fix illegal instruction during handle ptr creation in release mode

core/src/widget/handle.rs

@@ -1,4 +1,4 @@
-use std::{marker::Unsize, mem::MaybeUninit, ops::CoerceUnsized, sync::mpsc::Sender};
+use std::{marker::Unsize, ops::CoerceUnsized, sync::mpsc::Sender};
 
 use crate::{
     HasUi, Widget,
@@ -44,7 +44,7 @@ impl<W: ?Sized> WidgetHandle<W> {
             id,
             counter: RefCounter::new(),
             send,
-            ty: unsafe { MaybeUninit::zeroed().assume_init() },
+            ty: null_ptr(),
         }
     }
 
@@ -69,10 +69,7 @@ impl<W: ?Sized> WidgetHandle<W> {
 
 impl<W: ?Sized> WidgetRef<W> {
     pub(crate) fn new(id: WidgetId) -> Self {
-        Self {
+        Self { id, ty: null_ptr() }
-            id,
-            ty: unsafe { MaybeUninit::zeroed().assume_init() },
-        }
     }
 
     pub fn id(&self) -> WidgetId {
@@ -163,3 +160,12 @@ impl<'a, W: Widget + 'a, State: HasUi> FnOnce<(&'a mut State,)> for WidgetRef<W>
         &mut args.0.ui_mut()[self]
     }
 }
+
+fn null_ptr<W: ?Sized>() -> *const W {
+    if size_of::<&W>() == size_of::<*const dyn Widget>() {
+        let w: *const dyn Widget = &();
+        unsafe { std::mem::transmute_copy(&w) }
+    } else {
+        unsafe { std::mem::transmute_copy(&[0usize; 1]) }
+    }
+}