The linux distribution I co-maintain uses mold as our bootstrap linker to bootstrap rust itself, and it saved us -hours- on long version-by-version build chains. Mold being in c meant we could build it very early and use it as the default linker distro wide and enjoy build speedups everywhere.
Now sadly we will have to fork and maintain the c version as mold2 forever.
Rust is not actually the right tool for all problems.
Like some other commenters, I do not understand why using a cached binary isn’t sufficient. Why not use the mold3 binary and build that first, and then cache it and never rebuild it again? I’m guessing it has to do with hermiticity and build provenance guarantees in your distro.
Do you have any reading material that you can share that might help me understand better? Docs for the distro, or an issue tracker I can search through?
In short, the entire distro is always built in one-shot at any given commit, and we can only rely on cached binaries from a past release if they or nothing in their supply chains changed. Given rustc depends on almost everything, mold3 would be built far too late to be useful for the most expensive build in the whole tree, which is rust.
Recursive dependencies would break our threat model, so we cannot use any rust tools to bootstrap rust. We bootstrap rust from llvm which we bootstrap from gcc which we bootstrap from tinycc which we bootstrap from M2Planet and so on back to 186 bytes of machine code.
Anyone getting a rust package from stagex must be able to build the entire tree up until that package and get the same hash, with no binary dependencies, thus removing any trust in maintainers.
We use the llvm linker, lld, to link mold at the earliest point we can, then use mold exclusively after that. We are an LLVM native distro so we build llvm right away as the system compiler used to build the whole tree instead of gcc.
LLD would work fine for the whole tree, and did previously, but is much much slower than mold which is why we switched to mold.
Having to build all dependencies of rust including python and openssl and everything else before being able to use mold erases most of the full-tree build speedups as the path to rust is already about 80% of the full tree build time.
We are a distro that mandates independently verified 100% deterministic builds from source for any given release commit of the tree, so we have to build the whole tree several times for every release.
I have been thinking about Rust bootstrapping recently. Couldn't a Rust compiler without borrow checker be put together relatively easily?
Assuming the source code contains no issues (which can be checked later once the Rust compiler is built), one could leave that piece behind, and take the shortest path from .rs to executed code (C transpilation, or even an interpreter).
Our tree is entirely reproducible and hermetic. In fact we are the only distro that does this 100%.
The problem is changing any dependency of rust, even python or perl or musl or openssl or the llvm stack or any dependencies of the llvm stack have the potential of resulting in a different hash for rust.
Any time a dependency is changed all decedents must be rebuilt. Which we must do very frequently. That is where mold saved us a ton of time.
If the need is well justified, maybe there is great chance to ask adding #[no_mangle] and extern C support? Since release is very fresh. If that is causing the problem. Or is some dependency the issue?
Bootstrapping rust with mold2 is going to be the likely play. My complaint is that now we must maintain mold2 forever now as mold3 rust edition is now incompatible with most of our tree which is made up of dependencies of rust.
You could use https://github.com/thepowersgang/mrustc to get relatively modern Rust compiler (1.90 currently apparently, but every now and then that is updated). Then build newer rustc from there to reach the current 1.99.
But I don't get why some people are obsessed with bootstrapping. Yes it is good to be able to do it, but it isn't something you need to do regularly.
Especially since rust had a much better cross compilation story than C or C++ (not as good as go or zig though), so you don't need to bootstrap on a new architecture, just cross compile to it. Furthermore, new architectures for hosting a compiler (as opposed to just a target, like microcontrollers) is a rare event. Just something that happens every few years.
I'm a bit confused why a decision to decrease the maintenance burden of Mold by switching languages makes Rust the wrong tool here? Fearless concurrency sounds like a huge benefit for what they're doing, given the resources they have.
It's simply an ordering problem. When building the entire world from scratch, usually the C and C++ toolchains are built near the very first, and Rust toolchains built somewhat later. Anything written in Rust must come after the Rust toolchain is built. You need a linker as part of your C++ toolchain, so it must be written in a language ready to go at that point. If it is written in C, you are done. If it is written in Rust you have to wait. So a Rust-based linker can no longer be used from that very, very early C bootstrap.
It's not a big deal for normal users, where you have Rust ready to go. Kind of a bummer in this case, but this is a specialized one.
