buf_copy_options(buf_T *buf, int flags)
{
    int		should_copy = TRUE;
    char_u	*save_p_isk = NULL;	    // init for GCC
    int		dont_do_help;
    int		did_isk = FALSE;

    /*
     * Skip this when the option defaults have not been set yet.  Happens when
     * main() allocates the first buffer.
     */
    if (p_cpo != NULL)
    {
	/*
	 * Always copy when entering and 'cpo' contains 'S'.
	 * Don't copy when already initialized.
	 * Don't copy when 'cpo' contains 's' and not entering.
	 * 'S'	BCO_ENTER  initialized	's'  should_copy
	 * yes	  yes	       X	 X	TRUE
	 * yes	  no	      yes	 X	FALSE
	 * no	   X	      yes	 X	FALSE
	 *  X	  no	      no	yes	FALSE
	 *  X	  no	      no	no	TRUE
	 * no	  yes	      no	 X	TRUE
	 */
	if ((vim_strchr(p_cpo, CPO_BUFOPTGLOB) == NULL || !(flags & BCO_ENTER))
		&& (buf->b_p_initialized
		    || (!(flags & BCO_ENTER)
			&& vim_strchr(p_cpo, CPO_BUFOPT) != NULL)))
	    should_copy = FALSE;

	if (should_copy || (flags & BCO_ALWAYS))
	{
#ifdef FEAT_EVAL
	    CLEAR_FIELD(buf->b_p_script_ctx);
	    init_buf_opt_idx();
#endif
	    // Don't copy the options specific to a help buffer when
	    // BCO_NOHELP is given or the options were initialized already
	    // (jumping back to a help file with CTRL-T or CTRL-O)
	    dont_do_help = ((flags & BCO_NOHELP) && buf->b_help)
						       || buf->b_p_initialized;
	    if (dont_do_help)		// don't free b_p_isk
	    {
		save_p_isk = buf->b_p_isk;
		buf->b_p_isk = NULL;
	    }
	    /*
	     * Always free the allocated strings.  If not already initialized,
	     * reset 'readonly' and copy 'fileformat'.
	     */
	    if (!buf->b_p_initialized)
	    {
		free_buf_options(buf, TRUE);
		buf->b_p_ro = FALSE;		// don't copy readonly
		buf->b_p_tx = p_tx;
		buf->b_p_fenc = vim_strsave(p_fenc);
		switch (*p_ffs)
		{
		    case 'm':
			buf->b_p_ff = vim_strsave((char_u *)FF_MAC); break;
		    case 'd':
			buf->b_p_ff = vim_strsave((char_u *)FF_DOS); break;
		    case 'u':
			buf->b_p_ff = vim_strsave((char_u *)FF_UNIX); break;
		    default:
			buf->b_p_ff = vim_strsave(p_ff);
		}
		if (buf->b_p_ff != NULL)
		    buf->b_start_ffc = *buf->b_p_ff;
		buf->b_p_bh = empty_option;
		buf->b_p_bt = empty_option;
	    }
	    else
		free_buf_options(buf, FALSE);

	    buf->b_p_ai = p_ai;
	    COPY_OPT_SCTX(buf, BV_AI);
	    buf->b_p_ai_nopaste = p_ai_nopaste;
