Re: [boost] Proposal for moving Boost to CMake

Subject: Re: [boost] Proposal for moving Boost to CMake
From: Peter Dimov (lists_at_[hidden])
Date: 2017-06-22 12:11:40

Thomas Heller wrote:
> One way to go here is to have one Config.cmake for each build type. For 
> example structured like this:
>
> lib/cmake/boost-vc141-mt-1_65-dynamic/boost_system-config.cmake
> lib/cmake/boost-vc141-mt-1_65-static/boost_system-config.cmake
> lib/cmake/boost-vc141-mt-gd-1_65-dynamic/boost_system-config.cmake
> lib/cmake/boost-vc141-mt-gd-1_65-static/boost_system-config.cmake
> lib/cmake/boost-vc141-mt-s-1_65-dynamic/boost_system-config.cmake
> lib/cmake/boost-vc141-mt-s-1_65-static/boost_system-config.cmake
> lib/cmake/boost-vc141-mt-sgd-1_65-dynamic/boost_system-config.cmake
> lib/cmake/boost-vc141-mt-sgd-1_65-static/boost_system-config.cmake

I was thinking of something similar; since CMake will ignore suffix, one 
could install

lib/cmake/boost_system-config-vc141-mt-dyn-1_65.cmake

and so on. Inside, each config would only define its target if the 
properties match, and define nothing otherwise. But I'm not sure if CMake 
works this way, or it just picks up the first one it finds.

Or, the same conditional game could be played in the -version file instead.

For the actual selection, we probably need to define variables such as 
BOOST_BUILD_VARIANT, BOOST_RUNTIME_LINK, BOOST_RUNTIME_DEBUGGING, 
BOOST_TOOLSET_ID and do some heroic autodetection when these aren't set 
depending on the current CMake environment. Having the logic repeated in 
each config file won't be pretty though. Ideally, we'll be able to get it 
into CMake itself one day, else, we need to install a file containing it and 
include it from the config/version ones.