* lisp/emacs-lisp/lisp-mode.el: Don't highlight \( at BOL

(elisp--font-lock-backslash): Extract from lisp-el-font-lock-keywords-2.
Don't highlight \ at BOL.  Don't assume syntax-ppss preserves match-data.

diff --git a/lisp/emacs-lisp/lisp-mode.el b/lisp/emacs-lisp/lisp-mode.el
index d6293c030407427e0fe5ef3d774fb8d7b33c4716..b7a5eb774da04e2200da200e82bc3774c5f007d3 100644 (file)
--- a/lisp/emacs-lisp/lisp-mode.el
+++ b/lisp/emacs-lisp/lisp-mode.el
@@ -259,6 +259,24 @@ This will generate compile-time constants from BINDINGS."
                     (funcall loop bindings)))))))
     (funcall loop bindings)))
 
+(defun elisp--font-lock-backslash ()
+  (let* ((beg0 (match-beginning 0))
+         (end0 (match-end 0))
+         (ppss (save-excursion (syntax-ppss beg0))))
+    (and (nth 3 ppss)                  ;Inside a string.
+         (not (nth 5 ppss))            ;The \ is not itself \-escaped.
+         ;; Don't highlight the \( introduced because of
+         ;; `open-paren-in-column-0-is-defun-start'.
+         (not (eq ?\n (char-before beg0)))
+         (equal (ignore-errors
+                  (car (read-from-string
+                        (format "\"%s\""
+                                (buffer-substring-no-properties
+                                 beg0 end0)))))
+                (buffer-substring-no-properties (1+ beg0) end0))
+         `(face ,font-lock-warning-face
+                help-echo "This \\ has no effect"))))
+
 (let-when-compile
     ((lisp-fdefs '("defmacro" "defun"))
      (lisp-vdefs '("defvar"))
@@ -413,17 +431,7 @@ This will generate compile-time constants from BINDINGS."
           (1 font-lock-constant-face prepend))
          ;; Ineffective backslashes (typically in need of doubling).
          ("\\(\\\\\\)\\([^\"\\]\\)"
-          (1 (let ((ppss (save-excursion (syntax-ppss (match-beginning 0)))))
-               (and (nth 3 ppss)        ;Inside a string.
-                    (not (nth 5 ppss))  ;The \ is not itself \-escaped.
-                    (equal (ignore-errors
-                             (car (read-from-string
-                                   (format "\"%s\""
-                                           (match-string-no-properties 0)))))
-                           (match-string-no-properties 2))
-                    `(face ,font-lock-warning-face
-                           help-echo "This \\ has no effect")))
-             prepend))
+          (1 (elisp--font-lock-backslash) prepend))
          ;; Words inside ‘’ and `' tend to be symbol names.
          (,(concat "[`‘]\\(\\(?:\\sw\\|\\s_\\|\\\\.\\)"
                    lisp-mode-symbol-regexp "\\)['’]")