Avoid defining unneeded variables on Cygw32

lisp/term/w32-win.el contained definitions of variables which
were not used on Cygw32.  It is now to split into two files,
common part and Windows native build specific part. The latter
is a new file, lisp/term/w32-nt.el.
* src/image.c (Qlibpng_version, Qlibgif_version)
(Qlibjpeg_version): Don't define on Cygw32 build.
* src/treesit.c (Qtree_sitter__library_abi): Ditto.

* lisp/term/w32-win.el (dynamic-library-alist, libpng-version)
(libgif-version, libjpeg-version, libgnutls-version)
(tree-sitter--library-abi, gui-backend-set-selection)
(gui-backend-get-selection, gui-backend-selection-owner-p)
(gui-selection-exists-p): Moved to lisp/term/w32-nt.el.
* lisp/term/w32-nt.el: New file, separated Windows native build
specific part from lisp/term/w32-win.el.
* lisp/loadup.el: Load term/w32-nt.el on Windows native build.
(Bug#75926)

5 files changed, 156 insertions, 110 deletions

diff --git a/lisp/loadup.el b/lisp/loadup.el
index 9089da9a988..3e87f4811df 100644
--- a/lisp/loadup.el
+++ b/lisp/loadup.el
@@ -332,6 +332,7 @@
       (load "term/w32-win")
       (load "disp-table")
       (when (eq system-type 'windows-nt)
+        (load "term/w32-nt")
         (load "w32-fns")
         (load "ls-lisp")
         (load "dos-w32"))
diff --git a/lisp/term/w32-nt.el b/lisp/term/w32-nt.el
new file mode 100644
index 00000000000..7ff9472839d
--- /dev/null
+++ b/lisp/term/w32-nt.el
@@ -0,0 +1,153 @@
+;;; w32-nt.el --- MS-Windows native build specific definitions -*- lexical-binding: t -*-
+
+;; Copyright (C) 1993-1994, 2001-2025 Free Software Foundation, Inc.
+
+;; Author: FSF
+;; Keywords: terminals
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; w32-nt.el: this file contains MS-Windows native build specific
+;; definitions formerly included in w32-win.el.
+
+;;; Code:
+
+
+(eval-when-compile (require 'cl-lib))
+
+
+(defvar dynamic-library-alist)
+(defvar libpng-version)                 ; image.c #ifdef HAVE_NTGUI
+(defvar libgif-version)
+(defvar libjpeg-version)
+
+(defvar libgnutls-version)              ; gnutls.c
+
+(defvar tree-sitter--library-abi)       ; treesit.c
+
+;;; Set default known names for external libraries
+(setq dynamic-library-alist
+      (list
+       '(gdiplus "gdiplus.dll")
+       '(shlwapi "shlwapi.dll")
+       '(xpm "libxpm.dll" "xpm4.dll" "libXpm-nox4.dll")
+       ;; Versions of libpng 1.4.x and later are incompatible with
+       ;; earlier versions.  Set up the list of libraries according to
+       ;; the version we were compiled against.  (If we were compiled
+       ;; without PNG support, libpng-version's value is -1.)
+       (if (>= libpng-version 10400)
+           (let ((major (/ libpng-version 10000))
+                 (minor (mod (/ libpng-version 100) 10)))
+             (list 'png
+                   ;; libpngXY.dll is the default name when building
+                   ;; with CMake or from a lpngXYY tarball on w32,
+                   ;; libpngXY-XY.dll is the DLL name when building
+                   ;; with libtool / autotools
+                   (format "libpng%d%d.dll" major minor)
+                   (format "libpng%d%d-%d%d.dll" major minor major minor)))
+         '(png "libpng12d.dll" "libpng12.dll" "libpng3.dll" "libpng.dll"
+               ;; these are libpng 1.2.8 from GTK+
+               "libpng13d.dll" "libpng13.dll"))
+       '(tiff "libtiff-5.dll" "libtiff3.dll" "libtiff.dll")
+       (if (> libjpeg-version 62)
+           ;; Versions of libjpeg after 6b are incompatible with
+           ;; earlier versions, and each of versions 7, 8, and 9 is
+           ;; also incompatible with the preceding ones (the core data
+           ;; structures used for communications with the library
+           ;; gained additional members with each new version).  So we
+           ;; must use only the version of the library which Emacs was
+           ;; compiled against.