One of the explicit goals for Mold 3.0 is to promote its use as the default linker in Linux distributions, and bootstrapping complexity is certainly worthy of consideration in that realm.
> We will then conduct extensive compatibility testing and work closely with Linux distribution developers to make it practical for them to adopt mold as /usr/bin/ld. Making this happen is one of our highest priorities for mold 3.x.
There are classes of virus that are hard to detect. One is a compiler virus that passes itself from compiler to compiler. You only get rid of the vector by bootstrapping from 0.
I do understand what you are trying to say, but I think that this fails to be kind to Irvick and the other maintainers of the stage0 project who are actually being quite underfunded (someone like OAI should fund them in the name of security!)
So asking them to pay money is well.. not quite the solution.
What can happen as it often happens, is this, Mold creator created the project, Stage0 found it useful, Mold ports itself to rust, Stage0 now founds it not useful, Stage0 can comment on the new update and be slightly disappointed and comment how they would've preferred to not rust in this particular case for them.
Yes this doesn't prevent mold from changing to rust or anything as it was shown but I guess we can allow the ability for Irvick to drop a comment I guess without saying that's your responsibility while they are just being maintainers of the open source and an underfunded/mostly volunteer one of work at that.
Also, @Irvick, stage0 is extremely cool, I hope that a lot more companies sponsor the work that stage0 contributors are doing. I think that it can help the supply-chain issues that the industry is facing at, and is honestly just a really cool idea and I love reading your comments and thank you!
>Rust is not actually the right tool for all problems.
"my problems (that are not mold's) are not solved by mold. How dare mold make those decisions?"
Maybe you should rewrite more of your linux distribution in rust so it's available earlier in the build process and get back to it being the default linker.
Luckily Mr Clanker can do most of the work for you at least (I myself have already had Claude/Codex rewrite a couple of Rust projects in C, worked great)
Was the conversion assisted? I get the sense that Mold's author is an extremely competent guy and it would be quite feasible for someone like him to do it on his own.
Oh what? That was not on my bingo card for 2026. Mold already was incredible when it still was in C++ and I assume it is even better now that it is in rust
LLMs are very good at taking your existing structure and converting it as-is to a new language. But rewriting by hand gives you the opportunity to rethink previous design decisions or optimize the code for the new language. So I was disappointed that this appears to just be a straight port and no additional performance improvements were gained.
"Recent advances in AI-assisted coding have made large-scale rewrites considerably more practical, but they do not eliminate those risks, and we do not take them lightly."
Last time I checked it didn't make any difference or whatsoever when compared to lld so I would not go that far by saying "mold is a reference in the world of linkers" - made a test just few days ago on 10M LoC C++. So, rewriting the codebase in another language just because doesn't seem like an investment worth doing when there's much bigger fish to fry.
The days when AI always means slop are gone. It still often does, but the latest models can be used to get very high quality code in many situations. I haven't checked the code here but I would be surprised if it's bad.
What warrants an off the cuff comment like this?
I can take any piece of software and just say a vague statement like that. All of software... What does it even bring to the conversation? Just vague "they"s again we keep on propping up? Who is unethical? The mold team? The AI? The rust foundation? The ASCII character set? The cloud system it has been compiled on? Oh no obviously the backdoors in there?! Oh let us guess!!
If it was transpiled there would be what GNU calls a "preferred form" of the linker source in which it wasn't written in Rust.
This is true for - as an example - the WUFFS GIF decoder. You can get C which decodes GIFs and was transpiled from WUFFS, but that's awful code and nobody wants to modify that code, whereas the WUFFS source code for the decoder is fine.
When we look at rui314's changes to mold today after 3.0 release, they just modify the mold source code in Rust, as you'd expect if this was in fact now written in Rust.
Zig makes you choose that at build time. You can use safe builds for development to catch bugs, and fast builds for release. You can even use safe builds in of the release, and optimize hot paths with fast builds.
In practice, projects written in Zig very much can choose both.
That’s not entirely true. There’s a third choice. You can go the TigerBeetle route (TigerStyle). Zig is extremely well suited for software where you just avoid dynamic memory allocation all together. It’s extremely fast, very effective and arguably very safe. But not suitable for all applications obviously.
There’s also another caveat that there’s an effort to build in build time static memory safety checks in a way that’s more general than Rusts borrow checker, through a kind of plug in system rather than forced into the language. It’s not part of mainline Zig yet but this seems to be the direction Andrew wants to go.
