Merge from origin/emacs-27

bcd92b5708 (origin/emacs-27) Improve documentation of Hexl mode
c233f4eccd ; * etc/NEWS: Fix decoded-time-set-defaults typo.
4c3abb3dd1 Fix compilation errors with latest w32 API headers
127f1f330b Improve doc strings in log-edit.el
e36183ff46 ; * etc/TODO (etc/DOC): Update the todo entries.

# Conflicts:
#	etc/NEWS

15 files changed, 124 insertions, 90 deletions

diff --git a/doc/emacs/misc.texi b/doc/emacs/misc.texi
index fbb8122a1b8..c8027792505 100644
--- a/doc/emacs/misc.texi
+++ b/doc/emacs/misc.texi
@@ -2576,6 +2576,17 @@ Other Hexl commands let you insert strings (sequences) of binary
 bytes, move by @code{short}s or @code{int}s, etc.; type @kbd{C-h a
 hexl-@key{RET}} for details.
 
+  Hexl mode can also be used for editing text files.  This could come
+in handy if the text file includes unusual characters or uses unusual
+encoding (@pxref{Coding Systems}).  For this purpose, Hexl commands
+that insert bytes can also insert @acronym{ASCII} and
+non-@acronym{ASCII} characters, including multibyte characters.  To
+edit a text file with Hexl, visit the file as usual, and then type
+@w{@kbd{M-x hexl-mode @key{RET}}} to switch to Hexl mode.  You can now
+insert text characters by typing them.  However, inserting multibyte
+characters requires special care, to avoid the danger of creating
+invalid multibyte sequences: you should start typing such characters
+when point is on the first byte of a multibyte sequence in the file.
 
 @node Saving Emacs Sessions
 @section Saving Emacs Sessions
diff --git a/etc/NEWS.27 b/etc/NEWS.27
index 55045d10ee3..4b4c1a31455 100644
--- a/etc/NEWS.27
+++ b/etc/NEWS.27
@@ -2701,7 +2701,7 @@ days there are in a month in a specific year), 'date-ordinal-to-time'
 (that computes the date of an ordinal day), 'decoded-time-add' (for
 doing computations on a decoded time structure), 'make-decoded-time'
 (for making a decoded time structure with only the given keywords
-filled out), and 'encoded-time-set-defaults' (which fills in nil
+filled out), and 'decoded-time-set-defaults' (which fills in nil
 elements as if it's midnight January 1st, 1970) have been added.
 
 *** In the DST slot, 'encode-time' and 'parse-time-string' now return -1
diff --git a/etc/TODO b/etc/TODO
index f806b6ca4f1..1d6824c470a 100644
--- a/etc/TODO
+++ b/etc/TODO
@@ -1763,8 +1763,17 @@ apparently loses under Solaris, at least. [fx has mostly done this.]
 (Obsolete, since gmalloc.c is nowadays only used on MS-DOS.)
 
 ** Rewrite make-docfile to be clean and maintainable
-It might be better to replace it with Lisp, using the byte compiler.
+It might be better to replace with Lisp the part of make-docfile that
+produces the etc/DOC file by scanning *.el files, for example by
+reusing the code in the byte compiler or in autoload.el that already
+scans *.el files.
 https://lists.gnu.org/r/emacs-devel/2012-06/msg00037.html
+https://lists.gnu.org/r/emacs-devel/2021-05/msg00235.html
+
+** Eliminate the etc/DOC file altogether
+As an alternative to the previous item, we could try and eliminate the
+DOC file altogether.  See
+https://lists.gnu.org/r/emacs-devel/2021-05/msg00237.html
 
 ** Add an inferior-comint-minor-mode
 The purpose is to have a mode to capture the common set of operations
diff --git a/lisp/vc/log-edit.el b/lisp/vc/log-edit.el
index eabbaba32c0..f115a91a175 100644
--- a/lisp/vc/log-edit.el
+++ b/lisp/vc/log-edit.el
@@ -203,13 +203,15 @@ when this variable is set to nil.")
 ;;; Originally taken from VC-Log mode
 
