Replace (default-value 'enable-multibyte-characters) with t

Since Emacs-24, (default-value 'enable-multibyte-characters) can't be
changed any more, so we can remove all code which checks this value.

* lisp/x-dnd.el (x-dnd-handle-file-name):
* lisp/w32-fns.el (w32-set-default-process-coding-system):
* lisp/textmodes/ispell.el (ispell-send-string):
* lisp/term/internal.el (dos-codepage-setup):
* lisp/tar-mode.el (tar-header-block-tokenize, tar--extract):
* lisp/startup.el (command-line):
* lisp/server.el (server-process-filter):
* lisp/net/browse-url.el (browse-url-file-url):
* lisp/menu-bar.el (menu-bar-options-menu, menu-bar-describe-menu):
* lisp/mail/sendmail.el (mail-setup):
* lisp/mail/rmail.el (rmail-mode, rmail-get-new-mail):
* lisp/mail/rfc2047.el (rfc2047-encode-message-header):
* lisp/mail/emacsbug.el (report-emacs-bug):
* lisp/international/mule-diag.el (mule-diag):
* lisp/files.el (find-file-noselect-1):
* lisp/dos-fns.el (dos-set-default-process-coding-system):
* lisp/arc-mode.el (archive-mode):
* lisp/international/mule-cmds.el (mule-menu-keymap)
(set-default-coding-systems, set-language-info)
(set-language-environment, standard-display-european-internal)
(set-locale-environment): Simplify code.

20 files changed, 65 insertions, 141 deletions

diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index 8a8425cb84b..0a3a4617a2e 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -2712,8 +2712,7 @@ Initialize the process filter to @var{filter}.
 
 @item :filter-multibyte @var{multibyte}
 If @var{multibyte} is non-@code{nil}, strings given to the process
-filter are multibyte, otherwise they are unibyte.  The default is the
-default value of @code{enable-multibyte-characters}.
+filter are multibyte, otherwise they are unibyte.  The default is @code{t}.
 
 @item :sentinel @var{sentinel}
 Initialize the process sentinel to @var{sentinel}.
diff --git a/lisp/arc-mode.el b/lisp/arc-mode.el
index adb36699032..1dec40f2157 100644
--- a/lisp/arc-mode.el
+++ b/lisp/arc-mode.el
@@ -748,8 +748,7 @@ archive.
 	    (or file-name-coding-system
 		default-file-name-coding-system
 		locale-coding-system))
-      (if (default-value 'enable-multibyte-characters)
-	  (set-buffer-multibyte 'to))
+      (set-buffer-multibyte 'to)
       (archive-summarize nil)
       (setq buffer-read-only t)
       (when (and archive-visit-single-files
diff --git a/lisp/dos-fns.el b/lisp/dos-fns.el
index 87f7ed10fea..ebb8acb8608 100644
--- a/lisp/dos-fns.el
+++ b/lisp/dos-fns.el
@@ -212,9 +212,7 @@ returned unaltered."
 ;; Override settings chosen at startup.
 (defun dos-set-default-process-coding-system ()
   (setq default-process-coding-system
-	(if (default-value 'enable-multibyte-characters)
-	    '(undecided-dos . undecided-dos)
-	  '(raw-text-dos . raw-text-dos))))
+	'(undecided-dos . undecided-dos)))
 
 (add-hook 'before-init-hook 'dos-set-default-process-coding-system)
 
diff --git a/lisp/files.el b/lisp/files.el
index 7194b56fef2..00622cf6620 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -2232,8 +2232,7 @@ Do you want to revisit the file normally now? ")
       (kill-local-variable 'cursor-type)
       (let ((inhibit-read-only t))
 	(erase-buffer))
-      (and (default-value 'enable-multibyte-characters)
-	   (not rawfile)
+      (and (not rawfile)
 	   (set-buffer-multibyte t))
       (if rawfile
 	  (condition-case ()
diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index aeba954a3b2..34681662631 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -136,8 +136,7 @@
                  (expand-file-name "HELLO" data-directory))
         :help "Demonstrate various character sets"))
     (bindings--define-key map [set-various-coding-system]
-      `(menu-item "Set Coding Systems" ,set-coding-system-map
-		  :enable (default-value 'enable-multibyte-characters)))
+      `(menu-item "Set Coding Systems" ,set-coding-system-map))
 
