Did the layout of the trait object metadata change?

[05storm26]

I tried this code: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=a122541641e9a77365b11b861971d578

According to previous information the first usize pointed by the trait object's metadata/vtable is the size of the struct. This is reiterated in the documentation of the https://doc.rust-lang.org/beta/std/ptr/struct.DynMetadata.html. Did the layout of trait object metadata change?

I expected to see this happen: see the struct's size as the first usize pointed by the trait object's metadata pointer.

Instead, this happened: junk value printed, the second usize appears to be the size of the struct and the third is the alignment.

Is this related to the deprecation of std::raw::TraitObject/#84207?

[05storm26]

No it did not change I remembered it wrong the first usize is drop implementation:

/// The common prefix of all vtables. It is followed by function pointers for trait methods.
///
/// Private implementation detail of `DynMetadata::size_of` etc.
#[repr(C)]
struct VTable {
    drop_in_place: fn(*mut ()),
    size_of: usize,
    align_of: usize,
}

[jyn514]

Layout is never guaranteed, and nightly items especially are always subject to change.