@@ use shell && instead of multi-line rules since they don't consider
   atomic (e.g. if something failed other files won't be deleted). Or
   maybe not, think about it (and read the doc).

@@ Some implicit rule should actually be two rules: one that looks
   for the source under srd_root tree and the other under out_root.
   Theoretically, any source could be just an intermidiate file generated
   from something else (discovered while playing with idl).

@@ Compensating rules: 'clean all' example.

@@ Issues from "Multi-Architecture Builds Using GNU make":

   - big (bloated) makefiles

   - cannot say "make foo.o"

@@ How can I integrate building of realpath utility in configuration
   process?

@@ Executing make from non-source directory is painful. Can I make it
   easier?

%% When shared library is linked with absolute path the loader is looking
   for the library with the same path. See also -soname= and -rpath ls
   options.

@@ With multidir makefiles I loos the ability to say make where I am.
   This is especially nasty when I edit a file and then say make. This
   happens for example in CCF. The easy workaround is to say something
   "make -C dir/to/test/driver". Once this is done life get very nice.
   Actually I think this could be the best approach.

@@ Variable inheritance doesn't play well with 'make foo.o'.

@@ Configurations include absolute paths to imported libraries which
   makes it hard to reuse them. In this light configurations on installed
   libraries should not include any absolute paths.

@@ Better name for project_name? build_name?

@@ Repetition of paths in $(call message) is quite ugly. Anything I can do?

@@ -MP conflicts with --no-implicit-phony. The new approach uses a special
   terminal pattern rule to handle this. However headers without suffix
   cannot be handled by this method.

@! Delete-on-error does not cover .o.d files. I could specify it as a target
   together with .o but then it will try to rebuild it.

@! When you hide things from make (like .o.d or .l/.so) all sorts of bad things
   happen.

@@ What is a better term for development (not installed?) build?

@@ /usr/bin/g++ is a link but extracted include paths have precise version in
   them (e.g. 3.3.4). But then dependencies will trigger update, right?

@! I am using some of the features of GNU find which are not available in SUS.

@@ Since .l.cpp-options pattern does not have any prereqs then the file can
   always be created (example: I misspelled file name).

@@ Use abspath to prevent call-inclusion from -I dirs.

@@ lib.cpp-options should be lib.cpp_options?

@@ Use $@ in $$(dir $(out)/%).

@! Need to make content of .l compiler-independant (rpath stuff).

@@ export is now position-sensitive.