Exposing a CMake Subproject to a Meson Dependency

[ChristianJacobsen]

Hi!

Can I provide a CMake Subproject with a dependency from Meson?

The case here is the library opentelemetry-cpp, which uses the CMake build system.
When compiled using the option WITH_OTLP it depends on Protobuf, gRPC, and the JSON library by Niels Lohmann.
Since my wrap file for opentelemetry-cpp uses the tar-ball as a source (I know I can alter this, but bear with me), I "don't have access to" the Git submodules the project uses for its dependencies on the libraries mentioned above. I would also like to provision them using Meson for the dependency fetching/resolution.

The question then becomes: how do I let CMake know where to find these libraries?

For Protobuf I can specify Protobuf_LIBRARIES and Protobuf_INCLUDE_DIR using the options passable to the cmake.subproject() function, but getting the location from the dependency object (returned from my call to dependency('protobuf')) seems impossible, as no method on the dependency object returns the library path or include directory path. I believe the other libraries' dependencies are solvable in the same fashion.

I know I'm probably not going about this most straightforwardly, and maybe the better approach would've been for me to write a meson.build file for opentelemetry-cpp instead. The only problem is that I don't particularly want to maintain said file, nor do I think I will get it 100% correct.

Is what I'm asking about here impossible, or am I simply unable to find the correct page in the documentation?

Thanks in advance for your help ❤️

[eli-schwartz]

This sounds like essentially #8104

[ChristianJacobsen]

That's unfortunate, as the PR hasn't seen much activity in the past couple years...