[CMake] find_library and caching

[Nils Gladitz]

On 15.06.2014 19:33, Lucas Soltic wrote:
> I use a FindSomeLib.cmake script for my project, for which there is a variable (let's call it LINK_STATIC) to define if one wants to link 	against SomeLib statically. The default is to look for dynamic libraries.
>
> The issue is that when first running CMake's configure, the user may have forgotten to set LINK_STATIC, so the script finds the dynamic version of SomeLib and set a cache entry for it. Then in CMake's GUI the user realizes he wants static linking so he sets the LINK_STATIC flag, but at this point find_library has already cached the result and won't look again for static version of SomeLib.
>
> This ends up with the user thinking he's using static linking, which is not what's happening.
> I saw in CMake's doc that in order to let find_library search again, I'd need to clear the library entry it has found. But if I do this at each CMake configure run, it removes the interest of the cache.
>
> Would anyone know about the preferred way to fix this caching issue?
> I would be really grateful :)
>

Perhaps you could use distinct cache variables for static and shared 
libraries.

e.g.

find_library(FOO_STATIC_LIBRARY ...)
find_library(FOO_SHARED_LIBRARY ...)

set(FOO_LIBRARIES "")

if(FOO_LINK_STATIC)
     list(APPEND FOO_LIBRARIES ${FOO_STATIC_LIBRARY})
else()
     list(APPEND FOO_LIBRARIES ${FOO_SHARED_LIBRARY})
endif()

Nils