Remove (or double) redundant backslashes in string literals

See discussion at
https://lists.gnu.org/archive/html/emacs-devel/2020-01/msg00749.html .

* lisp/obsolete/iswitchb.el (iswitchb-summaries-to-end):
* test/src/regex-emacs-tests.el (regex-tests-BOOST-frob-escapes):
* test/lisp/help-fns-tests.el (help-fns-test-lisp-macro)
(help-fns-test-lisp-defun, help-fns-test-lisp-defsubst)
(help-fns-test-alias-to-defun, help-fns-test-bug23887):
Double backslashes for desired effect.
* lisp/org/ol.el (org-link-escape):
* lisp/net/nsm.el (nsm-protocol-check--rsa-kx)
(nsm-protocol-check--anon-kx, nsm-protocol-check--sha1-sig):
* lisp/obsolete/old-whitespace.el (whitespace-buffer):
* lisp/obsolete/rcompile.el (remote-compile-run-before):
* lisp/obsolete/vi.el (vi-end-of-blank-delimited-word):
* lisp/obsolete/vip.el (vip-current-major-mode)
(vip-paren-match, vip-switch-to-buffer)
(vip-switch-to-buffer-other-window, vip-kill-buffer)
(vip-get-ex-token, ex-edit):
* lisp/org/org-element.el (org-element--cache-sync-requests):
* lisp/org/org.el (org-sparse-tree):
* lisp/textmodes/reftex.el (reftex-report-bug):
* test/lisp/ibuffer-tests.el (ibuffer-save-filters):
* test/lisp/international/ucs-normalize-tests.el
(ucs-normalize-tests--insert-failing-lines):
* test/lisp/simple-tests.el (undo-test-kill-c-a-then-undo):
* test/lisp/textmodes/conf-mode-tests.el (conf-test-toml-mode):
* test/src/regex-emacs-tests.el (regex-tests-compare):
Remove redundant backslashes.

lisp/net/nsm.el

@@ -371,7 +371,7 @@ Reference:
 Sheffer, Holz, Saint-Andre (May 2015).  \"Recommendations for Secure
 Use of Transport Layer Security (TLS) and Datagram Transport Layer
 Security (DTLS)\", \"(4.1.  General Guidelines)\"
-`https://tools.ietf.org/html/rfc7525\#section-4.1'"
+`https://tools.ietf.org/html/rfc7525#section-4.1'"
   (let ((kx (plist-get status :key-exchange)))
     (and (string-match "^\\bRSA\\b" kx)
          (format-message
@@ -468,7 +468,7 @@ Reference:
 
 GnuTLS authors (2018). \"GnuTLS Manual 4.3.3 Anonymous
 authentication\",
-`https://www.gnutls.org/manual/gnutls.html\#Anonymous-authentication'"
+`https://www.gnutls.org/manual/gnutls.html#Anonymous-authentication'"
   (let ((kx (plist-get status :key-exchange)))
     (and (string-match "\\bANON\\b" kx)
          (format-message
@@ -603,7 +603,7 @@ References:
 full SHA-1\", `https://shattered.io/static/shattered.pdf'
 [2]: Chromium Security Education TLS/SSL.  \"Deprecated and Removed
 Features (SHA-1 Certificate Signatures)\",
-`https://www.chromium.org/Home/chromium-security/education/tls\#TOC-SHA-1-Certificate-Signatures'
+`https://www.chromium.org/Home/chromium-security/education/tls#TOC-SHA-1-Certificate-Signatures'
 [3]: Jones J.C (2017).  \"The end of SHA-1 on the Public Web\",
 `https://blog.mozilla.org/security/2017/02/23/the-end-of-sha-1-on-the-public-web/'
 [4]: Apple Support (2017).  \"Move to SHA-256 signed certificates to

