Microsoft Distinguished Engineer Galen Hunt announced an aggressive initiative to eliminate every line of C and C++ code from Microsoft’s codebases by 2030, replacing it with memory-safe Rust through AI-assisted mass refactoring. The goal, outlined in a December 2025 LinkedIn post, targets an unprecedented pace of “1 engineer, 1 month, 1 million lines of code” using proprietary algorithmic infrastructure and AI agents to automate rewrites of Windows, Azure, and other critical systems.
Hunt’s team within the Future of Scalable Software Engineering group in Microsoft CoreAI has built what he describes as “powerful code processing infrastructure” that creates scalable graphs of source code and applies AI-guided transformations at massive scale. The system reportedly operates on problems like code understanding today, with translation capabilities being expanded to handle Microsoft’s largest legacy codebases dating back decades.
The Rust Migration Timeline and Scope
Microsoft’s commitment to Rust accelerated dramatically in 2023 when Azure CTO Mark Russinovich effectively banned new C/C++ projects, requiring developers to use Rust instead for all new systems-level code. By 2025, Russinovich declared Microsoft “all-in” on Rust, with the company having already converted approximately 36,000 lines of Windows kernel code from C/C++ to Rust according to industry reports. The current initiative represents a quantum leap from gradual adoption to wholesale replacement across the entire Microsoft ecosystem.
| Timeline | Milestone | Scope |
|---|---|---|
| 2023 | Russinovich bans new C/C++ projects | Azure and new development |
| 2024-2025 | 36,000+ lines converted in Windows kernel | Critical OS components |
| 2025 | AI-assisted rewrite infrastructure deployed | Code understanding and early translation |
| 2030 (Target) | Complete C/C++ elimination | All Microsoft codebases |
The Technical Infrastructure Behind the Plan
Hunt’s approach combines algorithmic analysis with large language models to create what amounts to an automated translation pipeline. The system first builds comprehensive graphs representing the structure and dependencies of existing codebases, then deploys AI agents to perform transformations while preserving functionality. This differs from manual rewrites where developers must understand and recreate each component’s behavior from scratch.
The Principal Software Engineer role Hunt posted requires at least three years of production Rust experience, with compiler, database, or operating system implementation backgrounds highly desired. The position focuses specifically on evolving the infrastructure to handle Microsoft’s largest systems—Windows, Office, and Azure cloud services—suggesting the initial deployment targets smaller, more manageable codebases before scaling to mission-critical software.
Memory Safety: The Driving Force
Microsoft’s pivot to Rust stems from persistent security challenges inherent to C and C++. According to industry research cited by multiple sources, roughly 70% of security vulnerabilities in systems software trace back to memory safety issues—buffer overflows, use-after-free conditions, and dangling pointers that Rust’s ownership system prevents at compile time. Microsoft itself has acknowledged that memory bugs constitute the majority of security patches issued for Windows and Azure over the past decade.
Rust’s compiler enforces strict rules around memory ownership, borrowing, and lifetimes, making it essentially impossible to introduce common memory corruption vulnerabilities without explicitly using “unsafe” code blocks. This compile-time guarantee means bugs that would manifest as exploitable security holes in C/C++ simply fail to compile in Rust, shifting error detection from runtime debugging and security audits to the development phase.
Industry Skepticism and Technical Challenges
The “1 engineer, 1 month, 1 million lines of code” target has drawn significant criticism from systems programming communities. Experienced C++ developers argue that battle-tested legacy code represents decades of bug fixes, edge case handling, and performance optimizations that automated translation cannot reliably preserve. ACM Queue’s recent article on memory safety warns that large-scale rewrites are “expensive and frequently misguided,” often driven by aesthetic criticism rather than careful analysis of costs versus benefits.
Mozilla’s experience with Rust rewrites provides cautionary context. Despite Mozilla funding Rust’s early development specifically for the Servo browser engine, the first Rust code actually shipped in Firefox was a small MP4 parser—a targeted rewrite of a known vulnerability surface rather than wholesale replacement. The project took months of focused engineering effort for a component measured in thousands, not millions, of lines, suggesting Microsoft’s timeline may prove wildly optimistic.
The Rewrite Debate: Critics vs. Proponents
Skeptics point to fundamental challenges with automated code translation. Rust enforces stricter memory safety invariants than C/C++, meaning valid C++ patterns may have no direct Rust equivalent without restructuring program architecture. Shared mutable state, cyclic data structures, and certain lock-free concurrency patterns work naturally in C++ but require substantial redesign in Rust. AI tools attempting these translations at scale risk introducing subtle bugs while claiming memory safety.
Developer forums have documented cases where rushed Rust rewrites underperformed legacy C implementations. A widely discussed example involved Ubuntu’s experimental Rust-based GNU utilities replacement showing 17x slower performance in specific benchmarks—though supporters countered that such results reflect immature implementations rather than fundamental language limitations. The broader concern remains that eliminating decades of optimization work in pursuit of theoretical safety guarantees may create new classes of problems.
Alternative Approaches: Safe C++ Extensions
The C++ community has proposed competing solutions to avoid wholesale language migration. The “Safe C++ Extensions” proposal submitted to the C++ standards committee in 2024 aimed to bring Rust-style borrow checking and memory safety enforcement directly into C++. However, the C++ Safety and Security Working Group voted in mid-2025 to prioritize “Profiles”—a different approach allowing opt-in safety—over mandatory safety guarantees, effectively rejecting the Rust-inspired model.
Critics of the C++ committee’s decision argue that opt-in safety fails to solve the fundamental problem since legacy code and developer habits remain unchanged. Rust proponents contend that memory safety must be the default, with “unsafe” code requiring explicit opt-out rather than safety being an optional extra that developers must remember to enable. This philosophical divide between C++’s backward compatibility priorities and Rust’s safety-first design continues to fuel debate.
What Success Looks Like (and Costs)
If Microsoft achieves its 2030 goal, the company will have executed arguably the largest programming language migration in computing history. Success would demonstrate that AI-assisted code translation can handle industrial-scale complexity while maintaining functionality, performance, and reliability. The payoff would be dramatic reduction in security vulnerabilities, lower maintenance costs for memory-related bugs, and a modernized codebase positioned for long-term evolution.
However, the costs extend beyond engineering hours. The initiative requires training thousands of developers in Rust, accepting short-term productivity losses as teams adapt, and managing risks if translated code introduces regressions. Microsoft’s hiring push for Rust expertise—competing with demand from Amazon, Google, and other cloud providers pursuing similar strategies—suggests the company recognizes that automation alone cannot solve the problem without significant human oversight and validation.
Industry Implications Beyond Microsoft
Microsoft’s move amplifies an industry-wide shift toward memory-safe languages. Google recently pledged $1 million to the Rust Foundation to improve C++ interoperability, while the Linux kernel accepted Rust modules despite significant developer pushback. The U.S. National Security Agency and White House have both issued guidance urging migration away from memory-unsafe languages for critical infrastructure, creating regulatory pressure beyond technical considerations.
For the broader software industry, Microsoft’s timeline sets an aggressive benchmark. If the project succeeds ahead of schedule, expect accelerated adoption across the ecosystem as competitors race to demonstrate equivalent security improvements. If Microsoft misses targets or encounters significant technical obstacles, it may validate skeptics’ arguments that incremental modernization and improved C++ tooling represent more pragmatic paths forward than wholesale language replacement.
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