zig/doc/langref/test_pass_by_reference_or_value.zig

const Point = struct {
    x: i32,
    y: i32,
};

fn foo(point: Point) i32 {
    // Here, `point` could be a reference, or a copy. The function body
    // can ignore the difference and treat it as a value. Be very careful
    // taking the address of the parameter - it should be treated as if
    // the address will become invalid when the function returns.
    return point.x + point.y;
}

const expect = @import("std").testing.expect;

test "pass struct to function" {
    try expect(foo(Point{ .x = 1, .y = 2 }) == 3);
}

// test