 (defconst log-edit-maximum-comment-ring-size 32
-  "Maximum number of saved comments in the comment ring.")
+  "Maximum number of saved commit comments in `log-edit-comment-ring'.")
 (defvar log-edit-comment-ring (make-ring log-edit-maximum-comment-ring-size))
 (defvar log-edit-comment-ring-index nil)
 (defvar log-edit-last-comment-match "")
 
 (defun log-edit-new-comment-index (stride len)
-  "Return the comment index STRIDE elements from the current one.
+  "Return the comment whose index is STRIDE elements away from the current one.
+This accesses `log-edit-comment-ring', which stores commit log comments,
+i.e. descriptions of changes done by commits.
 LEN is the length of `log-edit-comment-ring'."
   (mod (cond
 	(log-edit-comment-ring-index (+ log-edit-comment-ring-index stride))
@@ -221,7 +223,7 @@ LEN is the length of `log-edit-comment-ring'."
        len))
 
 (defun log-edit-previous-comment (arg)
-  "Cycle backwards through comment history.
+  "Cycle backwards through VC commit comment history.
 With a numeric prefix ARG, go back ARG comments."
   (interactive "*p")
   (let ((len (ring-length log-edit-comment-ring)))
@@ -234,15 +236,15 @@ With a numeric prefix ARG, go back ARG comments."
       (insert (ring-ref log-edit-comment-ring log-edit-comment-ring-index)))))
 
 (defun log-edit-next-comment (arg)
-  "Cycle forwards through comment history.
+  "Cycle forwards through VC commit comment history.
 With a numeric prefix ARG, go forward ARG comments."
   (interactive "*p")
   (log-edit-previous-comment (- arg)))
 
 (defun log-edit-comment-search-backward (str &optional stride)
-  "Search backwards through comment history for substring match of STR.
+  "Search backwards through VC commit comment history for a match of STR.
 If the optional argument STRIDE is present, that is a step-width to use
-when going through the comment ring."
+when going through the comment ring, `log-edit-comment-ring'."
   ;; Why substring rather than regexp ?   -sm
   (interactive
    (list (read-string (format-prompt "Comment substring"
@@ -262,7 +264,7 @@ when going through the comment ring."
     (log-edit-previous-comment 0)))
 
 (defun log-edit-comment-search-forward (str)
-  "Search forwards through comment history for a substring match of STR."
+  "Search forwards through VC commit comment history for a match of STR."
   (interactive
    (list (read-string (format-prompt "Comment substring"
                                      log-edit-last-comment-match)
@@ -270,10 +272,15 @@ when going through the comment ring."
   (log-edit-comment-search-backward str -1))
 
 (defun log-edit-comment-to-change-log (&optional whoami file-name)
-  "Enter last VC comment into the change log for the current file.
-WHOAMI (interactive prefix) non-nil means prompt for user name
-and site.  FILE-NAME is the name of the change log; if nil, use
-`change-log-default-name'.
+  "Insert the last VC commit comment into the change log for the current file.
+This reuses the text of the last VC commit comment in `log-edit-comment-ring'
+for the change-log entry of the current file, which is handy when several
+related changes have the same commit comment.
+WHOAMI (interactively, prefix argument) non-nil means prompt for user name
+and email address of the person to whom to attribute the change.
+FILE-NAME is the name of the change log; if nil, use `change-log-default-name'
+Interactively, with prefix argument, prompt for both the name and address of
+the person who did the change and for FILE-NAME.
 
 This may be useful as a `vc-checkin-hook' to update change logs
 automatically."
@@ -332,7 +339,7 @@ automatically."
 
 (defconst log-edit-header-contents-regexp
   "[ \t]*\\(.*\\(\n[ \t].*\\)*\\)\n?"
-  "Regular expression matching a header field.
+  "Regular expression matching the header field in `log-edit-mode'.
 The first subexpression is the actual text of the field.")
 
