[cmake-developers] rpaths on Mac

[Brad King]

On 11/17/2011 11:49 AM, Clinton Stimpson wrote:
>
> I'm experimenting with using @rpath instead of @executable_path and
> @loader_path, because @rpath is useful in some situations where the others
> don't work as well.  For example, I want to avoid setting DYLD_LIBRARY_PATH
> when using a relocatable SDK.  Using @rpath allows a user to embed a path in
> their executable/library that gives the location of the SDK libraries that
> they linked with.  Public SDK libraries would also know how to find private SDK
> libraries with an rpath of @loader_path and dependencies starting with @rpath.
>
> What needs to be considered if the following is added to
> Platforms/Darwin.cmake?
>    set(CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG "-Wl,-rpath,")
>    set(CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG_SEP ":")

Is that all that is necessary to get the standard RPATH behavior on OS X?
Nice!

> Would that have undesirable side effects?

Since the original RPATH support in CMake pre-dated the feature on OS X
we implemented INSTALL_NAME_DIR instead.  We need to investigate how the
two features would/should interact.

> One possibility is adding -rpath link flags to those who currently don't
> have/want it.

We may need a switch to choose between RPATH and INSTALL_NAME_DIR.  The
default of the switch can be chosen based on the minimum required version
of CMake.  Over time everyone will start using RPATH instead.

-Brad