Re: [Boost-build] Boost Build configure checks improvement. [config/predef]

Subject: Re: [Boost-build] Boost Build configure checks improvement. [config/predef]
From: Edward Diener (eldiener_at_[hidden])
Date: 2017-06-12 19:46:52

On 6/12/2017 10:29 AM, Rene Rivera via Boost-build wrote:
> There's been a long standing "issue" with how the b2 configure checks 
> work. Or rather how some times they don't work. In particular the issue 
> is that the set of properties considered relevant for the configuration 
> checks was fixed. As of last night that is now resolved 
> <https://github.com/boostorg/build/commit/450c25c3b52f5ddcb323140f8423adf3b85b6b1a>.
> 
> As the commit mentions the set is no longer fixed and is configurable by 
> users. The changes now mean that:
> 
> 1. Any subfeatures of the top level relevant feature set are also 
> considered as part of the set. This means that one can a configuration 
> like below to support multiple invocations of the same toolset with 
> different options. In particular the STD options:
> 
> === user-config.jam ===
> import feature ;
> using clang ;
> feature.subfeature toolset clang : std : cxx03 cxx11 cxx14 cxx17 : 
> optional composite propagated ;
> feature.compose <toolset-clang:std>cxx03 : <cxxflags>-std=c++03 ;
> feature.compose <toolset-clang:std>cxx11 : <cxxflags>-std=c++11 ;
> feature.compose <toolset-clang:std>cxx14 : <cxxflags>-std=c++14 ;
> ===
> 
> And one can then invoke "b2 toolset=clang-cxx14,clang-cxx11" and get 
> non-colliding configuration checks.
> 
> 2. The set of relevant features is now soft wired as the set of 
> subfeatures of the "<composite>" feature. Which means ones can add to 
> the default set 
> <https://github.com/boostorg/build/blob/develop/src/build/configure.jam#L26>. 
> For example to add threading choice to the relevant features:
> 
> === user-config.jam ===
> import feature ;
> import configure ;
> feature.compose <configure> : <threading> ;
> ===
> 
> Enjoy.

Great news. Many thanks !!!

I had given up on feature.subfeature/compose, exactly because of the 
problem you have fixed, in favor of my own hardcoded compiler "version"s 
( which do work but which are not very flexible ). But 
feature.subfeature/compose is more flexible and I will try that again. 
It is really imnportant that every feature.subfeature composition get 
its own separate build, and I assume that us precisely what you have fixed.

> 
> -- 
> -- Rene Rivera
> -- Grafik - Don't Assume Anything
> -- Robot Dreams - http://robot-dreams.net <http://robot-dreams.net/>
> -- rrivera/acm.org 
> <http://acm.org/> (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail