Rust: The power to reshape Microsoft's development paradigm

Microsoft has included Rust in its first-level language, and the news is all talking about memory security, CVE numbers, and Mark Russinovich's speech. But I care more about the detail that no one likes to tell: engineers in the Windows kernel group now no longer need to reserve a special round in the code review for "pointer arithmetic" and "use after release" when submitting a PR. This is a sign that the paradigm has changed.

Windows and MSVC have evolved together for thirty years. C and C++ are not just languages. They are the skeleton of the platform, the flesh and blood of the tool chain, and the texture of the SDL process. There are hundreds of millions of lines of C++ code within Microsoft, and more than 70% of the new CVEs added every year are still memory security issues-this proportion has hardly changed from 2006 to 2024. The static analysis tool has been running for twenty years, the SAL annotation has written millions of lines, and the/analyze switch has not been turned off, but buffer overflows, double releases, and dangling pointers still remain in the safety bulletin of every release cycle like chronic diseases. Rust is not here to "replace" C++. It is here to forcibly pay off part of the three decades of technical debt with a compiler.

The so-called "first-level language" does not just add a badge to README. The path that Microsoft has paved for Rust internally is as follows: the tool chain is uniformly built, signed, and distributed by the platform team, and each version must pass SDL compliance testing; cargo can directly pull the internal private registry and rely on audits to access the company-level policy engine; the Rust Analyzer integration of VS and VS Code is maintained by a full-time team, and the debugger natively supports std::sync::Arc type of visualization; Even the metadata of the Windows SDK automatically generates a binding for windows crate. In the past, if the team wanted to use Rust, it had to spend half a year building a tool chain, negotiating legal approvals, and aligning compliance; now, when new projects open warehouses, choosing Rust is as simple as choosing C#. This is the value of "paving the road".

Of course, the opposition's views are very neat: "Modern C++ can be combined with Core Guidelines, Clang-Tidy, and AddressSanitizer to achieve the same security." This sounds right at first glance-Google's carbon language, C++26 Profile, and Checked C are all moving in this direction. But this ignores a fundamental difference: C++'s security is "after-the-fact", Rust's security is "pre-constraints." The borrowing checker locks ownership, borrowing, and life cycles at compile time, forcing you to think clearly about the security boundaries before writing the first line of unsafe. This is not a tool difference, but a thinking model difference. A C++ programmer who is accustomed to unique_ptr and shared_ptr has his first reaction when faced with data competition is to "add locks"; while a person who is accustomed to writing Rust has his first reaction to "turn the shared state into message passing." The latter does not change the code style, but the starting point for architectural decisions.

If this matter was placed in a domestic factory, there would have been an OKR that "fully embraces Rust": Q1 completed the rewriting of the core library, Q2 forced Rust for all new projects, Q3 replaced old code module by module, and the year-end assessment was suspended. This is the paradigm difference between the Internet in China and Silicon Valley-we are accustomed to using administrative orders to push for technological change and treat engineering issues as execution issues; Microsoft chooses to build platforms, pave roads, and lower thresholds, so that the team can naturally cut through when "the marginal cost of choosing Rust is lower than that of not choosing." The former is fast but crisp, the latter is slow but steady. No one in the Windows kernel group issued the command that "Rust must be used", but Azure's new control surface components, Hyper-V's new device emulation layer, and even some Office's synchronization engines were quietly used. Because the team that chose Rust, the code review meeting was shortened from two hours to 40 minutes, and the security scan report before going online no longer had a red screen.

Last year I met an engineer on the Windows Storage team, Lao Zhang, who had been writing file system filter drivers for 15 years. His biggest headache in the past was the race condition in the IRP completion routine: a request was completed when cancelled, and if the reference count was miscalculated, it would be a blue screen. The team wrote more than 300 lines of manual lock logic for this purpose, accompanied by dense comments and ASSERT. Last year they rewritten this module with Rust, replacing all manual syncing with Arc<Mutex<>> and channel. The compiler reported thirty-seven errors, each corresponding to boundary conditions that might have been missed before. After rewriting, the number of lines of code has been reduced by 40%, but Lao Zhang said that the best thing is not that he has written less code. When the code is reviewed, no one asks,"Will there be use-after-free here?" Everyone only discusses,"Is this cancellation semantic correct?" This is the use of a checker to shift the cognitive load from "why is there no error" to "whether the business is right?"

But don't take your words to death. The core driving force of Rust's promotion at Microsoft has never been "we love security", but that Azure cannot sell security. When corporate customers purchase cloud services, the "proportion of in-memory security languages" on the security compliance list is becoming a hard indicator. AWS is also pushing Rust, and Google is also pushing Rust. Microsoft doesn't keep up, no matter how perfect SDL is, it's yesterday's story. Therefore, Rust has become a first-level language, which is essentially a technical expression of the commercial moat-using compilers to put security costs forward and compressing the money originally spent on operation and maintenance, legal affairs, and public relations into the development period. Satya Nadella knew this account better than any engineer.

The real test is not in the Windows kernel, nor in the Azure control plane. The question is: When the next new service at the level of 100,000 lines is established, will the architect use Rust as the default option rather than the "experiment of the brave." If the answer is yes, that is paradigm reshaping. Otherwise, this is just C++ changing into a more decent vest and continuing to patch it in those thirty years of co-evolution.

The prerequisite for tools to reshape people is that people are willing to hand over their thinking patterns to tools to reshape them. Microsoft has paved the way, and the rest depends on whether each team is willing to go.