proposal for loading conan_cmakedeps_paths.cmake

[memsharded]

After conan-io/conan#17561

This PR does:

• Update all tests to use CMakeConfigDeps, explicitly
• Fix tests that changed the logic a bit because of CMakeConfigDeps
• Drop tests about find modules, no longer applicable to CMakeConfigDeps
• Removed the automatic injection of CMakeDeps. User conanfiles should define the generator. The warning has been there for a long time already
• Updated the readme to recommend CMakeConfigDeps

This doesn't really change or break users with CMakeDeps in their conanfiles.

[jcar87]

cc @jjcasmar

[ottmar-zittlau]

Hi,

maybe the following question is more related to the CMakeConfigDeps-generator in general than the cmake-conan-wrapper, but I came across it while testing the conan-provider.cmake of this PR.

I have put all files in a repository (https://github.com/ottmar-zittlau/conan-cmake-question) in case you'd like to follow my steps.

I have created a small (interface) library (in repo: test_lib) that only contains a header file.
The package_info of the associated conanfile.py reads:

    def package_info(self):
        self.cpp_info.builddirs = ["lib/cmake"]
        self.cpp_info.set_property("cmake_find_mode", "none")

This library is consumed by an executable (in repo: main_exe) by:

    def requirements(self):
        self.requires("test_lib/0.0.1")

If I follow the conventional approach (conan install + generated presets) everything works.
However, using the cmake-wrapper with the CMakeConfigDeps-generator doesn't work.
If I run

cmake -B build -S . -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=conan_provider.cmake -DCONAN_HOST_PROFILE="auto-cmake;../new_cmakedeps_profile"

cmake complains that target testLib::testLib can't be found.

My build folder contains conan_cmakedeps_paths.cmake and this file also contains some test_lib-related paths:

set(CMAKE_FIND_PACKAGE_PREFER_CONFIG ON)

list(APPEND CONAN_test_lib_DIR_MULTI "/home/oz/.conan2/p/b/test_3552486bd5308/p/lib/cmake")
set(CONAN_RUNTIME_LIB_DIRS "$<$<CONFIG:None>:/home/oz/.conan2/p/b/test_3552486bd5308/p/lib>" )
# Only for VS, needs CMake>=3.27
set(CMAKE_VS_DEBUGGER_ENVIRONMENT "PATH=${CONAN_RUNTIME_LIB_DIRS};%PATH%")
list(PREPEND CMAKE_PROGRAM_PATH "/home/oz/.conan2/p/b/test_3552486bd5308/p/bin")
list(PREPEND CMAKE_LIBRARY_PATH "/home/oz/.conan2/p/b/test_3552486bd5308/p/lib")
list(PREPEND CMAKE_INCLUDE_PATH "/home/oz/.conan2/p/b/test_3552486bd5308/p/include")
# Definition of CMAKE_MODULE_PATH to be able to include(module)
list(PREPEND CMAKE_MODULE_PATH "/home/oz/.conan2/p/b/test_3552486bd5308/p/lib/cmake")

I'm pretty confident that cmake reads this file (I printed the variable CONAN_test_lib_DIR_MULTI in my cmake-file to check) - so I think the changes to conan_provider.cmake have an effect.

I was comparing the variables set in conan_cmakedeps_paths.cmake with the search paths given in cmake config search procedure and I somehow can understand that cmake doesn't find the library. I would have expected that the path is added to either CMAKE_PREFIX_PATH or that TESTLIB_ROOT is set. The CMakeConfigDeps documentation states that a TESTLIB_DIR variable should be defined (and I can find this variable in the cmake documentation, but don't really understand if it should be set externally) - but also this variable doesn't seem to be set (my CMakeCache.txt file contains testLib_DIR:PATH=testLib_DIR-NOTFOUND).

How can I make this work? Do I maybe need to add something else to my library's package_info?

Thanks in advance and best regards
oz

[memsharded]

Hi @ottmar-zittlau

Thanks for the feedback.

We have just released CMakeConfigDeps, I had these changes pending to move this integration forward, I'll do it soon.
Thanks for the repro, I'll have a look when moving this PR forward to check what could be happening.

[ottmar-zittlau]

@memsharded Thanks a lot! It's not an urgent issue for me.

[memsharded]

Hi @ottmar-zittlau

I am going to merge and close this PR.
Regarding your issue above, it would be better to create a dedicated ticket for it, some quick observations:

• settings = ("build_type",) is most often not enough. At the very least the os and arch should be there, but also the compiler is almost always needed as input, even if for some cases it can be removed later for package_id
• tools.cmake.cmakedeps:new=will_break_next is no longer necessary, just use CMakeConfigDeps directly
• Update to the latest conan_provider.cmake after this PR is merged.