Function align_of_val_raw 

pub const unsafe fn align_of_val_raw<T: ?Sized>(val: *const T) -> usize

🔬This is a nightly-only experimental API. (layout_for_ptr #69835)

Returns the ABI-required minimum alignment of the type of the value that val points to, in bytes.

This function is identical to align_of_val(), except that it can be used with raw pointers in situations where it would be unsound or undesirable to convert them to & references and impose the aliasing rules that come with that.

Safety

This function is only safe to call if the following conditions hold:

• If T is Sized, this function is always safe to call.
• If the unsized tail of T is:
  • a slice, then the length of the slice tail must be an initialized integer, and the size of the entire value (dynamic tail length + statically sized prefix) must fit in isize. For the special case where the dynamic tail length is 0, this function is safe to call.
  • a trait object, then the vtable part of the pointer must point to a valid vtable acquired by an unsizing coercion, and the size of the entire value (dynamic tail length + statically sized prefix) must fit in isize.
  • an (unstable) extern type, then this function is always safe to call, but may panic or otherwise return the wrong value, as the extern type’s layout is not known. This is the same behavior as align_of_val on a reference to a type with an extern type tail.
  • otherwise, it is conservatively not allowed to call this function.

Examples

#![feature(layout_for_ptr)]
use std::mem;

assert_eq!(4, unsafe { mem::align_of_val_raw(&5i32) });

(Caution: it is not guaranteed that the alignment of i32 is 4; that is, the above assertion does not pass on all platforms.)