Dependence based on whether files has been changed

[Peng Yu]

Hi,

Scons has the support for updating target only if the dependent file
contents are changed.
http://www.scons.org/doc/0.98.5/HTML/scons-user/c779.html

I know that it may not always easy and possible to duplicate feature
of other tools. But GNU make is still faster than scons and sometime
much faster than scons (especially if there are many dependences in a
Makefile). Considering this I'd still rather use make than scons.

Therefore, I'm wondering if there is any plan to add the features
based on file contents in GNU make in the future.

-- 
Regards,
Peng