Subject: bug#6743: Backslash regexp in Elisp manual

From: Juanma Barranquero <[email-masked]>
Date: Wed, 28 Jul 2010 02:25:35 +0200

On Wed, Jul 28, 2010 at 01:31, Arni Magnusson <[email-masked]> wrote:

>  Therefore, the read syntax for a regular expression matching
>  @samp{\} is @code{"\\\\"}.
>
> should be
>
>  Therefore, the read syntax for a regular expression matching
>  @samp{\\} is @code{"\\\\"}.

Why do you think so?

The section is talking about the read syntax. To match \, you need a
regexp with \\, and to write \\ in a string, you need \\\\.

Try

  emacs -Q
  \ <left>
  M-: (looking-at "\\") <RET>   => (invalid-regexp "Trailing backslash")
  q
  M-: (looking-at "\\\\") <RET> => t

Note that \\\\ is matching a single \ on the buffer, not \\

    Juanma