[CMake] Static Linking C++ Library

[Brad King]

Mike Melanson wrote:
> Brad King wrote:
>> You can link the entire program statically if you don't have any of your
>> own shared libraries.  Then running "ldd myexe" will produce a message
>> that the executable is not dynamically linked.  This requires just
>> adding "-static" to CMAKE_EXE_LINKER_FLAGS (or the appropriate option
>> for your compiler).
> 
> Sounds simple enough. Except that there are 2 build targets for this
> project that embody most of the same functionality: A static executable
> and a shared library that other programs can call. That shared library
> changes the rules a bit, doesn't it?

Yes, specially if the shared library uses the C++ runtime.  In that case
you cannot use the static C++ runtime at all!

If you are trying to create a binary tarball distribution then you will
have to include the C++ library in it (and then put the source to the
GNU libstdc++ in a link off your download page to satisfy the license).
 We have several projects that do this.  They key to distributing
dynamically linked binaries in a tarball is to use a "shared forwarding"
executable to setup LD_LIBRARY_PATH correctly and then invoke the real
executable.  There is actually code that comes in the source of CMake
you can use for this:

http://www.cmake.org/cgi-bin/viewcvs.cgi/Source/kwsys/SharedForward.h.in?root=CMake&view=markup

The forwarding executable is a small C program that does not link to
anything that isn't provided everywhere.  It knows the relative path to
the shared libraries and the executable.  It sets up LD_LIBRARY_PATH in
its own environment and then runs the real executable with "execv".
This allows the application to run from anywhere that its tarball is
extracted.

-Brad