Errors indicated by ineffective backslashes in string literals

["Mattias Engdegård" <mattiase@acm.org>]

[-- Attachment #1: Type: text/plain, Size: 322 bytes --]

Sorry to bother you again, but while trying to get a better understanding of regexp usage and errors I found several ineffective backslashes in string literals (like "\.") and decided to do something about them.

Some were just superfluous and confusing, but others were apparent errors. Here is the resulting patch.


[-- Attachment #2: 0001-Fix-some-ineffective-backslashes-in-string-literals.patch --]
[-- Type: application/octet-stream, Size: 10943 bytes --]

From 3928725db206290ebc7df8a4eaabd56dbc42fee9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Sat, 16 Mar 2019 18:19:23 +0100
Subject: [PATCH] Fix some ineffective backslashes in string literals

Deal with lone backslashes that have no effect in string literals,
but indicate that something is amiss.

* lisp/auth-source-pass.el (auth-source-pass-entries):
* lisp/textmodes/artist.el (artist-figlet-get-font-list-windows):
* lisp/org/ob-abc.el (org-babel-expand-body:abc, org-babel-execute:abc):
* lisp/org/ob-forth.el (org-babel-forth-session-execute):
* lisp/vc/vc-git.el (vc-git--program-version):
Add backslash in regexp for correctness.

* lisp/gnus/nnmail.el (nnmail-split-abbrev-alist):
Replace `\||' with `\\|' to follow the obvious regexp intent.

* lisp/org/org-list.el (org-plain-list-ordered-item-terminator):
Add backslash in doc comment so that it appears as intended.

* lisp/progmodes/cc-engine.el (c-forward-decl-or-cast-1, c-end-of-decl-1):
* lisp/progmodes/f90.el (f90-font-lock-keywords-2):
* lisp/progmodes/etags.el (etags-tags-completion-table):
* lisp/progmodes/ruby-mode.el (ruby-syntax-propertize):
* test/lisp/emacs-lisp/cl-print-tests.el (cl-print-tests-1):
Remove superfluous backslashes from regexp.

* test/lisp/emacs-lisp/rx-tests.el (rx-char-any):
Remove superfluous backslash from doc comment.
---
 lisp/auth-source-pass.el               | 2 +-
 lisp/gnus/nnmail.el                    | 2 +-
 lisp/org/ob-abc.el                     | 4 ++--
 lisp/org/ob-forth.el                   | 2 +-
 lisp/org/org-list.el                   | 2 +-
 lisp/progmodes/cc-engine.el            | 6 +++---
 lisp/progmodes/etags.el                | 2 +-
 lisp/progmodes/f90.el                  | 2 +-
 lisp/progmodes/ruby-mode.el            | 2 +-
 lisp/textmodes/artist.el               | 2 +-
 lisp/vc/vc-git.el                      | 2 +-
 test/lisp/emacs-lisp/cl-print-tests.el | 2 +-
 test/lisp/emacs-lisp/rx-tests.el       | 2 +-
 13 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/lisp/auth-source-pass.el b/lisp/auth-source-pass.el
index e37cadb07c..deb805a6e1 100644
--- a/lisp/auth-source-pass.el
+++ b/lisp/auth-source-pass.el
@@ -189,7 +189,7 @@ often."
   (let ((store-dir (expand-file-name "~/.password-store/")))
     (mapcar
      (lambda (file) (file-name-sans-extension (file-relative-name file store-dir)))
-     (directory-files-recursively store-dir "\.gpg$"))))
+     (directory-files-recursively store-dir "\\.gpg$"))))
 
