printStruct

fn printStruct(
    options: *Options,
    out: *std.ArrayList(u8),
    comptime T: type,
    comptime val: std.builtin.Type.Struct,
    indent: u8,
) !void {
    const gpa = options.step.owner.allocator;
    const gop = try options.encountered_types.getOrPut(gpa, @typeName(T));
    if (gop.found_existing) return;

    try out.appendNTimes(gpa, ' ', indent);
    try out.print(gpa, "pub const {f} = ", .{std.zig.fmtId(@typeName(T))});

    switch (val.layout) {
        .@"extern" => try out.appendSlice(gpa, "extern struct"),
        .@"packed" => try out.appendSlice(gpa, "packed struct"),
        else => try out.appendSlice(gpa, "struct"),
    }

    try out.appendSlice(gpa, " {\n");

    inline for (val.field_names, val.field_types, val.field_attrs) |field_name, field_type, field_attrs| {
        try out.appendNTimes(gpa, ' ', indent);

        const type_name = @typeName(field_type);

        // If the type name doesn't contains a '.' the type is from zig builtins.
        if (std.mem.containsAtLeast(u8, type_name, 1, ".")) {
            try out.print(gpa, "    {f}: {f}", .{
                std.zig.fmtIdFlags(field_name, .{ .allow_underscore = true, .allow_primitive = true }),
                std.zig.fmtId(type_name),
            });
        } else {
            try out.print(gpa, "    {f}: {s}", .{
                std.zig.fmtIdFlags(field_name, .{ .allow_underscore = true, .allow_primitive = true }),
                type_name,
            });
        }

        if (field_attrs.defaultValue(field_type)) |default_value| {
            try out.appendSlice(gpa, " = ");
            switch (@typeInfo(field_type)) {
                .@"enum" => try out.print(gpa, ".{s},\n", .{@tagName(default_value)}),
                .@"struct" => |info| {
                    try printStructValue(options, out, info, default_value, indent + 4);
                },
                else => try printType(options, out, field_type, default_value, indent, null),
            }
        } else {
            try out.appendSlice(gpa, ",\n");
        }
    }

    // TODO: write declarations

    try out.appendNTimes(gpa, ' ', indent);
    try out.appendSlice(gpa, "};\n");

    inline for (val.field_types) |field_type| {
        try printUserDefinedType(options, out, field_type, 0);
    }
}