Subject: bug#46841: [PATCH] Make package downloading in inversion.el obsolete

From: Stefan Kangas <[email-masked]>
Date: Mon, 1 Mar 2021 10:08:48 -0600

(Copying in Eric Ludlam in case he has something to add.)

Lars Ingebrigtsen <[email-masked]> writes:

> Stefan Kangas <[email-masked]> writes:
>
>> There is some code to download packages in cedet/inversion.el which
>> seems completely redundant now that we have package.el.  I suggest
>> marking that part as obsolete, see the attached patch.
>>
>> To be honest, I don't exactly see that there is any need for
>> inversion.el since the problem it tries to solve is already solved by
>> package.el.  Perhaps we should just move the entire library to
>> obsolete/.
>
> Utility functions like `inversion-package-version' are used in the rest
> of CEDET, though?  (I just did a quick grep, but didn't actually read
> the call sites.)

Yes.  I took a closer look.  The uses all seem to be of dubious value
these days, and could probably themselves be obsoleted or changed to not
need inversion.  Here is what I could find:

./lisp/cedet/cedet.el106:		(filever (car (inversion-find-version sym)))

The function `cedet-version' produces a screen like this:

    CEDET Version:	2.0
      			Requested	File		Loaded
      Package		Version		Version		Version
      ----------------------------------------------------------
      cedet:		2.0		ok		ok
      eieio:		1.4		ok		ok
      semantic:		2.2		ok		Not Loaded
      srecode:		1.2		ok		Not Loaded
      ede:			1.2		2.0		Not Loaded

    C-h f cedet-version RET
      for details on output format.

But all these packages are distributed with Emacs itself.

./lisp/cedet/semantic/ede-grammar.el165:    (list "eieio" "semantic"
"inversion" "ede")))
./lisp/cedet/semantic/ede-grammar.el168:  ;; Inversion for versioning system.

Add inversion to loadpath in Makefiles produced by EDE, for some reason.
If inversion is obsolete, that would not be useful.

./lisp/cedet/semantic/db-file.el176:	  (if (not (inversion-test
'semanticdb-file fv))
./lisp/cedet/semantic/db-file.el177:	      (when (inversion-test
'semantic-tag tv)
./lisp/cedet/cedet-cscope.el156:	(if (inversion-check-version rev nil
cedet-cscope-min-version)
./lisp/cedet/cedet-idutils.el185:	(if (inversion-check-version rev nil
cedet-idutils-min-version)
./lisp/cedet/cedet-global.el160:	(if (inversion-check-version rev nil
cedet-global-min-version)

Several similar functions that just check for the installed version,
which is either the one distributed with Emacs or the latest released
version.  The latter would normally be the one you automatically
installed with package.el.

So it's all just about making sure the correct version of a package is
installed.  AFAICT, that is fully obsoleted by `package-install'.

./lisp/cedet/ede/make.el76:	(setq ans (not (inversion-check-version
rev nil ede-make-min-version))))

This parses the make version and ensures its recent enough.  Perhaps
useful, but could likely be replaced by the built-in `version<' or
somesuch.

./lisp/cedet/semantic.el61:  (inversion-test 'semantic

Here we have a function `semantic-require-version' that allows callers
to check if this is a recent enough version of Semantic.

They should instead be checking for the major version of Emacs, or if
Semantic is installed from the external CEDET repository deal with it
themselves, or if Semantic is turned into a core package and installed
that way they should just make sure their dependencies are correct.

Am I missing something here?  Eric?

> But, yes, the download bits don't seem very useful.

Thanks.