create union enum in Zig

create_union_enum.zig

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

const Variant = union(enum) {
    int: i32,
    boolean: bool,

    // void can be omitted when inferring enum tag type.
    none,

    fn truthy(self: Variant) bool {
        return switch (self) {
            Variant.int => |x_int| x_int != 0,
            Variant.boolean => |x_bool| x_bool,
            Variant.none => false,
        };
    }
};

test "union method" {
    var v1 = Variant{ .int = 1 };
    var v2 = Variant{ .boolean = false };

    try expect(v1.truthy());
    try expect(!v2.truthy());
}

test "create union" {
    const allocator = std.testing.allocator;

    var v1 = try allocator.create(Variant);
    defer allocator.destroy(v1);

    v1.* = .{ .int = 1 };
    try expect(v1.truthy());
}

test.log

$ zig test create_enum_union.zig 
All 2 tests passed.
$ zig version
0.10.0-dev.2880+6f0807f50