Buffer with HTML comment at EOB causes error

[kaushalmodi]

A buffer with HTML comment like <!--more--> at EOB (no trailing newline!) causes error: (wrong-type-argument integer-or-marker-p nil)

Expected Behavior

That error should not happen.

Actual Behavior

Error happens.

Steps to Reproduce

(see the following post in this thread)

Backtrace

I get this after having the markdown mode file buffer contain just <!--more-->. I have require-final-newline set to nil, go to the end of that line, do C-d, then save (C-x C-s), and then M-x revert-buffer to get this.

Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil)
  remove-text-properties(nil 12 (markdown-tilde-fence-begin nil markdown-tilde-fence-end nil markdown-fenced-code nil markdown-yaml-metadata-begin nil markdown-yaml-metadata-end nil markdown-yaml-metadata-section nil markdown-gfm-block-begin nil markdown-gfm-block-end nil markdown-gfm-code nil markdown-list-item nil markdown-pre nil markdown-blockquote nil markdown-hr nil markdown-comment nil markdown-heading nil markdown-heading-1-setext nil markdown-heading-2-setext nil markdown-heading-1-atx nil markdown-heading-2-atx nil markdown-heading-3-atx nil markdown-heading-4-atx nil markdown-heading-5-atx nil markdown-heading-6-atx nil markdown-metadata-key nil markdown-metadata-value nil markdown-metadata-markup nil))
  markdown-syntax-propertize-comments(6 12)
  markdown-syntax-propertize-comments(1 12)
  markdown-syntax-propertize(1 12)
  markdown-font-lock-extend-region-function(12 12 1)
  run-hook-with-args(markdown-font-lock-extend-region-function 12 12 1)
  jit-lock-after-change(12 12 1)
  delete-char(1)
  org-delete-char(1)
  funcall-interactively(org-delete-char 1)
  call-interactively(org-delete-char nil nil)
  command-execute(org-delete-char)

Software Versions

• Markdown Mode: markdown-mode, version 2.4-dev
• Emacs: GNU Emacs 27.0.50 (build 37, x86_64-pc-linux-gnu, GTK+ Version 2.24.23) of 2018-04-05
• OS: RHEL 6.6

/cc @zzamboni

This issue originated from kaushalmodi/ox-hugo#152.

[kaushalmodi]

OK, found an emacs -Q recipe:

Content of test.md

(Save that file after setting require-final-newline to nil.)

<!--more-->

Command

emacs -Q -l markdown-mode.el test.md --eval "(toggle-debug-on-error)"

