Function impl_assume_accessed_via_extract_self

pub fn impl_assume_accessed_via_extract_self<T: PessimizeCast>(
    self_: &mut T,
    extract_self: impl FnOnce(&mut T) -> T,
)

Implementation of BorrowPessimize::assume_accessed_impl for types where there is a cheap way to extract the inner T from an &mut T

For Copy types, this is a dereference, and for Default types where the default value is truly trivial and guaranteed to be optimized out (like Vec), this is core::mem::take.

The Drop impl of the value left in self_ by extract_self will not be called, make sure that this does not result in a resource leak.