+           (list 'jpeg (format "libjpeg-%d.dll" (/ libjpeg-version 10)))
+         '(jpeg "jpeg62.dll" "libjpeg.dll" "jpeg-62.dll" "jpeg.dll"))
+       ;; Versions of giflib 5.0.0 and later changed signatures of
+       ;; several functions used by Emacs, which makes those versions
+       ;; incompatible with previous ones.  We select the correct
+       ;; libraries according to the version of giflib we were
+       ;; compiled against.  (If we were compiled without GIF support,
+       ;; libgif-version's value is -1.)
+       (if (>= libgif-version 50100)
+           ;; Yes, giflib 5.0 uses 6 as the major version of the API,
+           ;; and giflib 5.1 uses 7, thus "libgif-7.dll" and
+           ;; "libgif-6.dll" below (giflib 4.x used 5 as the major API
+           ;; version).  giflib5.dll is from the lua-files project,
+           ;; and gif.dll is from luapower.
+           '(gif "libgif-7.dll")
+         (if (>= libgif-version 50000)
+             '(gif "libgif-6.dll" "giflib5.dll" "gif.dll")
+         '(gif "libgif-5.dll" "giflib4.dll" "libungif4.dll" "libungif.dll")))
+       '(svg "librsvg-2-2.dll")
+       '(webp "libwebp-7.dll" "libwebp.dll")
+       '(webpdemux "libwebpdemux-2.dll" "libwebpdemux.dll")
+       '(sqlite3 "libsqlite3-0.dll")
+       '(gdk-pixbuf "libgdk_pixbuf-2.0-0.dll")
+       '(glib "libglib-2.0-0.dll")
+       '(gio "libgio-2.0-0.dll")
+       '(gobject "libgobject-2.0-0.dll")
+       (if (>= libgnutls-version 30400)
+           '(gnutls "libgnutls-30.dll")
+         '(gnutls "libgnutls-28.dll" "libgnutls-26.dll"))
+       '(libxml2 "libxml2-2.dll" "libxml2.dll")
+       '(zlib "zlib1.dll" "libz-1.dll")
+       '(lcms2 "liblcms2-2.dll")
+       '(gccjit "libgccjit-0.dll")
+       ;; MSYS2 distributes libtree-sitter.dll, without API version
+       ;; number, upto and including version 0.24.3-2; later versions
+       ;; come with libtree-sitter-major.minor.dll (as in
+       ;; libtree-sitter-0.24.dll).  Sadly, the header files don't have
+       ;; any symbols for library version, so we can only use the
+       ;; library-language ABI version; according to
+       ;; https://github.com/tree-sitter/tree-sitter/issues/3925, the
+       ;; language ABI must change when the library's ABI is modified.
+       (if (<= tree-sitter--library-abi 14)
+           '(tree-sitter "libtree-sitter-0.24.dll"
+                         "libtree-sitter.dll"
+                         "libtree-sitter-0.dll")
+         '(tree-sitter "libtree-sitter-0.25.dll"))))
+
+
+;;;; Selections
+
+(declare-function w32--set-selection "w32-win.el")
+
+(declare-function w32--get-selection "w32-win.el")
+
+(declare-function w32--selection-owner-p "w32-win.el")
+
+(declare-function w32-selection-exists-p "w32select.c"
+                  (&optional selection terminal))
+
+;; Make copy&pasting in w32's console interact with the system's clipboard!
+(cl-defmethod gui-backend-set-selection (type value
+                                              &context (window-system nil))
+  (w32--set-selection type value))
+
+(cl-defmethod gui-backend-get-selection (type data-type
+                                              &context (window-system nil))
+  (w32--get-selection type data-type))
+
+(cl-defmethod gui-backend-selection-owner-p (selection
+                                             &context (window-system nil))
+  (w32--selection-owner-p selection))
+
+(cl-defmethod gui-selection-exists-p (selection
+                                      &context (window-system nil))
+  (w32-selection-exists-p selection))
+
+(provide 'term/w32-nt)
+
+;;; w32-nt.el ends here
diff --git a/lisp/term/w32-win.el b/lisp/term/w32-win.el
index af53345a377..fa7862d9bff 100644
--- a/lisp/term/w32-win.el
+++ b/lisp/term/w32-win.el
@@ -240,94 +240,6 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
   "Report an error when a suspend is attempted."
   (error "Suspending an Emacs running under W32 makes no sense"))
 