I'm curious about motivation - bounds checks for corrupted inputs seems like it would be one, but it also seems that fixing corrupted input handling in a C/C++ code base would not be too hard, and probably less of an effort? So why did you choose the rewrite?
And second, did you use any AI tools for the rewrite?
> fixing corrupted input handling in a C/C++ code base would not be too hard
The best programmers on the planet have tried and failed with this task for 50 years now, so I don't think this is true.
The main disadvantage of Rust right now is not supporting some more obscure platforms, but because mold wouldn't support them anyway I don't see that as a problem.
> The main disadvantage of Rust right now is not supporting some more obscure platforms
Last time I checked, I got impressed by the wide platform support, once you go down the tier list (https://doc.rust-lang.org/nightly/rustc/platform-support.htm...). What "obscure platform" specifically are you thinking about, that is currently missing from those lists?
My very naive understanding is that a part of what makes mold fast is concurrency, which I'd expect to be a lot more error-prone in C/C++. Not having to worry about data races might give more confidence with trying out more complex techniques for how to split up work in a way that ends up making things faster
It's possible to write safe code in C or C++ but it's extremely difficult to read existing code and prove it's safe, without using as much effort as it takes to write it in the first place. This includes the code you wrote last month whose surrounding code has changed. And you have to be right every time while the attacker only needs you to be wrong once. The problem is not writing the code, it is continually verifying it.
As someone who worked professionally with both C++ and Rust, I mostly agree with this, but I would say that writing the concurrent code in C++ is also hard.
The only way I found that works reliably is stick to a small well defined set of mostly safe primitives. E.g. at work we use message passing / event bus architecture everywhere, which works great for a robotics / industrial context. But even then, if you somehow mess up and have a variable accessed from event handlers in two different threads, it is tough to spot other than if you get lucky and observe it with a build using TSAN.
With rust that class of mistakes is just entirely eliminated, which makes it easier to to concentrate on the hard things that actually matter (like the domain specific logic).
I suspect fearless concurrency is another motivating factor. Better perf can be achieved by squeezing more parallelism, but without borrow checking it's difficult to do fine-grained parallelism correctly.
Apparently the old mold version had a couple of plain C source files in the source tree (both vendored 3rd party libs but also in the 'regular' source code), so technically C/C++ is correct in this case ...and looks like the Rust version also has some (very minimal) C code left (looks like mostly varargs stuff, I guess Rust doesn't have a concept of varargs?), so it could be called a C/Rust project ;)
The linux distribution I co-maintain uses mold as our bootstrap linker to bootstrap rust itself, and it saved us -hours- on long version-by-version build chains. Mold being in c meant we could build it very early and use it as the default linker distro wide and enjoy build speedups everywhere.
Now sadly we will have to fork and maintain the c version as mold2 forever.
Rust is not actually the right tool for all problems.
Like some other commenters, I do not understand why using a cached binary isn’t sufficient. Why not use the mold3 binary and build that first, and then cache it and never rebuild it again? I’m guessing it has to do with hermiticity and build provenance guarantees in your distro.
Do you have any reading material that you can share that might help me understand better? Docs for the distro, or an issue tracker I can search through?
https://stagex.tools
In short, the entire distro is always built in one-shot at any given commit, and we can only rely on cached binaries from a past release if they or nothing in their supply chains changed. Given rustc depends on almost everything, mold3 would be built far too late to be useful for the most expensive build in the whole tree, which is rust.
Recursive dependencies would break our threat model, so we cannot use any rust tools to bootstrap rust. We bootstrap rust from llvm which we bootstrap from gcc which we bootstrap from tinycc which we bootstrap from M2Planet and so on back to 186 bytes of machine code.
Anyone getting a rust package from stagex must be able to build the entire tree up until that package and get the same hash, with no binary dependencies, thus removing any trust in maintainers.
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Why not use LLD for linking Rust? You already must have the LLVM for Rust to be buildable, so that do not add any dependency.
We use the llvm linker, lld, to link mold at the earliest point we can, then use mold exclusively after that. We are an LLVM native distro so we build llvm right away as the system compiler used to build the whole tree instead of gcc.
LLD would work fine for the whole tree, and did previously, but is much much slower than mold which is why we switched to mold.
