Use Box::leak instead of Box:into_raw

It is better being explicit in your intentions. So, when the following
criteria are met, use Box::leak instead of Box::into_raw:
 - ownership is already transfered by some other means,
 - value of Box::into_raw is not used, i.e. it looks like a statement
 rather than as an expression.

This is my personal opinion, and it is based absolutely on nothing.

Author: ratijas

qmetaobject/src/qtdeclarative.rs

@@ -383,7 +383,7 @@ pub fn qml_register_type<T: QObject + Default + Sized>(
         unsafe {
             T::qml_construct(&b, c, ed);
         }
-        std::boxed::Box::into_raw(b);
+        Box::leak(b);
     };
     let creator_fn: extern "C" fn(c: *mut c_void) = creator_fn::<T>;
 
@@ -481,7 +481,7 @@ pub fn qml_register_singleton_type<T: QObject + QSingletonInit + Sized + Default
             let obj_box: Box<RefCell<T>> = Box::new(RefCell::new(T::default()));
             let obj_ptr = unsafe { T::cpp_construct(&obj_box) };
             obj_box.borrow_mut().init();
-            Box::into_raw(obj_box);
+            Box::leak(obj_box);
             obj_ptr
         }));
         match result {
@@ -570,7 +570,7 @@ pub fn qml_register_singleton_instance<T: QObject + Sized + Default>(
 
     let obj_box = Box::new(RefCell::new(obj));
     let obj_ptr = unsafe { T::cpp_construct(&obj_box) };
-    Box::into_raw(obj_box);
+    Box::leak(obj_box);
 
     cpp!(unsafe [
         uri_ptr as "char*",