-(defvar dynamic-library-alist)
-(defvar libpng-version)                 ; image.c #ifdef HAVE_NTGUI
-(defvar libgif-version)
-(defvar libjpeg-version)
-
-(defvar libgnutls-version)              ; gnutls.c
-
-(defvar tree-sitter--library-abi)       ; treesit.c
-
-;;; Set default known names for external libraries
-(setq dynamic-library-alist
-      (list
-       '(gdiplus "gdiplus.dll")
-       '(shlwapi "shlwapi.dll")
-       '(xpm "libxpm.dll" "xpm4.dll" "libXpm-nox4.dll")
-       ;; Versions of libpng 1.4.x and later are incompatible with
-       ;; earlier versions.  Set up the list of libraries according to
-       ;; the version we were compiled against.  (If we were compiled
-       ;; without PNG support, libpng-version's value is -1.)
-       (if (>= libpng-version 10400)
-           (let ((major (/ libpng-version 10000))
-                 (minor (mod (/ libpng-version 100) 10)))
-             (list 'png
-                   ;; libpngXY.dll is the default name when building
-                   ;; with CMake or from a lpngXYY tarball on w32,
-                   ;; libpngXY-XY.dll is the DLL name when building
-                   ;; with libtool / autotools
-                   (format "libpng%d%d.dll" major minor)
-                   (format "libpng%d%d-%d%d.dll" major minor major minor)))
-         '(png "libpng12d.dll" "libpng12.dll" "libpng3.dll" "libpng.dll"
-               ;; these are libpng 1.2.8 from GTK+
-               "libpng13d.dll" "libpng13.dll"))
-       '(tiff "libtiff-5.dll" "libtiff3.dll" "libtiff.dll")
-       (if (> libjpeg-version 62)
-           ;; Versions of libjpeg after 6b are incompatible with
-           ;; earlier versions, and each of versions 7, 8, and 9 is
-           ;; also incompatible with the preceding ones (the core data
-           ;; structures used for communications with the library
-           ;; gained additional members with each new version).  So we
-           ;; must use only the version of the library which Emacs was
-           ;; compiled against.
-           (list 'jpeg (format "libjpeg-%d.dll" (/ libjpeg-version 10)))
-         '(jpeg "jpeg62.dll" "libjpeg.dll" "jpeg-62.dll" "jpeg.dll"))
-       ;; Versions of giflib 5.0.0 and later changed signatures of
-       ;; several functions used by Emacs, which makes those versions
-       ;; incompatible with previous ones.  We select the correct
-       ;; libraries according to the version of giflib we were
-       ;; compiled against.  (If we were compiled without GIF support,
-       ;; libgif-version's value is -1.)
-       (if (>= libgif-version 50100)
-           ;; Yes, giflib 5.0 uses 6 as the major version of the API,
-           ;; and giflib 5.1 uses 7, thus "libgif-7.dll" and
-           ;; "libgif-6.dll" below (giflib 4.x used 5 as the major API
-           ;; version).  giflib5.dll is from the lua-files project,
-           ;; and gif.dll is from luapower.
-           '(gif "libgif-7.dll")
-         (if (>= libgif-version 50000)
-             '(gif "libgif-6.dll" "giflib5.dll" "gif.dll")
-         '(gif "libgif-5.dll" "giflib4.dll" "libungif4.dll" "libungif.dll")))
-       '(svg "librsvg-2-2.dll")
-       '(webp "libwebp-7.dll" "libwebp.dll")
-       '(webpdemux "libwebpdemux-2.dll" "libwebpdemux.dll")
-       '(sqlite3 "libsqlite3-0.dll")
-       '(gdk-pixbuf "libgdk_pixbuf-2.0-0.dll")
-       '(glib "libglib-2.0-0.dll")
-       '(gio "libgio-2.0-0.dll")
-       '(gobject "libgobject-2.0-0.dll")
-       (if (>= libgnutls-version 30400)
-           '(gnutls "libgnutls-30.dll")
-         '(gnutls "libgnutls-28.dll" "libgnutls-26.dll"))
-       '(libxml2 "libxml2-2.dll" "libxml2.dll")
-       '(zlib "zlib1.dll" "libz-1.dll")
-       '(lcms2 "liblcms2-2.dll")
-       '(gccjit "libgccjit-0.dll")
-       ;; MSYS2 distributes libtree-sitter.dll, without API version
-       ;; number, upto and including version 0.24.3-2; later versions
-       ;; come with libtree-sitter-major.minor.dll (as in
-       ;; libtree-sitter-0.24.dll).  Sadly, the header files don't have
-       ;; any symbols for library version, so we can only use the
-       ;; library-language ABI version; according to
-       ;; https://github.com/tree-sitter/tree-sitter/issues/3925, the
-       ;; language ABI must change when the library's ABI is modified.
-       (if (<= tree-sitter--library-abi 14)
-           '(tree-sitter "libtree-sitter-0.24.dll"
-                         "libtree-sitter.dll"
-                         "libtree-sitter-0.dll")
-         '(tree-sitter "libtree-sitter-0.25.dll"))))
-
 ;;; multi-tty support
 (defvar w32-initialized nil
   "Non-nil if the w32 window system has been initialized.")
@@ -554,26 +466,6 @@ also be textual."
                                               &context (window-system w32))
   (w32-selection-exists-p selection))
 
