Mark windows fields as nonzero

src/windows.rs

@@ -1,5 +1,5 @@
 use core::ffi::c_void;
-use core::ptr;
+use core::ptr::NonNull;
 
 /// Raw window handle for Windows.
 ///
@@ -14,9 +14,9 @@ use core::ptr;
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct WindowsHandle {
     /// A Win32 HWND handle.
-    pub hwnd: *mut c_void,
+    pub hwnd: Option<NonNull<c_void>>,
     /// The HINSTANCE associated with this type's HWND.
-    pub hinstance: *mut c_void,
+    pub hinstance: Option<NonNull<c_void>>,
     #[doc(hidden)]
     #[deprecated = "This field is used to ensure that this struct is non-exhaustive, so that it may be extended in the future. Do not refer to this field."]
     pub _non_exhaustive_do_not_use: crate::seal::Seal,
@@ -26,8 +26,8 @@ impl WindowsHandle {
     pub fn empty() -> WindowsHandle {
         #[allow(deprecated)]
         WindowsHandle {
-            hwnd: ptr::null_mut(),
-            hinstance: ptr::null_mut(),
+            hwnd: None,
+            hinstance: None,
             _non_exhaustive_do_not_use: crate::seal::Seal,
         }
     }