`safer_ffi::Vec` seems to be unsafe

[QuarticCat]

safer_ffi/src/vec.rs

Lines 41 to 70 in 310a2c9

	/// Convert a [`std::vec::Vec`] to a [`safer_ffi::Vec`].
	impl<T> From<rust::Vec<T>> for Vec<T> {
	#[inline]
	fn from(vec: rust::Vec<T>) -> Vec<T> {
	let len = vec.len();
	let cap = vec.capacity();
	let ptr = mem::ManuallyDrop::new(vec).as_mut_ptr();
	Self {
	ptr: unsafe {
	// Safety: `Vec` guarantees its pointer is nonnull.
	ptr::NonNull::new_unchecked(ptr)
	}
	.into(),
	len,
	cap,
	}
	}
	}
	/// Convert a [`safer_ffi::Vec`] to a [`std::vec::Vec`].
	impl<T> From<Vec<T>> for rust::Vec<T> {
	#[inline]
	fn from(value: Vec<T>) -> rust::Vec<T> {
	let mut this = mem::ManuallyDrop::new(value);
	unsafe {
	// Safety: pointers originate from `Vec`.
	rust::Vec::from_raw_parts(this.ptr.as_mut_ptr(), this.len, this.cap)
	}
	}
	}

There is no guarantee that the same allocator is used across the FFI boundary.