Subject: bug#25132: 26.0.50; emacs hangs when loading org file with python source blocks

From: [email-masked]
Date: Sat, 07 Jan 2017 16:20:16 -0500

tags 25132 patch
quit

[email-masked] writes:
> The problem is that org updates its temporary fontification buffer from
> its fontify rules which are called by jit-lock-function, which means
> that inhibit-modification-hooks is bound to t.  Therefore, when
> org-src-font-lock-fontify-block calls delete-region to remove leftover text from
> the previous source block fontification, the `before-change-functions'
> are not run.  In this case `syntax-ppss-flush-cache' is the important
> function that doesn't get run, so `syntax-propertize--done' is still set
> from before and messes up python.el's fontification routines.

I think with-silent-modifications should let-bind
inhibit-modification-hooks buffer locally:

>From da4f1c0338b2b98f97a553568c4b80872484ee97 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <[email-masked]>
Date: Sat, 7 Jan 2017 15:47:37 -0500
Subject: [PATCH v1] Inhibit modification hooks buffer locally

`with-silent-modifications' let-binds `inhibit-modification-hooks' to t
globally.  So modifications to other buffers don't trigger modication
hooks.  This causes unexpected results when functions called from
`jit-lock-function' use temporary buffers and modifies them (Bug#25132).

* lisp/subr.el (with-silent-modifications): Bind
inhibit-modification-hooks buffer locally.
---
 lisp/subr.el | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lisp/subr.el b/lisp/subr.el
index 5377416..fe20d68 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -3298,7 +3298,8 @@ with-silent-modifications
     `(let* ((,modified (buffer-modified-p))
             (buffer-undo-list t)
             (inhibit-read-only t)
-            (inhibit-modification-hooks t))
+            (inhibit-modification-hooks
+             (progn (make-local-variable 'inhibit-modification-hooks) t)))
        (unwind-protect
            (progn
              ,@body)
-- 
2.9.3

Perhaps the other variables it binds should be buffer local as well?

This bug is new in Emacs 25.1, but changing with-silent-modifications is
a bit risky.  Therefore, I propose the following for the emacs-25
branch:

>From 338aa0c37eba0401616e8e02f0143a57edffd486 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <[email-masked]>
Date: Sat, 7 Jan 2017 16:05:19 -0500
Subject: [PATCH v1] Call modification hooks in org-src fontify buffers

* lisp/org/org-src.el (org-src-font-lock-fontify-block): Let-bind
`inhibit-modification-hooks' to nil, since this function can be called
from jit-lock-function which binds that variable to t (Bug#25132).
---
 lisp/org/org-src.el | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lisp/org/org-src.el b/lisp/org/org-src.el
index d01f108..9b66907 100644
--- a/lisp/org/org-src.el
+++ b/lisp/org/org-src.el
@@ -913,8 +913,9 @@ org-src-font-lock-fontify-block
 	  (with-current-buffer
 	      (get-buffer-create
 	       (concat " org-src-fontification:" (symbol-name lang-mode)))
-	    (delete-region (point-min) (point-max))
-	    (insert string " ") ;; so there's a final property change
+	    (let ((inhibit-modification-hooks nil)) ; Avoid Bug#25132.
+              (delete-region (point-min) (point-max))
+              (insert string " ")) ;; so there's a final property change
 	    (unless (eq major-mode lang-mode) (funcall lang-mode))
             (org-font-lock-ensure)
 	    (setq pos (point-min))
-- 
2.9.3