[CMake] adding same subdirectory multiple times.

[Mika.Rajala at patria.fi]

cmake-bounces at cmake.org wrote on 11.03.2010 10:04:42:

> On 11.03.10 09:56:35, Mika.Rajala at patria.fi wrote:
> >
> > Hi
> >
> > The problem:
> >
> > >From a shared CMakeLists.txt i get the following error when defining a
> > library target.
> > Policy CMP0002 is not set: Logival target names must be globally
unique.
> >
> >
> > The situation:
> >
> > Let's assume i have the following cmake files in the following folders
with
> > the svn:externals properties.
> >
> > C:\project\CMakeLists.txt
> > add_subdirectory(ProjectA)
> > add_subdirectory(ProjectB)
> >
> > C:\project\ProjectA   (svn:externals LibraryA <svn_path_to_libA>)
> > add_subdirectory(LibraryA)
> >
> > c:\project\ProjectB    (svn:externals LibraryA <svn_path_to_libA>)
> > add_subdirectory(LibraryA)
> >
> > c:\project\LibraryA
> > add_library(LibraryA)
> >
> > Thoughts:
> >
> > I don't know if this causes any problem, I tried reading some
> > documentations but I couldn't figure it out.
>
> Yes it does. The library target is defined multiple times, thats not
> possible. Each version of "LibraryA/CMakeLists.txt" has to use its own
> name for LibraryA if you want that directory layout to work. Target
> names must be globally unique as the error message says.
>
> From a quick glance I see two options:
> - drop the externals and let the projects depend on a "LibraryA" target
>   being defined (you need to use the add_subdirectory call for it to the
>   fron then
> - find a way to test in LibraryA/CMakeLists.txt wether its under
>   ProjectA, ProjectB or project and adjust the target name then.
>
> Andreas
>
> --
> Questionable day.
>
> Ask somebody something.
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Thanks.

I'd still like to know if there is a way to handle this like including c++
header files

Something like

if(LibraryA)
      message(Already included, doing nothing)
else()
      <Normal CMakeLists content>
endif()

-mika