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Microsoft Says It's Not Planning To Use AI To Rewrite Windows From C To Rust 41

Microsoft has denied any plans to rewrite Windows 11 using AI and Rust after a LinkedIn post from one of its top-level engineers sparked a wave of online backlash by claiming the company's goal was to "eliminate every line of C and C++ from Microsoft by 2030."

Galen Hunt, a principal software engineer responsible for several large-scale research projects at Microsoft, made the claim in what was originally a hiring post for his team. His original wording described a "North Star" of "1 engineer, 1 month, 1 million lines of code" and outlined a strategy to "combine AI and Algorithms to rewrite Microsoft's largest codebases." The repeated use of "our" in the post led many to interpret it as an official company direction rather than a personal research ambition.

Frank X. Shaw, Microsoft's head of communications, told Windows Latest that the company has no such plans. Hunt subsequently edited his LinkedIn post to clarify that "Windows is NOT being rewritten in Rust with AI" and that his team's work is a research project focused on building technology to enable language-to-language migration. He characterized the reaction as "speculative reading between the lines."
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Microsoft Says It's Not Planning To Use AI To Rewrite Windows From C To Rust

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  • Omg (Score:5, Funny)

    by liqu1d ( 4349325 ) on Wednesday December 24, 2025 @06:07PM (#65880545)
    Copilot wrote it! It's trying to get out!
  • Changed their minds after massive backlash
  • by kellin ( 28417 )

    Are we sure Windows 11 will still be supported by 2030?

  • ...or you get fired. No matter that we told you to write the article in the first place.

    Scrap that new role opening, too.

  • And rejected the offer from Ivan in Moscow, Mei in Beijing, Patel in India, and Mrs. Gibson's third grade class in Casper, Wyoming.

  • It was the schedule (1 million lines per month) and believing it could be done through AI.

    The goal of replacing crappy C and C++ with Rust would be laudable, if executed correctly.

    • by karmawarrior ( 311177 ) on Wednesday December 24, 2025 @07:14PM (#65880657) Journal

      I believe an earlier project (was it Longhorn?) attempted to rewrite the bulk of the OS in .NET. This is surprisingly practical as .NET includes support for "unsafe" blocks in its VM. That said... I wonder if they planned to go as far as the kernel or device drivers, even with unsafe support.

      Anyway, that project ultimately proved to be a bit much, and Microsoft cancelled it and hurriedly put together Vista instead.

      This would be the second time, therefore, that Microsoft has at least considered the possibility of rewriting the OS in a safer language than C or C++. I suppose at least they're trying, but there's little reason, to me at least, to think a Rust rewrite would be more practical than a C#/Managed C++ rewrite, even with the help of LLMs.

      • by allo ( 1728082 )

        Windows 10 and their rolling release strategy also tried to rewrite the OS step by step and they failed. They have a huge problem with legacy code and it is totally unclear how to get out of it. I would not be surprise if they reconsider building a Linux distribution with an proprietary desktop and some other MS-only extras.

      • Longhorn was their dev name for Vista and AFAIK it is just a myth that they tried to rewrite their OS in .NET back in the day, heard that from several insiders that they never had such project.
    • It was totally the goal that was the problem! Who names their goal "North Star"? It sounds like a manager just read a historical romance audiobook and liked how it sounds.

      Nobody navigates by the stars any more, it's an anachronism and references a skill that has been mostly forgotten by society. Worse, neologisms are simply a bad choice for job postings, just who do they think is going to search for a keyword that someone just made up? Unless you're looking for candidates who are fans of that audiobook, t

    • by gweihir ( 88907 )

      if executed correctly.

      Common software engineering wisdom says that is very likely impossible at this project size or would take in the 100s of years. And AI would need to be magic to get around that. It is not.

      What can be done is what Apple did: Take an existing far superior kernel and essentially put a wrapper around it.

      • Common software engineering wisdom says that is very likely impossible at this project size or would take in the 100s of years. And AI would need to be magic to get around that. It is not.

        What can be done is what Apple did: Take an existing far superior kernel and essentially put a wrapper around it.

        I suspect the kernel is not where the problems are, but rather all that cruft that sits on top of the kernel, UI code, libraries, 'foundation classes', etc.

        • by gweihir ( 88907 )

          At then you look at some performance numbers and realize the Win11 kernel is dog slow and consumes much more resources than needed and, on top of that (and this is the worst part for a rewrite), has a far, far too large API with tons of inconsistencies and bugs promoted to documented features. No argument about much more cruft on top of it, but a kernel is on the highest difficulty level known.

          Just for kicks, the Win11 kernel is estimated at 70 Mega-loc. Putting that into the simple COCOMO gives you around

    • The goal of replacing crappy C and C++ with Rust would be laudable, if executed correctly.

      But therein lies the problem. While Rust won't fix a bad programmer, the kind of designs you get in crappy C and C++ code are basically impossible for the borrow checker to verify. This implies a much deeper refactoring which is slow and error prone.

  • So they are not rewriting Windows 11....but they are rewriting their largest codebases. So what are they rewriting (I've heard Outlook has more lines of code than Windows)?

    • Maybe they’re rewriting all the IComparable, IDisposable and IEquatable boilerplate repetition in all the C# classes, along with the corresponding information-free Doxygen comments for those functions. There’s probably a few million lines right there.
  • Everyone knows poop flinging monkeys are better!

  • [original post still available at the time of writing] "My goal is to eliminate every line of C and C++ from Microsoft by 2030" [linkedin.com]

    Liars, except if Windows is not written in C/C++ already. Is it Visual Basic ? COBOL / .Net ?
    • by piojo ( 995934 )

      The journalist Paul Thurrott is the one who lied. The quote is somewhat clear--that it's a personal goal--but the headline is a declaration about what Microsoft will do.

    • The Windows code base is mostly C++, written in varying modernity and dialect dating from 1980s to 2020s. There is also use of C++ variants such as C++/WinRT and C++/CX for various built-in UWP applications and services. There is also some C# in the applications. There’s probably some plain C in specialised parts but I never encountered any. From what I’ve seen the median age of code by LOC is probably 10 years: a lot of new development but also lot of code that is stable and hasn’t change

  • by gwjgwj ( 727408 ) on Thursday December 25, 2025 @05:21AM (#65881183) Homepage
    And rewrite it in JavaScript (for speed)
  • Such a surprise (Score:4, Interesting)

    by gweihir ( 88907 ) on Thursday December 25, 2025 @05:44AM (#65881203)

    Trying this would have been new exalted heights of stupidity even for Microsoft.

  • I hear new code from ai is bad, but this is existing code. The logic would remain the same. Has anyone done a proper analysis?
  • i am on the AI bandwagon (who wants to join the Button Guild?) but it seemed weird to announce that AI is going to rewrite the Windows Operating System top-to-bottom. as an AI user, i can say unequivocally that is impossible with today’s tech. you can’t point AI at something and say “go.” you still need to know your shit. currently, AI is only faster at typing than you are.

    good on microsoft for quickly correcting this misinformation.

  • Hey, Microsoft have already published that they are deprecating .NET in favour of HTML5 in Windows. Who cares if they use AI to do it.

    Its no mistake that everyone has to read between the lines because Microsoft is the least trustworthy IT company in the history of man..... sorry, I just got interrupted by an advertisement asking me to purchase a Microsoft subscription so it can help me finish writing this sentence. Where was I? Oh yes.....kind

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