On Fedora 21 x86-64, if I configure emacs with "./configure --with-ns
CFLAGS='-g3 -O2 -DGNUSTEP'" (the -DGNUSTEP is to work around Bug#19507),
the resulting executable fails with the following diagnostic:
2015-01-04 13:27:06.763 emacs[28811] Did not find correct version of
backend (libgnustep-back-024.bundle), falling back to std
(libgnustep-back.bundle).
2015-01-04 13:27:06.764 emacs[28811] NSApplication.m:304 Assertion
failed in initialize_gnustep_backend. Unable to find backend back
./emacs: Uncaught exception NSInternalInconsistencyException, reason:
NSApplication.m:304 Assertion failed in initialize_gnustep_backend.
Unable to find backend back
Sorry, I don't know what those diagnostics mean. I'm using just the
standard Fedora 21 installation as far as I know.