 (defun log-edit-match-to-eoh (_limit)
@@ -393,7 +400,9 @@ The first subexpression is the actual text of the field.")
     (log-edit--match-first-line (0 'log-edit-summary))))
 
 (defvar log-edit-font-lock-gnu-style nil
-  "If non-nil, highlight common failures to follow the GNU coding standards.")
+  "If non-nil, highlight common failures to follow VC commit log conventions.
+The conventions checked are those described in the GNU coding standards
+document.")
 (put 'log-edit-font-lock-gnu-style 'safe-local-variable 'booleanp)
 
 (defconst log-edit-font-lock-gnu-keywords
@@ -436,28 +445,28 @@ The first subexpression is the actual text of the field.")
 
 ;;;###autoload
 (defun log-edit (callback &optional setup params buffer mode &rest _ignore)
-  "Setup a buffer to enter a log message.
-The buffer is put in mode MODE or `log-edit-mode' if MODE is nil.
+  "Setup a buffer to enter a VC commit log message.
+The buffer is put in mode MODE, or `log-edit-mode' if MODE is nil.
 \\<log-edit-mode-map>
 If SETUP is non-nil, erase the buffer and run `log-edit-hook'.
 Set mark and point around the entire contents of the buffer, so
 that it is easy to kill the contents of the buffer with
-\\[kill-region].  Once the user is done editing the message,
-invoking the command \\[log-edit-done] (`log-edit-done') will
-call CALLBACK to do the actual commit.
+\\[kill-region].  Once the user is done editing the message, he
+or she is expected to invoke the command \\[log-edit-done] (`log-edit-done'),
+which will call CALLBACK, a function to do the actual commit.
 
-PARAMS if non-nil is an alist of variables and buffer-local
-values to give them in the Log Edit buffer.  Possible keys and
-associated values:
+PARAMS, if non-nil, is an alist of variables and buffer-local
+values to give to those variables in the Log Edit buffer.  Possible
+keys and associated values are:
  `log-edit-listfun' -- function taking no arguments that returns the list of
- files that are concerned by the current operation (using relative names);
+    files that are concerned by the current operation (using relative names);
  `log-edit-diff-function' -- function taking no arguments that
- displays a diff of the files concerned by the current operation.
+    displays a diff of the files concerned by the current operation.
  `vc-log-fileset' -- the VC fileset to be committed (if any).
 
-If BUFFER is non-nil `log-edit' will jump to that buffer, use it
+If BUFFER is non-nil, `log-edit' will switch to that buffer, use it
 to edit the log message and go back to the current buffer when
-done.  Otherwise, it uses the current buffer."
+done.  Otherwise, this function will use the current buffer."
   (let ((parent (current-buffer)))
     (if buffer (pop-to-buffer buffer))
     (when (and log-edit-setup-invert (not (eq setup 'force)))
@@ -483,12 +492,12 @@ done.  Otherwise, it uses the current buffer."
 	      "Press \\[log-edit-done] when you are done editing."))))
 
 (define-derived-mode log-edit-mode text-mode "Log-Edit"
-  "Major mode for editing version-control log messages.
-When done editing the log entry, just type \\[log-edit-done] which
-will trigger the actual commit of the file(s).
-Several other handy support commands are provided of course and
-the package from which this is used might also provide additional
-commands (under C-x v for VC, for example).
+  "Major mode for editing version-control (VC) commit log messages.
+When done editing the log entry, type \\[log-edit-done], which will
+trigger the actual commit of the file(s).
+Several other handy support commands are provided, and the package
+from which this is used might also provide additional commands (under
+the \"C-x v\" prefix for VC commands, for example).
 
 \\{log-edit-mode-map}"
   (setq-local font-lock-defaults '(log-edit-font-lock-keywords t))
@@ -520,7 +529,7 @@ commands (under C-x v for VC, for example).
     (insert "):")))
 
 (defun log-edit-fill-entry (&optional justify)
-  "Like \\[fill-paragraph], but handle ChangeLog entries.
+  "Like \\[fill-paragraph], but for filling ChangeLog-formatted entries.
 Consecutive function entries without prose (i.e., lines of the
 form \"(FUNCTION):\") will be combined into \"(FUNC1, FUNC2):\"
 according to `fill-column'."
@@ -570,7 +579,7 @@ according to `fill-column'."
     (ring-insert log-edit-comment-ring comment)))
 