-(when (eq system-type 'windows-nt)
-  ;; Make copy&pasting in w32's console interact with the system's clipboard!
-  ;; We could move those cl-defmethods outside of the `when' and use
-  ;; "&context (system-type (eql windows-nt))" instead!
-  (cl-defmethod gui-backend-set-selection (type value
-                                           &context (window-system nil))
-    (w32--set-selection type value))
-
-  (cl-defmethod gui-backend-get-selection (type data-type
-                                           &context (window-system nil))
-    (w32--get-selection type data-type))
-
-  (cl-defmethod gui-backend-selection-owner-p (selection
-                                               &context (window-system nil))
-    (w32--selection-owner-p selection))
-
-  (cl-defmethod gui-selection-exists-p (selection
-                                        &context (window-system nil))
-    (w32-selection-exists-p selection)))
-
 ;; 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.
diff --git a/src/image.c b/src/image.c
index b051e4ca796..65d8db24adc 100644
--- a/src/image.c
+++ b/src/image.c
@@ -13003,7 +13003,7 @@ non-numeric, there is no explicit limit on the size of images.  */);
   DEFSYM (Qgs_load_image, "gs-load-image");
 #endif /* HAVE_GHOSTSCRIPT */
 
-#ifdef HAVE_NTGUI
+#ifdef WINDOWSNT
   /* Versions of libpng, libgif, and libjpeg that we were compiled with,
      or -1 if no PNG/GIF support was compiled in.  This is tested by
      w32-win.el to correctly set up the alist used to search for the
diff --git a/src/treesit.c b/src/treesit.c
index 585be9efe29..9622addd09b 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -4683,7 +4683,7 @@ applies to LANGUAGE-A will be redirected to LANGUAGE-B instead.  */);
   defsubr (&Streesit_subtree_stat);
 #endif /* HAVE_TREE_SITTER */
   defsubr (&Streesit_available_p);
-#ifdef HAVE_NTGUI
+#ifdef WINDOWSNT
   DEFSYM (Qtree_sitter__library_abi, "tree-sitter--library-abi");
   Fset (Qtree_sitter__library_abi,
 #if HAVE_TREE_SITTER