VTables include uncallable methods (that take `self` by value)

[WaffleLapkin]

I expected that given the following method, both methods won't be included in the vtable (note that this trait is object safe, self "implies" where Self: Sized for object safety check)

trait Tr {
    fn method_that_takes_self(self);
    fn method_that_takes_self2(self) where Self: Sized {}
}

But, in reality, with 1.73.0-nightly (2023-07-23 8771282d4e7a5c4569e4), method_that_takes_self is included in the vtable, even though you can't call it:

vtable entries for `<String as Tr>`: [
    MetadataDropInPlace,
    MetadataSize,
    MetadataAlign,
    Method(<String as Tr>::method_that_takes_self - shim(vtable)),
]

This is especially sub-optimal in the presence of trait upcasting, since this makes otherwise empty (wrt to trait objects) traits non-empty, adding need for more vptrs.

[WaffleLapkin]

I'm closing this as not planned, since this can't be "fixed". With unsized_params feature method_that_takes_self is actually callable.