font-lock-fontify-buffer crashes on gitit doc

[conal]

The following Markdown doc crashes mmm-mode breaks mmm-mode:

---
title: gitit doc
...


```
ham
```

More than three hyphens below, and (font-lock-fontify-buffer) crashes.
----

Note that in gitit pages, meta-data blocks end with three dots, not three hyphens.

I first encountered this issue when using markdown-mode with mmm-mode. I submitted an mmm-mode issue, but it appears to be independent of mmm-mode, and indeed can be triggered by font-lock-fontify-buffer.

I'm running markdown-mode version 2.1 from MELPA.

Backtrace:

Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil)
  markdown-match-inline-generic("\\(?:\\`\\|[^\\]\\)\\(\\(`+\\)\\(\\(?:.\\|\n[^\n]\\)*?[^`]\\)\\(\\2\\)\\)\\(?:[^`]\\|\\'\\)" 130)
  markdown-match-code(130)
  font-lock-fontify-keywords-region(1 130 nil)
  font-lock-default-fontify-region(1 130 nil)
  font-lock-fontify-region(1 130 nil)
  byte-code("\212\303 �\304\216\305ed   #\210\306 \210\307\211�+\207" [save-match-data-internal verbose font-lock-fontified match-data ((byte-code "\301�\302\"\207" [save-match-data-internal set-match-data evaporate] 3)) font-lock-fontify-region font-lock-after-fontify-buffer t] 4)
  font-lock-default-fontify-buffer()
  eval((font-lock-default-fontify-buffer) nil)
  eval-expression((font-lock-default-fontify-buffer) nil)
  call-interactively(eval-expression nil nil)
  command-execute(eval-expression)

[syohex]

I cannot reproduce this issue on Emacs 24.5 and development Emacs. Can you reproduce this issue with latest version ?

And could you tell us how to reproduce this issue in more detail ?

• Emacs version
• Minimum configuration
• etc

[conal]

@syohex I just tried again and didn't get the error. However, this one (as used by mmm-mode) does:

(font-lock-fontify-region (point-min) (point-max))

Okay when the last line has only three hyphens, but crashes on four.

I also fixed the formatting in my issue report above, to clarify that the "More than" and "---" lines are part of the test case.

The following Emacs startup code suffices for me to provoke the error:

(setq debug-on-error t)

(require 'package)
(add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/") t)
(package-initialize)

(require 'markdown-mode)

emacs-version tells me:

GNU Emacs 24.5.1 (x86_64-apple-darwin15.4.0, NS apple-appkit-1404.46) of 2016-06-17 on 80e65028ef76

[conal]

It does seem that there may be some connection to mmm-mode to trigger this problem in ordinary operation. I'm not sure that I've gotten to the heart of it. More information here.

To see the problematic interaction between mmm-mode and markdown-mode, the following Emacs init code suffices for me:

(setq debug-on-error t)

(require 'package)
(add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/") t)
(package-initialize)

(package-install 'markdown-mode)
(package-install 'mmm-mode)

(require 'markdown-mode)
(require 'mmm-mode)

To trigger the error, visit the markdown example given above, and do M-x mmm-mode-on.

[syohex]

Please reopen if you still have problem.