Having to build all dependencies of rust including python and openssl and everything else before being able to use mold erases most of the full-tree build speedups as the path to rust is already about 80% of the full tree build time.
We are a distro that mandates independently verified 100% deterministic builds from source for any given release commit of the tree, so we have to build the whole tree several times for every release.
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Agreed -- not my wheelhouse, but couldn't you just build rust earlier in your process using LLD, then build mold, then build everything else?
Would that meant that building rust is slower, but everything else is the same, and you don't have to maintain a fork of another complex project?
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Because mold is faster. Linking is a significant bottleneck when building large projects.
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I have been thinking about Rust bootstrapping recently. Couldn't a Rust compiler without borrow checker be put together relatively easily?
Assuming the source code contains no issues (which can be checked later once the Rust compiler is built), one could leave that piece behind, and take the shortest path from .rs to executed code (C transpilation, or even an interpreter).
This exists: https://github.com/thepowersgang/mrustc.
It seems like you would benefit from having reproducible and hermetic builds with a good caching layer so you don't do the same work again and again.
Then you can just use the latest built version to build mold and the next version of rust.
Our tree is entirely reproducible and hermetic. In fact we are the only distro that does this 100%.
The problem is changing any dependency of rust, even python or perl or musl or openssl or the llvm stack or any dependencies of the llvm stack have the potential of resulting in a different hash for rust.
Any time a dependency is changed all decedents must be rebuilt. Which we must do very frequently. That is where mold saved us a ton of time.
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If the need is well justified, maybe there is great chance to ask adding #[no_mangle] and extern C support? Since release is very fresh. If that is causing the problem. Or is some dependency the issue?
The need here is bootstrapping. If mold is written in Rust you cannot even compile it.
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Could you not either bootstrap rust with lld or bootstrap rust with mold2?
Bootstrapping rust with mold2 is going to be the likely play. My complaint is that now we must maintain mold2 forever now as mold3 rust edition is now incompatible with most of our tree which is made up of dependencies of rust.
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how's bootstrapping rust story nowadays?
You could use https://github.com/thepowersgang/mrustc to get relatively modern Rust compiler (1.90 currently apparently, but every now and then that is updated). Then build newer rustc from there to reach the current 1.99.
But I don't get why some people are obsessed with bootstrapping. Yes it is good to be able to do it, but it isn't something you need to do regularly.
Especially since rust had a much better cross compilation story than C or C++ (not as good as go or zig though), so you don't need to bootstrap on a new architecture, just cross compile to it. Furthermore, new architectures for hosting a compiler (as opposed to just a target, like microcontrollers) is a rare event. Just something that happens every few years.
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I'm a bit confused why a decision to decrease the maintenance burden of Mold by switching languages makes Rust the wrong tool here? Fearless concurrency sounds like a huge benefit for what they're doing, given the resources they have.
It's simply an ordering problem. When building the entire world from scratch, usually the C and C++ toolchains are built near the very first, and Rust toolchains built somewhat later. Anything written in Rust must come after the Rust toolchain is built. You need a linker as part of your C++ toolchain, so it must be written in a language ready to go at that point. If it is written in C, you are done. If it is written in Rust you have to wait. So a Rust-based linker can no longer be used from that very, very early C bootstrap.
It's not a big deal for normal users, where you have Rust ready to go. Kind of a bummer in this case, but this is a specialized one.
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One of the explicit goals for Mold 3.0 is to promote its use as the default linker in Linux distributions, and bootstrapping complexity is certainly worthy of consideration in that realm.
> We will then conduct extensive compatibility testing and work closely with Linux distribution developers to make it practical for them to adopt mold as /usr/bin/ld. Making this happen is one of our highest priorities for mold 3.x.
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Have you considered using Eurydice?
I am not finding any linkers by that name.
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Why do you need to bootstrap a toolchain to bootstrap a distro?
I know this is common but it seems like either an aesthetic decision, or glibc cruft.
There are classes of virus that are hard to detect. One is a compiler virus that passes itself from compiler to compiler. You only get rid of the vector by bootstrapping from 0.
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I do understand what you are trying to say, but I think that this fails to be kind to Irvick and the other maintainers of the stage0 project who are actually being quite underfunded (someone like OAI should fund them in the name of security!)
So asking them to pay money is well.. not quite the solution.
