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What to do with C++ modules?

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Re: What to do with C++ modules?

#121

Post by ozars »

lenkite wrote: post #116
ozars wrote: post #71

Earlier quoted context omitted.

Rust has Arc and Weak that can be used for solving it in a similar way C++ does. The primary difference is forcing usage of Mutex to avoid a large class of data race issues IMHO, and that's what makes it harder to get right. Async in Rust is also more mature than C++ coroutines. So there's also that. https://play.rust-lang.org/?version=nightly&mode=debug&editi...

Rust doesn't have computed goto (gcc/clang extension heavily used in interpreters like CPython and LuaJIT for direct threading). You’re forced into function-call or jump-table dispatch, which tends to be slower.

huh. I had no idea. Fair.

Re: What to do with C++ modules?

#122

Post by FooBarWidget »

modeless wrote: post #18

The sensible way to speed up compilation 5x was implemented almost 10 years ago, worked amazingly well, and was completely ignored. I don't expect progress from the standards committees. Here it is if you're interested: https://github.com/yrnkrn/zapcc The next major advance to be completely ignored by standards committees will be the 100% memory safe C/C++ compiler, which is also implemented and works amazingly well:…

zapcc looks really promising! Unfortunately it seems to be unmaintained: haven't seen any commits in 5 years.

Re: What to do with C++ modules?

#123

Post by OvbiousError »

throwawaty76543 wrote: post #37
modeless wrote: post #18

The sensible way to speed up compilation 5x was implemented almost 10 years ago, worked amazingly well, and was completely ignored. I don't expect progress from the standards committees. Here it is if you're interested: https://github.com/yrnkrn/zapcc The next major advance to be completely ignored by standards committees will be the 100% memory safe C/C++ compiler, which is also implemented and works amazingly well:…

> The sensible way to speed up compilation 5x was implemented almost 10 years ago, worked amazingly well, and was completely ignored. I don't expect progress from the standards committees. Here it is if you're interested: https://github.com/yrnkrn/zapcc Of course it was completely ignored. Did you expect the standards committee to enforce caching in compilers? That's just not its job. > The next major advance to be c…

FWIW tooling being as important as it is, it always seems like a mistake to me that the standard committee doesn't standardize compilers.

Re: What to do with C++ modules?

#124

Post by karmakurtisaani »

mtoner23 wrote: post #87
WalterBright wrote: post #47

Earlier quoted context omitted.

D modules are very fast. Many of our customers rely on D being way faster than C++ to compile.

[flagged]

What kind of argument is that? It's like an ad hominem, but in some weirdly complementing way.

Re: What to do with C++ modules?

#125

Post by agent327 »

WalterBright wrote: post #5

Back in the 90s, I implemented precompiled headers for my C++ compiler (Symantec C++). They were very much like modules. There were two modes of operation: 1. all the .h files were compiled, and emitted as a binary that could be rolled in all at once 2. each .h file created its own precompiled header. Sounds like modules, right? Anyhow, I learned a lot, mostly that without semantic improvements to C++, while it made…

C++ modules aren't influenced by macros on import, nor do they export any macros, so I'm curious what the problem is?

Re: What to do with C++ modules?

#126

Post by agent327 »

motorest wrote: post #97
modeless wrote: post #18

The sensible way to speed up compilation 5x was implemented almost 10 years ago, worked amazingly well, and was completely ignored. I don't expect progress from the standards committees. Here it is if you're interested: https://github.com/yrnkrn/zapcc The next major advance to be completely ignored by standards committees will be the 100% memory safe C/C++ compiler, which is also implemented and works amazingly well:…

> The sensible way to speed up compilation 5x was implemented almost 10 years ago, worked amazingly well, and was completely ignored. I don't expect progress from the standards committees. Here it is if you're interested: https://github.com/yrnkrn/zapcc Tools like ccache have been around for over two decades, and all you need to do to onboard them is to install the executable and set an environment flag. What value d…

> What value do you think something like zapcc brings that tools like ccache haven't been providing already?

It avoid instantiating the same templates over and over in every translation unit, instead caching the first instantiation of each. ccache doesn't do this: it only caches complete object files, but does not avoid repeated instantiation costs in each object file.

Re: What to do with C++ modules?

#127

Post by flohofwoe »

holowoodman wrote: post #2

Why bother? The world seems to have moved on to Rust, C++ is only for legacy maintenance stuff anymore.

Rust isn't exactly famous for its fast build times. It's probably the only language that actually builds slower than C++, which is an impressive achievement on its own ;)

And give Rust one or two more decades and it will be the same messy kitchen sink language as C++. If anything, Rust is speedrunning C++ history (with the notable exception of fixing static memory safety of course).

Re: What to do with C++ modules?

#128

Post by flohofwoe »

feelamee wrote: post #64
InCom-0 wrote: post #29

Earlier quoted context omitted.

This is true ... except that Rust doesn't actually do any better in that regard. Rust solves 1 category of problems in a way that is not without its costs and other consequences. That is it. There are projects where this is very important, there are other projects where its virtually useless and the consequences just get in the way. It is not magic. It doesn't make anything actually 'safe'.

sure, but don't forget that rust gives us also a nice tooling, functional syntax sugar like pattern matching, enums, monads; and other more or less useful things like explicit lifetimes

Tbh, only a mother can love Rust's syntax. It has even more "punctuation" than C++.

Re: What to do with C++ modules?

#129

Post by flohofwoe »

ra1231963 wrote: post #86
okanat wrote: post #7

Earlier quoted context omitted.

Newer stuff yes and it is great. However from basic rendering to browsers and the most complex applications (CAD, office software, finance, complex solvers like airline planning) are still in C++. Nobody will accept rewriting 35+ years of history. C++ code bases are really a lot longer-lived than any other software builds upon them. Hence we cannot drop it. Starting with C++17, I think committee has been doing the la…

I believe with a little (okay a lot of) motivation and a solid LLM, these can all be rewritten faster than everyone says. Especially if it’s gradual. Mozilla and Dropbox did it. LLMs are good at translating between languages, and writing unit tests to make sure things still work the same.

How much Rust is actually in Firefox these days? The last numbers I see from 3 years ago is 10%.

Re: What to do with C++ modules?

#130

Post by flohofwoe »

fooker wrote: post #13
holowoodman wrote: post #2

Why bother? The world seems to have moved on to Rust, C++ is only for legacy maintenance stuff anymore.

C++ has a habit of incorporating all the best ideas from it's 'succcessor' languages once these ideas are mature.

...and unfortunately butchering those good features beyond recognition, see C++20 vs C99 designated init. Typical "design by committee" outcome though :/
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