[CMake] target_link_libraries: prefer static to dynamic

[Bill Hoffman]

Pau Garcia i Quiles wrote:
> On Sun, Dec 27, 2009 at 6:26 PM, Bill Hoffman <bill.hoffman at kitware.com> wrote:
>> Pau Garcia i Quiles wrote:
>>> Hello,
>>>
>>> I think this has already been discussed and the answer is negative but
>>> still: when I do target_link_libraries to an external library (for
>>> instance, my application needs to link to sqlite), is it possible to
>>> tell CMake to link to the static version of sqlite instead of the
>>> dynamic version?
>>>
>>> For instance, in Debian the libsqlite3-dev package contains both the
>>> static and the dynamic versions of the library and they have the very
>>> same name:
>>>
>>> /usr/lib/libsqlite3.a
>>> /usr/lib/libsqlite3.so
>>>
>>> ( http://packages.debian.org/sid/i386/libsqlite3-dev/filelist )
>>>
>>> Is this feature going to be implemented any time soon? I have not
>>> looked at the sources for target_link_libraries but at first sight it
>>> doesn't look difficult to add  something like
>>> "static;optimized;libsqlite3.a;dynamic;optimized;libsqlite3.so".
>>> There's the problem of find_library on Windows confusing the .lib as
>>> the import for a .dll with a static .lib library but IIRC it's
>>> possible to detect that.
>>>
>> If you use the full path then it should work fine.  find_library will always
>> return the full path.  So if you do target_link_libraries(foo ${SQLITELIB})
>> where SQLITELIB = /usr/lib/libswlite3.a then it will work just fine.
> 
> That will not work in the case I was describing, where you have both
> the shared and the static versions of the library installed. Futher,
> it would be even worse if both the static and the shared versions of
> the library are installed but in different paths, because you would
> depend on what path is searched first.
> 
> As I said if you install libsqlite3-dev on a Debian-based distro, it
> will install both /usr/lib/libsqlite3.a and /usr/lib/libsqlite3.so.
> How can I be sure find_library will find the static version before the
> dynamic one. What happens if the path to the static library is
> searched after the path to the shared library?
> 

What version of CMake are you using?  This should work...  As of 2.6.2 
(I think...) CMake uses full paths to libraries, see policy CMP0003: 
http://www.cmake.org/cmake/help/cmake-2-8-docs.html#policy:CMP0003.  It 
does not matter if there are two libraries in the same directory.  There 
is no way to force find_library to find the static one.  However, if you 
tell CMake to link to a full path to /usr/lib/libsqlite3.a, it should 
link to /usr/lib/libsqlite3.a even if /usr/lib/libsqlite3.so exists.

-Bill