lisp/obsolete/iswitchb.el

@@ -1393,7 +1393,7 @@ Copied from `icomplete-tidy'."
   "Move the summaries to the end of the list.
 This is an example function which can be hooked on to
 `iswitchb-make-buflist-hook'.  Any buffer matching the regexps
-`Summary' or `output\*$'are put to the end of the list."
+`Summary' or `output\\*$'are put to the end of the list."
   (let ((summaries (delq nil
 			 (mapcar
 			  (lambda (x)

lisp/obsolete/old-whitespace.el

@@ -383,10 +383,10 @@ To disable timer scans, set this to zero."
 (defun whitespace-buffer (&optional quiet)
   "Find five different types of white spaces in buffer.
 These are:
-1. Leading space \(empty lines at the top of a file\).
-2. Trailing space \(empty lines at the end of a file\).
-3. Indentation space \(8 or more spaces, that should be replaced with TABS\).
-4. Spaces followed by a TAB. \(Almost always, we never want that\).
+1. Leading space \(empty lines at the top of a file).
+2. Trailing space \(empty lines at the end of a file).
+3. Indentation space \(8 or more spaces, that should be replaced with TABS).
+4. Spaces followed by a TAB. \(Almost always, we never want that).
 5. Spaces or TABS at the end of a line.
 
 Check for whitespace only if this buffer really contains a non-empty file

lisp/obsolete/rcompile.el

@@ -89,7 +89,7 @@ nil means use the value returned by \\[user-login-name]."
   "Command to run before compilation.
 This can be used for setting up environment variables,
 since rsh does not invoke the shell as a login shell and files like .login
-\(tcsh\) and .bash_profile \(bash\) are not run.
+\(tcsh) and .bash_profile \(bash) are not run.
 nil means run no commands."
   :type '(choice string (const nil))
   :group 'remote-compile)

lisp/obsolete/vi.el

@@ -1225,7 +1225,7 @@ SPECIAL FEATURE: char argument can be used to specify shift amount(1-9)."
 (defun vi-end-of-blank-delimited-word (count)
   "Forward to the end of the COUNT'th blank-delimited word."
   (interactive "p")
-  (if (re-search-forward "[^ \t\n\']+[ \t\n\']" nil t count)
+  (if (re-search-forward "[^ \t\n']+[ \t\n']" nil t count)
       (if (not (eobp)) (backward-char 2))))
 
 (defun vi-home-window-line (arg)

lisp/obsolete/vip.el

@@ -80,7 +80,7 @@
 
 (defvar vip-current-major-mode nil
   "vip-current-major-mode is the major-mode vi considers it is now.
-\(buffer specific\)")
+\(buffer specific)")
 
 (make-variable-buffer-local 'vip-current-major-mode)
 
@@ -1510,7 +1510,7 @@ used.  This behavior is controlled by the sign of prefix numeric value."
 	       (* (/ (point-max) 100) arg)
 	     (/ (* (point-max) arg) 100)))
 	  (back-to-indentation))
-    (cond ((looking-at "[\(\[{]")
+    (cond ((looking-at "[([{]")
 	   (if com (move-marker vip-com-point (point)))
 	   (forward-sexp 1)
 	   (if com
@@ -1719,7 +1719,7 @@ STRING.  Search will be forward if FORWARD, otherwise backward."
   (let (buffer)
     (setq buffer
 	  (read-buffer
-	   (format "switch to buffer \(%s\): "
+	   (format "switch to buffer (%s): "
 		   (buffer-name (other-buffer (current-buffer))))))
     (switch-to-buffer buffer)
     (vip-change-mode-to-vi)))
@@ -1730,7 +1730,7 @@ STRING.  Search will be forward if FORWARD, otherwise backward."
   (let (buffer)
     (setq buffer
 	  (read-buffer
-	   (format "Switch to buffer \(%s\): "
+	   (format "Switch to buffer (%s): "
 		   (buffer-name (other-buffer (current-buffer))))))
     (switch-to-buffer-other-window buffer)
     (vip-change-mode-to-vi)))
@@ -1741,7 +1741,7 @@ STRING.  Search will be forward if FORWARD, otherwise backward."
   (let (buffer buffer-name)
     (setq buffer-name
 	  (read-buffer
-	   (format "Kill buffer \(%s\): "
+	   (format "Kill buffer (%s): "
 		   (buffer-name (current-buffer)))))
     (setq buffer
 	  (if (null buffer-name)
@@ -2162,7 +2162,7 @@ is a command.")
 