 (defun log-edit-done ()
-  "Finish editing the log message and commit the files.
+  "Finish editing the VC commit log message, and commit the files.
 If you want to abort the commit, simply delete the buffer."
   (interactive)
   ;; Clean up empty headers.
@@ -617,9 +626,9 @@ If you want to abort the commit, simply delete the buffer."
       (call-interactively log-edit-callback))))
 
 (defun log-edit-kill-buffer ()
-  "Kill the current buffer.
-Also saves its contents in the comment history and hides
-`log-edit-files-buf'."
+  "Kill the current VC commit log buffer.
+This command saves the contents of the log buffer in the VC commit
+comment history, see `log-edit-comment-ring', and hides `log-edit-files-buf'."
   (interactive)
   (log-edit-hide-buf)
   (let ((buf (current-buffer)))
@@ -699,7 +708,7 @@ different header separator appropriate for `log-edit-mode'."
         (eobp))))
 
 (defun log-edit-insert-message-template ()
-  "Insert the default template with Summary and Author."
+  "Insert the default VC commit log template with Summary and Author."
   (interactive)
   (when (or (called-interactively-p 'interactive)
             (log-edit-empty-buffer-p))
@@ -710,7 +719,7 @@ different header separator appropriate for `log-edit-mode'."
     (message-position-point)))
 
 (defun log-edit-insert-cvs-template ()
-  "Insert the template specified by the CVS administrator, if any.
+  "Insert the commit log template specified by the CVS administrator, if any.
 This simply uses the local CVS/Template file."
   (interactive)
   (when (or (called-interactively-p 'interactive)
@@ -722,7 +731,7 @@ This simply uses the local CVS/Template file."
       (insert-file-contents "CVS/Template"))))
 
 (defun log-edit-insert-cvs-rcstemplate ()
-  "Insert the rcstemplate from the CVS repository.
+  "Insert the RCS commit log template from the CVS repository.
 This contacts the repository to get the rcstemplate file and
 can thus take some time."
   (interactive)
@@ -756,7 +765,7 @@ can thus take some time."
       (insert (mapconcat 'identity files ", ") ": "))))
 
 (defun log-edit-add-to-changelog ()
-  "Insert this log message into the appropriate ChangeLog file."
+  "Insert this VC commit log message into the appropriate ChangeLog file."
   (interactive)
   (log-edit-remember-comment)
   (dolist (f (log-edit-files))
@@ -770,7 +779,7 @@ can thus take some time."
   "Non-nil means rewrite (tiny change).")
 
 (defvar log-edit-rewrite-fixes nil
-  "Rule to rewrite bug numbers into Fixes: headers.
+  "Rule to rewrite bug numbers into Fixes: headers in commit log messages.
 The value should be of the form (REGEXP . REPLACEMENT)
 where REGEXP should match the expression referring to a bug number
 in the text, and REPLACEMENT is an expression to pass to `replace-match'
@@ -788,10 +797,11 @@ to build the Fixes: header.")
 (declare-function diff-add-log-current-defuns "diff-mode" ())
 
 (defun log-edit-generate-changelog-from-diff ()
-  "Insert a log message by looking at the current diff.
+  "Insert a VC commit log message by looking at the current diff.
+This command is intended to be uses on the \"*vc-log*\" buffer.
 This command will generate a ChangeLog entries listing the
-functions.  You can then add a description where needed, and use
-\\[fill-paragraph] to join consecutive function names."
+changed functions.  You can then add a description where needed,
+and use \\[fill-paragraph] to join consecutive function names."
   (interactive)
   (change-log-insert-entries
    (with-current-buffer
@@ -809,21 +819,21 @@ functions.  You can then add a description where needed, and use
      (diff-add-log-current-defuns))))
 
 (defun log-edit-insert-changelog (&optional use-first)
-  "Insert a log message by looking at the ChangeLog.
+  "Insert a VC commit log message by looking at the ChangeLog.
 The idea is to write your ChangeLog entries first, and then use this
-command to commit your changes.
+command to commit your changes with that log.
 
