Why Is Microsoft’s Azure CTO Calling for the End of C/C++? The Rise of Rust

Microsoft Azure CTO Mark Russinovich said yesterday that C and C++ are unsafe and should no longer be used for new projects, recommending Rust for scenarios that require a non‑GC language.

This was a personal opinion expressed on Twitter, not an official Microsoft policy.

His comment is noteworthy because many core Microsoft products such as Windows, Office, and SQL Server are written in C/C++, and the open‑source Linux ecosystem—widely deployed on Azure—also relies heavily on these languages.

Rust is already making inroads into the Linux kernel, with parts expected to appear in the upcoming 6.1 release, as reported by Linus Torvalds.

Microsoft has supported Rust for years. In 2019 the Microsoft Security Response Center (MSRC) called Rust the best available alternative to C/C++ for safety, noting that about 70% of CVEs assigned by MSRC are memory‑safety issues that could be eliminated if the software were written in Rust.

Memory‑safety techniques ensure that data read from memory is complete and valid, but they can fail when languages allow manual memory management, buffer overruns, use‑after‑free, or data races in multithreaded code.

Higher‑level languages such as JavaScript, Java, Python, and C# are generally safer because they include garbage collection, though their runtime overhead makes them unsuitable for low‑level system programming.

Rust is designed for system programming and enforces ownership rules at compile time, providing strong memory‑safety guarantees. Developers can still use the unsafe keyword to perform low‑level operations when necessary, but such code is isolated in explicit blocks.

Despite strong technical arguments, Rust still trails C and C++ in popularity rankings (C++ at #7, C at #10, Rust at #19), due to factors such as a shortage of Rust developers, immature toolchains, a steep learning curve, and interoperability challenges with existing codebases.

Bjarne Stroustrup, creator of C++, responded that while new languages are exciting, they require many years and substantial effort to match the maturity of established languages, and that safety is already a focus of modern C++ standards.

He also warned that any language claiming safety, including Rust, still contains unsafe code paths.

Stroustrup added that directly replacing C++ code with Rust or making it safer is a daunting, incremental task, and that unsafe C++ code will likely persist for a long time.

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