Implement cygw32

Here, we use the generic window-system configuration system we just
implemented to support the w32 window-system in the mainline build
under Cygwin.  (Previously, the w32 window system could only be
compiled as part of the NT-native Emacs build process.)

The changes in this patch need to be applied atomically in order to
avoid breaking Emacs.  The changes include:

  - Changes throughout the Lisp and C code to not assume that
      NT Emacs and the w32 window system are synonymous.

  - Wiring up the regular select(2) event loop to Windows messages

  - Cleaning up the w32 drag-and-drop receiving code.

  - Exposing Cygwin path conversion functions to elisp.

  - Unicode file dialog support when compiling for Cygwin.

  - Splitting the w32 term lisp initialization code into code
    applicable to any w32 window-system and code specific to
    system-type windows-nt.

  - Integrating the old and new w32 code into the build system.

11 files changed, 57 insertions, 144 deletions

diff --git a/lisp/battery.el b/lisp/battery.el
index 8e98291b11c..69d25643bb9 100644
--- a/lisp/battery.el
+++ b/lisp/battery.el
@@ -60,7 +60,7 @@
                          (> (buffer-size) 0)))
                 (error nil)))
          'battery-pmset)
-        ((eq system-type 'windows-nt)
+        ((fboundp 'w32-battery-status)
          'w32-battery-status))
   "Function for getting battery status information.
 The function has to return an alist of conversion definitions.
diff --git a/lisp/faces.el b/lisp/faces.el
index 6a477e172e1..d004ae650cb 100644
--- a/lisp/faces.el
+++ b/lisp/faces.el
@@ -96,7 +96,7 @@ ALTERNATIVE2 etc."
 ;; This is defined originally in xfaces.c.
 (defcustom face-font-registry-alternatives
   (mapcar (lambda (arg) (mapcar 'purecopy arg))
-  (if (eq system-type 'windows-nt)
+  (if (featurep 'w32)
       '(("iso8859-1" "ms-oemlatin")
         ("gb2312.1980" "gb2312" "gbk" "gb18030")
         ("jisx0208.1990" "jisx0208.1983" "jisx0208.1978")
diff --git a/lisp/frame.el b/lisp/frame.el
index 01225639ecf..9be64a6b7ff 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -524,7 +524,7 @@ The optional argument PARAMETERS specifies additional frame parameters."
            (ns-initialize-window-system))
          (make-frame `((window-system . ns)
                        (display . ,display) . ,parameters)))
-        ((eq system-type 'windows-nt)
+        ((eq window-system 'w32)
          ;; On Windows, ignore DISPLAY.
          (make-frame parameters))
         (t
@@ -1260,7 +1260,7 @@ frame's display)."
     (cond
      ((eq frame-type 'pc)
       (msdos-mouse-p))
-     ((eq system-type 'windows-nt)
+     ((eq frame-type 'w32)
       (with-no-warnings
        (> w32-num-mouse-buttons 0)))
      ((memq frame-type '(x ns))
diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index 2fc9759972e..177ac8eaa91 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -2670,7 +2670,8 @@ See also `locale-charset-language-names', `locale-language-names',
     ;; On Windows, override locale-coding-system,
     ;; default-file-name-coding-system, keyboard-coding-system,
     ;; terminal-coding-system with system codepage.
-    (when (boundp 'w32-ansi-code-page)
+    (when (and (eq system-type 'windows-nt)
+               (boundp 'w32-ansi-code-page))
       (let ((code-page-coding (intern (format "cp%d" w32-ansi-code-page))))
         (when (coding-system-p code-page-coding)
           (unless frame (setq locale-coding-system code-page-coding))
diff --git a/lisp/loadup.el b/lisp/loadup.el
index a460fcab339..c70b417822f 100644
--- a/lisp/loadup.el
+++ b/lisp/loadup.el
@@ -224,15 +224,18 @@
       (load "term/common-win")
       (load "term/x-win")))
 
