[CMake] Controlling the targets in an export set

[Nils Gladitz]

On 07/24/2014 01:57 AM, Adar Dembo wrote:
> I have a project that generates a shared library foo. As part of the
> build, the bar1, bar2, and bar3 static archives are created, and
> eventually, foo is linked against all of them. Thus, the project's sole
> deliverable is libfoo.so; all the necessary symbols from the bar1..bar3
> archives are found within libfoo.so.
>
> If I try to export foo using "install(TARGETS foo EXPORT foo ...) and
> "install(EXPORT foo ...)", cmake complains that target foo requires
> targets bar1, bar2, and bar3, which are not in the export set. I have to
> add "install(TARGETS bar1 EXPORT foo ...)" for bar1..bar3 if I want this
> to succeed. However, this also means that I'm exporting my static
> archives, which as I wrote earlier aren't necessary.
>
> How can I exercise finer-grained control over foo's export set? How can
> I build an export set containing foo but excluding bar1, bar2, and bar3?

You can link your static libraries to your shared library privately 
hence removing them from foo's interface:

   target_link_libraries(foo PRIVATE bar1 bar2 bar3)

You are probably already aware but just in case ...

To portably link archives to shared libraries you need position 
independent code[1].

Of the objects contained in your archives only those will get included 
which are required to resolve some reference when creating libfoo.so.
Symbols that were contained in objects which were not required in the 
link will hence not be available.

This might seemed to have worked within the project until now given that 
the archives were in your link interface.

Nils

[1] http://cmake.org/cmake/help/v3.0/prop_tgt/POSITION_INDEPENDENT_CODE.html