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CC Mode: check for and fix missing call to before_change_functions.

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Fixes bug #24094 and bug #24074.

This can happen with `revert-buffer' or sometimes `find-file', when the file
is already in a buffer, but the file has been changed outside of Emacs.

* lisp/progmodes/cc-mode (c-after-change): When we detect a missing
invocation of c-before-change-functions, we assume the changed region is the
entire buffer, and call c-before-change explicitly before proceding.
This commit is contained in:
Alan Mackenzie 2016-08-09 16:09:18 +00:00
parent 8b789c8cfe
commit 9cf9095838
1 changed files with 21 additions and 4 deletions
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25
lisp/progmodes/cc-mode.el
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@ -492,10 +492,15 @@ preferably use the `c-mode-menu' language constant directly."
(defvar c-just-done-before-change nil)
(make-variable-buffer-local 'c-just-done-before-change)
;; This variable is set to t by `c-before-change' and to nil by
;; `c-after-change'. It is used to detect a spurious invocation of
;; `before-change-functions' directly following on from a correct one. This
;; happens in some Emacsen, for example when `basic-save-buffer' does (insert
;; ?\n) when `require-final-newline' is non-nil.
;; `c-after-change'. It is used for two purposes: (i) to detect a spurious
;; invocation of `before-change-functions' directly following on from a
;; correct one. This happens in some Emacsen, for example when
;; `basic-save-buffer' does (insert ?\n) when `require-final-newline' is
;; non-nil; (ii) to detect when Emacs fails to invoke
;; `before-change-functions'. This can happend when reverting a buffer - see
;; bug #24094. It seems these failures happen only in GNU Emacs; XEmacs
;; seems to maintain the strict alternation of calls to
;; `before-change-functions' and `after-change-functions'.
(defun c-basic-common-init (mode default-style)
"Do the necessary initialization for the syntax handling routines
@ -1251,6 +1256,18 @@ Note that the style variables are always made local to the buffer."
;; This calls the language variable c-before-font-lock-functions, if non nil.
;; This typically sets `syntax-table' properties.
;; We can sometimes get two consecutive calls to `after-change-functions'
;; without an intervening call to `before-change-functions' when reverting
;; the buffer (see bug #24094). Whatever the cause, assume that the entire
;; buffer has changed.
(when (not c-just-done-before-change)
(save-restriction
(widen)
(c-before-change (point-min) (point-max))
(setq beg (point-min)
end (point-max)
old-len (- end beg))))
;; (c-new-BEG c-new-END) will be the region to fontify. It may become
;; larger than (beg end).
(setq c-new-END (- (+ c-new-END (- end beg)) old-len))