	    buf->b_p_sw = p_sw;
	    COPY_OPT_SCTX(buf, BV_SW);
	    buf->b_p_tw = p_tw;
	    COPY_OPT_SCTX(buf, BV_TW);
	    buf->b_p_tw_nopaste = p_tw_nopaste;
	    buf->b_p_tw_nobin = p_tw_nobin;
	    buf->b_p_wm = p_wm;
	    COPY_OPT_SCTX(buf, BV_WM);
	    buf->b_p_wm_nopaste = p_wm_nopaste;
	    buf->b_p_wm_nobin = p_wm_nobin;
	    buf->b_p_bin = p_bin;
	    COPY_OPT_SCTX(buf, BV_BIN);
	    buf->b_p_bomb = p_bomb;
	    COPY_OPT_SCTX(buf, BV_BOMB);
	    buf->b_p_fixeol = p_fixeol;
	    COPY_OPT_SCTX(buf, BV_FIXEOL);
	    buf->b_p_et = p_et;
	    COPY_OPT_SCTX(buf, BV_ET);
	    buf->b_p_et_nobin = p_et_nobin;
	    buf->b_p_et_nopaste = p_et_nopaste;
	    buf->b_p_ml = p_ml;
	    COPY_OPT_SCTX(buf, BV_ML);
	    buf->b_p_ml_nobin = p_ml_nobin;
	    buf->b_p_inf = p_inf;
	    COPY_OPT_SCTX(buf, BV_INF);
	    if (cmdmod.cmod_flags & CMOD_NOSWAPFILE)
		buf->b_p_swf = FALSE;
	    else
	    {
		buf->b_p_swf = p_swf;
		COPY_OPT_SCTX(buf, BV_INF);
	    }
	    buf->b_p_cpt = vim_strsave(p_cpt);
	    COPY_OPT_SCTX(buf, BV_CPT);
#ifdef BACKSLASH_IN_FILENAME
	    buf->b_p_csl = vim_strsave(p_csl);
	    COPY_OPT_SCTX(buf, BV_CSL);
#endif
#ifdef FEAT_COMPL_FUNC
	    buf->b_p_cfu = vim_strsave(p_cfu);
	    COPY_OPT_SCTX(buf, BV_CFU);
	    buf->b_p_ofu = vim_strsave(p_ofu);
	    COPY_OPT_SCTX(buf, BV_OFU);
#endif
#ifdef FEAT_EVAL
	    buf->b_p_tfu = vim_strsave(p_tfu);
	    COPY_OPT_SCTX(buf, BV_TFU);
#endif
	    buf->b_p_sts = p_sts;
	    COPY_OPT_SCTX(buf, BV_STS);
	    buf->b_p_sts_nopaste = p_sts_nopaste;
#ifdef FEAT_VARTABS
	    buf->b_p_vsts = vim_strsave(p_vsts);
	    COPY_OPT_SCTX(buf, BV_VSTS);
	    if (p_vsts && p_vsts != empty_option)
		tabstop_set(p_vsts, &buf->b_p_vsts_array);
	    else
		buf->b_p_vsts_array = 0;
	    buf->b_p_vsts_nopaste = p_vsts_nopaste
				 ? vim_strsave(p_vsts_nopaste) : NULL;
#endif
	    buf->b_p_sn = p_sn;
	    COPY_OPT_SCTX(buf, BV_SN);
	    buf->b_p_com = vim_strsave(p_com);
	    COPY_OPT_SCTX(buf, BV_COM);
#ifdef FEAT_FOLDING
	    buf->b_p_cms = vim_strsave(p_cms);
	    COPY_OPT_SCTX(buf, BV_CMS);
#endif
	    buf->b_p_fo = vim_strsave(p_fo);
	    COPY_OPT_SCTX(buf, BV_FO);
	    buf->b_p_flp = vim_strsave(p_flp);
	    COPY_OPT_SCTX(buf, BV_FLP);
	    // NOTE: Valgrind may report a bogus memory leak for 'nrformats'
	    // when it is set to 8 bytes in defaults.vim.