-(if (eq system-type 'windows-nt)
+(if (or (eq system-type 'windows-nt)
+        (featurep 'w32))
     (progn
-      (load "w32-vars")
       (load "term/common-win")
+      (load "w32-vars")
       (load "term/w32-win")
-      (load "ls-lisp")
       (load "disp-table")
-      (load "dos-w32")
-      (load "w32-fns")))
+      (load "w32-common-fns")
+      (when (eq system-type 'windows-nt)
+        (load "w32-fns")
+        (load "ls-lisp")
+        (load "dos-w32"))))
 (if (eq system-type 'ms-dos)
     (progn
       (load "dos-w32")
diff --git a/lisp/mouse.el b/lisp/mouse.el
index 4ea84288f69..14e69c9f34d 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -1151,7 +1151,7 @@ regardless of where you click."
   (or mouse-yank-at-point (mouse-set-point click))
   (let ((primary
          (cond
-          ((eq system-type 'windows-nt)
+          ((eq (framep (selected-frame)) 'w32)
            ;; MS-Windows emulates PRIMARY in x-get-selection, but not
            ;; in x-get-selection-value (the latter only accesses the
            ;; clipboard).  So try PRIMARY first, in case they selected
diff --git a/lisp/simple.el b/lisp/simple.el
index b7a24f4f970..b81e0d7ee88 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -6870,7 +6870,7 @@ call `normal-erase-is-backspace-mode' (which see) instead."
        (if (if (eq normal-erase-is-backspace 'maybe)
                (and (not noninteractive)
                     (or (memq system-type '(ms-dos windows-nt))
-                        (memq window-system '(ns))
+                        (memq window-system '(w32 ns))
                         (and (memq window-system '(x))
                              (fboundp 'x-backspace-delete-keys-p)
                              (x-backspace-delete-keys-p))
diff --git a/lisp/term/common-win.el b/lisp/term/common-win.el
index 067b996d1ff..b44e092cc0a 100644
--- a/lisp/term/common-win.el
+++ b/lisp/term/common-win.el
@@ -57,7 +57,7 @@ clipboard as well.
 
 On Nextstep, put TEXT in the pasteboard (`x-select-enable-clipboard'
 is not used)."
-  (cond ((eq system-type 'windows-nt)
+  (cond ((eq (framep (selected-frame)) 'w32)
          (if x-select-enable-clipboard
              (w32-set-clipboard-data text))
          (setq x-last-selected-text text))
diff --git a/lisp/term/w32-win.el b/lisp/term/w32-win.el
index a4fac3441db..dd577af0ae1 100644
--- a/lisp/term/w32-win.el
+++ b/lisp/term/w32-win.el
@@ -1,4 +1,4 @@
-;;; w32-win.el --- parse switches controlling interface with W32 window system
+;;; w32-win.el --- parse switches controlling interface with W32 window system -*- lexical-binding: t -*-
 
 ;; Copyright (C) 1993-1994, 2001-2012  Free Software Foundation, Inc.
 
@@ -102,7 +102,22 @@
 ;;   (interactive "e")
 ;;   (princ event))
 
-(defun w32-drag-n-drop (event)
+(defun w32-handle-dropped-file (window file-name)
+  (let ((f (if (eq system-type 'cygwin)
+               (cygwin-convert-path-from-windows file-name t)
+             (subst-char-in-string ?\\ ?/ file-name)))
+        (coding (or file-name-coding-system
+                    default-file-name-coding-system)))
+
+    (setq file-name
+          (mapconcat 'url-hexify-string
+                     (split-string (encode-coding-string f coding)
+                                   "/")
+                     "/")))
+                (dnd-handle-one-url window 'private
+                                    (concat "file:" file-name)))
+
+(defun w32-drag-n-drop (event &optional new-frame)
   "Edit the files listed in the drag-n-drop EVENT.
 Switch to a buffer editing the last file dropped."
   (interactive "e")
@@ -116,26 +131,21 @@ Switch to a buffer editing the last file dropped."
            (y (cdr coords)))
       (if (and (> x 0) (> y 0))
           (set-frame-selected-window nil window))
-      (mapc (lambda (file-name)
-                (let ((f (subst-char-in-string ?\\ ?/ file-name))
-                      (coding (or file-name-coding-system
-                                  default-file-name-coding-system)))
-                  (setq file-name
-                        (mapconcat 'url-hexify-string
-                                   (split-string (encode-coding-string f coding)
-                                                 "/")
-                                   "/")))
-                (dnd-handle-one-url window 'private
-                                    (concat "file:" file-name)))
-                (car (cdr (cdr event)))))
-  (raise-frame)))
+
+      (when new-frame
+        (select-frame (make-frame)))
+      (raise-frame)
+      (setq window (selected-window))
+
+      (mapc (apply-partially #'w32-handle-dropped-file window)
+            (car (cdr (cdr event)))))))
 
