Microsoft says Rust is now a Tier-1 language internally, alongside C++, C# and TypeScript

Victor Ciura, a principal engineer on the Rust tooling team in Microsoft's DevDiv and CoreAI, published a guest post on the Rust Foundation blog today saying Rust now sits with C++, C#, and TypeScript as one of the four Tier-1 languages for internal development at Microsoft. Ciura writes that Tier-1 means a paved path from local development to production, covering "secure toolchain builds, productive developer tooling, quality workflows, deep platform integration, and compliance with the SDL requirements Microsoft software must meet."

The compiler backend behind the claim

The vehicle is a project called rustc_codegen_utc, an alternative code-generation backend for the Rust compiler that sits in the same architectural family as the LLVM, GCC, and Cranelift backends and connects the shared parts of rustc to Microsoft's own MSVC backend, known internally as UTC. Ciura says it lets a Rust build participate in the same MSVC toolchain workflow used for C++: Windows ABI compatibility, binary hardening and code-security features, post-link compliance and Hotpatch servicing, cross-language inlining and Sample Profile Guided Optimization, crash-dump analysis, profiling, and coverage. The point, in his words, is a unified code-generation platform for Rust and C++ on Windows, so that platform features Microsoft ships for C++ apply to Rust automatically instead of needing a parallel implementation.

Two numbers to hold on to. Ciura writes that rustc_codegen_utc has been "production-ready since early 2026" and self-hosted since Rust 1.90, and that "more than 100 Microsoft project repositories build with it today", with more repositories adopting it each week.

What is new here, and what is not

This is not the first Microsoft Rust news. Azure CTO Mark Russinovich set out a strategy for using Rust in native code at last year's RustConf, and Microsoft has invested "millions of dollars" in the Rust project across recent years, per Ciura. What today's post pins down is the organisational commitment: Rust is no longer a Microsoft experiment or a special case. It gets the same paved path an internal C# or TypeScript team gets, including the security and compliance workflows that ship Windows.

The other part is technical. On non-Windows platforms, a hybrid Rust and C++ project that compiles the C++ with Clang can already share the LLVM backend. rustc_codegen_utc gives Windows-native projects that same shared-backend option through MSVC, which is the specific gap that has kept Rust at arm's length from parts of the Windows engineering ecosystem for years.

For a team outside Microsoft, the immediate takeaway is one of direction rather than a download. rustc_codegen_utc is described as part of an internal Rust platform, not a public toolchain release. But if a Rust plan has been held back by worries about Windows tooling depth, the argument that Rust cannot be a full participant on Windows is now much harder to sustain, because Microsoft says its own systems software teams are already running Rust through the MSVC toolchain in production. Read the post for the Interoperability Initiative link on the language-level interop work that is still open.

Source

Guest Post: Rust Is Tier-1 Language at Microsoft by Victor Ciura on the Rust Foundation blog, 10 September 2026. Hacker News discussion.