     (bindings--define-key map [separator-input-method] menu-bar-separator)
     (bindings--define-key map [describe-input-method]
@@ -355,8 +354,7 @@ This also sets the following values:
   (if (eq system-type 'darwin)
       ;; The file-name coding system on Darwin systems is always utf-8.
       (setq default-file-name-coding-system 'utf-8-unix)
-    (if (and (default-value 'enable-multibyte-characters)
-	     (or (not coding-system)
+    (if (and (or (not coding-system)
 		 (coding-system-get coding-system 'ascii-compatible-p)))
 	(setq default-file-name-coding-system
 	      (coding-system-change-eol-conversion coding-system 'unix))))
@@ -1158,10 +1156,7 @@ see `language-info-alist'."
 	    ((eq key 'nonascii-translation)
 	     (set-language-environment-nonascii-translation lang-env))
 	    ((eq key 'charset)
-	     (set-language-environment-charset lang-env))
-	    ((and (not (default-value 'enable-multibyte-characters))
-		  (or (eq key 'unibyte-syntax) (eq key 'unibyte-display)))
-	     (set-language-environment-unibyte lang-env)))))
+	     (set-language-environment-charset lang-env)))))
 
 (defun set-language-info-internal (lang-env key info)
   "Internal use only.
@@ -1897,9 +1892,6 @@ the new language environment, it runs `set-language-environment-hook'."
   (set-language-environment-input-method language-name)
   (set-language-environment-nonascii-translation language-name)
   (set-language-environment-charset language-name)
-  ;; Unibyte setups if necessary.
-  (unless (default-value 'enable-multibyte-characters)
-    (set-language-environment-unibyte language-name))
 
   (let ((func (get-language-info language-name 'setup-function)))
     (if (functionp func)
@@ -1978,28 +1970,22 @@ See `set-language-info-alist' for use in programs."
 (defun standard-display-european-internal ()
   ;; Actually set up direct output of non-ASCII characters.
   (standard-display-8bit (if (eq window-system 'pc) 128 160) 255)
-  ;; Unibyte Emacs on MS-DOS wants to display all 8-bit characters with
-  ;; the native font, and codes 160 and 146 stand for something very
-  ;; different there.
-  (or (and (eq window-system 'pc) (not (default-value
-					 'enable-multibyte-characters)))
-      (progn
-	;; Most X fonts used to do the wrong thing for latin-1 code 160.
-	(unless (and (eq window-system 'x)
-		     ;; XFree86 4 has fixed the fonts.
-		     (string= "The XFree86 Project, Inc" (x-server-vendor))
-		     (> (aref (number-to-string (nth 2 (x-server-version))) 0)
-			?3))
-	  ;; Make non-line-break space display as a plain space.
-	  (aset standard-display-table (unibyte-char-to-multibyte 160) [32]))
-	;; Most Windows programs send out apostrophes as \222.  Most X fonts
-	;; don't contain a character at that position.  Map it to the ASCII
-	;; apostrophe.  [This is actually RIGHT SINGLE QUOTATION MARK,
-	;; U+2019, normally from the windows-1252 character set.  XFree 4
-	;; fonts probably have the appropriate glyph at this position,
-	;; so they could use standard-display-8bit.  It's better to use a
-	;; proper windows-1252 coding system.  --fx]
-	(aset standard-display-table (unibyte-char-to-multibyte 146) [39]))))
+  ;; Most X fonts used to do the wrong thing for latin-1 code 160.
+  (unless (and (eq window-system 'x)
+	       ;; XFree86 4 has fixed the fonts.
+	       (string= "The XFree86 Project, Inc" (x-server-vendor))
+	       (> (aref (number-to-string (nth 2 (x-server-version))) 0)
+		  ?3))
+    ;; Make non-line-break space display as a plain space.
+    (aset standard-display-table (unibyte-char-to-multibyte 160) [32]))
+  ;; Most Windows programs send out apostrophes as \222.  Most X fonts
+  ;; don't contain a character at that position.  Map it to the ASCII
+  ;; apostrophe.  [This is actually RIGHT SINGLE QUOTATION MARK,
+  ;; U+2019, normally from the windows-1252 character set.  XFree 4
+  ;; fonts probably have the appropriate glyph at this position,
+  ;; so they could use standard-display-8bit.  It's better to use a
+  ;; proper windows-1252 coding system.  --fx]
+  (aset standard-display-table (unibyte-char-to-multibyte 146) [39]))
 
