Re: build broken: no defun org-float-time. Who's guilty, and what does he propose?

[Stefan Monnier]

>> Other files could be autoloaded during compilation, and should be
>> listed as dependencies too.
> We have `features' and `load-history' to help us.

It's doable, yes.  Note that just looking at the `require's and
`provide's will give you a graph with cycles.

> Files loaded by loadup.el are easily extracted by simple text
> scanning, and the byte compiler itself indeed _is_ a prerequisite for
> every other compilation.

Note that a basic hypothesis here, is that "make bootstrap" is not
a good solution, so any solution that ends recompiling similar amounts
of code is not good either.  But if you look in detail, you'll see that
only bootstrap does it really right: the byte-compiler is
a prerequisitie of all elc files, and the byte-compiler itself uses
potentially any code in loadup.el (and then some), so any change to
a preloaded file should fundamentally require recompiling all
Lisp files.  Anything short of that is an optimistic optimization.

> Btw, I don't understand what problem do you see with files preloaded
> by loadup.  They should simply be all prerequisites of temacs, and
> that's it, right?

Of temacs, no, but of `emacs' or `emacs-bootstrap', yes.
A recent case to ponder is the addition of define-obsolete-face-alias.
Maybe we can handle this one in the following way:

  When byte-compiling elc files with a preexisting emacs-bootstrap
  binary, re-load all the files that were preloaded but that have been
  changed since building emacs-bootstrap, before doing the actual
  recompilation (i.e. when starting emacs-bootstrap, check the
  load-history to see if any of those files have changed and reload them
  if needed).

Of course, this will bump into a few bugs at first, since some of the
preloaded files do not like to be re-loaded.


-- Stefan