Returns None if the pointer is null, or else returns a shared reference to the value wrapped in Some. If the value may be uninitialized, [as_uninit_ref] must be used instead. If the value is known to be non-null, [as_ref_unchecked] can be used instead.

Safety

When calling this method, you have to ensure that either the pointer is null or the pointer is convertible to a reference.

Panics during const evaluation

This method will panic during const evaluation if the pointer cannot be determined to be null or not. See [is_null] for more information.

Null-unchecked version

If you are sure the pointer can never be null, you can use as_ref_unchecked which returns &mut T instead of Option<&mut T>.