What can happen as it often happens, is this, Mold creator created the project, Stage0 found it useful, Mold ports itself to rust, Stage0 now founds it not useful, Stage0 can comment on the new update and be slightly disappointed and comment how they would've preferred to not rust in this particular case for them.
Yes this doesn't prevent mold from changing to rust or anything as it was shown but I guess we can allow the ability for Irvick to drop a comment I guess without saying that's your responsibility while they are just being maintainers of the open source and an underfunded/mostly volunteer one of work at that.
Also, @Irvick, stage0 is extremely cool, I hope that a lot more companies sponsor the work that stage0 contributors are doing. I think that it can help the supply-chain issues that the industry is facing at, and is honestly just a really cool idea and I love reading your comments and thank you!
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>Rust is not actually the right tool for all problems.
"my problems (that are not mold's) are not solved by mold. How dare mold make those decisions?"
Maybe you should rewrite more of your linux distribution in rust so it's available earlier in the build process and get back to it being the default linker.
They were solved by mold. And then mold decided to un-solve them.
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Luckily Mr Clanker can do most of the work for you at least (I myself have already had Claude/Codex rewrite a couple of Rust projects in C, worked great)
And repeat that work every time you sync with upstream?
I expected this to be a multi-months rewrite, not 3 weeks. I almost forgot we live in the agents era now.
Edit: this seems to have been cooking for a while when the first commit dropped: https://github.com/rui314/mold/commit/f41bfcd5c72ca30cce6498...
Was the conversion assisted? I get the sense that Mold's author is an extremely competent guy and it would be quite feasible for someone like him to do it on his own.
> Was the conversion assisted?
Yes. Comment by mold's author:
https://www.reddit.com/r/rust/comments/1w45j6n/comment/p7ac5...
He decided to use LLM assistance exactly because he's an extremely competent guy.
Assisted, yes. Claude is a coauthor for some of the commits and I think he also said that explicitly. Vibe-coded, he claims not.
So what differentiates mold from wild now ? Is wild using different data structures?
(Wild is another fast linker, that only supports Linux)
Wild's primary purpose is incremental linking - I guess now the primary difference is a race + subtle differences in performance between projects.
wild's primary purpose is incremental linking, which it incidentally does not support at all, while still being faster than mold by a long shot.
Thanks for pointing out Wild.
Oh what? That was not on my bingo card for 2026. Mold already was incredible when it still was in C++ and I assume it is even better now that it is in rust
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new???
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This is NOT a slop linker, Mold is a reference in the world of linkers and this port is official.
LLMs are very good at taking your existing structure and converting it as-is to a new language. But rewriting by hand gives you the opportunity to rethink previous design decisions or optimize the code for the new language. So I was disappointed that this appears to just be a straight port and no additional performance improvements were gained.
https://github.com/rui314/mold/releases/tag/v2.42.1
"Recent advances in AI-assisted coding have made large-scale rewrites considerably more practical, but they do not eliminate those risks, and we do not take them lightly."
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Last time I checked it didn't make any difference or whatsoever when compared to lld so I would not go that far by saying "mold is a reference in the world of linkers" - made a test just few days ago on 10M LoC C++. So, rewriting the codebase in another language just because doesn't seem like an investment worth doing when there's much bigger fish to fry.
They just threw out the code base and replaced it with a vibe coded rust port.
The days when AI always means slop are gone. It still often does, but the latest models can be used to get very high quality code in many situations. I haven't checked the code here but I would be surprised if it's bad.
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What warrants an off the cuff comment like this? I can take any piece of software and just say a vague statement like that. All of software... What does it even bring to the conversation? Just vague "they"s again we keep on propping up? Who is unethical? The mold team? The AI? The rust foundation? The ASCII character set? The cloud system it has been compiled on? Oh no obviously the backdoors in there?! Oh let us guess!!
I didn't think it needed to be said... If you need it spelled out the LLM rust rewrite is very clearly what is being referred to.
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Numbered throwaway account means you know this is against the guidelines.
It was transpiled, not rewritten, rewrite implies by hand
If it was transpiled there would be what GNU calls a "preferred form" of the linker source in which it wasn't written in Rust.
This is true for - as an example - the WUFFS GIF decoder. You can get C which decodes GIFs and was transpiled from WUFFS, but that's awful code and nobody wants to modify that code, whereas the WUFFS source code for the decoder is fine.
