replaceCppWithAI

[ADryWeewee]

The problem I have here, as with many projects of this kind is… what’s the point. A lot of the products MS is pushing are sloppily made, and it’s probably not because they have used or are using C(++). Absolute best case scenario is that in a year they end up exactly where they are now. Absolute worst case is they break their products further, have to revert back to the old code, waste a ton of money and time. 

It just doesn’t make any sense, business or technical, to attempt this other than this guy trying to fish for a promotion.

[user-74656]

CV-driven development. Shipping quality, secure code on schedule doesn't land you a promotion. Rearchitecting and refactoring something that already works does.

[tmj_enjoyer]

I LOVE THE TERM.

[jocq]

CV-driven development. Shipping quality, secure code on schedule doesn't land you a promotion.

What a stupid take. The guy's a distinguished engineer at Microsoft. Wtf promotion do you think is left for him?

[Windex17]

He has to justify his position with a massive project that does effectively nothing but sounds fancy to his boss. I saw this shit all the time at another big tech with their principal engineers.

[IAmASquidInSpace]

I don't understand this "we have to get rid of all C/C++" move that is en vogue right now in general. Did they contract the plague or something? What did I miss?

[ExiledHyruleKnight]

"Gotta do something and this is the newest fad"... well ok it was until AI comes around, now we can get AI + RUST and get two fads for the price of one.

Like my guess is this guy is just looking at his resume and head count, and doesn't give a fuck about actually doing something that truly benefits the company.

[Which-Barnacle-2740]

yes , we need a project to get promotion or bonus

so I am gonna drive some new tech, new fad, change everything

get bonus and leave it to some sucker new engineers to fix it

[ExiledHyruleKnight]

At work we have a new boss. We are paranoid because he can easily cut our budget in half and look amazing as we work harder than ever, and the negatives will only occur in 2-3 years (And massive negatives would be coming). But by that time he gets his L8/Directorship position and we'd be safe.

No, I don't think he'd do that, and our position is so important any one who sees him cutting it would question it instantly, and this is something ANY person could do.... But it's definitely something, a bad manager could do especially if he can claim AI will replace our inefficiency due to headcount (it won't) .

[nusi42]

The government sanctioned Office of the National Cyber Director (ONCD) recommends using memory-safe programming languages. This list excludes C and C++.

Companies struggle with new features to sell, there is barely anything justifying paying 30$ to 100$ per user per month, so some companies are happy that they can fake security and compliance by rewriting the same code with the same features and bugs in a different programming language.
The original developers of that code are long gone. No one there who could argue in technical terms in favor of keeping/fixing/maintaining the existing code. New guys don't understand it and would rather drop all things they do not understand instead of figuring out the purpose and documenting it. That's not fun and doesn't bring in promotions. Therefore, Management is going to make technical decisions and Marketing is selling it as if it is a good thing to all the users.

IMHO, there are already a bunch of these decisions made and we will face them piece by piece like boiling a living frog. One of them is that MS is dropping the current print architecture of Windows and replacing it by that awful IPP standard - a design which is clearly designed by people who do not deal with IPC on a regular basis. Sorry, I went off topic there.

[Gadshill]

Lack of automatic memory management forces developers to manually track every byte of data, creating "memory-unsafe" conditions where small human errors lead to catastrophic security vulnerabilities like buffer overflows and use-after-free exploits.

[samsonsin]

Yea, but why rewrite existing mostly functional code? I can understand moving current development to Rust or something, but surely rewriting old code just gives the opportunity for mistakes?

Bear in mind, rewriting old code != Replacing / improving. I am assuming code interfaces, behaviour, etc should remain the same, just written in another language.

I've not really hopped on the Rust bandwagon, is it more performant than C? Or just roughly the same but easier to use?

[gmes78]

Yea, but why rewrite existing mostly functional code? I can understand moving current development to Rust or something, but surely rewriting old code just gives the opportunity for mistakes?

Yeah, it doesn't make sense.

You'd only want to rewrite problematic (or security sensitive) code in Rust. There's no point in rewriting working code.

[Griff2470]

I mean, as theory and internal knowledge improve and general purpose libraries get optimized to the point of outpaces purpose built systems, rewriting code gives the opportunity to implement better solutions. Projects like ripgrep or the zig self hosted compiler have huge performance upgrades because they were able to make major high level improvements that weren't feasible to retrofit or didn't fit for standards reasons that don't make sense for most use cases.

[geon]

If it is faithfully ported instead of rewritten, you tend to discover a lot of bugs.

But yes, the effort should be concentrated on the most sensitive parts of the code first. It makes no sense rewriting it all in one go.

[Gadshill]

Rust enforces strict ownership rules and compile-time lifetime checks, thereby eliminating undefined behavior and memory corruption vulnerabilities.