 (defun set-language-environment-coding-systems (language-name)
   "Do various coding system setups for language environment LANGUAGE-NAME."
@@ -2665,12 +2651,8 @@ See also `locale-charset-language-names', `locale-language-names',
 	  (unless frame
 	    (set-language-environment language-name))
 
-	  ;; If the default enable-multibyte-characters is nil,
-	  ;; we are using single-byte characters,
-	  ;; so the display table and terminal coding system are irrelevant.
-	  (when (default-value 'enable-multibyte-characters)
-	    (set-display-table-and-terminal-coding-system
-	     language-name coding-system frame))
+	  (set-display-table-and-terminal-coding-system
+	   language-name coding-system frame)
 
 	  ;; Set the `keyboard-coding-system' if appropriate (tty
 	  ;; only).  At least X and MS Windows can generate
diff --git a/lisp/international/mule-diag.el b/lisp/international/mule-diag.el
index 7e225607a5a..87a2e993bb4 100644
--- a/lisp/international/mule-diag.el
+++ b/lisp/international/mule-diag.el
@@ -1103,8 +1103,6 @@ system which uses fontsets)."
       (insert "Version of this emacs:\n  " (emacs-version) "\n\n")
       (insert "Configuration options:\n  " system-configuration-options "\n\n")
       (insert "Multibyte characters awareness:\n"
-	      (format "  default: %S\n" (default-value
-					  'enable-multibyte-characters))
 	      (format "  current-buffer: %S\n\n" enable-multibyte-characters))
       (insert "Current language environment: " current-language-environment
 	      "\n\n")
diff --git a/lisp/mail/emacsbug.el b/lisp/mail/emacsbug.el
index cb34a75fa1c..43e8d3b526c 100644
--- a/lisp/mail/emacsbug.el
+++ b/lisp/mail/emacsbug.el
@@ -286,11 +286,6 @@ usually do not have translators for other languages.\n\n")))
        "LC_ALL" "LC_COLLATE" "LC_CTYPE" "LC_MESSAGES"
        "LC_MONETARY" "LC_NUMERIC" "LC_TIME" "LANG" "XMODIFIERS"))
     (insert (format "  locale-coding-system: %s\n" locale-coding-system))
-    ;; Only ~ 0.2% of people from a sample of 3200 changed this from
-    ;; the default, t.
-    (or (default-value 'enable-multibyte-characters)
-	(insert (format "  default enable-multibyte-characters: %s\n"
-			(default-value 'enable-multibyte-characters))))
     (insert "\n")
     (insert (format "Major mode: %s\n"
 		    (format-mode-line
diff --git a/lisp/mail/rfc2047.el b/lisp/mail/rfc2047.el
index dbfde57224a..c0cd4ee8c43 100644
--- a/lisp/mail/rfc2047.el
+++ b/lisp/mail/rfc2047.el
@@ -290,8 +290,7 @@ Should be called narrowed to the head of the message."
 		(let ((rfc2047-encoding-type 'mime))
 		  (rfc2047-encode-region (point) (point-max))))
 	       ((eq method 'default)
-		(if (and (default-value 'enable-multibyte-characters)
-			 mail-parse-charset)
+		(if mail-parse-charset
 		    (encode-coding-region (point) (point-max)
 					  mail-parse-charset)))
 	       ;; We get this when CC'ing messages to newsgroups with
@@ -305,18 +304,17 @@ Should be called narrowed to the head of the message."
 	       ;; in accordance with changes elsewhere.
 	       ((null method)
 		(rfc2047-encode-region (point) (point-max)))
-;;;	       ((null method)
-;;;		(if (or (message-options-get
-;;;			 'rfc2047-encode-message-header-encode-any)
-;;;			(message-options-set
-;;;			 'rfc2047-encode-message-header-encode-any
-;;;			 (y-or-n-p
