GprBuild and linker options

[Felix Krause <fordprefect86@googlemail.com>]

I need GprBuild to use a custom linker option (in this case, for linking against an OSX framework). So I include this in my project file:

package Linker is
   for Linker_Options use ("-framework OpenCL", "-v");
end Linker;

When I try to build this project, this is the output I get at linking phase, which fails:

/usr/local/gnat/bin/gcc [...] -framework OpenCL -v [...]
[...]
COLLECT_GCC_OPTIONS=[...] '-framework OpenCL' '-v' [...]
 /usr/local/gnat/libexec/gcc/x86_64-apple-darwin10.2.0/4.5.3/collect2 [...]

After that, I get a list of undefined symbols. This is due to "-framework OpenCL" not being given to the collect2 call. I have no idea what COMPILE_GCC_OPTIONS does, but I noticed my switch being listed there. Now when I copypaste the above call to /usr/local/gnat/bin/gcc into my shell and execute it there, my switch isn't listed in COLLECT_GCC_OPTIONS anymore, but instead is given to the collect2 call, and everything links correctly.

Now of course, I want the build to work directly without having to copy commands to the shell. One thing I tried is splitting the switch into two strings:

for Linker_Options use ("-framework", "OpenCL", "-v");

The linking phase now executes the following:

/usr/local/gnat/bin/gcc [...] -framework /users/felix/projects/libs/openclada//OpenCL -v [...]

This obviously results in an error because this framework can't be found. I searched in the GprBuild user's guide for some hint on what causes this behavior, but I didn't find anything. Can anyone tell me how to either make the GprBuild execution with "-framework OpenCL" work like when I execute it in the shell, or prevent GprBuild from prepending the working path to "OpenCL" when passing two strings to Linker_Options?

Thanks.
Felix