Re: Bug: org-set-tags-command deletes inherited tags [9.3.7 (9.3.7-18-g093b47-elpaplus @ /home/ionasal/.emacs.d/elpa/org-plus-contrib-20200810/)]

[Kyle Meyer]

Thanks for the patch.

Allen Li writes:

> Example Org file:
>
> * Parent :foo:bar:baz:
> ** Child :foo:bar:spam:
>
> Invoking org-set-tags-command with point on Child prepopulates the
> minibuffer prompt with only the tags :spam:
>
> This is because org-get-tags doesn't distinguish between inherited only
> tags and inherited tags which are also explicitly set on a heading, so
> org-set-tags-command treats :foo:bar: as inherited only rather than also
> set locally on the heading.
>
> This is undesirable because having tags set directly on a heading has
> different semantics even if they are also inherited (e.g., the TAGS
> special property, or when headings will be refiled to a different
> location later).

I agree, that's undesirable and likely unintended.

> Subject: [PATCH] org.el: Don't exclude local tags that are also inherited
>
> * lisp/org.el (org-set-tags-command): Don't exclude local tags even if 
> inherited.
> ---
>  lisp/org.el | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)

It'd be good to add something along the lines of your example as a case
in test-org/set-tags-command.

> diff --git a/lisp/org.el b/lisp/org.el
> index fb95590fc..49d7d24f2 100644
> --- a/lisp/org.el
> +++ b/lisp/org.el
> @@ -11880,9 +11880,7 @@ in Lisp code use `org-set-tags' instead."
>                                 (org-global-tags-completion-table
>                                  (org-agenda-files)))
>                            (or org-current-tag-alist (org-get-buffer-tags)))))
> -            (current-tags
> -             (cl-remove-if (lambda (tag) (get-text-property 0 'inherited 
> tag))
> -                           all-tags))
> +            (current-tags (org-get-tags nil t))
>              (inherited-tags
>               (cl-remove-if-not (lambda (tag) (get-text-property 0 'inherited 
> tag))
>                                 all-tags))

That looks good as far as fixing the misbehavior you report.  I wonder
though whether there's a deeper org-get-tags issue here worth
considering.  Its documentation says

    ... the returned list of tags contains tags in this order: file
    tags, tags inherited from parent headlines, local tags.

But it's not specified what happens when a tag is both local and
inherited.  The current implementation drops the local tag variant
through its delete-dups call:

    (delete-dups
     (append (org-remove-uninherited-tags itags) ltags))

I would have expected the local tag to get priority here.  If that were
the case (e.g., something like below), that would also solve the issue
you describe.

Thoughts?

-- >8 --
diff --git a/lisp/org.el b/lisp/org.el
index fb95590fc..3dac42b7b 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -12310,8 +12310,10 @@ (defun org-get-tags (&optional pos local)
                                           (org--get-local-tags))
                                   itags)))
             (setq itags (append org-file-tags itags))
-            (delete-dups
-             (append (org-remove-uninherited-tags itags) ltags))))))))
+            (nreverse
+             (delete-dups
+              (nreverse (nconc (org-remove-uninherited-tags itags)
+                               ltags))))))))))
 
 (defun org-get-buffer-tags ()
   "Get a table of all tags used in the buffer, for completion."