-;;;			  "Some texts are not encoded. Encode anyway?")))
-;;;		    (rfc2047-encode-region (point-min) (point-max))
-;;;		  (error "Cannot send unencoded text")))
+	       ;; ((null method)
+	       ;;  (if (or (message-options-get
+	       ;;  	 'rfc2047-encode-message-header-encode-any)
+	       ;;  	(message-options-set
+	       ;;  	 'rfc2047-encode-message-header-encode-any
+	       ;;  	 (y-or-n-p
+	       ;;  	  "Some texts are not encoded. Encode anyway?")))
+	       ;;      (rfc2047-encode-region (point-min) (point-max))
+	       ;;    (error "Cannot send unencoded text")))
 	       ((mm-coding-system-p method)
-		(when (default-value 'enable-multibyte-characters)
-		  (encode-coding-region (point) (point-max) method)))
+		(encode-coding-region (point) (point-max) method))
 	       ;; Hm.
 	       (t)))
 	    (goto-char (point-max))))))))
diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index 7b542638743..4e182525511 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -1331,8 +1331,7 @@ Instead, these commands are available:
   (let ((finding-rmail-file (not (eq major-mode 'rmail-mode))))
     (rmail-mode-2)
     (when (and finding-rmail-file
-	       (null coding-system-for-read)
-	       (default-value 'enable-multibyte-characters))
+	       (null coding-system-for-read))
       (let ((rmail-enable-multibyte t))
 	(rmail-require-mime-maybe)
 	(rmail-convert-file-maybe)
@@ -1759,7 +1758,7 @@ not be a new one).  It returns non-nil if it got any new messages."
   (or (eq buffer-undo-list t)
       (setq buffer-undo-list nil))
   (let ((all-files (if file-name (list file-name) rmail-inbox-list))
-	(rmail-enable-multibyte (default-value 'enable-multibyte-characters))
+	(rmail-enable-multibyte t)
 	found)
     (unwind-protect
 	(progn
diff --git a/lisp/mail/sendmail.el b/lisp/mail/sendmail.el
index da2d3174ce1..212a6c74baa 100644
--- a/lisp/mail/sendmail.el
+++ b/lisp/mail/sendmail.el
@@ -607,7 +607,7 @@ This also saves the value of `send-mail-function' via Customize."
   (kill-local-variable 'buffer-file-coding-system)
   ;; This doesn't work for enable-multibyte-characters.
   ;; (kill-local-variable 'enable-multibyte-characters)
-  (set-buffer-multibyte (default-value 'enable-multibyte-characters))
+  (set-buffer-multibyte t)
   (if current-input-method
       (deactivate-input-method))
 
diff --git a/lisp/menu-bar.el b/lisp/menu-bar.el
index e2ebd981196..25e016247b3 100644
--- a/lisp/menu-bar.el
+++ b/lisp/menu-bar.el
@@ -1379,11 +1379,7 @@ mail status in mode line"))
       ;; It is better not to use backquote here,
       ;; because that makes a bootstrapping problem
       ;; if you need to recompile all the Lisp files using interpreted code.
-      `(menu-item "Multilingual Environment" ,mule-menu-keymap
-                  ;; Most of the MULE menu actually does make sense in
-                  ;; unibyte mode, e.g. language selection.
-                  ;; :visible '(default-value 'enable-multibyte-characters)
-                  ))
+      `(menu-item "Multilingual Environment" ,mule-menu-keymap))
     ;;(setq menu-bar-final-items (cons 'mule menu-bar-final-items))
     ;;(bindings--define-key menu [preferences]
     ;;  `(menu-item "Preferences" ,menu-bar-preferences-menu
@@ -1697,18 +1693,14 @@ mail status in mode line"))
 
