[O] Bug: Broken fontification of code blocks [7.5 (release_7.5.525.gd6fb5)]

[Oleksandr Manzyuk]

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what in fact did happen.  You don't know how to make a good report?  See

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How to reproduce:

1.  Launch Emacs with the following minimal =.emacs= (adjust the path
to `org-mode' if necessary):

(add-to-list 'load-path "~/.emacs.d/site-lisp/org-mode/lisp")
(add-to-list 'load-path "~/.emacs.d/site-lisp/org-mode/contrib/lisp")

(require 'org-install)

(add-to-list 'auto-mode-alist '("\\.org$" . org-mode))

(setq org-src-fontify-natively t)

2.  Edit the following minimal example:

#+begin_src
(defun id (x) x)
#+end_src

It is expected that the text between #+begin_src and #+end_src be
fontified (in my case, using the reverse video mode of Emacs with the
default color theme, it should be grey70).  This doesn't happen, the
text is white.  If I change the first line to

#+begin_src emacs-lisp

the interior of the code block is properly fontified according to the
mode.  If I remove `emacs-lisp', the text becomes white again.

I think I've nailed down the problem.  The following patch works for
me (although I didn't test it thoroughly):

diff --git a/lisp/org.el b/lisp/org.el
index 3162cc3..2f79298 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -5166,7 +5166,7 @@ will be prompted for."
   "Fontify #+ lines and blocks, in the correct ways."
   (let ((case-fold-search t))
     (if (re-search-forward
-        "^\\([ \t]*#\\+\\(\\([a-zA-Z]+:?\\|
\\|$\\)\\(_\\([a-zA-Z]+\\)\\)?\\)[ \t]*\\(\\([^ \t\n]*\\)[
\t]*\\(.*\\)\\)\\)"
+        "^\\([ \t]*#\\+\\(\\([a-zA-Z]+:?\\|
\\|$\\)\\(_\\([a-zA-Z]+\\)\\)?\\)[ \t]*\\(\\([^ \t\n]+\\)?[
\t]*\\(.*\\)\\)\\)"
         limit t)
        (let ((beg (match-beginning 0))
              (block-start (match-end 0))

The problem is that with the old regexp, if no language is specified,
the 7th group still matches and becomes "", the empty string, not nil,
and therefore the condition (and lang org-src-fontify-natively) always
succeeds provided that `org-src-fontify-natively' is set to t.

Emacs  : GNU Emacs 23.2.1 (x86_64-pc-linux-gnu, GTK+ Version 2.20.1)
 of 2010-09-02 on pluot, modified by Debian
Package: Org-mode version 7.5 (release_7.5.525.gd6fb5)

current state:
==============
(setq
 org-export-latex-after-initial-vars-hook '(org-beamer-after-initial-vars)
 org-speed-command-hook '(org-speed-command-default-hook
org-babel-speed-command-hook)
 org-src-fontify-natively t
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-export-blocks-postblock-hook '(org-exp-res/src-name-cleanup)
 org-export-latex-format-toc-function 'org-export-latex-format-toc-default
 org-tab-first-hook '(org-hide-block-toggle-maybe
org-src-native-tab-command-maybe
                      org-babel-hide-result-toggle-maybe)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
                     org-src-mode-configure-edit-buffer)
 org-confirm-shell-link-function 'yes-or-no-p
 org-export-first-hook '(org-beamer-initialize-open-trackers)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
                  org-cycle-show-empty-lines
                  org-optimize-window-after-visibility-change)
 org-export-preprocess-before-normalizing-links-hook
'(org-remove-file-link-modifiers)
 org-mode-hook '((lambda nil
                  (org-add-hook (quote change-major-mode-hook)
                   (quote org-show-block-all) (quote append) (quote local))
                  )
                 (lambda nil
                  (org-add-hook (quote change-major-mode-hook)
                   (quote org-babel-show-result-all) (quote append) (quote 
local))
                  )
                 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point
org-babel-execute-safely-maybe)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-export-interblocks '((lob org-babel-exp-lob-one-liners)
                          (src org-babel-exp-inline-src-blocks))
 org-occur-hook '(org-first-headline-recenter)
 org-export-preprocess-before-selecting-backend-code-hook
'(org-beamer-select-beamer-code)
 org-export-latex-final-hook '(org-beamer-amend-header org-beamer-fix-toc
                               org-beamer-auto-fragile-frames
                               org-beamer-place-default-actions-for-lists)
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-export-blocks '((src org-babel-exp-src-block nil)
                     (comment org-export-blocks-format-comment t)
                     (ditaa org-export-blocks-format-ditaa nil)
                     (dot org-export-blocks-format-dot nil))
 )