GBoxed
    ├── hb_blob_t
    ├── hb_buffer_t
    ├── hb_face_t
    ├── hb_feature_t
    ├── hb_font_funcs_t
    ├── hb_font_t
    ├── hb_glyph_info_t
    ├── hb_glyph_position_t
    ├── hb_ot_math_glyph_part_t
    ├── hb_ot_math_glyph_variant_t
    ├── hb_segment_properties_t
    ├── hb_set_t
    ├── hb_shape_plan_t
    ├── hb_unicode_funcs_t
    ╰── hb_user_data_key_t
    GEnum
    ├── hb_buffer_cluster_level_t
    ├── hb_buffer_content_type_t
    ├── hb_buffer_serialize_format_t
    ├── hb_direction_t
    ├── hb_memory_mode_t
    ├── hb_ot_layout_glyph_class_t
    ├── hb_ot_math_constant_t
    ├── hb_ot_math_kern_t
    ├── hb_script_t
    ├── hb_unicode_combining_class_t
    ╰── hb_unicode_general_category_t
    GFlags
    ├── hb_buffer_diff_flags_t
    ├── hb_buffer_flags_t
    ├── hb_buffer_serialize_flags_t
    ├── hb_glyph_flags_t
    ╰── hb_ot_math_glyph_part_flags_t