lang::struct

Status: shipped

Product type declaration.

Functional record update

A struct literal may spread a base value with ..base and override individual fields:

let p2 = Point { ..p1, x: 10 }   // x overridden, the rest copied from p1
let p3 = Point { x: 10, ..p1 }   // the spread may appear in any position

• Explicit fields win over the base for the same name.
• Exactly one ..base spread is allowed (a second is a parse error).
• Fields copied from the base share its heap children and are retained, so the base stays usable after the update with no double-free. Output is identical across the VM, Cranelift, and LLVM tiers.