When migrating a legacy C++ codebase to a new system or platform, it is common to encounter challenges with the build system. The legacy code may have been using a specific build system, such as Make or Autotools, which may not be well-supported or compatible with the new environment.

In order to ensure a successful migration, it is crucial to adapt the build system to the new platform. This typically involves choosing a modern build system that is well-supported and integrating it with the codebase. In this blog post, we will explore some popular build systems and discuss how to support them after migrating from legacy C++ code.

Table of Contents

1. Introduction
2. Choosing a New Build System
3. Integrating the Build System
4. Supporting Different Build Systems
5. Conclusion

Introduction

When migrating a legacy codebase, it is important to consider the build system early in the process. The build system is responsible for compiling the code, linking dependencies, and generating the final executable or library. Selecting a suitable build system for the new platform is critical to ensure smooth development and deployment.

Choosing a New Build System

There are several modern build systems available that provide more flexibility and better support compared to the older legacy build systems. Some popular options for C++ projects include:

1. CMake: CMake is a cross-platform build system generator that allows developers to describe the build process using a simple scripting language. It supports a wide range of platforms and integrates well with popular IDEs.

2. Bazel: Bazel is an open-source build system developed by Google. It offers fast and incremental builds, along with support for distributed builds and caching. Bazel also provides extensive support for many programming languages and platforms.

3. Meson: Meson is a fast and user-friendly build system that focuses on simplicity and ease of use. It supports multiple programming languages, including C++, and is designed to be highly efficient.

When choosing a new build system, it is important to consider factors such as platform compatibility, community support, and ease of use. Evaluating the documentation and community resources can help in making an informed decision.

Integrating the Build System

Once a new build system has been selected, the next step is to integrate it with the legacy C++ codebase. This involves creating build scripts or configuration files that describe how the project should be built.

The process may vary depending on the chosen build system. However, the general steps involved include:

1. Configuring the build system to recognize the project structure, source files, and dependencies.

2. Specifying the compiler flags, optimization settings, and other build options.

3. Defining targets or build rules that describe how the code should be compiled, linked, and packaged.

4. Configuring any additional build steps or pre/post-build actions required for the project.

5. Testing the build configuration to ensure that the project can be successfully built.

Supporting Different Build Systems

In some cases, it may be necessary to support multiple build systems to accommodate different platforms or developer preferences. This can be achieved by providing build scripts or configuration files for each supported build system.

For example, if CMake is chosen as the primary build system, additional build scripts can be provided for Make or Autotools users. These scripts can translate the CMake configuration into commands compatible with the chosen legacy build system.

It is important to keep these additional build scripts or configurations up-to-date as the project evolves. Any changes made to the primary build system should be reflected in the alternate build configurations as well.

Conclusion

Supporting different build systems after migrating from legacy C++ code is crucial to ensure the smooth transition of the codebase to new platforms. By choosing a modern build system, integrating it with the codebase, and providing support for multiple build systems when necessary, developers can overcome the challenges associated with migrating legacy C++ code and ensure a successful transition.

Migrating from a legacy build system to a modern one can offer numerous benefits, including improved build times, better dependency management, and increased productivity. However, it requires careful planning and attention to detail. By following the steps outlined in this post, developers can navigate the process smoothly and enjoy the advantages of a modern build system.

#buildsystems #legacycode