harfbuzz_sys::hb_unicode_decompose_func_t

type hb_unicode_decompose_func_t = Option<extern fn(ufuncs: *mut hb_unicode_funcs_t, ab: hb_codepoint_t, a: *mut hb_codepoint_t, b: *mut hb_codepoint_t, user_data: *mut c_void) -> hb_bool_t>;