[PATCH] Prevent spurious clash warnings when looking at an ERC log file and logging to it

[Aidan Kehoe]

When I open an ERC log file read-only in a buffer and am concurrently
writing to it (with erc-enable-logging and activity in the relevant
channel), I get told regularly that [file] has changed on disk; really edit
the buffer? (I put a backtrace call in
#’ask-user-about-supersession-threat-minibuf and there’s some sample output
below.) This is inappropriate--actual clashes will be detected in the actual
buffer, later, and won’t be for read-only buffers--and can be avoided by
binding inhibit-clash-detection to to in #'erc-save-buffer-in-logs.

xemacs-packages/erc/ChangeLog addition:

2007-09-30  Aidan Kehoe  <kehoea at parhasard.net>

	* erc-log.el (erc-save-buffer-in-logs):
	Prevent spurious warnings when looking at a log file and
	concurrently saving to it. 


XEmacs Packages source patch:
Diff command:   cvs -q diff -Nu
Files affected: xemacs-packages/erc/erc-log.el
===================================================================
RCS

Index: xemacs-packages/erc/erc-log.el
===================================================================
RCS file: /pack/xemacscvs/XEmacs/packages/xemacs-packages/erc/erc-log.el,v
retrieving revision 1.9
diff -u -u -r1.9 erc-log.el
--- xemacs-packages/erc/erc-log.el	2006/02/19 12:57:29	1.9
+++ xemacs-packages/erc/erc-log.el	2007/09/30 12:39:34
@@ -328,7 +328,8 @@
   (or buffer (setq buffer (current-buffer)))
   (when (erc-logging-enabled buffer)
     (let ((file (erc-current-logfile buffer))
-	  (coding-system-for-write erc-log-file-coding-system))
+	  (coding-system-for-write erc-log-file-coding-system)
+	  (inhibit-clash-detection t))
       (save-excursion
 	(with-current-buffer buffer
 	  (save-restriction

-- 
On the quay of the little Black Sea port, where the rescued pair came once
more into contact with civilization, Dobrinton was bitten by a dog which was
assumed to be mad, though it may only have been indiscriminating. (Saki)

