Bug: org-id-add-location fails when cloning a subtree [9.1.9 (release_9.1.9-65-g5e4542 @ /home/ieure/.emacs.d/straight/build/org/)]

[Ian Eure]

If you have a subtree of entries with :ID: properties and call M-x 
`org-clone-subtree-with-time-shift' on it, an error occurs:

   Wrong type argument: stringp, nil

This is due to the interaction of 
`org-clone-subtree-with-time-shift' and `org-id-add-location'. 
When the former is called, it creates a temp buffer to operate on: 
https://code.orgmode.org/bzg/org-mode/src/master/lisp/org.el#L7801

Then calls `org-id-get-create': 
https://code.orgmode.org/bzg/org-mode/src/master/lisp/org.el#L7808

Which calls `org-id-get', which calls `buffer-file-name', which 
evals to nil, because no file backs the temp buffer.  That nil is 
then passed to `org-id-add-location': 
https://code.orgmode.org/bzg/org-mode/src/master/lisp/org-id.el#L277

Which unconditionally calls `abbreviate-file-name': 
https://code.orgmode.org/bzg/org-mode/src/master/lisp/org-id.el#L575

Which signals the error.

I’ve confirmed that this is still a problem in the 9.3.6, which is 
the latest release, as well as Git master.

A simplistic fix would be to swap the let and when lines in 
`org-id-add-location':

diff --git a/lisp/org-id.el b/lisp/org-id.el
index 1ff433bd8..945a9a1f6 100644
--- a/lisp/org-id.el
+++ b/lisp/org-id.el
@@ -572,8 +572,8 @@ When FILES is given, scan also these files."
(defun org-id-add-location (id file)
  "Add the ID with location FILE to the database of ID 
  locations."
  ;; Only if global tracking is on, and when the buffer has a 
  file
-  (let ((afile (abbreviate-file-name file)))
-    (when (and org-id-track-globally id file)
+  (when (and org-id-track-globally id file)
+    (let ((afile (abbreviate-file-name file)))
      (unless org-id-locations (org-id-locations-load))
      (puthash id afile org-id-locations)
      (unless (member afile org-id-files)

However, this causes a more subtle bug, which is that the IDs of 
cloned subtrees won’t be tracked correctly.  Perhaps a solution to 
that is to use an indirect buffer of the source when cloning, 
instead of a temp buffer.


Emacs  : GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, X toolkit, 
Xaw3d scroll bars)
of 2019-09-22, modified by Debian
Package: Org mode version 9.1.9 (release_9.1.9-65-g5e4542 @ 
/home/ieure/.emacs.d/straight/build/org/)