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GN



GN (Generate Ninja) is a build configuration system developed by Google that generates files for the Ninja build system. The primary purpose of GN is to simplify the process of managing complex builds, particularly for large projects like the Chromium browser. While GN is designed to generate Ninja build files, it is not limited to Ninja and can be adapted to other build systems. GN was created to overcome the limitations of GYP, another build configuration system used by the Chromium project, and to offer a more scalable, faster, and easier-to-use solution.

GN uses its own high-level scripting language to define the build configuration. This language is designed to be both simple and expressive, making it easy for developers to write build configurations that are easy to maintain. Unlike other build systems that may require verbose and complex configuration files, GN emphasizes simplicity and readability. This makes it particularly useful for large, fast-moving projects that need to be built and tested frequently.

One of the key strengths of GN is its speed. GN is optimized for generating build files quickly, even for large projects with thousands of source files. In contrast to other build systems that may take significant time to parse and process build configurations, GN performs these tasks efficiently. This speed is critical for projects like Chromium, where developers need to build and test changes rapidly to ensure that new features and bug fixes are integrated smoothly.

While there is no specific RFC associated with GN itself, its behavior is influenced by several build and dependency management concepts defined in broader RFC standards. For example, RFC 7231 on HTTP semantics plays a role in some of the web-related components that are built with GN, especially when handling networked build tasks. Although GN focuses primarily on generating Ninja files, its design philosophy is grounded in efficiency and performance standards that align with general industry best practices.

One of the design goals of GN is to provide a build system that is easier to understand than existing alternatives like GYP and CMake. GN achieves this by focusing on a smaller set of concepts and abstractions. For example, GN avoids the complexity of dependency graphs, instead focusing on build targets that define specific outputs. These targets are connected through simpler relationships, which makes the system easier to reason about and maintain over time.

GN supports both static and shared libraries, as well as executable targets, which means it can be used for a wide range of projects. Whether the goal is to build a command-line utility or a large-scale project like a web browser, GN is flexible enough to handle the job. Its support for multiple target types makes it versatile and applicable to various software development projects, from small tools to massive enterprise-level applications.

One of the most notable aspects of GN is its integration with Ninja. The Ninja build system is well-known for its speed and efficiency, and GN was designed specifically to generate Ninja build files. This close integration ensures that developers can take full advantage of Ninja’s performance while benefiting from the more user-friendly configuration language provided by GN. By generating Ninja build files, GN allows developers to maintain fast and efficient build processes even as projects grow in size and complexity.

Another benefit of GN is its support for multiple platforms. While GN is primarily used for Chromium development on Linux, macOS, and Windows, it is flexible enough to support other platforms as well. This cross-platform capability is crucial for projects that need to be deployed across different operating systems and environments. GN ensures that developers can write build configurations that work consistently across these platforms, without needing to maintain separate configurations for each target environment.

One of the key features of GN is its ability to define build arguments, which are variables that control how the build is configured. These arguments allow developers to customize the build process easily, adjusting settings such as optimization levels, debug information, or target architectures. By using build arguments, developers can tailor the build process to their specific needs without making significant changes to the underlying configuration files.

In terms of dependency management, GN handles dependencies between build targets automatically. When a target depends on another target, GN ensures that the dependent target is built first before the consuming target is built. This automatic management of dependencies reduces the likelihood of build errors due to missing or out-of-date dependencies, making the build process more reliable and predictable.

GN also provides extensive support for source file discovery. Rather than manually listing all the source files in a project, developers can use simple patterns to tell GN where to find the source files. This feature makes it easier to manage large projects, where keeping track of every source file would be time-consuming and error-prone. By automating this process, GN reduces the potential for human error and simplifies project maintenance.

The simplicity of GN’s language and build model makes it easy to extend. Developers can write custom functions and templates to encapsulate common build logic, which can then be reused across multiple targets. This extensibility allows developers to define custom build workflows that are tailored to their project’s specific needs while maintaining the overall simplicity and clarity of the build configuration.

GN's documentation and community support have played a significant role in its adoption. Developers working on large, complex projects like Chromium have contributed to improving GN and ensuring that it meets the needs of modern software development. As a result, GN is continuously evolving, with new features and improvements being added to keep it relevant in today’s fast-paced development environments.

Another important feature of GN is its integration with testing frameworks. GN can be configured to run tests automatically as part of the build process, ensuring that code changes are validated as soon as they are made. This continuous integration of testing into the build process helps catch bugs early, improving the overall stability and quality of the software being developed.

As software projects continue to grow in complexity, the need for efficient build systems like GN will only increase. By focusing on simplicity, speed, and scalability, GN addresses many of the challenges faced by developers working on large projects. Its ability to generate efficient build files for Ninja ensures that even the largest projects can be built and tested quickly, without sacrificing performance or reliability.

The separation of build configuration from the actual build execution is another key design principle of GN. By focusing on configuration and leaving the execution to Ninja, GN allows developers to maintain a clear distinction between how a project is configured and how it is built. This separation makes the system more modular and easier to reason about, reducing the cognitive overhead required to manage large projects.

GN is an open-source project, and its source code is freely available on GitHub. Developers can contribute to the project, report bugs, or request new features through the GitHub repository. This open development model has contributed to the continuous improvement of GN, ensuring that it remains a relevant and powerful tool for modern software development.

Conclusion



GN is a powerful and efficient build configuration system designed to generate Ninja build files. It simplifies the process of managing complex builds, making it particularly useful for large projects like Chromium. Although there is no specific RFC that directly governs GN, its design is influenced by industry best practices for build systems and dependency management. GN's integration with Ninja, cross-platform support, and flexibility make it an essential tool for modern software development. Its focus on speed, simplicity, and extensibility ensures that developers can manage large projects efficiently and maintain fast, reliable build processes. As projects continue to grow in size and complexity, GN will remain a key component of scalable, high-performance development workflows.

GitHub: https://gn.googlesource.com/gn/