.
The C committee doesn't want to rescue intmax_t. If they had a time machine most members would prevent it ever being added. But it was and now it can't be removed; it takes decades to get breaking changes into the standard.
intmax_t is a thornier problem than time_t and needs a more comprehensive approach that requires some careful assistance from the C standard itself. There's no completely fixing the mess. The goal is to find an acceptable solution that allows everybody to begin to move past intmax_t given the various technical and practical constraints. The goal is not to find a solution that allows for expanded use of intmax_t, at least not in the standard, though it may be the case it can never completely go away.
In the end, OS/CPU combinations define ABIs, compiler toolchains (no matter what language) can't do much more then follow (if they want to be able to talk to the operating system at least). E.g. if one day operating systems implement stable Rust-friendly ABIs, then C compilers will have to adapt to those conventions instead.
See https://faultlore.com/blah/c-isnt-a-language/ for more detailed analysis.
Also IIRC it was really only UNIX which had this "whatever our C compiler does" mishmash. On most other operating systems it was the other way around, C compilers had to implement whatever calling convention the OS already had defined before there even was a C compiler for that OS (for instance early Windows version used a PASCAL calling conventions, and others (CP/M, DOS, AmigaOS...) some random rules that were most convenient for handwritten assembly code).
PS: and yeah I know that other article (or rather: incoherent rant). It's basically a lot of barking up the wrong tree.
I'd push back on this a bit. The ABI is "put the arguments on the stack this way and jump to this address". The fact that it's easy to do in C doesn't really make a difference, or make that process "C specific" at all, any other language would need to do the same thing.
If you require those arguments to represent rust objects or be reference-counted in some way, it would impose more restrictions on the caller, not fewer.
When Rust chose an unstable ABI it did so for a good reason. I personally think the only place where a stable ABI would be warranted is inside the panic machinery and this is mostly because it is kind of annoying to write perfect no panic Rust just to get rid of the 300KiB overhead but even here I'd take my time, possibly decades, before making the decision to have a stable ABI.
The wrong decision is to choose to support a stable ABI and lock in design mistakes early on.
I'm already hinting at the solution so I'll be taking my leave for now.
Because in hardware, programmers, aside from researchers, are often paid much less and work in worse conditions compared to their software counterparts. At a software company, code is the product itself. But in manufacturing, software is treated as a cost attached to machines worth billions of dollars. While equipment and sensors keep getting updated and more expensive, the people connecting everything are seen as a cost cutting target. So hardware programmers generally have good job security, but their salaries aren't high. In that situation, asking them to learn something new instead of sticking with the old ways usually gets resistance, because they're not being properly compensated for that learning
And on top of that... these things are battle tested, often running machinery that isn't just worth millions of dollars but runs goods worth orders of magnitude more. Stuff breaking because some new shiny thing has been introduced... no one bats too much an eye when Reddit's UI is missing a widget here and there because someone pushed vibecoded garbage to prod again, but a car manufacturing line? A chemical plant that needs to operate 24/7 so that nothing solidifies in pipes, wrecking the entire facility to the point you need to fully dismantle it?
When this kind of consequences are in the air, everyone is much much more conservative, because no one wants to be left holding that bag.
It's not just legacy code. Some of it is literally certified, that is, it has gone through a certification process. That is a slow and expensive thing to redo; nobody wants to do it for a change that doesn't add real user value.
In my opinion, that's the correct thing to do anyhow, even for bigger systems
[0]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3913.htm
Does it follow the lua spec?
How are tables implemented?
How fast is it compared to normal Lua, luajit interpreter, and luajit jit?
C doesn't need saving, it will continue to survive on its own and even flourish in niches for decades to come. So will "Java"Script. Worse is Better, respectfully, or at least Old and Simple is Tough as F, living long and prosper. See, C doesn't need you but we need C, apparently for the foreseeable future.
Rust is the new black and it will supplant C/C++ and almost everything else short of virtual machine languages like Java/C#.
Especially more relevant when going with microservices, microkernels, serverless, static linking (and still have plugins),...
I'm not sure about the others, but COM is an ABI. There's a bunch of stuff surrounding it that is RPC-like but the core specification is just binary layouts and calling conventions. It's arguably more cross-language than the C ABI since it lets you generate type-safe bindings for any language, unlike in the latter where you need to parse header files.
> You could have an RPC protocol be your only interface to the OS, and that would be a valid design, but would have a performance cost
Maybe it would, but I doubt anybody would notice. The whole "everything is a file" concept on unix is basically just this (also X11/Wayland).