Thank you for the tips, /boost//headers is very useful and I was looking forward to something like that.

The problem is my shared libraries are not used like:

exe foo : foo.cc foo_shared : <threading>multi ;

I use them with dlopen and LoadLibrary, and it drivers me to another chalenge, create the simplest

build working on Windows, Linux and MacOS. On Windows I am not able to create a DLL with this:

lib foo_shared : foo_shared.cc foo_static : <link>shared  : : <library>/boost//thread/<link>static ;

because gives me that:

libfoo_static.lib(foo_static.obj) : error LNK2019: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::system_category(void)" (?system_category@system@boost@@YAABVerror_category@12@XZ) referenced in function "public: __thiscall boost::thread_exception::thread_exception(int,char const *)" (??0thread_exception@boost@@QAE@HPBD@Z)

libfoo_static.lib(foo_static.obj) : error LNK2019: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::generic_category(void)" (?generic_category@system@boost@@YAABVerror_category@12@XZ) referenced in function "void __cdecl boost::system::`dynamic initializer for 'errno_ecat''(void)" (??__Eerrno_ecat@system@boost@@YAXXZ)

libfoo_static.lib(foo_static.obj) : error LNK2019: unresolved external symbol "public: __thiscall boost::thread::thread(void)" (??0thread@boost@@QAE@XZ) referenced in function "int __cdecl foo_static(void)" (?foo_static@@YAHXZ)

libfoo_static.lib(foo_static.obj) : error LNK2019: unresolved external symbol "public: void __thiscall boost::thread::detach(void)" (?detach@thread@boost@@QAEXXZ) referenced in function "public: __thiscall boost::thread::~thread(void)" (??1thread@boost@@QAE@XZ)

bin\msvc-12.0\debug\foo_shared.dll : fatal error LNK1120: 4 unresolved externals

so I have to use:

lib foo_shared : foo_shared.cc foo_static : <link>shared <library>/boost//thread/<link>static : : <library>/boost//thread/<link>static ;

or use <target-os>windows:<library>/boost//thread/<link>static and solve Windows and Linux

in an ugly way. I just don't know the best approach, and I think <cxxflags>-fPIC should be

inherited regardless anything else. With this flags not being inherited, I have other problems

like using <cxxflags>-std=c++11 and Boost.Filesystem generates "undefined reference" under Linux.

What you think? Is there any workaround, maybe force inheritance?

Thank you

On Wed, Feb 19, 2014 at 7:59 PM, Thomas Suckow <thomas.suckow@pnnl.gov> wrote:

On 02/19/2014 11:33 AM, Paulo Márcio Figueiredo Alves wrote:

I have made a simple test to show the problem (attached file). If you do
not use Boost.Thread, the problem does not occur.
Adjust boost path (line 1) and call b2 -a, you'll see "recompile with
-fPIC". Choose one of the commented choices
for target foo_static and you will see that there is no way to make it
work, unless you call b2 -a cxxflags=-fPIC.

Is it a bug? Is there any workaround? Am I doing something wrong?

It would appear that the override of <link>static is preventing boost-build from knowing it needs to use -fPIC.

That said, it bugs me thinking that the boost libraries are being linked into more than one of your shared libraries.

In your library, since random is header-only, I would use:
: <use>/boost//headers <implicit-dependency>/boost//headers ;
AFAIK, this is the most correct syntax. I've been trying to figure out the best syntax since modular-boost changes some things.

This is the best I could come up with:
lib foo_static : foo_static.cc : <link>static <cxxflags>-fPIC <use>/boost//headers <implicit-dependency>/boost//headers ;

lib foo_shared : foo_shared.cc foo_static : <link>shared  : : <library>/boost//thread/<link>static ;

exe foo : foo.cc foo_shared : <threading>multi ;


I am kind of disappointed in this solution :-/

-
Thomas
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