Microsoft activated stricter license enforcement for its popular C/C++ extension for Visual Studio Code earlier this month, a move that now prevents the add-on from working in unofficial VS Code distributions like VSCodium and the AI-focused editor Cursor.
The company achieved this by embedding an environment check within the extension’s proprietary binary components, a move that enforces license terms which, while existing for years, hadn’t previously been technically applied in this manner.
This action, taking effect with the April 3 release of version 1.24.5, has stirred debate among developers about competitive practices, particularly as it coincides with Microsoft enhancing its own GitHub Copilot features, and the overall openness of the VS Code platform.
Proprietary Binaries and Licensing Fine Print
Starting around April 3rd, users of forks attempting to initialize the updated C/C++ extension were greeted with errors. Reports on GitHub issues for VSCodium and Cursor documented the specific message: “The C/C++ extension may be used only with Microsoft Visual Studio, Visual Studio for Mac, Visual Studio Code, Azure DevOps, Team Foundation Server, and successor Microsoft products and services to develop and test your applications.”
The crux of the issue lies in the extension’s composition. While the extension’s TypeScript source code is available under an MIT license, the core functionality relies on several closed-source, pre-compiled binary files (including `cpptools`, `cpptools-srv`, and `cpptools-wordexp`).
These binaries, as detailed in comments within the VSCodium issue thread and confirmed by the extension’s specific runtime license terms, contain the actual environment check and are explicitly restricted from use outside designated Microsoft products, a clause that has existed for years but seemingly wasn’t technically enforced until this April update.
This licensing strategy isn’t entirely new; Microsoft’s Pylance extension for Python has operated under similar constraints preventing use in forks for years, and a Microsoft employee confirmed back in 2018 that the C# extension’s debugger was also limited to official builds. These marketplace and extension limitations were key factors motivating the creation of the community-managed Open VSX marketplace by the Eclipse Foundation, offering a source for extensions compatible with freely-licensed VS Code builds.
Forks and Developers Seek Alternatives
The enforcement prompted immediate workarounds within the affected communities. Developers discovered that downgrading the C/C++ extension to v1.23.6, the last version before the check was implemented, and disabling automatic updates allowed continued use, albeit temporarily.
Addressing the situation on GitHub, Cursor CEO Michael Truell acknowledged the broader scope, stating, “MSFT has a handful of extensions which are closed-source,” specifically listing Remote Access, Pylance, C/C++, and C#.
He confirmed, “The latest releases of the specific extensions no longer work in Cursor or other non-MSFT editors.” Truell outlined Cursor’s response: “Moving forward, Cursor is transitioning away from these extensions. We are investing in open-source alternatives which already exist in the community and will bundle these into the next version to enable a seamless transition.”
The situation for Cursor is further nuanced by allegations from some users that the editor might have used a reverse proxy – a server that can relay network requests and obscure their true origin – to access Microsoft’s official extension marketplace, an action that would contravene marketplace terms of service.
Adding to user friction, separate complaints surfaced on forums regarding Cursor hijacking the standard `code` command-line alias, further fueling debate about the startup’s development practices.
Amid this, developers are actively promoting the open-source `clangd` extension as the primary alternative for C++ language features like code completion, with some finding it superior in performance to the official Microsoft tool.
Debugging, however, may necessitate separate open-source extensions like `webfreak.debug` available on Open VSX. The overall incident has renewed discussions about the sustainability of relying on the VS Code ecosystem if key components remain proprietary and subject to Microsoft’s strategic shifts, pushing some towards alternatives like Zed or traditional editors like Neovim or Emacs which also offer Copilot integration.
AI Competition and Ecosystem Control
Microsoft’s decision to enforce the C/C++ extension’s license arrived just as the company significantly advanced its own AI coding tool, GitHub Copilot, within VS Code.
Coinciding with the extension block in early April 2025, GitHub announced the general availability of Copilot Agent Mode, shifting Copilot towards being an active participant capable of executing commands and navigating codebases.
This built upon features introduced in VS Code 1.97 (February 2025), which itself introduced predictive “Next Edit Suggestions” powered by Copilot and an optional auto-accept feature for AI-generated edits.
Notably, that February update also rolled out a stricter extension security measure requiring explicit publisher trust for UI installations. Given that AI-centric editors like Cursor are direct competitors to the enhanced Copilot, the timing of the C/C++ extension clampdown has led some developers to voice concerns about anti-competitive behavior.
As reported by The Register, at least one developer allegedly filed a complaint with the US Federal Trade Commission, citing Microsoft’s actions as potentially unfair market practices designed to favor its own AI ecosystem.
Last Updated on April 28, 2025 10:16 am CEST
Okay, we hear you, MS as usual, should have known better.
Could you be coherent on alternatives?
What do you think is their next move since it’s triggered old suspicions?