Microsoft wants to replace its entire C and C++ codebase, perhaps by 2030

https://www.theregister.com/2025/12/24/microsoft_rust_codebase_migration/

36 Comments

  1. Microsoft: We want to eliminate technical debt

    Also Microsoft: We’re going to use AI to mass-translate 40 years of legacy C++ into a language it barely understands

  2. ParentPostLacksWang on

    **Technical manager 1**: “This vibe coding thing is awesome, it’s going to save us so many salaries!”
    **Technical manager 2**: “We keep getting memory leaks and the code quality is questionable and hard to review!”
    **Technical manager 1**: “Is there some way we can get it to write code that doesn’t leak and enforces stuff better so we can lay off some of the QA staff too?”
    **Technical manager 2**: Let me check…
    **Copilot**: “Many hoopy froods slather themselves with blended buttersquash, Rust Rust mmm cover me in leakproof Rust”
    **Technical manager 2**: “I have an idea!”

  3. They need to replace they marketing department… and whoever makes decisions about creative ways to screw customers.

  4. Nothing improves reliability like rewriting millions of lines of tested, bug-fixed, and shipping code.

    Rust doesn’t prevent logic (behavior) bugs, as has been seen in numerous examples of CVEs in Rust code. Those are the kinds of bugs that have been hammered out of production code over the years.

    This is a foolish endeavor.

  5. Dense_Gate_5193 on

    they are just mad the can’t use golang because of their terrible file and DLL system. rust is their only alternative.

  6. Latter-Ingenuity-853 on

    You guys are forgetting AI can write passing tests, doesn’t have to put conditions on the tests

  7. The answer to this, for the rest of us, is don’t buy Microsoft products. Simples.

    Or at least don’t buy Microsoft products that don’t work. Which is the same thing.

  8. So what you are saying is that we are switching to Linux for the next 10 years until things stabilize. Got it.

  9. Cool, how about actually fixing the bugs/terribly inefficient code that are around for 10+ years?

    I mean how the hell is outlook still crashing if you have an internet connection but the server region blocks your location? How is explorer still freezing when moving some file across the symbol for a network location while there is no connection to that? How does “Set time automatically” still not work at all?

  10. 1. We are going to use a tool we don’t understand to translate the code we don’t understand into a language we don’t understand.

    2. Cut the humans out of the loop.

    3. ???

    4. Profit.

  11. I don’t understand the hate here. Windows are falling behind and need to do something. 

    The Mac M chips are a game changer and Microsoft need to transition from x86 to ARM to try catch up.

    This makes it way way easier for developers on the platform.

    They’ve tried doing the x86 and ARM thing separately but that was a dud, developers don’t want to develop for two platforms and a transition needs to take place. The processors are just soo much more efficient.

  12. Unhappy-Community454 on

    This is so stupid i cannot express it enough (whereas I rarely used the word for anyone)!
    It’s utterly incredible how management becomes so unprofessional and full on their own hubris in last few years.
    News flash: You know nothing. Ask no man + yes man engineers and let them discuss for good outcome. Scale up.

  13. I really need to move to Linux, I use Linux server for work and windows for gaming with dual boot. I think I’ll have to soon move to a single boot Linux UI.

  14. orions_shiney_belt on

    Isn’t C++ like one level above assembly code? Like the fastest and most efficient code possible is straight binary assembly, but C++ gives one abstraction layer to make coding by non-genious level humans actually possible? Perhaps we should lean into efficient code so we don’t need continual, exponential growth in processing power…

  15. maybe 2026 is the year I switch my boot order and have the fedora drive boot as primary and leave LTSC Win one as backup for the games that are yet to be ported to linux….

  16. This is so idiotic. Writing all your new code in Rust? Sure, there may be benefits to that. Rewriting all your old code? Just insane.

  17. ExperienceDry5044 on

    If you actually look at the linked LinkedIn post, the second line is literally:

    > Just to clarify… Windows is *NOT* being rewritten in Rust with AI. 

  18. Important_You_7309 on

    I really want to know what they were smoking when they came up with the idea to vibe-code their way to bankruptcy.

  19. Ah, the Galen Hunt who aspired to create the new standard for secure devices. Remember Azure Sphere? No? Exactly.

    “I want to replace all C/C++ with Rust”. Like it’s his choice to make on behalf of the entire Windows org.

  20. Rewriting the most critical code used by millions of people with low quality AI code – what could go wrong? 😂 Expect more bugs in MS software…

  21. Knowing there are millions (if not billions) lines of C and C++ in Windows, from kernel to UI, and knowing how hard is rust to implement, I didn’t see how they’ll achieve this goal. Here’s hoping they don’t just ask CoPilot to do it for them.

  22. IncorrectAddress on

    Really, this is no different to converting from one language to another, it’s all the same principles, they are just going to use AI to speed up the process, and they need the extra eyes to see all the flagged issues in the lowest period of time.

    Realistically, if they want to do this they can, there’s no reason not to try it, they can always revert.

  23. If you follow this article through to the linkedin post it’s quoting you’ll find the post has been edited to clarify that they are not planning on doing this.

  24. You expect any engineer to read, let alone understand, 1 million lines of code in a single month?! That’s 1,000 files each containing 1,000 lines of code.

  25. Replacing every line of C/C++ in 5 years seems… I don’t know about “impossible”, but “unlikely” and “ill-advised” seem more topical. Are they gonna have Copilot do all that for them? What about all the software that depends on APIs that are provided through C/C++ code? This seems like yet another thing to say, but which will never be followed through on.

  26. Why don’t they use their AI, the think they’re betting hard on? Wouldn’t that be accelerated to next year? Lmao