xnee 3.19 doesn't link on macOS. The error is:

clang: error: no such file or directory: 'CCC'

The link command was:

libtool: link: /usr/bin/clang -D_REENTRANT -DORBIT2=1 -I/opt/local/include/libgnomeui-2.0 -I/opt/local/include/gnome-keyring-1 -I/opt/local/include/libbonoboui-2.0 -I/opt/local/include/libxml2 -I/opt/local/include/libgnome-2.0 -I/opt/local/include/libbonobo-2.0 -I/opt/local/include/bonobo-activation-2.0 -I/opt/local/include/libgnomecanvas-2.0 -I/opt/local/include/gail-1.0 -I/opt/local/include/libart-2.0 -I/opt/local/include/gtk-2.0 -I/opt/local/lib/gtk-2.0/include -I/opt/local/include/pango-1.0 -I/opt/local/include/gio-unix-2.0 -I/opt/local/include/cairo -I/opt/local/include/atk-1.0 -I/opt/local/include/pango-1.0 -I/opt/local/include/harfbuzz -I/opt/local/include/pango-1.0 -I/opt/local/include/fribidi -I/opt/local/include/cairo -I/opt/local/include/pixman-1 -I/opt/local/include/harfbuzz -I/opt/local/include/freetype2 -I/opt/local/include/gdk-pixbuf-2.0 -I/opt/local/include/libpng16 -I/opt/local/include/gnome-vfs-2.0 -I/opt/local/lib/gnome-vfs-2.0/include -I/opt/local/include/gconf/2 -I/opt/local/include/orbit-2.0 -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include/gtk-2.0 -I/opt/local/lib/gtk-2.0/include -I/opt/local/include/pango-1.0 -I/opt/local/include/gio-unix-2.0 -I/opt/local/include/cairo -I/opt/local/include/atk-1.0 -I/opt/local/include/gdk-pixbuf-2.0 -I/opt/local/include/pango-1.0 -I/opt/local/include/harfbuzz -I/opt/local/include/pango-1.0 -I/opt/local/include/fribidi -I/opt/local/include/cairo -I/opt/local/include/pixman-1 -I/opt/local/include/harfbuzz -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include/freetype2 -I/opt/local/include/libpng16 -DXNEE_XINPUT_SUPPORT -pipe -Os -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk -arch x86_64 -Wl,-headerpad_max_install_names -Wl,-syslibroot -Wl,/Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk -arch x86_64 -o gnee gnee-main.o gnee-support.o gnee-interface.o gnee-callbacks.o gnee-recordables.o gnee-gnee_xnee.o CCC  -L/opt/local/lib -L../../libxnee/ -L../../libxnee/.. -L../../libxnee/src /opt/local/var/macports/build/_Volumes_Shared_macports-ports_x11_xnee/xnee/work/xnee-3.19/libxnee/src/.libs/libxnee.a -lXtst -lgnomeui-2 -lSM -lICE -lbonoboui-2 -lgnome-2 -lpopt -lbonobo-2 -lbonobo-activation -lORBit-2 -lgnomecanvas-2 -lart_lgpl_2 -lgnomevfs-2 -lgconf-2 -lgthread-2.0 -lgmodule-2.0 -lgtk-x11-2.0 -lgdk-x11-2.0 -lpangocairo-1.0 -lXrender -lXinerama -lXi -lXrandr -lXcursor -lXcomposite -lXdamage -lXfixes -lX11 -lXext -latk-1.0 -lcairo -lgdk_pixbuf-2.0 -lgio-2.0 -lpangoft2-1.0 -lpango-1.0 -lgobject-2.0 -lglib-2.0 -lintl -lharfbuzz -lfontconfig -lfreetype

Note the unexpected `CCC` in there. This comes from the configure script:

AC_CHECK_LIB(c, sem_init, LIBSEMA="CCC", [AC_CHECK_LIB(pthread, sem_init, LIBSEMA="-lpthread")])

The fix appears to be to remove `CCC` from that line as in the attached patch.

`CCC` was added here but I don't know why:

https://cvs.savannah.gnu.org/viewvc/xnee/xnee/configure.in?r1=1.50&r2=1.51