Zig Copy Semantics

copytest.zig

const std = @import("std");
test {
    const U = union(enum) {
        Val: isize,
        Point: struct { x: isize, y: isize },
    };
    var u = U { .Point = .{ .x = 123, .y = 456 } };
    const p = &u.Point;
    u = U { .Val = p.x + p.y };
    std.testing.expect(u.Val == 579);
}