Asio is not installed by CMake in Boost 1.89.0

[pdimov]

See boostorg/cmake#85. Probably caused by boostorg/asio@be4af2d.

When making changes to CMakeLists.txt, please test installation (and ideally add_subdirectory use as well.)

[yurybura]

@pdimov @chriskohlhoff Please check out my patch: boostorg/asio#454. Thank you!

[pdimov]

Actually, I just tested Asio installation, and then use, and it works correctly. So the original report might be a vcpkg-specific issue.

Nevertheless, adding a test is a good idea. :-)

[pdimov]

So, I started working on a PR to add CMake subdir and install tests, and discovered that I have already done so, two years ago: boostorg/asio#424

I updated the PR to reflect the 2025 reality. Please merge it. :-)

[yurybura]

Actually, I just tested Asio installation, and then use, and it works correctly. So the original report might be a vcpkg-specific issue.

Nevertheless, adding a test is a good idea. :-)

vcpkg downloads and installs libraries independently. In this case, some dependencies may not be found.

To find dependencies, BoostRoot.cmake (I'm talking about the script included with version 1.89.0) simply searches for strings in text, which leads to a variety of problems. In this case, the script identifies Boost::asio_core as an external library dependency, which is incorrect.

@pdimov Did you test installation for 1.89,0?

[pdimov]

No, I tested it with the current develop, which has an updated dependency scanner that knows about these targets.

But I don't quite understand why the old BoostRoot incorrectly identifying Boost::asio_core as an "external library dependency" would cause any issues. That's only used for implicitly adding dependencies when BOOST_INCLUDE_LIBRARIES is used, and doesn't affect installation in any way.

[yurybura]

No, I tested it with the current develop, which has an updated dependency scanner that knows about these targets.

But I don't quite understand why the old BoostRoot incorrectly identifying Boost::asio_core as an "external library dependency" would cause any issues. That's only used for implicitly adding dependencies when BOOST_INCLUDE_LIBRARIES is used, and doesn't affect installation in any way.

Yes, this part is specific to vcpkg, since it calls find_package to find the dependent Boost libraries that __boost_scan_dependencies returned.

[pdimov]

I'm still not sure what the problem is.

The original issue says

CMake Error at D:/github/miyanyan/vcpkg/scripts/buildsystems/vcpkg.cmake:896 (_find_package):
  Could not find a package configuration file provided by "boost_asio_core"
  (requested version 1.89.0) with any of the following names:

    boost_asio_coreConfig.cmake
    boost_asio_core-config.cmake

but boost_asio_core-config.cmake is installed by this part:

https://github.com/boostorg/asio/blob/44722ea0246e001e5fbac6a8b3b8ee153882c83e/CMakeLists.txt#L76-L86

This has nothing to do with the dependency scanner in BoostRoot - it's a command in asio/CMakeLists.txt that's always executed regardless of what the scanner says.