+## To understand the order of -I flags, consider what happens if you run
+## ./configure in the source tree, and then run
+## $(srcdir).2.26/configure in some other build tree.
+## Where will the generated files like config.h be included from?
+## This is also why you _must_ use <...> instead of "..."
+## when #include'ing generated files.
+cppflags = -Demacs -I. -I../src -I$(srcdir) -I$(top_srcdir)/src $(CPPFLAGS)