automatic regeneration for all of this template substitution, and for
config.status etc. is done for you.
+Summary of directory reference syntaxes
+---------------------------------------
+
+ In build tree In source tree
+ Relative Absolute Relative Absolute
+
+ &file $(abs)/&file
+ This directory &/file $(abs)/&/file &^/file &~/file
+ & f g h & ^ f g h & ~ f g h
+
+ Top level file $(abs)/file $(ts)/file $(ats)/file
+ f g h
+
Substitution syntax
-------------------
Makefile.in and rename it to Subdir.sd.mk, and add the appropriate
stuff to configure.ac, and fix everything up. Leave the existing
$(MAKE) -C for your existing subdirectories alone. Then you can
-convert individual subdirectories, or classes of subdirectories.
+convert individual subdirectories, or classes of subdirectories, at
+your leisure. (You must be /sure/ that each subdirectory will be
+entered only once at a time, but your existing recursive make descent
+system should already do that or you already have concurrency bugs.)
Aside from this, be very wary of any invocation of $(MAKE) anywhere.
This is a frequent source of concurrency bugs in recursive make build