Re: [boost] shared-linkable-true, runtime-link-dynamic and runtime-link-static

From: David Abrahams (dave_at_[hidden])
Date: 2002-10-15 17:11:32

Alkis Evlogimenos <alkis_at_[hidden]> writes:

> So if I get it correctly:
> runtime-link-static: creates a static library that is statically linked to the 
> C++ runtime

No, the use of runtime-link-static is not limited to static library
building. If your Jamfile says:

   exe foo : foo.cpp : <runtime-link>static ;

it creates an executable which is always statically linked to the
runtime library. So <runtime-link>static compiles and links objects
which are suitable for linking statically to the runtime.

> runtime-link-dynamic: creates a static library that is dynamically linked to 
> the C++ runtime (is this possible?)

Likewise, not specific to static libraries.

> shared-linkable-true: creates a shared library that is dynamically linked to 
> the C++ library

No, <shared-linkable>true generates code which can be linked
dynamically. On linux gcc this means it uses -fPIC.

> I am using linux and both runtime-link-dynamic and
> runtime-link-static are static libraries.

Let's just get the terminology straight. They are not static
libraries. They are subvariant path components which correspond to the
build properties <runtime-link>dynamic and <runtime-link>static,
respectively. In that build directory tree you will find a
built product. Depending on the type of main target you've built, it
will be a static or dynamic library, an executable, or a python module.

>  They also have the same
> size but the binaries differ (at least this is what diff says).
> 
> As an example I dumped the symbols for 
> ./libs/thread/build/bin/libboost_thread.a/rs/debug/runtime-link-{static,dynamic}/threading-multi/libboost_thread.a 
> and I get the following diff:

Ah, so you're building libboost_thread.

> It looks like only the name mangling differs. 

<snip>

> So I assume linking to either 
> one will result in an executable that will behave the same. Maybe linux 
> doesn't do a distinction between linking dynamically to the C++ runtime or 
> not?

Yes, it does. That's what -static in the g++ command-line means. You
can inspect the build command lines by passing 

   -n -a

to bjam when you invoke it. Inspecting the differences will tell you a
lot.

-- 
           David Abrahams * Boost Consulting
dave_at_[hidden] * http://www.boost-consulting.com