Re: [boost] Installing CMake configuration files

Subject: Re: [boost] Installing CMake configuration files
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2018-10-19 16:14:11

AMDG

On 10/12/2018 09:00 PM, Peter Dimov via Boost wrote:
> I've taken another stab at installing CMake configuration files along
> with the libraries in `b2 install`. CMake configuration files are .cmake
> files, typically installed into $prefix/lib or $prefix/lib/cmake, that
> allow f.ex. `find_package(boost_system)` in a CMakeLists.txt file to
> find the installed Boost.System library and declare a CMake target
> Boost::system that refers to it. CMake targets can then link to
> Boost::system and all is well.
> 

Just a couple comments:
* If generate-cmake-config takes the library as a source,
  then it's possible to derive both the library dependencies
  and the exact library name from the library target.  The
  dependencies can be found at the virtual target level in
  generate-cmake-config, and the exact file name will appear
  as the source in generate-cmake-config-.  Doing it this way
  also has the side effect that the CMake configuration won't
  be installed if the library fails to build, which may be a
  good thing.
* I'm not fond of the ROOT parameter for boost-install.boost-install.
  * Dependencies can be referenced with /boost/$(deps)//[stage|install]
  * You can find the full path to the boost-install.jam with
    [ path.root [ modules.binding $(__name__) ] [ path.pwd ] ]
    This avoids hard-coding the location of boost_install relative
    to the superproject.
  * That just leaves the stage directory, which is tied to the
    project root, and should perhaps be calculated in Jamroot
    instead of in boost_install.
* This seems to handle --layout=versioned, but I'm not clear on
  how well it handles --layout=system where we expect to use a
  single compiled library for all configurations.
* Are the error messages that you get from CMake when there
  isn't a configuration that matches the request intelligible?
  It looks like the target will exist but will silently do nothing?
  What if something goes wrong and there are multiple matches?

> The work in its current state is available on the feature/cmake-config
> branch of the superproject:
> 

In Christ,
Steven Watanabe