‘1 engineer, 1 month, 1 million lines of code’: Microsoft wants to replace C and C++ code with Rust by 2030 – but a senior engineer insists the company has no plans on using AI to rewrite Windows source code

Microsoft plans to replace C and C++ with Rust within the next five years as part of a major engineering modernization project – but a senior company figure insists AI won’t be doing the heavy lifting after a social media backlash.

In a post on LinkedIn advertising a job opening last week, Galen Hunt, Distinguished Engineer at Microsoft, said the tech giant plans to “eliminate every line of C and C++ from Microsoft by 2030”.

The scale of the project here is significant, with Hunt suggesting that developers will be working toward refactoring upwards of one million lines of code on a monthly basis.

“Our North Star is ‘1 engineer, 1 month, 1 million lines of code’,” Hunt wrote. “To accomplish this previously unimaginable task, we’ve built a powerful code processing infrastructure. Our algorithmic infrastructure creates a scalable graph over source code at scale.”

“Our AI processing infrastructure then enables us to apply AI agents, guided by algorithms, to make code modifications at scale,” he added. “The core of this infrastructure is already operating at scale on problems such as code understanding.”

The move from Microsoft marks the latest in its shift to the Rust programming language in recent years. In 2022, David Weston, corporate VP for OS security and enterprise at Microsoft, revealed the company was investing around $10 million in Rust to make it the company's "1st class language" for engineering systems.

As ITPro reported back in 2023, the company made a significant leap on this front with the introduction of Rust-based kernel features on Windows as part of the Windows 11 Insider Preview Build 25905.

Progress has continued at pace in the intervening years. During a keynote presentation at RustCon 2025 in September, Azure CTO Mark Russinovich detailed the company’s efforts to embrace Rust, per reports from The New Stack.

Microsoft's Rust project courts controversy

Initially, Hunt hinted at the use of AI in helping Microsoft deliver on the goal of rewriting some of the company’s largest codebases.

The suggestion tracks with how the tech giant is using the technology in software development over the last two years. In May this year, CEO Satya Nadella revealed up to 30% of the company’s code is now written by AI.

However, Hunt’s comments appear to have courted controversy, prompting an edit on the original post to clarify that “Windows is *NOT* being rewritten in Rust with AI”.

Hunt insisted this is a research project aimed at “building tech to make migration from language to language possible”.

“The intent of my post was to find like-minded engineers to join us on the next stage of this multi-year endeavor—not to set a new strategy for Windows 11+ or to imply that Rust is an endpoint,” he wrote.

Rust is in vogue

Microsoft isn’t the only company making the shift to Rust. Last year, Lars Bergstrom, director of engineering at Google’s Android team, said developer teams embracing the programming language have unlocked marked productivity and efficiency benefits.

A 2024 project from DARPA also saw the US government agency announce plans on this front, this time actually using AI tools to translate C code to Rust.

A key factor behind the shift to Rust lies in security. Popular languages such as C and C++ have suffered from recurring security-related issues, making them vulnerable to bugs due to how they use memory.

These ‘memory-safety vulnerabilities’ have become a frequent pain point for enterprise security teams and developers alike, and have caught the attention of security agencies on both sides of the Atlantic.

In 2022, the US National Security Agency (NSA) urged organisations to shift to memory-safe programming languages, such as Rust, Python, or Java. More recent guidance from the NSA and CISA, meanwhile, once again urged devs to make the shift.

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