 (defun vip-get-ex-token ()
   "get an ex-token which is either an address or a command.
-a token has type \(command, address, end-mark\) and value."
+a token has type \(command, address, end-mark) and value."
   (with-current-buffer " *ex-working-space*"
     (skip-chars-forward " \t")
     (cond ((looking-at "[k#]")
@@ -2668,7 +2668,7 @@ a token has type \(command, address, end-mark\) and value."
   "ex-edit"
   (vip-get-ex-file)
   (if (and (not ex-variant) (buffer-modified-p) buffer-file-name)
-      (error "No write since last change \(:e! overrides\)"))
+      (error "No write since last change (:e! overrides)"))
   (vip-change-mode-to-emacs)
   (set-buffer
    (find-file-noselect (concat default-directory ex-file)))

lisp/org/ol.el

@@ -845,8 +845,8 @@ E.g. \"%C3%B6\" becomes the german o-Umlaut."
     (insert link)
     (insert (make-string (- (skip-chars-backward "\\\\"))
 			 ?\\))
-    (while (search-backward "\]" nil t)
-      (when (looking-at-p "\\]\\(?:[][]\\|\\'\\)")
+    (while (search-backward "]" nil t)
+      (when (looking-at-p "]\\(?:[][]\\|\\'\\)")
 	(insert (make-string (1+ (- (skip-chars-backward "\\\\")))
 			     ?\\))))
     (buffer-string)))

lisp/org/org-element.el

@@ -4892,7 +4892,7 @@ with `org-element--cache-compare'.  This cache is used in
 
 A request is a vector with the following pattern:
 
- \[NEXT BEG END OFFSET PARENT PHASE]
+ [NEXT BEG END OFFSET PARENT PHASE]
 
 Processing a synchronization request consists of three phases:
 

lisp/org/org.el

@@ -11410,8 +11410,8 @@ D      Show deadlines and scheduled items between a date range."
   (setq type (or type org-sparse-tree-default-date-type))
   (setq org-ts-type type)
   (message "Sparse tree: [r]egexp [t]odo [T]odo-kwd [m]atch [p]roperty
-             \[d]eadlines [b]efore-date [a]fter-date [D]ates range
-             \[c]ycle through date types: %s"
+             [d]eadlines [b]efore-date [a]fter-date [D]ates range
+             [c]ycle through date types: %s"
 	   (cl-case type
 	     (all "all timestamps")
 	     (scheduled "only scheduled")

lisp/textmodes/reftex.el

@@ -2371,7 +2371,7 @@ what in fact did happen.
 Check if the bug is reproducible with an up-to-date version of
 RefTeX available from https://www.gnu.org/software/auctex/.
 
-If the bug is triggered by a specific \(La)TeX file, you should try
+If the bug is triggered by a specific (La)TeX file, you should try
 to produce a minimal sample file showing the problem and include it
 in your report.
 

test/lisp/help-fns-tests.el

@@ -56,28 +56,28 @@ Return first line of the output of (describe-function-1 FUNC)."
     (should (string-match regexp result))))
 
 (ert-deftest help-fns-test-lisp-macro ()
-  (let ((regexp "a Lisp macro in .subr\.el")
+  (let ((regexp "a Lisp macro in .subr\\.el")
         (result (help-fns-tests--describe-function 'when)))
     (should (string-match regexp result))))
 
 (ert-deftest help-fns-test-lisp-defun ()
-  (let ((regexp "a compiled Lisp function in .subr\.el")
+  (let ((regexp "a compiled Lisp function in .subr\\.el")
         (result (help-fns-tests--describe-function 'last)))
     (should (string-match regexp result))))
 
