[boost] boost-install-ing zlib (Was: Re: [Release] Boost 1.70.0 Beta 1 Release Candidate 2)

Subject: [boost] boost-install-ing zlib (Was: Re: [Release] Boost 1.70.0 Beta 1 Release Candidate 2)
From: Peter Dimov (pdimov_at_[hidden])
Date: 2019-03-13 18:14:23

> I'll need to try and see what happens with <source> in user-config. 
> Probably nothing good, because one would expect neither <build-name> nor 
> <tag> to be specified in such a case.

If I remove the check for ZLIB_SOURCE, and just do

    alias boost_zlib : /zlib//zlib ;
    libraries-to-install += boost_zlib ;

unconditionally in libs/iostreams/build/Jamfile, this is what happens:

- when `using zlib : : <source>C:/Projects/zlib-1.2.11 ;` is in user-config, 
the default `b2 install` fails because `address-model=32,64 
variant=debug,release` conflict as all try to build `libz.lib`. When 
address-model=32 variant=debug is given, `libz.lib` is installed in 
C:\Boost\lib, and the CMake configuration for boost_zlib correctly points to 
it.

- when using a prebuilt `using zlib : : <include>C:/Projects/include 
<search>C:/Projects/lib <name>zlib-8 ;`, the CMake configuration file for 
boost_zlib points to "${_BOOST_LIBDIR}/zlib-8", which is not correct.