Implement macro: generated From<&mut Foo> for IFoo implementation seems sketchy

[samlh]

This generated impl looks sketchy - what happens if you call it on a value that isn't wrapped in the ..._box?

windows-rs/crates/deps/macros/src/implement.rs

Line 160 in c604d64

impl <#constraints> ::std::convert::From<&mut #impl_ident> for #interface_ident {

e.g.

#[implement(Windows::UI::Xaml::Data::ICustomProperty)]
pub struct CustomProperty {
  bar: ()
}

Generates:

impl< > ::std::convert::From< &mut CustomProperty:: < > >for Windows::UI::Xaml::Data::ICustomProperty {
  fn from(implementation: &mut CustomProperty:: < >) -> Self {
    unsafe {
      let mut ptr = (implementation as*mut_as*mut::windows::runtime::RawPtr).sub(2+1)as*mut CustomProperty_box:: < > ;
      (*ptr).count.add_ref();
      ::std::mem::transmute_copy(& ::std::ptr::NonNull::new_unchecked(&mut(*ptr).vtables.0 as*mut_as_))
    }
  }
}

Mistaken usage:

let foo = CustomProperty { bar: () };
ICustomProperty::from(foo).DoSomething();      // OK
ICustomProperty::from(&mut foo).DoSomething(); // Out-of-bounds access?

Happily, I've never actually needed this conversion, but if it is kept, I recommend making it unsafe like the to_impl method.

[kennykerr]

This trait is no longer being generated. Let me know if there any other concerns with the new implement macro. #1345

[samlh]

Thanks for the update!

I've updated to using the new trait-based implement macro, and I'm quite happy with the results.

Thanks for the hard work - the windows crate just keeps getting better!