Re: [Boost-build] Build Boost on WIndows with zlib

Subject: Re: [Boost-build] Build Boost on WIndows with zlib
From: Paolo Tosco (paolo.tosco_at_[hidden])
Date: 2016-05-15 14:21:47

Dear Steven,

I found a solution to my problem: in my application, I added the 
following before including zlib.hpp:

#define BOOST_IOSTREAMS_DYN_LINK
#include <boost/iostreams/filter/zlib.hpp>

This allows the const variable symbols to be correctly imported from the 
DLL.

Thanks for your time, kind regards
Paolo

On 15/05/2016 17:59, Paolo Tosco wrote:
> Dear Steven,
>
> thank you very much for your reply.
>
> On 14/05/2016 02:00, Steven Watanabe wrote:
>> AMDG
>>
>> On 05/12/2016 12:59 PM, Paolo Tosco wrote:
>>> Dear all,
>>>
>>> I have tried to build Boost 1.59.0 on Windows with MSVC 2015 including
>>> zlib support for iostreams.
>>> While this has never been a problem on Linux, I cannot get the "zlib :
>>> yes" message from b2, and I always get both
>>> libboost_iostreams-vc140-mt-1_59.lib and
>>> libboost_zlib-vc140-mt-1_59.lib, while I should only get the former if
>>> zlib had been recognized.
>>>
>>    So, what exactly is the problem?  You are
>> asking to build zlib from source, and
>> it appears to work.  The "zlib : yes" is
>> not actually printed in this case.
> You are right, actually the "zlib : yes" message is only printed when 
> the -sZLIB_BINARY and -sZLIB_LIBPATH switches are used.
> However, even though boost_iostreams has been built with zlib support, 
> I am unable to link a very simple test program:
>
> #include <boost/iostreams/filter/zlib.hpp>
>
> int main() {
>   int a = boost::iostreams::zlib::default_compression;
>   return 0;
> }
>
> cl /EHsc /DBOOST_ALL_NO_LIB /MD /I. /IC:\build\zlib-1.2.8 testzlib.cpp 
> stage\lib\boost_iostreams-vc140-mt-1_59.lib C:\build\zlib-1.2.8\zlib.lib
>
> Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23918 for x64
> Copyright (C) Microsoft Corporation.  All rights reserved.
>
> testzlib.cpp
> Microsoft (R) Incremental Linker Version 14.00.23918.0
> Copyright (C) Microsoft Corporation.  All rights reserved.
>
> /out:testzlib.exe
> testzlib.obj
> stage\lib\boost_iostreams-vc140-mt-1_59.lib
> C:\build\zlib-1.2.8\zlib.lib
> testzlib.obj : error LNK2019: unresolved external symbol "int const 
> boost::iostreams::zlib::default_compression" 
> (?default_compression_at_zlib@iostreams_at_boost@@3HB) referenced in 
> function main
> testzlib.exe : fatal error LNK1120: 1 unresolved externals
>
> However, the symbol is correctly exported in the DLL:
>
> dumpbin.exe /EXPORTS stage\lib\boost_iostreams-vc140-mt-1_59.lib | 
> grep default_compression
>                   ?default_compression_at_zlib@iostreams_at_boost@@3HB (int 
> const boost::iostreams::zlib::default_compression)
>
> The test program builds correctly if I build against the zlib.obj file 
> rather than against boost_iostreams-vc140-mt-1_59.lib:
>
> cl /EHsc /DBOOST_ALL_NO_LIB /MD /I. /IC:\build\zlib-1.2.8 testzlib.cpp 
> bin.v2\libs\iostreams\build\msvc-14.0\release\address-model-64\threading-multi\zlib.obj 
> C:\build\zlib-1.2.8\zlib.lib
>
> I don't have problems in linking the test program against 
> boost_iostreams on Linux.
> I have the impression that the problem is that Windows does not 
> support exporting global static constants in DLLs.
>
> In fact, if I add the following to zlib.hpp:
>
> BOOST_IOSTREAMS_DECL const int get_default_compression();
>
> and the following to zlib.cpp:
>
> BOOST_IOSTREAMS_DECL const int get_default_compression() {
>   return default_compression;
> }
>
> and I modify the test program as follows:
>
> #include <boost/iostreams/filter/zlib.hpp>
>
> int main() {
>   int a = boost::iostreams::zlib::get_default_compression();
>   return 0;
> }
>
> it then links fine against boost_iostreams:
>
> cl /EHsc /DBOOST_ALL_NO_LIB /MD /I. /IC:\build\zlib-1.2.8 testzlib.cpp 
> stage\lib\boost_iostreams-vc140-mt-1_59.lib C:\build\zlib-1.2.8\zlib.lib
> Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23918 for x64
> Copyright (C) Microsoft Corporation.  All rights reserved.
>
> testzlib.cpp
> Microsoft (R) Incremental Linker Version 14.00.23918.0
> Copyright (C) Microsoft Corporation.  All rights reserved.
>
> /out:testzlib.exe
> testzlib.obj
> stage\lib\boost_iostreams-vc140-mt-1_59.lib
> C:\build\zlib-1.2.8\zlib.lib
>
> Do you have any suggestions how to fix the problem?
>
> I really appreciate your help, and please bear with me if the above is 
> not clear or if I inadvertently did some silly mistake.
>
> Kind regards,
> Paolo
>
>>> This is the command line that I have used:
>>>
>>> b2 -a -q -j4 address-model=64 link=static threading=multi
>>> runtime-link=shared variant=release --with-iostreams
>>> -sZLIB_SOURCE="C:/64/boost_1_59_0_py35_build/source/zlib-1.2.8"
>>>
>>> according to the instructions found in
>>>
>>> http://lists.boost.org/boost-users/2014/04/81927.php
>>>
>>> I have also tried to set the environment variable as suggested in
>>>
>>> http://lists.boost.org/boost-users/2014/04/81894.php
>>>
>>> but this didn't help either.
>>>
>>> Could someone tell me what am I doing wrong?
>>>
>> In Christ,
>> Steven Watanabe
>>
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>