[question] CMake generators - how to use libraries form a different build config

Hello,

I would want to fetch googletest via Conan, I am using v1.50 on debian Linux with Make/Ninja generators. The problem is generally that you don’t necessarily want the same config on your project as on your dependencies. For my example I would want to build my project with debug/sanitize/coverage configuration, while gtest and other dependencies are the release variants.

I cant do this currently, using the CMakeDeps generator atleast. Doing a debug-build the find_package(GTest) call will work, but those targets are empty and using gtest headers will fail.

Why isnt this done more like “normal” CMake installations where the property IMPORTED_CONFIGURATIONS is set, and CMake picks the correct flavor, while also allowing handpicked overrides via MAP_IMPORTED_CONFIG_<CONFIG>.

So in short, your generated imports should:

• Drop all $<$<CONFIG:.*>:.*> stuff. otherwise its not possible to use them elsewhere.
• use IMPORTED_CONFIGURATIONS instead.
• check_build_type_defined shouldnt be necessary?

That way, conan packages could be used just like regular installed CMake packages when created with the official helpers. Output of these helpers looks like this.

• I’ve read the CONTRIBUTING guide.

[666melkor666]

Hi. It looks like I’m hit by the same problem.

I need to be able to independently change the build_type of dependencies and their consumer. The use case is the following: I have an application and want to use the release version of the dependencies regardless of the config my application is being built or change the build_type for a certain dependency only. Using debug versions for all dependencies may lead to significant performance degradation.

The only workaround I’ve found is to override the generate method in the following way:

def generate(self):
    deps = CMakeDeps(self)
    deps.configuration = "Release"
    deps.generate()
    deps.configuration = "Debug"
    deps.generate()

and then conan install -s build_type="Release" ... This way I have release version of dependencies, and I can change the consumer CMAKE_BUILD_TYPE between Release and Debug. This approach, however, is very inconvenient, especially if I want to have some consumer specific CMAKE_BULD_TYPE, which for example, turns on a lot of additional logging.

It would be great to have the ability to tell the CMakeDeps generator to ignore the build_type setting. In case I’ve missed something, please advise how I can build the described workflow using conan.

[fanselm]

I also hit this recently, and I guess a lot of people must have by now.

I also agree with @nolange that the Conan generated .cmake files (e.g. <PKG>Config.cmake) should be completely free of configuration specifications like $CONFIG:Release - it is not Conan’s job to interfere with how the project is configured, it should just hand you the include directories and libraries no matter what. If one wants a debug version of a dependency that is specified in the conanfile.txt.

@memsharded can you comment on this?