Steps

1. Type above command
2. C-e
3. C-d
4. Error!

Backtrace

Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil)
  remove-text-properties(nil 12 (markdown-tilde-fence-begin nil markdown-tilde-fence-end nil markdown-fenced-code nil markdown-yaml-metadata-begin nil markdown-yaml-metadata-end nil markdown-yaml-metadata-section nil markdown-gfm-block-begin nil markdown-gfm-block-end nil markdown-gfm-code nil markdown-list-item nil markdown-pre nil markdown-blockquote nil markdown-hr nil markdown-comment nil markdown-heading nil markdown-heading-1-setext nil markdown-heading-2-setext nil markdown-heading-1-atx nil markdown-heading-2-atx nil markdown-heading-3-atx nil markdown-heading-4-atx nil markdown-heading-5-atx nil markdown-heading-6-atx nil markdown-metadata-key nil markdown-metadata-value nil markdown-metadata-markup nil))
  (let ((comment-end (match-end 0)) (comment-begin (nth 8 (syntax-ppss)))) (put-text-property (1- comment-end) comment-end 'syntax-table (string-to-syntax ">")) (remove-text-properties comment-begin comment-end markdown--syntax-properties) (put-text-property comment-begin comment-end 'markdown-comment (list comment-begin comment-end)) (markdown-syntax-propertize-comments (min (1+ comment-end) end (point-max)) end))
  (cond ((and (not in-comment) (re-search-forward markdown-regex-comment-start end t) (not (markdown-inline-code-at-point-p)) (not (markdown-code-block-at-point-p))) (let ((open-beg (match-beginning 0))) (put-text-property open-beg (1+ open-beg) 'syntax-table (string-to-syntax "<")) (markdown-syntax-propertize-comments (min (1+ (match-end 0)) end (point-max)) end))) ((and in-comment (re-search-forward markdown-regex-comment-end end t)) (let ((comment-end (match-end 0)) (comment-begin (nth 8 (syntax-ppss)))) (put-text-property (1- comment-end) comment-end 'syntax-table (string-to-syntax ">")) (remove-text-properties comment-begin comment-end markdown--syntax-properties) (put-text-property comment-begin comment-end 'markdown-comment (list comment-begin comment-end)) (markdown-syntax-propertize-comments (min (1+ comment-end) end (point-max)) end))) (t nil))
  (let* ((in-comment (nth 4 (syntax-ppss)))) (goto-char start) (cond ((and (not in-comment) (re-search-forward markdown-regex-comment-start end t) (not (markdown-inline-code-at-point-p)) (not (markdown-code-block-at-point-p))) (let ((open-beg (match-beginning 0))) (put-text-property open-beg (1+ open-beg) 'syntax-table (string-to-syntax "<")) (markdown-syntax-propertize-comments (min (1+ (match-end 0)) end (point-max)) end))) ((and in-comment (re-search-forward markdown-regex-comment-end end t)) (let ((comment-end (match-end 0)) (comment-begin (nth 8 (syntax-ppss)))) (put-text-property (1- comment-end) comment-end 'syntax-table (string-to-syntax ">")) (remove-text-properties comment-begin comment-end markdown--syntax-properties) (put-text-property comment-begin comment-end 'markdown-comment (list comment-begin comment-end)) (markdown-syntax-propertize-comments (min (1+ comment-end) end (point-max)) end))) (t nil)))
  markdown-syntax-propertize-comments(6 12)
  (let ((open-beg (match-beginning 0))) (put-text-property open-beg (1+ open-beg) 'syntax-table (string-to-syntax "<")) (markdown-syntax-propertize-comments (min (1+ (match-end 0)) end (point-max)) end))
  (cond ((and (not in-comment) (re-search-forward markdown-regex-comment-start end t) (not (markdown-inline-code-at-point-p)) (not (markdown-code-block-at-point-p))) (let ((open-beg (match-beginning 0))) (put-text-property open-beg (1+ open-beg) 'syntax-table (string-to-syntax "<")) (markdown-syntax-propertize-comments (min (1+ (match-end 0)) end (point-max)) end))) ((and in-comment (re-search-forward markdown-regex-comment-end end t)) (let ((comment-end (match-end 0)) (comment-begin (nth 8 (syntax-ppss)))) (put-text-property (1- comment-end) comment-end 'syntax-table (string-to-syntax ">")) (remove-text-properties comment-begin comment-end markdown--syntax-properties) (put-text-property comment-begin comment-end 'markdown-comment (list comment-begin comment-end)) (markdown-syntax-propertize-comments (min (1+ comment-end) end (point-max)) end))) (t nil))
  (let* ((in-comment (nth 4 (syntax-ppss)))) (goto-char start) (cond ((and (not in-comment) (re-search-forward markdown-regex-comment-start end t) (not (markdown-inline-code-at-point-p)) (not (markdown-code-block-at-point-p))) (let ((open-beg (match-beginning 0))) (put-text-property open-beg (1+ open-beg) 'syntax-table (string-to-syntax "<")) (markdown-syntax-propertize-comments (min (1+ (match-end 0)) end (point-max)) end))) ((and in-comment (re-search-forward markdown-regex-comment-end end t)) (let ((comment-end (match-end 0)) (comment-begin (nth 8 (syntax-ppss)))) (put-text-property (1- comment-end) comment-end 'syntax-table (string-to-syntax ">")) (remove-text-properties comment-begin comment-end markdown--syntax-properties) (put-text-property comment-begin comment-end 'markdown-comment (list comment-begin comment-end)) (markdown-syntax-propertize-comments (min (1+ comment-end) end (point-max)) end))) (t nil)))
