Including project_options in the installed package for interface libraries

[ClausKlein]

see a178b9c

bash-3.2$ cd -
/Users/clausklein/cmake/cmakelib/test_install/build
bash-3.2$ ninja
[0/1] Re-running CMake...
-- vcpkg is already installed at /Users/clausklein/vcpkg.
-- Running vcpkg install
Detecting compiler hash for triplet x64-osx...
All requested packages are currently installed.
Restored 0 packages from /Users/clausklein/.cache/vcpkg/archives in 2.44 us. Use --debug to see more details.

Total elapsed time: 1.746 s

The package eigen3 provides CMake targets:

    find_package(Eigen3 CONFIG REQUIRED)
    target_link_libraries(main PRIVATE Eigen3::Eigen)

The package fmt provides CMake targets:

    find_package(fmt CONFIG REQUIRED)
    target_link_libraries(main PRIVATE fmt::fmt)

    # Or use the header-only version
    find_package(fmt CONFIG REQUIRED)
    target_link_libraries(main PRIVATE fmt::fmt-header-only)

-- Running vcpkg install - done
CMake Error at /Users/clausklein/vcpkg/scripts/buildsystems/vcpkg.cmake:782 (_find_package):
  Found package configuration file:

    /Users/clausklein/cmake/cmakelib/install/share/myproj_header_only_lib/myproj_header_only_libConfig.cmake

  but it set myproj_header_only_lib_FOUND to FALSE so package
  "myproj_header_only_lib" is considered to be NOT FOUND.  Reason given by
  package:

  The following imported targets are referenced, but are missing:
  myproj::project_options myproj::project_warnings

Call Stack (most recent call first):
  CMakeLists.txt:45 (find_package)


-- Configuring incomplete, errors occurred!
See also "/Users/clausklein/cmake/cmakelib/test_install/build/CMakeFiles/CMakeOutput.log".
See also "/Users/clausklein/cmake/cmakelib/test_install/build/CMakeFiles/CMakeError.log".
FAILED: CMakeFiles/impl-Debug.ninja build-Debug.ninja CMakeFiles/impl-Release.ninja build-Release.ninja CMakeFiles/impl-RelWithDebInfo.ninja build-RelWithDebInfo.ninja build.ninja 
/usr/local/Cellar/cmake/3.22.1/bin/cmake --regenerate-during-build -S/Users/clausklein/cmake/cmakelib/test_install -B/Users/clausklein/cmake/cmakelib/test_install/build
ninja: error: rebuilding 'build.ninja': subcommand failed
bash-3.2$ 

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[aminya]

This is impossible in CMake. The interface libraries cannot have private dependencies.

[ClausKlein]

This is impossible in CMake. The interface libraries cannot have private dependencies.

I know, but if you install this interface, it is also impossible to use this header only lib without project_options!

[aminya]

We should also install project_options for header-only libraries.

[aminya]

Well, I don't think we actually need this. package_project already generates the project_options and project_warnings targets:

Running test_install, then looking at myprojTargets.cmake:

[ClausKlein]

If I use a header only lib i.e. boost::asio I will not import there development setting like:

--coverage

-Wpedantic -Werror... or

the worst case: g++ specific warnings, if I want to use clang++

I created this issue to show it is a wrong usage of project_options to export the project_options for every installed lib, independent of it is an interface or a normal lib!

[aminya]

The config files generated by CMake are not portable! They have absolute paths in them, and they are generated based on the options you pass to project_options.

To avoid having test/sanitizer-related flags in the generated config, you should use FEATURE_TESTS flag.

https://github.com/cpp-best-practices/cpp_vcpkg_project/blob/830685f328fba4bbdcfb0540d0fbcecd95aaab5c/CMakeLists.txt#L30-L48

I will add this to the readme if it is not clear.

[aminya]

The example in the readme is updated. Now, the FEATURE_TESTS option handles the sanitizer flag exports.