 (defun auth-source-pass--find-all-by-entry-name (entryname user)
   "Search the store for all entries either matching ENTRYNAME/USER or ENTRYNAME.
diff --git a/lisp/gnus/nnmail.el b/lisp/gnus/nnmail.el
index f6d7525293..a95cdb4a4f 100644
--- a/lisp/gnus/nnmail.el
+++ b/lisp/gnus/nnmail.el
@@ -489,7 +489,7 @@ Example:
     (from . "from\\|sender\\|resent-from")
     (nato . "to\\|cc\\|resent-to\\|resent-cc")
     (naany . "from\\|to\\|cc\\|sender\\|resent-from\\|resent-to\\|resent-cc")
-    (list . "list-id\\|list-post\\|x-mailing-list\||x-beenthere\\|x-loop"))
+    (list . "list-id\\|list-post\\|x-mailing-list\\|x-beenthere\\|x-loop"))
   "Alist of abbreviations allowed in `nnmail-split-fancy'."
   :group 'nnmail-split
   :type '(repeat (cons :format "%v" symbol regexp)))
diff --git a/lisp/org/ob-abc.el b/lisp/org/ob-abc.el
index cefbe716e1..43ee1d9921 100644
--- a/lisp/org/ob-abc.el
+++ b/lisp/org/ob-abc.el
@@ -47,7 +47,7 @@
 	     (value (cdr pair)))
 	 (setq body
 	       (replace-regexp-in-string
-		(concat "\$" (regexp-quote name))
+		(concat "\\$" (regexp-quote name))
 		(if (stringp value) value (format "%S" value))
 		body))))
      vars)
@@ -59,7 +59,7 @@
   (message "executing Abc source code block")
   (let* ((cmdline (cdr (assq :cmdline params)))
 	 (out-file (let ((file (cdr (assq :file params))))
-		     (if file (replace-regexp-in-string "\.pdf$" ".ps" file)
+		     (if file (replace-regexp-in-string "\\.pdf$" ".ps" file)
 		       (error "abc code block requires :file header argument"))))
 	 (in-file (org-babel-temp-file "abc-"))
 	 (render (concat "abcm2ps" " " cmdline
diff --git a/lisp/org/ob-forth.el b/lisp/org/ob-forth.el
index 8ca292656a..88ed964fd7 100644
--- a/lisp/org/ob-forth.el
+++ b/lisp/org/ob-forth.el
@@ -53,7 +53,7 @@ This function is called by `org-babel-execute-src-block'"
 (defun org-babel-forth-session-execute (body params)
   (require 'forth-mode)
   (let ((proc (forth-proc))
-	(rx " \\(\n:\\|compiled\n\\\|ok\n\\)")
+	(rx " \\(\n:\\|compiled\n\\|ok\n\\)")
 	(result-start))
     (with-current-buffer (process-buffer (forth-proc))
       (mapcar (lambda (line)
diff --git a/lisp/org/org-list.el b/lisp/org/org-list.el
index ef85b402f0..22692d224a 100644
--- a/lisp/org/org-list.el
+++ b/lisp/org/org-list.el
@@ -236,7 +236,7 @@ into
 
 (defcustom org-plain-list-ordered-item-terminator t
   "The character that makes a line with leading number an ordered list item.
-Valid values are ?. and ?\).  To get both terminators, use t.
+Valid values are ?. and ?\\).  To get both terminators, use t.
 
 This variable needs to be set before org.el is loaded.  If you
 need to make a change while Emacs is running, use the customize
diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index fd66928099..cc3753a7eb 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -8968,7 +8968,7 @@ This function might do hidden buffer changes."
 
 	 (setq at-decl-end
 	       (looking-at (cond ((eq context '<>) "[,>]")
-				 ((not (memq context '(nil top))) "[,\)]")
+				 ((not (memq context '(nil top))) "[,)]")
 				 (t "[,;]"))))
 