-To select default log text, we:
-- find the ChangeLog entries for the files to be checked in,
-- verify that the top entry in the ChangeLog is on the current date
-  and by the current user; if not, we don't provide any default text,
-- search the ChangeLog entry for paragraphs containing the names of
-  the files we're checking in, and finally
-- use those paragraphs as the log text.
+To select default log text, this command:
+- finds the ChangeLog entries for the files to be checked in;
+- verifies that the top entry in the ChangeLog is on the current date
+    and by the current user; if not, it doesn't provide any default text;
+- searches the ChangeLog entry for paragraphs containing the names of
+    the files to be checked in; and finally
+- uses those paragraphs as the log text.
 
 If the optional prefix arg USE-FIRST is given (via \\[universal-argument]),
-or if the command is repeated a second time in a row, use the first log entry
-regardless of user name or time."
+or if the command is repeated, use the first log entry regardless of user
+name or time."
   (interactive "P")
   (save-excursion
     (let ((eoh (save-excursion (rfc822-goto-eoh) (point))))
@@ -873,7 +883,7 @@ regardless of user name or time."
 ;;;;
 
 (defun log-edit-narrow-changelog ()
-  "Narrow to the top page of the current buffer, a ChangeLog file.
+  "Narrow to the top page of the current buffer, which visits a ChangeLog file.
 Actually, the narrowed region doesn't include the date line.
 A \"page\" in a ChangeLog file is the area between two dates."
   (or (eq major-mode 'change-log-mode)
@@ -921,7 +931,7 @@ If we are between sub-paragraphs, return the previous subparagraph."
 
 (defun log-edit-changelog-entry ()
   "Return the bounds of the ChangeLog entry containing point.
-The variable `log-edit-changelog-full-paragraphs' decides whether an
+The variable `log-edit-changelog-full-paragraphs' determines whether an
 \"entry\" is a paragraph or a subparagraph; see its documentation string
 for more details."
   (save-excursion
@@ -1047,8 +1057,12 @@ where LOGBUFFER is the name of the ChangeLog buffer, and each
                             "\\($\\|[^[:alnum:]]\\)")))))
 
 (defun log-edit-changelog-insert-entries (buffer beg end &rest files)
-  "Insert the text from BUFFER between BEG and END.
-Rename relative filenames in the ChangeLog entry as FILES."
+  "Insert the text from ChangeLog BUFFER between BEG and END.
+Rename relative filenames in the ChangeLog entry with FILES.
+FILES are supposed to name the same files whose relative filenames
+are to be replaced, and their names relative to the directory of
+BUFFER are expected to match the relative file names in the ChangeLog
+entry."
   (let ((opoint (point))
 	(log-name (buffer-file-name buffer))
 	(case-fold-search nil)
@@ -1130,7 +1144,7 @@ Return t if toggled on (or TOGGLE is nil), otherwise nil."
     val))
 
 (defun log-edit-extract-headers (headers comment)
-  "Extract headers from COMMENT to form command line arguments.
+  "Extract headers from VC commit COMMENT to form command line arguments.
 HEADERS should be an alist with elements (HEADER . CMDARG)
 or (HEADER . FUNCTION) associating headers to command line
 options and the result is then a list of the form (MSG ARGUMENTS...)
diff --git a/src/dynlib.c b/src/dynlib.c
index 1338e9109c9..a8c88439615 100644
--- a/src/dynlib.c
+++ b/src/dynlib.c
@@ -135,7 +135,7 @@ dynlib_addr (void (*funcptr) (void), const char **fname, const char **symname)
   void *addr = (void *) funcptr;
 
   /* Step 1: Find the handle of the module where ADDR lives.  */
-  if (os_subtype == OS_9X
+  if (os_subtype == OS_SUBTYPE_9X
       /* Windows NT family version before XP (v5.1).  */
       || ((w32_major_version + (w32_minor_version > 0)) < 6))
     {
diff --git a/src/w32.c b/src/w32.c
index 467e6cb4271..26cc28f877c 100644
--- a/src/w32.c
+++ b/src/w32.c
@@ -4747,7 +4747,7 @@ sys_rename_replace (const char *oldname, const char *newname, BOOL force)
   /* volume_info is set indirectly by map_w32_filename.  */
   oldname_dev = volume_info.serialnum;
 
