stage0 VS chibicc

Somewhat tangential, but I'm curious how big the bootstrap seed for Nix is. That is, if you wanted to build the entire world, what's a minimum set of binaries you'd need?

Guix has put quite a bit of work into this, AFAIU, and it's getting close to being bootstrappable all the way from stage0 [0]. Curious if some group is also working on similar things for Nix.

[0]:https://github.com/oriansj/stage0

https://www.bootstrappable.org/ has some good info. Reading the source of https://github.com/oriansj/stage0 is also very enlightening. It's set its goal to be understandable by 70% of programmers.

Even if they aren't, people absolutely should be able to bootstrap new platforms from scratch. It's important to have confidence in our tools, in our ability to rebuild from scratch, and to be safe against the "trusting trust" attack among other things.

Lately I've been catching up on the state of the art in bootstrapping. Check out the live-bootstrap project. stage0 starts with a seed "compiler" of a couple hundred bytes that basically turns hex codes into bytes while stripping comments. A series of such text files per architecture work their way up to a full macro assembler, which is then used to write a mostly architecture-independent minimal C compiler, which then builds a larger compiler written in this subset of C. This then bootstraps a Scheme in which a full C compiler (mescc) is written, which then builds TinyCC, which then builds GCC 4, which works its way up to modern GCC for C++... It's a fascinating read:

https://github.com/oriansj/stage0

https://github.com/fosslinux/live-bootstrap/blob/master/part...

Even if no one is "using" this it should still be a primary motivator for keeping C simple.

One countermeasure not mentioned here is bootstrapping a compiler with a program small enough to be manually verified. The stage0 project is under 1KB (small enough that the binary can be, and has been, manually checked against the hand written assembly), and GNU Guix (a system for reproducible, isolated builds) is currently working on moving it's bootstrap speed to stage0. That means that, fairly soon, there will be a large set of software that doesn't have a connection to an original C compiler.

If a --k&r mode was to be reliable, wouldn't it need to get specified first? Otherwise people would start relying on some edge case.

If speed is not a requirement for the --k&r mode, you could just take the tis-interpreter and note that if it runs without UB, it is still much faster than an actual computer was when k&r were active.

Would it even be possible to specify a variant of C that contains no UB (e.g. would define exactly what happens on unaligned access), but can compile practical existing C89 programs? I wonder if it could be written such that it could actually specify the behaviour consistently across the language intersection supported by both of e.g. GCC 2.95 and Chibicc[0].

Or maybe there are so many bugs in GCC 2.95 that it would simply be infeasible? How much time would it take to specify?

[0]: https://github.com/rui314/chibicc

I was on the Eclipse Foundation call a few days ago regarding this topic and they said there was a well-established 3-part test for this in the EU courts. But I don't think I managed to take a screenshot, sorry.

Here is a snippet from the EU Blue Guide linked the from the Eclipse blog post:

"Commercial activity is understood as providing goods in a business related context. Non-profit organisations may be considered as carrying out commercial activities if they operate in such a context. This can only be appreciated on a case by case basis taking into account the regularity of the supplies, the characteristics of the product, the intentions of the supplier, etc. In principle, occasional supplies by charities or hobbyists should not be considered as taking place in a business related context."

I would consider GCC or React to fit this definition, while a hobby project like https://github.com/rui314/chibicc not to fit it.

chibicc

chibicc: https://github.com/rui314/chibicc (A reasonably digestible C implementation)

When you say a fork of LLVM, am I correct in assuming that you specifically mean a fork of Clang? I don't see how the compiler backend would affect support for language extensions, regardless of whether it's an exception to that such as Tcc, Cproc, the MIR C jitter, lacc, 8cc, 9cc, and chibicc. Most of those are not for production, excluding Cproc and Tcc (at least according to Suckless or Oasis).