     (bindings--define-key menu [mule-diag]
       '(menu-item "Show All of Mule Status" mule-diag
-                  :visible (default-value 'enable-multibyte-characters)
                   :help "Display multilingual environment settings"))
     (bindings--define-key menu [describe-coding-system-briefly]
       '(menu-item "Describe Coding System (Briefly)"
-                  describe-current-coding-system-briefly
-                  :visible (default-value 'enable-multibyte-characters)))
+                  describe-current-coding-system-briefly))
     (bindings--define-key menu [describe-coding-system]
-      '(menu-item "Describe Coding System..." describe-coding-system
-                  :visible (default-value 'enable-multibyte-characters)))
+      '(menu-item "Describe Coding System..." describe-coding-system))
     (bindings--define-key menu [describe-input-method]
       '(menu-item "Describe Input Method..." describe-input-method
-                  :visible (default-value 'enable-multibyte-characters)
                   :help "Keyboard layout for specific input method"))
     (bindings--define-key menu [describe-language-environment]
       `(menu-item "Describe Language Environment"
diff --git a/lisp/net/browse-url.el b/lisp/net/browse-url.el
index 98b0acfc0c6..8086495aaaa 100644
--- a/lisp/net/browse-url.el
+++ b/lisp/net/browse-url.el
@@ -713,8 +713,7 @@ Use variable `browse-url-filename-alist' to map filenames to URLs."
   (let ((coding (if (equal system-type 'windows-nt)
 		    ;; W32 pretends that file names are UTF-8 encoded.
 		    'utf-8
-		  (and (default-value 'enable-multibyte-characters)
-		       (or file-name-coding-system
+		  (and (or file-name-coding-system
 			   default-file-name-coding-system)))))
     (if coding (setq file (encode-coding-string file coding))))
   (setq file (browse-url-url-encode-chars file "[*\"()',=;?% ]"))
diff --git a/lisp/server.el b/lisp/server.el
index ac0d7018513..d91a51e425a 100644
--- a/lisp/server.el
+++ b/lisp/server.el
@@ -1061,9 +1061,8 @@ The following commands are accepted by the client:
           ;; supported any more.
           (cl-assert (eq (match-end 0) (length string)))
 	  (let ((request (substring string 0 (match-beginning 0)))
-		(coding-system (and (default-value 'enable-multibyte-characters)
-				    (or file-name-coding-system
-					default-file-name-coding-system)))
+		(coding-system (or file-name-coding-system
+				   default-file-name-coding-system))
 		nowait     ; t if emacsclient does not want to wait for us.
 		frame      ; Frame opened for the client (if any).
 		display    ; Open frame on this display.
diff --git a/lisp/startup.el b/lisp/startup.el
index 86beef70a37..8c36c19e828 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -1159,8 +1159,7 @@ please check its value")
     (let (debug-on-error-from-init-file
 	  debug-on-error-should-be-set
 	  (debug-on-error-initial
-	   (if (eq init-file-debug t) 'startup init-file-debug))
-	  (orig-enable-multibyte (default-value 'enable-multibyte-characters)))
+	   (if (eq init-file-debug t) 'startup init-file-debug)))
       (let ((debug-on-error debug-on-error-initial)
 	    ;; This function actually reads the init files.
 	    (inner
@@ -1275,23 +1274,7 @@ the `--debug-init' option to view a complete error backtrace."
 	    (setq debug-on-error-should-be-set t
 		  debug-on-error-from-init-file debug-on-error)))
       (if debug-on-error-should-be-set
-	  (setq debug-on-error debug-on-error-from-init-file))
-      (unless (or (default-value 'enable-multibyte-characters)
-		  (eq orig-enable-multibyte (default-value
-					      'enable-multibyte-characters)))
-	;; Init file changed to unibyte.  Reset existing multibyte
-	;; buffers (probably *scratch*, *Messages*, *Minibuf-0*).
-	;; Arguably this should only be done if they're free of
-	;; multibyte characters.
-	(mapc (lambda (buffer)
-		(with-current-buffer buffer
-		  (if enable-multibyte-characters
-		      (set-buffer-multibyte nil))))
-	      (buffer-list))
-	;; Also re-set the language environment in case it was
-	;; originally done before unibyte was set and is sensitive to
-	;; unibyte (display table, terminal coding system &c).
-	(set-language-environment current-language-environment)))
+	  (setq debug-on-error debug-on-error-from-init-file)))
 
