Re: Hunting the culprit package

[Stefan Monnier]

> Also, when I install all the packages afresh, then also emacs works fine
> i.e. a freshly created ~/.emacs.d/elpa is *not* creating any issue.  So
> something is wrong in my old ~/.emacs.d/elpa.  So I tried to figure out
> what is happening in my old ~/.emacs.d/elpa directory.

In my experience, the problem in such circumstances is most of the time
a file that was miscompiled for some reason.

> --8<---------------cut here---------------start------------->8---
> diff -r elpa/dash-20220608.1931/dash-autoloads.el 
> elnew/dash-20220608.1931/dash-autoloads.el
> 42c42
> < (fn &optional ARG)" t nil)
> ---
>> (fn &optional ARG)" t)
> 66c66
> < (fn &optional ARG)" t nil)
> ---
>> (fn &optional ARG)" t)
> 69c69
> < This allows Dash symbols to be looked up with \\[info-lookup-symbol]." t 
> nil)
> ---
>> This allows Dash symbols to be looked up with \\[info-lookup-symbol]." t)

Changes to `<PKG>-autoloads.el` are normal: those files are generated
locally during the package's installation, so they can be different
depending on the version of Emacs used to install the package.
The above differences should have no impact since they just add/remove
explicit nil values for optional arguments.

> diff -r elpa/yaml-mode-20220104.1503/yaml-mode-pkg.el 
> elnew/yaml-mode-20220104.1503/yaml-mode-pkg.el
> 2c2
> < (define-package "yaml-mode" "20220104.1503" "Major mode for editing YAML
> files" '((emacs "24.1")) :commit
> "535273d5a1eb76999d20afbcf4d9f056d8ffd2da" :authors '(("Yoshiki Kurihara"
> . "clouder@gmail.com") ("Marshall T. Vandegrift"
> . "llasram@gmail.com")) :maintainer '("Vasilij Schneidermann"
> . "mail@vasilij.de") :keywords '("data" "yaml") :url
> "https://github.com/yoshiki/yaml-mode";)
> ---
>> (define-package "yaml-mode" "20220104.1503" "Major mode for editing YAML
>> files" '((emacs "24.1")) :commit
>> "a79d2a7b9281f8c56f461d717b1ba40fc58e22fd" :authors '(("Yoshiki Kurihara"
>> . "clouder@gmail.com") ("Marshall T. Vandegrift"
>> . "llasram@gmail.com")) :maintainer '("Vasilij Schneidermann"
>> . "mail@vasilij.de") :keywords '("data" "yaml") :url
>> "https://github.com/yoshiki/yaml-mode";)
> --8<---------------cut here---------------end--------------->8---

This is not expected: the `<PGK>-pkg.el` files are not generated
locally, they come straight from the tarballs (i.e. they're generated
once and for all when the tarball is created).  This said, this is
a MELPA package and it may be that MELPA re-builds all its tarballs "all
the time", so it's possible that the `yaml-mode-20220104.1503` from
a month ago holds a different `<PKG>-pkg.el` than the
`yaml-mode-20220104.1503` from today if the scripts used to build that
tarball have changed in-between.
NOTE: I said "may be", because I don't know whether it's the case
or not.  On `elpa.(non)gnu.org` tarballs are not *re*built, so for
(Non)GNU ELPA packages this should never happen.

> Also, if this is not the correct way to approach then how to find which
> the old package that was creating the issue.

Do the usual debugging from the details of issue itself, walking our way
back to its source?


        Stefan