Generate Ddoc without compiling?

[Jonathan M. Wilbur]

I want to put in a feature request, but I want to gauge whether 
it is even feasible or not, but a little background first:

I am trying to create a Makefile to build the HTML documentation 
for a Dlang project. I would like to be able to update a single 
HTML file if the corresponding source changes, without having to 
recompile all of the others. My rule looks like this:

$(DCOMPILER) -o- -op -d -Df$@ $<

But that does not work, because some of the compiled modules 
import other modules, and the rule fails because DCOMPILER can't 
intelligently pull in the other source files. I think requiring a 
complete compile of all source to build the HTML documentation is 
a big impediment to making D highly scalable.

Having said that, I don't see why it would be technically 
impossible to make DMD build the HTML (almost) without regard to 
the validity of the source code. Is this possible? And moreover: 
*should* it be done? Is it a bad idea?