bug#59923: Error when installing non-existent package add trailing dash character to package name

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Fri, 9 Dec 2022 02:57:15 -0800
> 
> When evaluating the following to install a package that is not
> available,
> 
>     (package-install 'foobar)
> 
> I get the error message
> 
>     Package ‘foobar-’ is unavailable
> 
> This makes me think I made a typo, and have added a trailing dash that
> shouldn't have been there.  I would expect the package name to not
> contain that trailing dash.
> 
> Here's the backtrace:
> 
> Debugger entered--Lisp error: (error "Package ‘foobar-’ is unavailable")
>   error("Package `%s-%s' is unavailable" foobar "")
>   package-compute-transaction(nil ((foobar)))
>   package-install(foobar)
>   elisp--eval-last-sexp(nil)
>   eval-last-sexp(nil)
>   funcall-interactively(eval-last-sexp nil)
>   command-execute(eval-last-sexp)
> 
> Perhaps this is an okay fix?
> 
> diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
> index a9fd8c741e..4d33311cb7 100644
> --- a/lisp/emacs-lisp/package.el
> +++ b/lisp/emacs-lisp/package.el
> @@ -1949,8 +1949,10 @@ package-compute-transaction
>                (if (eq next-pkg 'emacs)
>                    (error "This package requires Emacs version %s"
>                           (package-version-join next-version))
> -                (error "Package `%s-%s' is unavailable"
> -                       next-pkg (package-version-join next-version))))))
> +                (error (if (not next-version)
> +                           (format "Package `%s' is unavailable" next-pkg)
> +                         (format "Package `%s' (version %s) is unavailable"
> +                                 next-pkg (package-version-join
> next-version))))))))
>            (setq packages
>                  (package-compute-transaction (cons found packages)
>                                               (package-desc-reqs found)
> 

Barring objections or better ideas from Stefan (CC'ed), I think you
should install the above.

Thanks.