     ;; Do this here in case the init file sets mail-host-address.
     (and mail-host-address
diff --git a/lisp/tar-mode.el b/lisp/tar-mode.el
index 07d902c1bb0..2beeb7484a7 100644
--- a/lisp/tar-mode.el
+++ b/lisp/tar-mode.el
@@ -265,11 +265,10 @@ write-date, checksum, link-type, and link-name."
           (setq name (concat (substring string tar-prefix-offset
                                         (1- (match-end 0)))
                              "/" name)))
-        (if (default-value 'enable-multibyte-characters)
-            (setq name
-                  (decode-coding-string name coding)
-                  linkname
-                  (decode-coding-string linkname coding)))
+        (setq name
+              (decode-coding-string name coding)
+              linkname
+              (decode-coding-string linkname coding))
         (if (and (null link-p) (string-match "/\\'" name))
             (setq link-p 5))            ; directory
 
@@ -907,8 +906,7 @@ tar-file's buffer."
         (if (or (not coding)
                 (eq (coding-system-type coding) 'undecided))
             (setq coding (detect-coding-region start end t)))
-        (if (and (default-value 'enable-multibyte-characters)
-                 (coding-system-get coding :for-unibyte))
+        (if (coding-system-get coding :for-unibyte)
             (with-current-buffer buffer
               (set-buffer-multibyte nil)))
         (widen)
diff --git a/lisp/term/internal.el b/lisp/term/internal.el
index 2cf560694c6..0cdf0c1a7c3 100644
--- a/lisp/term/internal.el
+++ b/lisp/term/internal.el
@@ -595,8 +595,7 @@ list.  You can (and should) also run it if and when the value of
     (set-selection-coding-system coding-dos)
     (IT-setup-unicode-display coding-unix)
     (prefer-coding-system coding-dos)
-    (and (default-value 'enable-multibyte-characters)
-	 (setq unibyte-display-via-language-environment t))
+    (setq unibyte-display-via-language-environment t)
     ;; Some codepages have sporadic support for Latin-1, Greek, and
     ;; symbol glyphs, which don't belong to their native character
     ;; set.  It's a nuisance to have all those glyphs here, for all
diff --git a/lisp/textmodes/ispell.el b/lisp/textmodes/ispell.el
index 9288a77ba3e..512dfcfa6a7 100644
--- a/lisp/textmodes/ispell.el
+++ b/lisp/textmodes/ispell.el
@@ -1818,11 +1818,9 @@ Only works for Aspell and Enchant."
 	(setq default-directory defdir)
 	(insert string)
 	(if (not (memq cmd cmds-to-defer))
-	    (let (coding-system-for-read coding-system-for-write status)
-	      (if (and (boundp 'enable-multibyte-characters)
-		       enable-multibyte-characters)
-		  (setq coding-system-for-read (ispell-get-coding-system)
-			coding-system-for-write (ispell-get-coding-system)))
+	    (let* ((coding-system-for-read (ispell-get-coding-system))
+                   (coding-system-for-write coding-system-for-read)
+                   status)
 	      (set-buffer output-buf)
 	      (erase-buffer)
 	      (set-buffer session-buf)
diff --git a/lisp/w32-fns.el b/lisp/w32-fns.el
index 18f987e26bd..b400c8d4a6f 100644
--- a/lisp/w32-fns.el
+++ b/lisp/w32-fns.el
@@ -126,22 +126,16 @@ You should set this to t when using a non-system shell.\n\n"))))