-  if (os_subtype == OS_9X)
+  if (os_subtype == OS_SUBTYPE_9X)
     {
       char * o;
       char * p;
@@ -10468,7 +10468,7 @@ shutdown_handler (DWORD type)
 HANDLE
 maybe_load_unicows_dll (void)
 {
-  if (os_subtype == OS_9X)
+  if (os_subtype == OS_SUBTYPE_9X)
     {
       HANDLE ret = LoadLibrary ("Unicows.dll");
       if (ret)
diff --git a/src/w32common.h b/src/w32common.h
index cbe05c5d8d1..6493b9c88d5 100644
--- a/src/w32common.h
+++ b/src/w32common.h
@@ -41,8 +41,8 @@ extern int    	      w32_minor_version;
 extern int    	      w32_build_number;
 
 enum {
-  OS_9X = 1,
-  OS_NT
+  OS_SUBTYPE_9X = 1,
+  OS_SUBTYPE_NT
 };
 
 extern int os_subtype;
diff --git a/src/w32console.c b/src/w32console.c
index cb9e288e880..99546c2d754 100644
--- a/src/w32console.c
+++ b/src/w32console.c
@@ -803,7 +803,7 @@ initialize_w32_display (struct terminal *term, int *width, int *height)
       ceol_initialized = FALSE;
     }
 
-  if (os_subtype == OS_NT)
+  if (os_subtype == OS_SUBTYPE_NT)
     w32_console_unicode_input = 1;
   else
     w32_console_unicode_input = 0;
diff --git a/src/w32fns.c b/src/w32fns.c
index e5edd62abbc..14d1154a2bc 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -7993,7 +7993,7 @@ DEFUN ("system-move-file-to-trash", Fsystem_move_file_to_trash,
 
       /* The Unicode version of SHFileOperation is not supported on
 	 Windows 9X. */
-      if (w32_unicode_filenames && os_subtype != OS_9X)
+      if (w32_unicode_filenames && os_subtype != OS_SUBTYPE_9X)
 	{
 	  SHFILEOPSTRUCTW file_op_w;
 	  /* We need one more element beyond MAX_PATH because this is
@@ -9122,7 +9122,7 @@ The coordinates X and Y are interpreted in pixels relative to a position
   /* When "mouse trails" are in effect, moving the mouse cursor
      sometimes leaves behind an annoying "ghost" of the pointer.
      Avoid that by momentarily switching off mouse trails.  */
-  if (os_subtype == OS_NT
+  if (os_subtype == OS_SUBTYPE_NT
       && w32_major_version + w32_minor_version >= 6)
     ret = SystemParametersInfo (SPI_GETMOUSETRAILS, 0, &trail_num, 0);
   SetCursorPos (xval, yval);
@@ -9297,7 +9297,7 @@ DEFUN ("default-printer-name", Fdefault_printer_name, Sdefault_printer_name,
   if (!OpenPrinter (pname_buf, &hPrn, NULL))
     return Qnil;
   /* GetPrinterW is not supported by unicows.dll.  */
-  if (w32_unicode_filenames && os_subtype != OS_9X)
+  if (w32_unicode_filenames && os_subtype != OS_SUBTYPE_9X)
     GetPrinterW (hPrn, 2, NULL, 0, &dwNeeded);
   else
     GetPrinterA (hPrn, 2, NULL, 0, &dwNeeded);
@@ -9307,7 +9307,7 @@ DEFUN ("default-printer-name", Fdefault_printer_name, Sdefault_printer_name,
       return Qnil;
     }
   /* Call GetPrinter again with big enough memory block.  */
-  if (w32_unicode_filenames && os_subtype != OS_9X)
+  if (w32_unicode_filenames && os_subtype != OS_SUBTYPE_9X)
     {
       /* Allocate memory for the PRINTER_INFO_2 struct.  */
       ppi2w = xmalloc (dwNeeded);
@@ -9443,9 +9443,9 @@ cache_system_info (void)
   w32_minor_version = version.info.minor;
 
   if (version.info.platform & 0x8000)
-    os_subtype = OS_9X;
+    os_subtype = OS_SUBTYPE_9X;
   else
-    os_subtype = OS_NT;
+    os_subtype = OS_SUBTYPE_NT;
 
