[question] How to require a build requirement

[elvisdukaj]

What is your question?

I have the following tool packages my-toolchain and some binary utilities tool-1, tool-2. Then I have a library my-lib that needs the toolchain in otder to build. my-lib is also containging some cmake files that is using these tools.

my-lib is having something similar to the following snippet in the package_info:

    def package_info(self):
       # ...

        # extra cmake modules to be included when using find_package
        build_modules = [
            os.path.join(self._cmake_install_base_path, "tool-1.cmake"),
            os.path.join(self._cmake_install_base_path, "tool-2.cmake"),
            os.path.join(self._cmake_install_base_path, "tool-3.cmake"),
        ]
        self.cpp_info.set_property("cmake_build_modules", build_modules)

My issue is that is that these tools are not really required to build my-library but are more for who is linking agains the library. Ideally the client code should just do something like:

[requires]
my-library/version

[generators]
CMakeDeps
CMakeToolchain

[layout]
cmake_layout

And in the CMakeFiles:

# the following line makes the tools visible in the PATH and pulls the tool-*.cmake files
find_package(my-library::my-library CONFIG REQUIRED) 

I don't know how to achieve this with CMake. What I was trying is to expose from my-lib the tool requirements, which is not a good practice, but I don't know how to do this better.

As a workaround I put some error message in the cmake files that are added by my-lib to include the proper tool_requires and added this tool_requires in the profile. But I don't like this approach because the my-lib and the tool require connection is hidden and it's hard to make more explicit.

As alternative I could put self.tool_require("tool-1/version", visible=True) but this was not recomended. What are other options to accomplish this?