More over-engineering

[Stefan Monnier <monnier@iro.umontreal.ca>]

What's up with allocate_emacs_value in emacs-modules.c?

Are we really allocating a structure for every Lisp_Object value we pass
through the modules API?  Why do that?

The GC will find all Lisp_Object values that are stored in other Lisp
object or on the stack, so there are rather few remaining cases where
a Lisp_Object value has to be protected from GC.  For those remaining
cases, we do want to provide a way for the C code to "pin" the object
(we call it "gc-protect" them in Emacs's C code), but looking at the 
emacs-modules.c is looks like we don't even do that because those
emacs_value objects are auto-reclaimed when upon return, so they only
"protect" data whose lifetime doesn't escape the current module call
(and most of those cases correspond to having a Lisp_Object on the
stack, so there's no need for GC protection anyway).


        Stefan