How to use environment variable in xcconfig #include?

Question

in my project, I want to refer to an other xcconfig file, located in InDesign SDK. As this SDK may be installed at different locations, depending upon the machine, I prefer to declare an environment variable for locating it.

Nest step is obviously to use variable (aptly named ID_CS5_SDK_DIR) in my xcconfig include directive.

Unfortunatly, when I try the simple

// InDesign sdk project build settings (based on common build settings)
#include "$(ID_CS5_SDK_ROOT)/build/mac/prj/_shared_build_settings/common.xcconfig"

XCode throws me a

 [WARN]AutocatPlugin.xcconfig line 7: Unable to find included file "$(ID_CS5_SDK_ROOT)/build/mac/prj/_shared_build_settings/common.xcconfig"

How can I make it work ?

Answer 1

I've been trying to do this too and also came to the conclusion that it is not possible.

Answer 2

I once tried to achieve that and came to the conclusion that you can't. I would be happy if someone proves us it's possible though then delete my answer