slotThe/vc-use-package

Cannot load package

lzhoucs opened this issue · 5 comments

lzhoucs commented

I got the following error

⛔ Error (use-package): Failed to install zenburn-emacs: Package ‘zenburn-emacs’ is unavailable
⛔ Error (use-package): Cannot load zenburn-emacs

when trying to install a package with the following:

(unless (package-installed-p 'vc-use-package)
  (package-vc-install "https://github.com/slotThe/vc-use-package"))
(require 'vc-use-package)
(require 'use-package)

;; Theme
(use-package zenburn-emacs
  :vc (:fetcher "github" :repo "bbatsov/zenburn-emacs")
  :ensure
  :config (load-theme 'zenburn t))

I am on Emacs 29.0.

It does seem the package is somehow installed from github despite the error. My gut feeling is the package name is not consistent across vc-use-package, vc-package-install and use-package which caused the error even though the package is installed, it's not loaded so it's not useable.

slotThe commented

Hi,

the issue you are running into is described here. In short: :vc always tries to install a package if it's not installed already, so passing :ensure is not necessary. Further, since :ensure gets evaluated so early, the expanded code will always look like

(progn
  (use-package-ensure-elpa 'zenburn-emacs 'nil 'nil)
  (apply #'vc-use-package--install
         '(:fetcher "https://github.com/" :repo "bbatsov/zenburn-emacs" :name zenburn-emacs))
  …)

I.e., use-package first tries to install the package with elpa and, upon failing to do that, continues with what we actually want. If you don't have use-package-always-ensure set, then just removing the :ensure should fix this.

See also: #7

lzhoucs commented

Thanks for the reply.
I don't have use-package-always-ensure set and made sure it's value is nil. It seems after removing ensure the first error is gone as you imagined, but the 2nd error still exists:

⛔ Error (use-package): Cannot load zenburn-emacs

This is what I have right now:

(require 'use-package)
(unless (package-installed-p 'vc-use-package)
  (package-vc-install "https://github.com/slotThe/vc-use-package"))
(require 'vc-use-package)

(use-package zenburn-emacs
  :vc (:fetcher "github" :repo "bbatsov/zenburn-emacs")
  :config (load-theme 'zenburn t))
slotThe commented

Ah, indeed, the package is named zenburn-emacs on GitHub, but the actual package name is zenburn-theme. Try this:

(use-package zenburn-theme
  :vc (:fetcher "github" :repo "bbatsov/zenburn-emacs")
  :config (load-theme 'zenburn t))
lzhoucs commented

It worked. Thanks a lot! I didn't know the name actually matters. I thought it was just an identifier given vc-package is doing the install. If you don't mind, I wonder how to identify the package name? Is it the from the file name zenburn-theme.el, or this line: https://github.com/bbatsov/zenburn-emacs/blob/master/zenburn-theme.el#L36?

Thanks for your help. I am pretty new to elisp.

slotThe commented

If you don't mind, I wonder how to identify the package name?

I general, Emacs packages are always named like their file names, and themes are always suffixed with -theme.

If you want to know precisely what a package will be called, just look for the provide at the end of the file. For example, for zenburn.el one can see

(provide-theme 'zenburn)

This is basically just (provide (get 'zenburn 'theme-feature)), and evaluating the inner form I get zenburn-theme.

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