Function metadata 

pub const fn metadata<T: PointeeSized>(
    ptr: *const T,
) -> <T as Pointee>::Metadata

🔬This is a nightly-only experimental API. (ptr_metadata #81513)

Extracts the metadata component of a pointer.

Values of type *mut T, &T, or &mut T can be passed directly to this function as they implicitly coerce to *const T.

Example

#![feature(ptr_metadata)]

assert_eq!(std::ptr::metadata("foo"), 3_usize);