I am working on this![0] But this is actually a herculean task, I've been chipping at it for weeks and even trying to cheat somewhat by translating mrustc from C++ to C89. If anyone has ideas/cheaper ways to run it I would like to know.

In the meantime, months ago I achieved bootstrap of TCC (then GCC 4.6) via the same path as the live-bootstrap project but replacing the Scheme part with a C compiler in Ben Lynn's Haskell dialect.[1] This was a project I wish I had time to do years ago[2] but never had the time or motivation for, and the type of things agents can do well now (they couldn't write good Haskell a year ago).

[0] https://github.com/siraben/mrustc/tree/siraben/cmrustc

[1] https://github.com/siraben/blynn-bootstrap

[2] https://logs.guix.gnu.org/bootstrappable/2021-05-26.log#1438...

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Rochus 2 days ago | parent [-]

> If anyone has ideas/cheaper ways to run it I would like to know

GCC 4.7.4 was the last version of GCC fully written in C, with full C++98/03 support and a decent subset of C++11. As far as I know it is used by the bootstrap project presented in the article.

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siraben 2 days ago | parent [-]

Specifically the expensive part is getting a C89 port of mrustc to compile rustc 1.90.0. mrustc needs C++ right now, bootstrapping via TCC by writing it in C89 would be the shorter chain.

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Rochus 2 days ago | parent [-]

Sounds pretty difficult (if not impossible, see cfront 4.0) to translate C++ code to C89. You have to keep track of all constructors and destructors and their progress along the body yourself, and I assume it must be fit for exceptions as well?

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siraben 2 days ago | parent [-]

Yes, this isn't meant to be a complete port and I only started dipping into mrustc because the previous agents were going off the rails. I have mostly been throwing spare weekly quotas at this but deeper thought will be required to get an actual working Rust compiler in C. Rust is an enormously more complex language, so it might just be at the capability limit.

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Rochus 2 days ago | parent [-]

> Rust is an enormously more complex language

I have no doubt that a Rust compiler can be implemented in C. But it's a different project to write one in C from start than trying to migrate an existing C++14 based project to C. The former is likely "easier". An alternative approach could be to migrate the C++14 code back to C++98 and get rid of the exceptions, which makes it transpilable to C (using the cfront approach). Though the result might not be maintainable C, but still C.

EDIT: if you manage to migrate it back to a sufficiently moderate C++11 subset, or even C++98, you could use GCC 4.7.4 to compile it, which itself is written in C.

	▲	siraben 2 days ago \| parent [-]
		Thanks, will look into this as another avenue!