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bug#39585: after-change-functions called with invalid positions in call-
bug#39585: after-change-functions called with invalid positions in call-process
Wed, 12 Feb 2020 22:56:49 -0500
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1
Recent changes in call-process have introduced surprising behavior in
after-change-functions (and caused bugs in flycheck, e.g.
https://github.com/flycheck/flycheck/issues/1677). From the documentation, I
expected that functions added to the after-change-functions hook would be
called only with valid positions. However, the following snippets shows that
it's not the case:
(defun ~/after-change (beg end len)
(message "(after-change %S %S %S); (buffer %S %S %S)"
beg end len (point-min) (point-max) (buffer-size)))
(with-current-buffer (get-buffer-create "*tmp*")
(add-hook 'after-change-functions #'~/after-change)
(call-process "echo" nil t t "Hello"))
Running it repeatedly, this is what I observe:
(after-change 7 13 0); (buffer 1 7 6)
(after-change 13 19 0); (buffer 1 13 12)
(after-change 19 25 0); (buffer 1 19 18)
(after-change 25 31 0); (buffer 1 25 24)
Note how each time the after-change-functions hook is called with a region past
the end of the buffer. It's as if after-change-functions was in fact call
right before the insertion, instead of after.
Previous versions of Emacs didn't call after-change-functions in this case; it
seems that the new behavior was introduced by this commit:
Author: Alan Mackenzie <address@hidden>
Date: Wed Jan 22 19:50:30 2020 +0000
Make call_process call signal_after_change. This fixes bug #38691.
Now, functions such as call-proess-region invoke after-change-functions
* src/callproc.c (call_process): Call prepare_to_modify_buffer in a
place, no longer delegating the task to insert_1_both, etc. Call
signal_after_change in each of two code branches, such that
before-change-functions and after-change-functions are always called in
Alan, is this behavior expected?
- bug#39585: after-change-functions called with invalid positions in call-process,
Clément Pit-Claudel <=