bug#10738: insert before setting the mark means the mark wont be set

bug#10738: insert before setting the mark means the mark wont be set

[Christopher Monsanto]

From emacs -q, consider the following program:

(defun foo ()
  (interactive)
  (insert "bar")
  (push-mark)
  (forward-line)
  (activate-mark))

M-x foo, bar appears, but the mark is not set.

(defun baz ()
   (interactive)
   (push-mark)
   (forward-line)
   (activate-mark))

I wouldn't expect a command *before* setting the mark to affect if the
mark was actually set. Is this a concurrency bug?



In GNU Emacs 24.0.93.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.24.6)
 of 2012-02-04 on WORKCOMPUTER
Windowing system distributor `The X.Org Foundation', version 11.0.11004000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
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  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

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t - e m a c s - b u g <return>

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Christopher Monsanto
chris@monsan.to  --  http://monsan.to/

bug#10738: insert before setting the mark means the mark wont be set

[Stefan Monnier]

>> From emacs -q, consider the following program:
> (defun foo ()
>   (interactive)
>   (insert "bar")
>   (push-mark)
>   (forward-line)
>   (activate-mark))

> M-x foo, bar appears, but the mark is not set.

> (defun baz ()
>    (interactive)
>    (push-mark)
>    (forward-line)
>    (activate-mark))

> I wouldn't expect a command *before* setting the mark to affect if the
> mark was actually set. Is this a concurrency bug?

The mark gets deactivated after a command that modifies the buffer.
`foo' above is a command that modifies the buffer, so the mark is
deactivated afterwards.  This is done via the
`deactivate-mark' variable.
You can let-bind it around the call to `insert' to prevent that variable
from being set.


        Stefan