Attribute Macro hopper_pod 

#[hopper_pod]

Derive the Hopper zero-copy marker contract for a user-defined struct.

Unlike #[hopper::state] (which emits the full Hopper layout: 16-byte header, layout_id, schema export, typed load helpers), #[hopper::pod] is the minimal opt-in: it asserts that the struct satisfies the Pod + FixedLayout + alignment-1 + non-padded + non-zero-sized contract at compile time, and emits the matching unsafe impl Pod and impl FixedLayout so it can participate in every Hopper segment / raw access API.

This is the Hopper Safety Audit’s “derive macros for Pod and layout” recommendation delivered standalone: use it on sub-structs, wire helpers, or any #[repr(C)] overlay that isn’t a full top-level account layout.

Example

#[hopper::pod]
#[repr(C)]
pub struct Cursor {
    pub head: WireU64,
    pub tail: WireU64,
    pub capacity: WireU64,
}

// Now usable as:
let c: Ref<'_, Cursor> = account.segment_ref::<Cursor>(&mut borrows, 0, 24)?;