   /* Cache page size, allocation unit, processor type, etc.  */
   GetSystemInfo (&sysinfo_cache);
@@ -9456,7 +9456,7 @@ cache_system_info (void)
   GetVersionEx (&osinfo_cache);
 
   w32_build_number = osinfo_cache.dwBuildNumber;
-  if (os_subtype == OS_9X)
+  if (os_subtype == OS_SUBTYPE_9X)
     w32_build_number &= 0xffff;
 
   w32_num_mouse_buttons = GetSystemMetrics (SM_CMOUSEBUTTONS);
@@ -9635,7 +9635,7 @@ w32_kbd_patch_key (KEY_EVENT_RECORD *event, int cpId)
 
   /* On NT, call ToUnicode instead and then convert to the current
      console input codepage.  */
-  if (os_subtype == OS_NT)
+  if (os_subtype == OS_SUBTYPE_NT)
     {
       WCHAR buf[128];
 
@@ -11049,7 +11049,7 @@ see `w32-ansi-code-page'.  */);
   w32_multibyte_code_page = _getmbcp ();
 #endif
 
-  if (os_subtype == OS_NT)
+  if (os_subtype == OS_SUBTYPE_NT)
     w32_unicode_gui = 1;
   else
     w32_unicode_gui = 0;
diff --git a/src/w32heap.c b/src/w32heap.c
index e002f72608a..0f228bfb221 100644
--- a/src/w32heap.c
+++ b/src/w32heap.c
@@ -269,7 +269,7 @@ init_heap (bool use_dynamic_heap)
 	}
 #endif
 
-      if (os_subtype == OS_9X)
+      if (os_subtype == OS_SUBTYPE_9X)
         {
           the_malloc_fn = malloc_after_dump_9x;
           the_realloc_fn = realloc_after_dump_9x;
@@ -312,7 +312,7 @@ init_heap (bool use_dynamic_heap)
 	}
       heap = s_pfn_Rtl_Create_Heap (0, data_region_base, 0, 0, NULL, &params);
 
-      if (os_subtype == OS_9X)
+      if (os_subtype == OS_SUBTYPE_9X)
         {
           fprintf (stderr, "Cannot dump Emacs on Windows 9X; exiting.\n");
           exit (-1);
diff --git a/src/w32notify.c b/src/w32notify.c
index b9e90633923..889fd9f3c9f 100644
--- a/src/w32notify.c
+++ b/src/w32notify.c
@@ -566,7 +566,7 @@ generate notifications correctly, though.  */)
   CHECK_LIST (filter);
 
   /* The underlying features are available only since XP.  */
-  if (os_subtype == OS_9X
+  if (os_subtype == OS_SUBTYPE_9X
       || (w32_major_version == 5 && w32_minor_version < 1))
     {
       errno = ENOSYS;
diff --git a/src/w32proc.c b/src/w32proc.c
index ffa56e135d0..702ea122e65 100644
--- a/src/w32proc.c
+++ b/src/w32proc.c
@@ -623,7 +623,7 @@ init_timers (void)
      need to probe for its availability dynamically, and call it
      through a pointer.  */
   s_pfn_Get_Thread_Times = NULL; /* in case dumped Emacs comes with a value */
-  if (os_subtype != OS_9X)
+  if (os_subtype != OS_SUBTYPE_9X)
     s_pfn_Get_Thread_Times = (GetThreadTimes_Proc)
       get_proc_addr (GetModuleHandle ("kernel32.dll"), "GetThreadTimes");
 
@@ -2654,7 +2654,7 @@ find_child_console (HWND hwnd, LPARAM arg)
 