When we look at rui314's changes to mold today after 3.0 release, they just modify the mold source code in Rust, as you'd expect if this was in fact now written in Rust.
No it doesn't.
Damn. I thought Zig would be a perfect rewrite language for Mold since it's a better C in many ways
Zig makes you choose either safe or fast, not both. With Rust you can get both (generally).
Part of the safety you get with Rust is runtime bounds checking, which is equivalent to Zig in "safe" mode.
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Zig makes you choose that at build time. You can use safe builds for development to catch bugs, and fast builds for release. You can even use safe builds in of the release, and optimize hot paths with fast builds.
In practice, projects written in Zig very much can choose both.
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That’s not entirely true. There’s a third choice. You can go the TigerBeetle route (TigerStyle). Zig is extremely well suited for software where you just avoid dynamic memory allocation all together. It’s extremely fast, very effective and arguably very safe. But not suitable for all applications obviously.
There’s also another caveat that there’s an effort to build in build time static memory safety checks in a way that’s more general than Rusts borrow checker, through a kind of plug in system rather than forced into the language. It’s not part of mainline Zig yet but this seems to be the direction Andrew wants to go.
https://github.com/ityonemo/clr
When choosing a language, people don’t only look at language features but also at community adoption, the library ecosystem, industry backing etc.
Zig isn’t even in the same league as Rust regarding these things. Zig may still be around and active 10 years from now, Rust is guaranteed to be.
Additionally, Zig just released 0.17, Rust's 1.0 was 11 years ago. The choice may have been mostly for non-technical reasons.
I'm curious about motivation - bounds checks for corrupted inputs seems like it would be one, but it also seems that fixing corrupted input handling in a C/C++ code base would not be too hard, and probably less of an effort? So why did you choose the rewrite?
And second, did you use any AI tools for the rewrite?
> fixing corrupted input handling in a C/C++ code base would not be too hard
The best programmers on the planet have tried and failed with this task for 50 years now, so I don't think this is true.
The main disadvantage of Rust right now is not supporting some more obscure platforms, but because mold wouldn't support them anyway I don't see that as a problem.
> The main disadvantage of Rust right now is not supporting some more obscure platforms
Last time I checked, I got impressed by the wide platform support, once you go down the tier list (https://doc.rust-lang.org/nightly/rustc/platform-support.htm...). What "obscure platform" specifically are you thinking about, that is currently missing from those lists?
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My very naive understanding is that a part of what makes mold fast is concurrency, which I'd expect to be a lot more error-prone in C/C++. Not having to worry about data races might give more confidence with trying out more complex techniques for how to split up work in a way that ends up making things faster
It's possible to write safe code in C or C++ but it's extremely difficult to read existing code and prove it's safe, without using as much effort as it takes to write it in the first place. This includes the code you wrote last month whose surrounding code has changed. And you have to be right every time while the attacker only needs you to be wrong once. The problem is not writing the code, it is continually verifying it.
As someone who worked professionally with both C++ and Rust, I mostly agree with this, but I would say that writing the concurrent code in C++ is also hard.
The only way I found that works reliably is stick to a small well defined set of mostly safe primitives. E.g. at work we use message passing / event bus architecture everywhere, which works great for a robotics / industrial context. But even then, if you somehow mess up and have a variable accessed from event handlers in two different threads, it is tough to spot other than if you get lucky and observe it with a build using TSAN.
With rust that class of mistakes is just entirely eliminated, which makes it easier to to concentrate on the hard things that actually matter (like the domain specific logic).
I suspect fearless concurrency is another motivating factor. Better perf can be achieved by squeezing more parallelism, but without borrow checking it's difficult to do fine-grained parallelism correctly.
> And second, did you use any AI tools for the rewrite?
IMO, given the recent commits: almost certainly.
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> in a C/C++ code base
It's like "in a Zodiac boat / aircraft carrier navy". This customary putting C and C++ into the same bucket is as amusing as it is unproductive.
Apparently the old mold version had a couple of plain C source files in the source tree (both vendored 3rd party libs but also in the 'regular' source code), so technically C/C++ is correct in this case ...and looks like the Rust version also has some (very minimal) C code left (looks like mostly varargs stuff, I guess Rust doesn't have a concept of varargs?), so it could be called a C/Rust project ;)
https://github.com/rui314/mold/tree/main/c
Unfortunately too many folks still do C style programming in C++.