 (ert-deftest help-fns-test-lisp-defsubst ()
-  (let ((regexp "a compiled Lisp function in .subr\.el")
+  (let ((regexp "a compiled Lisp function in .subr\\.el")
         (result (help-fns-tests--describe-function 'posn-window)))
     (should (string-match regexp result))))
 
 (ert-deftest help-fns-test-alias-to-defun ()
-  (let ((regexp "an alias for .set-file-modes. in .subr\.el")
+  (let ((regexp "an alias for .set-file-modes. in .subr\\.el")
         (result (help-fns-tests--describe-function 'chmod)))
     (should (string-match regexp result))))
 
 (ert-deftest help-fns-test-bug23887 ()
   "Test for https://debbugs.gnu.org/23887 ."
-  (let ((regexp "an alias for .re-search-forward. in .subr\.el")
+  (let ((regexp "an alias for .re-search-forward. in .subr\\.el")
         (result (help-fns-tests--describe-function 'search-forward-regexp)))
     (should (string-match regexp result))))
 

test/lisp/ibuffer-tests.el

@@ -82,7 +82,7 @@
         (test1 '((mode . org-mode)
                  (or (size-gt . 10000)
                      (and (not (starred-name))
-                          (directory . "\<org\>")))))
+                          (directory . "<org>")))))
         (test2 '((or (mode . emacs-lisp-mode) (file-extension . "elc?")
                      (and (starred-name) (name . "elisp"))
                      (mode . lisp-interaction-mode))))

test/lisp/international/ucs-normalize-tests.el

@@ -299,7 +299,7 @@ implementations:
   (list " var var))
   (dolist (linos (seq-partition newval 8))
     (insert (mapconcat #'number-to-string linos " ") "\n"))
-  (insert ")\)"))
+  (insert "))"))
 
 (defun ucs-normalize-check-failing-lines ()
   (interactive)

test/lisp/simple-tests.el

@@ -427,7 +427,7 @@ See bug#35036."
   (with-temp-buffer
     (switch-to-buffer (current-buffer))
     (setq buffer-undo-list nil)
-    (insert "a\nb\n\c\n")
+    (insert "a\nb\nc\n")
     (goto-char (point-max))
     ;; We use a keyboard macro because it adds undo events in the same
     ;; way as if a user were involved.

test/lisp/textmodes/conf-mode-tests.el

@@ -162,7 +162,7 @@ image/tiff			tiff tif
 (ert-deftest conf-test-toml-mode ()
   ;; From `conf-toml-mode' docstring.
   (with-temp-buffer
-    (insert "\[entry]
+    (insert "[entry]
 value = \"some string\"")
     (goto-char (point-min))
     (conf-toml-mode)

test/src/regex-emacs-tests.el

@@ -161,7 +161,7 @@ what failed, if anything; valid values are 'search-failed,
 'compilation-failed and nil.  I compare the beginning/end of each
 group with their expected values.  This is done with either
 BOUNDS-REF or SUBSTRING-REF; one of those should be non-nil.
-BOUNDS-REF is a sequence \[start-ref0 end-ref0 start-ref1
+BOUNDS-REF is a sequence [start-ref0 end-ref0 start-ref1
 end-ref1 ....] while SUBSTRING-REF is the expected substring
 obtained by indexing the input string by start/end-ref.
 
@@ -327,7 +327,7 @@ emacs requires an extra symbol character"
 (defun regex-tests-BOOST-frob-escapes (s ispattern)
   "Mangle \\ the way it is done in frob_escapes() in
 regex-tests-BOOST.c in glibc: \\t, \\n, \\r are interpreted;
-\\\\, \\^, \{, \\|, \} are unescaped for the string (not
+\\\\, \\^, \\{, \\|, \\} are unescaped for the string (not
 pattern)"
 
   ;; this is all similar to (regex-tests-unextend)