Hello,

This one is a long standing issue. I didn't include it in the projects
thread since the patch was almost finished.

Basically, syntax between export blocks and special blocks is ambiguous,
as it depends on the export back-end loaded. For example,

  #+begin_odt
  <<target>>
  #+end_odt

will be parsed very differently if `ox-odt' is loaded or not. In the
former case, the target is inactive whereas in the latter case, it can
be reached with an internal link.

As a solution, export blocks are explicitly marked as such at the syntax
level to disambiguate their parsing from special blocks. The new syntax
is:

  #+BEGIN_EXPORT backend
  ...
  #+END_EXPORT

instead of

  #+BEGIN_backend
  ...
  #+END_backend

So, basically, "export" is a reserved block type, much like "src". As
a consequence, =INCLUDE= keywords syntax is modified, e.g.,

,#+INCLUDE: "file.org" HTML

becomes

,#+INCLUDE: "file.org" export html

The following function, included in ORG-NEWS, updates any Org document
to the new syntax. It is meant to be applied after applying the patch.

  (defun org-repair-export-blocks ()
    "Repair export blocks and INCLUDE keywords in current buffer."
    (when (eq major-mode 'org-mode)
      (let ((case-fold-search t)
            (back-end-re (regexp-opt
                          '("HTML" "ASCII" "LATEX" "ODT" "MARKDOWN" "MD" "ORG"
                            "MAN" "BEAMER" "TEXINFO" "GROFF" "KOMA-LETTER")
                          t)))
        (org-with-wide-buffer
         (goto-char (point-min))
         (let ((block-re (concat "^[ \t]*#\\+BEGIN_" back-end-re)))
           (save-excursion
             (while (re-search-forward block-re nil t)
               (let ((element (save-match-data (org-element-at-point))))
                 (when (eq (org-element-type element) 'special-block)
                   (save-excursion
                     (goto-char (org-element-property :end element))
                     (save-match-data (search-backward "_"))
                     (forward-char)
                     (insert "EXPORT")
                     (delete-region (point) (line-end-position)))
                   (replace-match "EXPORT \\1" nil nil nil 1))))))
         (let ((include-re
                (format "^[ \t]*#\\+INCLUDE: .*?%s[ \t]*$" back-end-re)))
           (while (re-search-forward include-re nil t)
             (let ((element (save-match-data (org-element-at-point))))
               (when (and (eq (org-element-type element) 'keyword)
                          (string= (org-element-property :key element) "INCLUDE"))
                 (replace-match "EXPORT \\1" nil nil nil 1)))))))))

The patch is still lacking documentation update. Once applied, I plan to
implement two checkers in Org lint: one to detect old syntax and another
one to signal a missing back-end after BEGIN_EXPORT string.

Feedback welcome,


Regards,

-- 
Nicolas Goaziou                                                0x80A93738