 	 ;; Now we've collected info about various characteristics of
@@ -10321,7 +10321,7 @@ comment at the start of cc-engine.el for more info."
 			  ;; Check for `c-opt-block-decls-with-vars-key'
 			  ;; before the first paren.
 			  (c-syntactic-re-search-forward
-			   (concat "[;=\(\[{]\\|\\("
+			   (concat "[;=([{]\\|\\("
 				   c-opt-block-decls-with-vars-key
 				   "\\)")
 			   lim t t t)
@@ -10329,7 +10329,7 @@ comment at the start of cc-engine.el for more info."
 			  (not (eq (char-before) ?_))
 			  ;; Check that the first following paren is
 			  ;; the block.
-			  (c-syntactic-re-search-forward "[;=\(\[{]"
+			  (c-syntactic-re-search-forward "[;=([{]"
 							 lim t t t)
 			  (eq (char-before) ?{))))))
 	    ;; The declaration doesn't have any of the
diff --git a/lisp/progmodes/etags.el b/lisp/progmodes/etags.el
index c2715be537..910c320ab8 100644
--- a/lisp/progmodes/etags.el
+++ b/lisp/progmodes/etags.el
@@ -1281,7 +1281,7 @@ buffer-local values of tags table format variables."
       ;; This regexp matches an explicit tag name or the place where
       ;; it would start.
       (while (re-search-forward
-              "[\f\t\n\r()=,; ]?\177\\\(?:\\([^\n\001]+\\)\001\\)?"
+              "[\f\t\n\r()=,; ]?\177\\(?:\\([^\n\001]+\\)\001\\)?"
 	      nil t)
 	(push	(prog1 (if (match-beginning 1)
 			   ;; There is an explicit tag name.
diff --git a/lisp/progmodes/f90.el b/lisp/progmodes/f90.el
index 3ec145b547..9de80635e9 100644
--- a/lisp/progmodes/f90.el
+++ b/lisp/progmodes/f90.el
@@ -648,7 +648,7 @@ forall\\|block\\|critical\\)\\)\\_>"
 \\|enumerator\\|procedure\\|\
 logical\\|double[ \t]*precision\\|type[ \t]*(\\(?:\\sw\\|\\s_\\)+)\\|none\\)[ \t]*"
       (1 font-lock-keyword-face) (2 font-lock-type-face))
-    '("\\_<\\(namelist\\|common\\)[ \t]*/\\(\\(?:\\sw\\|\\s_\\)+\\)?\/"
+    '("\\_<\\(namelist\\|common\\)[ \t]*/\\(\\(?:\\sw\\|\\s_\\)+\\)?/"
       (1 font-lock-keyword-face) (2 font-lock-constant-face nil t))
     "\\_<else\\([ \t]*if\\|where\\)?\\_>"
     '("\\(&\\)[ \t]*\\(!\\|$\\)"  (1 font-lock-keyword-face))
diff --git a/lisp/progmodes/ruby-mode.el b/lisp/progmodes/ruby-mode.el
index 707875d130..5998ac8e39 100644
--- a/lisp/progmodes/ruby-mode.el
+++ b/lisp/progmodes/ruby-mode.el
@@ -1867,7 +1867,7 @@ It will be properly highlighted even when the call omits parens.")
       ("^[ \t]*def +\\(`\\)" (1 "_"))
       ;; Ternary operator colon followed by opening paren or bracket
       ;; (semi-important for indentation).
-      ("\\(:\\)\\(?:[\({]\\|\\[[^]]\\)"
+      ("\\(:\\)\\(?:[({]\\|\\[[^]]\\)"
        (1 (string-to-syntax ".")))
       ;; Regular expressions.  Start with matching unescaped slash.
       ("\\(?:\\=\\|[^\\]\\)\\(?:\\\\\\\\\\)*\\(/\\)"
diff --git a/lisp/textmodes/artist.el b/lisp/textmodes/artist.el
index d75a1ca2f9..e9b17795a9 100644
--- a/lisp/textmodes/artist.el
+++ b/lisp/textmodes/artist.el
@@ -2895,7 +2895,7 @@ Returns a list of strings."
        dir-list)
       (mapcar
        (lambda (file)
-         (replace-regexp-in-string "\.flf\\'" "" file))
+         (replace-regexp-in-string "\\.flf\\'" "" file))
        result))))
 
 (defun artist-figlet-choose-font ()
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index c6806ba5cd..c990b0659d 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -253,7 +253,7 @@ The following place holders should be present in the string:
                        ;; Git for Windows appends ".windows.N" to the
                        ;; numerical version reported by Git.
                        (string-match
-                        "git version \\([0-9.]+\\)\\(\.windows.[0-9]+\\)?$"
+                        "git version \\([0-9.]+\\)\\(\\.windows.[0-9]+\\)?$"
                         version-string))
                   (match-string 1 version-string)
                 "0")))))
diff --git a/test/lisp/emacs-lisp/cl-print-tests.el b/test/lisp/emacs-lisp/cl-print-tests.el
index e163fb8a8d..406c528dce 100644
--- a/test/lisp/emacs-lisp/cl-print-tests.el
+++ b/test/lisp/emacs-lisp/cl-print-tests.el
@@ -34,7 +34,7 @@
     (let ((print-circle t))
       (should (equal (cl-prin1-to-string `((x . ,x) (y . ,x)))
                      "((x . #1=#s(cl-print--test :a 1 :b 2)) (y . #1#))")))
-    (should (string-match "\\`#f(compiled-function (x) \"[^\"]+\" [^\)]*)\\'"
+    (should (string-match "\\`#f(compiled-function (x) \"[^\"]+\" [^)]*)\\'"
                           (cl-prin1-to-string (symbol-function #'caar))))))
 
 (ert-deftest cl-print-tests-2 ()
diff --git a/test/lisp/emacs-lisp/rx-tests.el b/test/lisp/emacs-lisp/rx-tests.el
index fa3d9b0d5e..7dd5e3b8de 100644
--- a/test/lisp/emacs-lisp/rx-tests.el
+++ b/test/lisp/emacs-lisp/rx-tests.el
@@ -25,7 +25,7 @@
 ;;; Code:
 
 (ert-deftest rx-char-any ()
-  "Test character alternatives with `\]' and `-' (Bug#25123)."
+  "Test character alternatives with `]' and `-' (Bug#25123)."
   (should (string-match
            (rx string-start (1+ (char (?\] . ?\{) (?< . ?\]) (?- . ?:)))
                string-end)
-- 
2.17.2 (Apple Git-113)