   ;; (and some programs ported from Unix require it) but most will
   ;; produce DOS line endings on output.
   (setq default-process-coding-system
-	(if (default-value 'enable-multibyte-characters)
-	    '(undecided-dos . undecided-unix)
-	  '(raw-text-dos . raw-text-unix)))
+	'(undecided-dos . undecided-unix))
   ;; Make cmdproxy default to using DOS line endings for input,
   ;; because some Windows programs (including command.com) require it.
   (add-to-list 'process-coding-system-alist
-	       `("[cC][mM][dD][pP][rR][oO][xX][yY]"
-		 . ,(if (default-value 'enable-multibyte-characters)
-			'(undecided-dos . undecided-dos)
-		      '(raw-text-dos . raw-text-dos))))
+	       '("[cC][mM][dD][pP][rR][oO][xX][yY]"
+		 . (undecided-dos . undecided-dos)))
   ;; plink needs DOS input when entering the password.
   (add-to-list 'process-coding-system-alist
-	       `("[pP][lL][iI][nN][kK]"
-		 . ,(if (default-value 'enable-multibyte-characters)
-			'(undecided-dos . undecided-dos)
-		      '(raw-text-dos . raw-text-dos)))))
+	       '("[pP][lL][iI][nN][kK]"
+		 . (undecided-dos . undecided-dos))))
 (define-obsolete-function-alias 'set-default-process-coding-system
   #'w32-set-default-process-coding-system "26.1")
 (add-hook 'before-init-hook #'w32-set-default-process-coding-system)
diff --git a/lisp/x-dnd.el b/lisp/x-dnd.el
index fe2202cfc68..5f8578444a0 100644
--- a/lisp/x-dnd.el
+++ b/lisp/x-dnd.el
@@ -264,9 +264,8 @@ STRING is the uri-list as a string.  The URIs are separated by \\r\\n."
 WINDOW is the window where the drop happened.
 STRING is the file names as a string, separated by nulls."
   (let ((uri-list (split-string string "[\0\r\n]" t))
-	(coding (and (default-value 'enable-multibyte-characters)
-		     (or file-name-coding-system
-			 default-file-name-coding-system)))
+	(coding (or file-name-coding-system
+		    default-file-name-coding-system))
 	retval)
     (dolist (bf uri-list)
       ;; If one URL is handled, treat as if the whole drop succeeded.
diff --git a/src/process.c b/src/process.c
index e6465e2347e..daa0dc68ae6 100644
--- a/src/process.c
+++ b/src/process.c
@@ -1248,10 +1248,7 @@ passed to the filter.
 The filter gets two arguments: the process and the string of output.
 The string argument is normally a multibyte string, except:
 - if the process's input coding system is no-conversion or raw-text,
-  it is a unibyte string (the non-converted input), or else
-- if `default-enable-multibyte-characters' is nil, it is a unibyte
-  string (the result of converting the decoded input multibyte
-  string to unibyte with `string-make-unibyte').  */)
+  it is a unibyte string (the non-converted input).  */)
   (Lisp_Object process, Lisp_Object filter)
 {
   CHECK_PROCESS (process);
@@ -3761,8 +3758,7 @@ The stopped state is cleared by `continue-process' and set by
 
 :filter-multibyte BOOL -- If BOOL is non-nil, strings given to the
 process filter are multibyte, otherwise they are unibyte.
-If this keyword is not specified, the strings are multibyte if
-the default value of `enable-multibyte-characters' is non-nil.
+If this keyword is not specified, the strings are multibyte.
 
 :sentinel SENTINEL -- Install SENTINEL as the process sentinel.