  backtrace(t t)
  (progn (backtrace standard-output t) (let (answer) (while (null answer) (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) " (file-name-nondirectory filename)) (let ((tem (downcase (let ((cursor-in-echo-area t)) (read-char))))) (setq answer (if (= tem help-char) (quote help) (cdr (assoc tem (quote ((?n . yield) (?\^G . yield) (?y . proceed) (?r . revert) (?\? . help))))))) (cond ((null answer) (beep) (message "Please type y, n or r; or ? for help") (sit-for 3)) ((eq answer (quote help)) (ask-user-about-supersession-help) (setq answer nil)) ((eq answer (quote revert)) (revert-buffer nil (not (buffer-modified-p))) (signal (quote file-supersession) (list "File reverted" filename))) ((eq answer (quote yield)) (signal (quote file-supersession) (list "File changed on disk" filename)))))) (message "File on disk now will become a backup file if you save these changes.") (setq buffer-backed-up nil)))
  # (unwind-protect ...)
  (unwind-protect (progn (backtrace standard-output t) (let (answer) (while (null answer) (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) " (file-name-nondirectory filename)) (let ((tem (downcase (let ((cursor-in-echo-area t)) (read-char))))) (setq answer (if (= tem help-char) (quote help) (cdr (assoc tem (quote ((?n . yield) (?\^G . yield) (?y . proceed) (?r . revert) (?\? . help))))))) (cond ((null answer) (beep) (message "Please type y, n or r; or ? for help") (sit-for 3)) ((eq answer (quote help)) (ask-user-about-supersession-help) (setq answer nil)) ((eq answer (quote revert)) (revert-buffer nil (not (buffer-modified-p))) (signal (quote file-supersession) (list "File reverted" filename))) ((eq answer (quote yield)) (signal (quote file-supersession) (list "File changed on disk" filename)))))) (message "File on disk now will become a backup file if you save these changes.") (setq buffer-backed-up nil))) (set-window-configuration G62625))
  # bind (G62625)
  (let ((G62625 (current-window-configuration))) (unwind-protect (progn (backtrace standard-output t) (let (answer) (while (null answer) (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) " (file-name-nondirectory filename)) (let ((tem (downcase (let ((cursor-in-echo-area t)) (read-char))))) (setq answer (if (= tem help-char) (quote help) (cdr (assoc tem (quote ((?n . yield) (?\^G . yield) (?y . proceed) (?r . revert) (?\? . help))))))) (cond ((null answer) (beep) (message "Please type y, n or r; or ? for help") (sit-for 3)) ((eq answer (quote help)) (ask-user-about-supersession-help) (setq answer nil)) ((eq answer (quote revert)) (revert-buffer nil (not (buffer-modified-p))) (signal (quote file-supersession) (list "File reverted" filename))) ((eq answer (quote yield)) (signal (quote file-supersession) (list "File changed on disk" filename)))))) (message "File on disk now will become a backup file if you save these changes.") (setq buffer-backed-up nil)))!
  (set-window-configuration G62625)))
  (save-window-excursion (backtrace standard-output t) (let (answer) (while (null answer) (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) " (file-name-nondirectory filename)) (let ((tem (downcase (let ((cursor-in-echo-area t)) (read-char))))) (setq answer (if (= tem help-char) (quote help) (cdr (assoc tem (quote ((?n . yield) (?\^G . yield) (?y . proceed) (?r . revert) (?\? . help))))))) (cond ((null answer) (beep) (message "Please type y, n or r; or ? for help") (sit-for 3)) ((eq answer (quote help)) (ask-user-about-supersession-help) (setq answer nil)) ((eq answer (quote revert)) (revert-buffer nil (not (buffer-modified-p))) (signal (quote file-supersession) (list "File reverted" filename))) ((eq answer (quote yield)) (signal (quote file-supersession) (list "File changed on disk" filename)))))) (message "File on disk now will become a backup file if you save these changes.") (setq buffer-backed-up nil)))
  # bind (filename)
  ask-user-about-supersession-threat-minibuf("/home/aidan/.irc/logs/#linguistics!kehoea at irc.freenode.net:7000.txt")
  # bind (filename)
  ask-user-about-supersession-threat("/home/aidan/.irc/logs/#linguistics!kehoea at irc.freenode.net:7000.txt")
  # (unwind-protect ...)
  write-region-internal(15331 15446 "/home/aidan/.irc/logs/#linguistics!kehoea at irc.freenode.net:7000.txt" t nomessage nil escape-quoted)
  # bind (func coding-system lockname visit append filename end start)
  write-region(15331 15446 "/home/aidan/.irc/logs/#linguistics!kehoea at irc.freenode.net:7000.txt" t nomessage)
  # (unwind-protect ...)
  # (unwind-protect ...)
  # (unwind-protect ...)
  # bind (file coding-system-for-write buffer)
  erc-save-buffer-in-logs()
  run-hooks(erc-save-buffer-in-logs)
  # (unwind-protect ...)
  # (unwind-protect ...)
  # (unwind-protect ...)
  # bind (string buffer-undo-list inhibit-read-only insert-position)
  # (unwind-protect ...)
  # bind (buffer string)
  erc-display-line-1("*** }{obbes (n=pinnerup at ip247.rev112.brygge.net) has quit: Read error: 110 (Connection timed out)" #<buffer "#linguistics">)
  # bind (--dolist-temp--12738 buf inhibit-point-motion-hooks new-bufs buffer string)
  erc-display-line("*** }{obbes (n=pinnerup at ip247.rev112.brygge.net) has quit: Read error: 110 (Connection timed out)" (#<buffer "#linguistics">))
  # bind (string args msg buffer type parsed)
  erc-display-message([cl-struct-erc-response ":}{obbes!n=pinnerup at ip247.rev112.brygge.net QUIT :Read error: 110 (Connection timed out)" "}{obbes!n=pinnerup at ip247.rev112.brygge.net" "QUIT" ("Read error: 110 (Connection timed out)") "Read error: 110 (Connection timed out)"] notice (#<buffer "#linguistics">) QUIT ?n "}{obbes" ?u "n=pinnerup" ?h "ip247.rev112.brygge.net" ?r "Read error: 110 (Connection timed out)")
  # bind (host login nick G13502 reason bufs parsed proc)
  erc-server-QUIT(#<network connection "erc-irc.freenode.net-7000" (7000 . "irc.freenode.net") state:run> [cl-struct-erc-response ":}{obbes!n=pinnerup at ip247.rev112.brygge.net QUIT :Read error: 110 (Connection timed out)" "}{obbes!n=pinnerup at ip247.rev112.brygge.net" "QUIT" ("Read error: 110 (Connection timed out)") "Read error: 110 (Connection timed out)"])
  run-hook-with-args-until-success(erc-server-QUIT #<network connection "erc-irc.freenode.net-7000" (7000 . "irc.freenode.net") state:run> [cl-struct-erc-response ":}{obbes!n=pinnerup at ip247.rev112.brygge.net QUIT :Read error: 110 (Connection timed out)" "}{obbes!n=pinnerup at ip247.rev112.brygge.net" "QUIT" ("Read error: 110 (Connection timed out)") "Read error: 110 (Connection timed out)"])
  # bind (hook message process)
  erc-call-hooks(#<network connection "erc-irc.freenode.net-7000" (7000 . "irc.freenode.net") state:run> [cl-struct-erc-response ":}{obbes!n=pinnerup at ip247.rev112.brygge.net QUIT :Read error: 110 (Connection timed out)" "}{obbes!n=pinnerup at ip247.rev112.brygge.net" "QUIT" ("Read error: 110 (Connection timed out)") "Read error: 110 (Connection timed out)"])
  # bind (parsed-response process)
  erc-handle-parsed-server-response(#<network connection "erc-irc.freenode.net-7000" (7000 . "irc.freenode.net") state:run> [cl-struct-erc-response ":}{obbes!n=pinnerup at ip247.rev112.brygge.net QUIT :Read error: 110 (Connection timed out)" "}{obbes!n=pinnerup at ip247.rev112.brygge.net" "QUIT" ("Read error: 110 (Connection timed out)") "Read error: 110 (Connection timed out)"])
  # bind (posn msg)
  # (unwind-protect ...)
  # bind (match-data string proc)
  erc-parse-server-response(#<network connection "erc-irc.freenode.net-7000" (7000 . "irc.freenode.net") state:run> ":}{obbes!n=pinnerup at ip247.rev112.brygge.net QUIT :Read error: 110 (Connection timed out)")
  # bind (line erc-server-processing-p)
  # (unwind-protect ...)
  # bind (string process)
  erc-server-filter-function(#<network connection "erc-irc.freenode.net-7000" (7000 . "irc.freenode.net") state:run> ":}{obbes!n=pinnerup at ip247.rev112.brygge.net QUIT :Read error: 110 (Connection timed out)\n")
  # (condition-case ... . error)
  # (catch top-level ...)