       GetClassName (hwnd, window_class, sizeof (window_class));
       if (strcmp (window_class,
-		  (os_subtype == OS_9X)
+		  (os_subtype == OS_SUBTYPE_9X)
 		  ? "tty"
 		  : "ConsoleWindowClass") == 0)
 	{
@@ -2878,7 +2878,7 @@ sys_kill (pid_t pid, int sig)
       if (NILP (Vw32_start_process_share_console) && cp && cp->hwnd)
 	{
 #if 1
-	  if (os_subtype == OS_9X)
+	  if (os_subtype == OS_SUBTYPE_9X)
 	    {
 /*
    Another possibility is to try terminating the VDM out-right by
@@ -3793,7 +3793,7 @@ w32_compare_strings (const char *s1, const char *s2, char *locname,
 
   if (!g_b_init_compare_string_w)
     {
-      if (os_subtype == OS_9X)
+      if (os_subtype == OS_SUBTYPE_9X)
 	{
 	  pCompareStringW = (CompareStringW_Proc)
             get_proc_addr (LoadLibrary ("Unicows.dll"),
diff --git a/src/w32select.c b/src/w32select.c
index 85f8e5556a2..f19b85a2aec 100644
--- a/src/w32select.c
+++ b/src/w32select.c
@@ -1207,7 +1207,7 @@ globals_of_w32select (void)
   QANSICP = coding_from_cp (ANSICP);
   QOEMCP = coding_from_cp (OEMCP);
 
-  if (os_subtype == OS_NT)
+  if (os_subtype == OS_SUBTYPE_NT)
     Vselection_coding_system = Qutf_16le_dos;
   else if (inhibit_window_system)
     Vselection_coding_system = QOEMCP;
diff --git a/src/w32term.c b/src/w32term.c
index 4f910296ecc..ad4d1a32829 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -1916,7 +1916,7 @@ w32_draw_image_foreground (struct glyph_string *s)
 	      /* HALFTONE produces better results, especially when
 		 scaling to a larger size, but Windows 9X doesn't
 		 support HALFTONE.  */
-	      if (os_subtype == OS_NT
+	      if (os_subtype == OS_SUBTYPE_NT
 		  && (pmode = SetStretchBltMode (s->hdc, HALFTONE)) != 0)
 		SetBrushOrgEx (s->hdc, 0, 0, NULL);
 	      StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
@@ -1952,7 +1952,7 @@ w32_draw_image_foreground (struct glyph_string *s)
 	    {
 	      int pmode = 0;
 	      /* Windows 9X doesn't support HALFTONE.  */
-	      if (os_subtype == OS_NT
+	      if (os_subtype == OS_SUBTYPE_NT
 		  && (pmode = SetStretchBltMode (s->hdc, HALFTONE)) != 0)
 		SetBrushOrgEx (s->hdc, 0, 0, NULL);
 	      StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
@@ -6644,7 +6644,7 @@ frame_set_mouse_pixel_position (struct frame *f, int pix_x, int pix_y)
   /* When "mouse trails" are in effect, moving the mouse cursor
      sometimes leaves behind an annoying "ghost" of the pointer.
      Avoid that by momentarily switching off mouse trails.  */
-  if (os_subtype == OS_NT
+  if (os_subtype == OS_SUBTYPE_NT
       && w32_major_version + w32_minor_version >= 6)
     ret = SystemParametersInfo (SPI_GETMOUSETRAILS, 0, &trail_num, 0);
   SetCursorPos (pt.x, pt.y);
@@ -7638,7 +7638,7 @@ specified by `file-name-coding-system'.
 This variable is set to non-nil by default when Emacs runs on Windows
 systems of the NT family, including W2K, XP, Vista, Windows 7 and
 Windows 8.  It is set to nil on Windows 9X.  */);
-  if (os_subtype == OS_9X)
+  if (os_subtype == OS_SUBTYPE_9X)
     w32_unicode_filenames = 0;
   else
     w32_unicode_filenames = 1;
diff --git a/src/w32term.h b/src/w32term.h
index 7d351df871d..160be357821 100644
--- a/src/w32term.h
+++ b/src/w32term.h
@@ -761,7 +761,7 @@ extern bool w32_image_rotations_p (void);
 extern void setup_w32_kbdhook (void);
 extern void remove_w32_kbdhook (void);
 extern int check_w32_winkey_state (int);
-#define w32_kbdhook_active (os_subtype != OS_9X)
+#define w32_kbdhook_active (os_subtype != OS_SUBTYPE_9X)
 #else
 #define w32_kbdhook_active 0
 #endif