This is gnustep-make 2.6.2. Type 'make print-gnustep-make-help' for help.
/usr/share/GNUstep/Makefiles/objc.make:30: objc.make is deprecated. Please use tool.make instead
My own attempt, though quite obsolete now, may be a good starting point.
https://sources.debian.net/src/oolite/
Select latest version, then debian/patches/gnustep_app_builder.diff.
When I compile under linux - warn is shown:
This is gnustep-make 2.6.2. Type 'make print-gnustep-make-help' for help. /usr/share/GNUstep/Makefiles/objc.make:30: objc.make is deprecated. Please use tool.make instead