Скачать или смотреть Resolving Bazel's Output Directory Issue: Aligning C+ + Header and WinMD Files

Discover how to ensure your Bazel-generated C+ + header file and WinMD file are located in the same directory. Follow our step-by-step guide to effectively implement this solution.
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Resolving Bazel's Output Directory Issue: Aligning C+ + Header and WinMD Files

When working with Bazel, it is common to run into various challenges, especially when generating C+ + header files and Windows Metadata (WinMD) files from Interface Definition Language (IDL) files using the MIDL tool. A typical issue that developers encounter is having the generated header file (MyType.h) and the WinMD file (MyType.winmd) locate in different output directories. If you're facing this problem, you're not alone! In this guide, we'll explore the root of this issue and provide a clear and achievable solution.

The Problem

When generating files from an IDL file by using Bazel, you may notice that:

The MyType.winmd file appears in the output folder generated by Bazel.

The MyType.h header file is placed within the same directory as the source IDL file (MyType.idl).

If your goal is to have both files (MyType.h and MyType.winmd) in the same directory, it requires some adjustments in your Bazel build setup. Let's dive into the steps needed to resolve this.

Understanding the Solution

The solution to align the output directories of your generated files involves modifying the Bazel build configuration slightly. Below are two key strategies to implement this fix:

Step 1: Update the MIDL Command Script

First, we need to modify the midl.bat batch file to include an output directory argument. This ensures the generated files are directed to the correct location. You can do this by adding the ctx.configuration.genfiles_dir.path as the /out option in the midl.bat:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Declare Output Files in the Bazel Rule

In your Bazel build rule, you will need to utilize ctx.actions.declare_file to not only declare the WinMD file but also include the header file. Here’s how you can achieve that:

[[See Video to Reveal this Text or Code Snippet]]

Final Steps

After making these modifications, all you need to do is run the Bazel command:

[[See Video to Reveal this Text or Code Snippet]]

You should now find both the MyType.h header file and the MyType.winmd file located in the desired output directory, allowing you to maintain an organized project structure.

Conclusion

Addressing the issue of mismatched output directories for generated C+ + header files and WinMD files when using Bazel is relatively straightforward with the right modifications. By adjusting the batch script and refining your Bazel rule, you can ensure that these important files coexist in the same folder. This not only streamlines your workflow but also minimizes confusion in larger projects.

We hope this guide has been helpful. Happy coding!