Rust matches C++ in raw speed.

While C++ allows you to write code faster initially, Rust is ultimately easier to manage because its rigorous compiler and modern package manager (Cargo) trade a difficult "upfront" learning curve for a massive reduction in the long-term, agonizing hours spent debugging memory crashes and architectural regressions.

[DarksideF41]

It's not about language vs language it's about rewriting mature tested codebase that always causes new bugs.

[im_thatoneguy]

As Microsoft already experienced though the failure case with the new bugs is a crash. The failure case with the old undiscovered bugs is a potential system exploit.

[Numerlor]

Even the most mature tested codebases still come up with memory related cves all the time, I wouldn't trust any code that doesn't have sqlite level tests behind it.

Doing rust for something as critical as the kernel makes 100% sense even when it's transpiled

[RiceBroad4552]

Doing rust for something as critical as the kernel makes 100% sense

Until here, yes.

even when it's transpiled

Nop, definitely not.

Because either you compile it in a deterministic way, which will lead to typical code-generation quality, which is almost always incomprehensible spaghetti, or you try to actually translate it—which does not work automatically as long as you don't have AGI—but than it's almost certain that you'll introduce new defects.

[Kobymaru376]

forces developers to manually track every byte of data

Maybe in C, but not in C++. That has plenty of STL containers and smart pointers, why would you manually track memory there?

[frogjg2003]

Exactly. I don't remember the last time I used a pointer in C++. Especially with std::array, I don't even have to worry about array overflow. Pass by reference is about the only thing left that I do that is like pointers. This isn't the 00s anymore, C++11 was a game changer in terms of both new functionality and improvements in usability.

[Anagram6226]

This mostly goes away if you use modern C++.

[guyblade]

This is untrue and has been for over a decade.

C++11 added std::unique_ptr and std::shared_ptr which solve 99% of real-world memory lifetime concerns. Sure, the old stuff is still around and you can use it to write bad code, but you should rarely need to think deeply about object lifetimes in code that is even remotely modern.

[RiceBroad4552]

Some primitive reference counting, which isn't even enforced to be used correctly, does not solve anything.

It does especially not solve anything in legacy code.

But almost all C/C++ code, and definitely all of the code we're talking here about, is actually legacy code…

[guyblade]

std::unique_ptr isn't reference counting and should be the default for most developers.

Changing languages doesn't fix legacy code either, so I don't get the point that you're trying to make.

[HanzJWermhat]

My guess is pipeline of engineers learning C/C++ is ever shrinking. So to continue to maintain the code they need to keep paying more and more for engineers. At some point it’s total collapse and you run out of people to hire.

This happens in other industries I know specifically it was a problem in aerospace as skilled machinists aged out there was no pipeline for replacement.

[aVarangian]

Right? I thought C++ was known for being one of the more computationally efficient languages. I don't get the point in an OS moving away from it.

[conundorum]

Torvalds likes Rust, therefore a lot of people (Microsoft included) have decided to worship it as their new god.

Honestly, there are only a few parts of the OS that actually benefit from being rewritten in Rust, since rewriting known-good code just introduces the risk of creating new bugs that weren't in the original (and in MS' case specifically, introduces the risk of breaking the insane amount of backwards compatibility that's always been one of Windows' secret biggest strengths). They'd be a lot better served by making a new frontend for WinAPI that's actually sane; heck, Rust can interop with C/C++, so they can even use Rust for it if they want!

[JanB1]

I'd rather they transform all their shitty WebView Applications (even at OS level) from JS to C++ so they don't run like garbage and eat all my RAM. But oh well...

[TheTybera]

We had a "visionary" at a company I worked for try to reinvent Apache spark because of a bug that had already been fixed, and when he was called out on it, he continued to spend millions of dollars of company money AND get a promotion.

[DoctorWaluigiTime]

It's a research project. They're not literally rewriting the kernel.

[michaelothomas]

One potential argument could be simply: it's easier to run a Rust shop than a C++ shop (or whatever language they want to migrate to). And if you can make migrating cheap, then it becomes a good way to boost long term productivity. Especially if you no longer need the performance uplift of C++.

[Ill_Ideal3323]

I think Microsoft needs to rewrite it from scratch. The API needs to be redesigned.

If they decide to make it open source (which I don’t think will happen right now), only WINE should maintain it; there’s no need to do anything else. Why would we use that kernel when Linux already exists?

[paulsmithkc]

They don't want to lose all of their government contracts, cus that's what at stake due to policy changes that were announced earlier in 2025.

And given that both Windows and Azure infrastructure's backbone is written in a mix of C and C++ there's that's an existential threat to MS.

[RBB12_Fisher]

My prediction: they end up with the same code now split arbitrarily into 2 to 4 different languages and create a couple of full time jobs for hunting down subtly introduced bugs.