 (defun w32-drag-n-drop-other-frame (event)
   "Edit the files listed in the drag-n-drop EVENT, in other frames.
 May create new frames, or reuse existing ones.  The frame editing
 the last file dropped is selected."
   (interactive "e")
-  (mapcar 'find-file-other-frame (car (cdr (cdr event)))))
+  (w32-drag-n-drop event t))
 
 ;; Bind the drag-n-drop event.
 (global-set-key [drag-n-drop] 'w32-drag-n-drop)
diff --git a/lisp/w32-fns.el b/lisp/w32-fns.el
index 1769ee73be5..813a8fd4d96 100644
--- a/lisp/w32-fns.el
+++ b/lisp/w32-fns.el
@@ -26,34 +26,20 @@
 
 ;;; Code:
 (require 'w32-vars)
+(require 'w32-common-fns)
 
 (defvar explicit-shell-file-name)
 
 ;;;; Function keys
 
 (declare-function set-message-beep "w32console.c")
-(declare-function w32-get-clipboard-data "w32select.c")
 (declare-function w32-get-locale-info "w32proc.c")
 (declare-function w32-get-valid-locale-ids "w32proc.c")
-(declare-function w32-set-clipboard-data "w32select.c")
 
 ;; Map all versions of a filename (8.3, longname, mixed case) to the
 ;; same buffer.
 (setq find-file-visit-truename t)
 
-(declare-function x-server-version "w32fns.c" (&optional display))
-
-(defun w32-version ()
-  "Return the MS-Windows version numbers.
-The value is a list of three integers: the major and minor version
-numbers, and the build number."
-  (x-server-version))
-
-(defun w32-using-nt ()
-  "Return non-nil if running on a Windows NT descendant.
-That includes all Windows systems except for 9X/Me."
-  (and (eq system-type 'windows-nt) (getenv "SystemRoot")))
-
 (defun w32-shell-name ()
   "Return the name of the shell being used."
   (or (bound-and-true-p shell-file-name)
@@ -240,53 +226,6 @@ requires it (see `w32-shell-dos-semantics')."
           (setq start (match-end 0))))
       name)))
 
-;;; Fix interface to (X-specific) mouse.el
-(defun x-set-selection (type data)
-  "Make an X selection of type TYPE and value DATA.
-The argument TYPE (nil means `PRIMARY') says which selection, and
-DATA specifies the contents.  TYPE must be a symbol.  \(It can also
-be a string, which stands for the symbol with that name, but this
-is considered obsolete.)  DATA may be a string, a symbol, an
-integer (or a cons of two integers or list of two integers).
-
-The selection may also be a cons of two markers pointing to the same buffer,
-or an overlay.  In these cases, the selection is considered to be the text
-between the markers *at whatever time the selection is examined*.
-Thus, editing done in the buffer after you specify the selection
-can alter the effective value of the selection.
-
-The data may also be a vector of valid non-vector selection values.
-
-The return value is DATA.
-
-Interactively, this command sets the primary selection.  Without
-prefix argument, it reads the selection in the minibuffer.  With
-prefix argument, it uses the text of the region as the selection value.
-
-Note that on MS-Windows, primary and secondary selections set by Emacs
-are not available to other programs."
-  (put 'x-selections (or type 'PRIMARY) data))
-
-(defun x-get-selection (&optional type _data-type)
-  "Return the value of an X Windows selection.
-The argument TYPE (default `PRIMARY') says which selection,
-and the argument DATA-TYPE (default `STRING') says
-how to convert the data.
-
-TYPE may be any symbol \(but nil stands for `PRIMARY').  However,
-only a few symbols are commonly used.  They conventionally have
-all upper-case names.  The most often used ones, in addition to
-`PRIMARY', are `SECONDARY' and `CLIPBOARD'.
-
-DATA-TYPE is usually `STRING', but can also be one of the symbols
-in `selection-converter-alist', which see."
-  (get 'x-selections (or type 'PRIMARY)))
-
-;; x-selection-owner-p is used in simple.el
-(defun x-selection-owner-p (&optional type)
-  (and (memq type '(nil PRIMARY SECONDARY))
-       (get 'x-selections (or type 'PRIMARY))))
-
 (defun set-w32-system-coding-system (coding-system)
   "Set the coding system used by the Windows system to CODING-SYSTEM.
 This is used for things like passing font names with non-ASCII
@@ -311,14 +250,6 @@ This function is provided for backward compatibility, since
 ;; Set to a system sound if you want a fancy bell.
 (set-message-beep nil)
 
