Function raw_ptr_with_size 

fn raw_ptr_with_size(
    genv: GlobalEnv<'_, '_>,
    kind: &RawPtrKind,
    ctor: SubsetTyCtor,
) -> Result<Ty, CheckerError>

Converts a reference into a raw-ptr, tracking size etc.

&mut T => *mut{p: p.size == T::size_of() && p.base == p.addr && p.addr % T::align_of() == 0 } T

see test fn ref_to_ptr_read in crates/flux/tests/tests/with_deps/pos/extern_specs/flux_core_ptr01.rs