  markdown-syntax-propertize-comments(1 12)
  (save-excursion (remove-text-properties start end markdown--syntax-properties) (markdown-syntax-propertize-fenced-block-constructs start end) (markdown-syntax-propertize-list-items start end) (markdown-syntax-propertize-pre-blocks start end) (markdown-syntax-propertize-blockquotes start end) (markdown-syntax-propertize-headings start end) (markdown-syntax-propertize-hrs start end) (markdown-syntax-propertize-comments start end))
  (progn (save-excursion (remove-text-properties start end markdown--syntax-properties) (markdown-syntax-propertize-fenced-block-constructs start end) (markdown-syntax-propertize-list-items start end) (markdown-syntax-propertize-pre-blocks start end) (markdown-syntax-propertize-blockquotes start end) (markdown-syntax-propertize-headings start end) (markdown-syntax-propertize-hrs start end) (markdown-syntax-propertize-comments start end)))
  (unwind-protect (progn (save-excursion (remove-text-properties start end markdown--syntax-properties) (markdown-syntax-propertize-fenced-block-constructs start end) (markdown-syntax-propertize-list-items start end) (markdown-syntax-propertize-pre-blocks start end) (markdown-syntax-propertize-blockquotes start end) (markdown-syntax-propertize-headings start end) (markdown-syntax-propertize-hrs start end) (markdown-syntax-propertize-comments start end))) (if modified nil (restore-buffer-modified-p nil)))
  (let* ((modified (buffer-modified-p)) (buffer-undo-list t) (inhibit-read-only t) (inhibit-modification-hooks t)) (unwind-protect (progn (save-excursion (remove-text-properties start end markdown--syntax-properties) (markdown-syntax-propertize-fenced-block-constructs start end) (markdown-syntax-propertize-list-items start end) (markdown-syntax-propertize-pre-blocks start end) (markdown-syntax-propertize-blockquotes start end) (markdown-syntax-propertize-headings start end) (markdown-syntax-propertize-hrs start end) (markdown-syntax-propertize-comments start end))) (if modified nil (restore-buffer-modified-p nil))))
  markdown-syntax-propertize(1 12)
  (progn (markdown-syntax-propertize (car res) (cdr res)))
  (unwind-protect (progn (markdown-syntax-propertize (car res) (cdr res))) (set-match-data save-match-data-internal 'evaporate))
  (let ((save-match-data-internal (match-data))) (unwind-protect (progn (markdown-syntax-propertize (car res) (cdr res))) (set-match-data save-match-data-internal 'evaporate)))
  (progn (let ((save-match-data-internal (match-data))) (unwind-protect (progn (markdown-syntax-propertize (car res) (cdr res))) (set-match-data save-match-data-internal 'evaporate))))
  (if (= end (point-max)) (progn (let ((save-match-data-internal (match-data))) (unwind-protect (progn (markdown-syntax-propertize (car res) (cdr res))) (set-match-data save-match-data-internal 'evaporate)))))
  (progn (if (= end (point-max)) (progn (let ((save-match-data-internal (match-data))) (unwind-protect (progn (markdown-syntax-propertize (car res) (cdr res))) (set-match-data save-match-data-internal 'evaporate))))) (setq jit-lock-start (car res) jit-lock-end (cdr res)))
  (if res (progn (if (= end (point-max)) (progn (let ((save-match-data-internal (match-data))) (unwind-protect (progn (markdown-syntax-propertize (car res) (cdr res))) (set-match-data save-match-data-internal 'evaporate))))) (setq jit-lock-start (car res) jit-lock-end (cdr res))))
  (let ((res (markdown-syntax-propertize-extend-region start end))) (if res (progn (if (= end (point-max)) (progn (let ((save-match-data-internal (match-data))) (unwind-protect (progn (markdown-syntax-propertize (car res) (cdr res))) (set-match-data save-match-data-internal 'evaporate))))) (setq jit-lock-start (car res) jit-lock-end (cdr res)))))
  markdown-font-lock-extend-region-function(12 12 1)
  run-hook-with-args(markdown-font-lock-extend-region-function 12 12 1)
  jit-lock-after-change(12 12 1)
  delete-char(1 nil)
  funcall-interactively(delete-char 1 nil)
  call-interactively(delete-char nil nil)
  command-execute(delete-char)

[kaushalmodi]

@jrblevin Can you please look at this?

[jrblevin]

Thanks for the report. I think this is fixed now, but could you please confirm?

[gwern]

I run into this problem regularly with my files. I just upgraded to the Github dev version after noticing that the stable version doesn't have this fix, and the problem appears to be gone for me. (Which I appreciate because, quite aside from all the syntax highlighting and features, I've managed to screw up a number of indented lists in affected pages by forgetting that non-markdown-mode doesn't indent enough...)