-;; The "Windows" keys on newer keyboards bring up the Start menu
-;; whether you want it or not - make Emacs ignore these keystrokes
-;; rather than beep.
-(global-set-key [lwindow] 'ignore)
-(global-set-key [rwindow] 'ignore)
-
-(defvar w32-charset-info-alist)         ; w32font.c
-
 (defun w32-add-charset-info (xlfd-charset windows-charset codepage)
   "Function to add character sets to display with Windows fonts.
 Creates entries in `w32-charset-info-alist'.
@@ -380,40 +311,6 @@ bit output with no translation."
                         'w32-charset-info-alist "21.1")
 
 
-;;;; Selections
-
-;; We keep track of the last text selected here, so we can check the
-;; current selection against it, and avoid passing back our own text
-;; from x-selection-value.
-(defvar x-last-selected-text nil)
-
-(defun x-get-selection-value ()
-  "Return the value of the current selection.
-Consult the selection.  Treat empty strings as if they were unset."
-  (if x-select-enable-clipboard
-      (let (text)
-        ;; Don't die if x-get-selection signals an error.
-        (condition-case c
-            (setq text (w32-get-clipboard-data))
-          (error (message "w32-get-clipboard-data:%s" c)))
-        (if (string= text "") (setq text nil))
-        (cond
-         ((not text) nil)
-         ((eq text x-last-selected-text) nil)
-         ((string= text x-last-selected-text)
-          ;; Record the newer string, so subsequent calls can use the 'eq' test.
-          (setq x-last-selected-text text)
-          nil)
-         (t
-          (setq x-last-selected-text text))))))
-
-(defalias 'x-selection-value 'x-get-selection-value)
-
-;; Arrange for the kill and yank functions to set and check the clipboard.
-(setq interprogram-cut-function 'x-select-text)
-(setq interprogram-paste-function 'x-get-selection-value)
-
-
 ;;;; Support for build process
 
 ;; From autoload.el
diff --git a/lisp/w32-vars.el b/lisp/w32-vars.el
index c8716ef6c36..0e152b125bc 100644
--- a/lisp/w32-vars.el
+++ b/lisp/w32-vars.el
@@ -44,17 +44,19 @@ X does.  See `w32-fixed-font-alist' for the font menu definition."
   "Include proportional fonts in the default font dialog.")
 (make-obsolete-variable 'w32-list-proportional-fonts "no longer used." "23.1")
 
-(defcustom w32-allow-system-shell nil
-  "Disable startup warning when using \"system\" shells."
-  :type 'boolean
-  :group 'w32)
-
-(defcustom w32-system-shells '("cmd" "cmd.exe" "command" "command.com"
-                               "4nt" "4nt.exe" "4dos" "4dos.exe"
-                               "tcc" "tcc.exe" "ndos" "ndos.exe")
-  "List of strings recognized as Windows system shells."
-  :type '(repeat string)
-  :group 'w32)
+(unless (eq system-type 'cygwin)
+  (defcustom w32-allow-system-shell nil
+    "Disable startup warning when using \"system\" shells."
+    :type 'boolean
+    :group 'w32))
+
+(unless (eq system-type 'cygwin)
+ (defcustom w32-system-shells '("cmd" "cmd.exe" "command" "command.com"
+                                "4nt" "4nt.exe" "4dos" "4dos.exe"
+                                "tcc" "tcc.exe" "ndos" "ndos.exe")
+   "List of strings recognized as Windows system shells."
+   :type '(repeat string)
+   :group 'w32))
 
 ;; Want "menu" custom type for this.
 (defcustom w32-fixed-font-alist