	    buf->b_p_nf = vim_strsave(p_nf);
	    COPY_OPT_SCTX(buf, BV_NF);
	    buf->b_p_mps = vim_strsave(p_mps);
	    COPY_OPT_SCTX(buf, BV_MPS);
#ifdef FEAT_SMARTINDENT
	    buf->b_p_si = p_si;
	    COPY_OPT_SCTX(buf, BV_SI);
#endif
	    buf->b_p_ci = p_ci;
	    COPY_OPT_SCTX(buf, BV_CI);
#ifdef FEAT_CINDENT
	    buf->b_p_cin = p_cin;
	    COPY_OPT_SCTX(buf, BV_CIN);
	    buf->b_p_cink = vim_strsave(p_cink);
	    COPY_OPT_SCTX(buf, BV_CINK);
	    buf->b_p_cino = vim_strsave(p_cino);
	    COPY_OPT_SCTX(buf, BV_CINO);
#endif
	    // Don't copy 'filetype', it must be detected
	    buf->b_p_ft = empty_option;
	    buf->b_p_pi = p_pi;
	    COPY_OPT_SCTX(buf, BV_PI);
#if defined(FEAT_SMARTINDENT) || defined(FEAT_CINDENT)
	    buf->b_p_cinw = vim_strsave(p_cinw);
	    COPY_OPT_SCTX(buf, BV_CINW);
#endif
#ifdef FEAT_LISP
	    buf->b_p_lisp = p_lisp;
	    COPY_OPT_SCTX(buf, BV_LISP);
#endif
#ifdef FEAT_SYN_HL
	    // Don't copy 'syntax', it must be set
	    buf->b_p_syn = empty_option;
	    buf->b_p_smc = p_smc;
	    COPY_OPT_SCTX(buf, BV_SMC);
	    buf->b_s.b_syn_isk = empty_option;
#endif
#ifdef FEAT_SPELL
	    buf->b_s.b_p_spc = vim_strsave(p_spc);
	    COPY_OPT_SCTX(buf, BV_SPC);
	    (void)compile_cap_prog(&buf->b_s);
	    buf->b_s.b_p_spf = vim_strsave(p_spf);
	    COPY_OPT_SCTX(buf, BV_SPF);
	    buf->b_s.b_p_spl = vim_strsave(p_spl);
	    COPY_OPT_SCTX(buf, BV_SPL);
	    buf->b_s.b_p_spo = vim_strsave(p_spo);
	    COPY_OPT_SCTX(buf, BV_SPO);
#endif
#if defined(FEAT_CINDENT) && defined(FEAT_EVAL)
	    buf->b_p_inde = vim_strsave(p_inde);
	    COPY_OPT_SCTX(buf, BV_INDE);
	    buf->b_p_indk = vim_strsave(p_indk);
	    COPY_OPT_SCTX(buf, BV_INDK);
#endif
	    buf->b_p_fp = empty_option;
#if defined(FEAT_EVAL)
	    buf->b_p_fex = vim_strsave(p_fex);
	    COPY_OPT_SCTX(buf, BV_FEX);
#endif
#ifdef FEAT_CRYPT
	    buf->b_p_key = vim_strsave(p_key);
	    COPY_OPT_SCTX(buf, BV_KEY);
#endif
#ifdef FEAT_SEARCHPATH
	    buf->b_p_sua = vim_strsave(p_sua);
	    COPY_OPT_SCTX(buf, BV_SUA);
#endif
#ifdef FEAT_KEYMAP
	    buf->b_p_keymap = vim_strsave(p_keymap);
	    COPY_OPT_SCTX(buf, BV_KMAP);
	    buf->b_kmap_state |= KEYMAP_INIT;
#endif
#ifdef FEAT_TERMINAL
	    buf->b_p_twsl = p_twsl;
	    COPY_OPT_SCTX(buf, BV_TWSL);
#endif
	    // This isn't really an option, but copying the langmap and IME
	    // state from the current buffer is better than resetting it.
	    buf->b_p_iminsert = p_iminsert;
	    COPY_OPT_SCTX(buf, BV_IMI);
	    buf->b_p_imsearch = p_imsearch;
	    COPY_OPT_SCTX(buf, BV_IMS);

	    // options that are normally global but also have a local value
	    // are not copied, start using the global value
	    buf->b_p_ar = -1;
	    buf->b_p_ul = NO_LOCAL_UNDOLEVEL;
	    buf->b_p_bkc = empty_option;
	    buf->b_bkc_flags = 0;
#ifdef FEAT_QUICKFIX
	    buf->b_p_gp = empty_option;
	    buf->b_p_mp = empty_option;
	    buf->b_p_efm = empty_option;
#endif
	    buf->b_p_ep = empty_option;
	    buf->b_p_kp = empty_option;
	    buf->b_p_path = empty_option;
	    buf->b_p_tags = empty_option;
	    buf->b_p_tc = empty_option;
	    buf->b_tc_flags = 0;
#ifdef FEAT_FIND_ID
	    buf->b_p_def = empty_option;
	    buf->b_p_inc = empty_option;
# ifdef FEAT_EVAL
	    buf->b_p_inex = vim_strsave(p_inex);
	    COPY_OPT_SCTX(buf, BV_INEX);
# endif
#endif
	    buf->b_p_dict = empty_option;
	    buf->b_p_tsr = empty_option;
#ifdef FEAT_TEXTOBJ
	    buf->b_p_qe = vim_strsave(p_qe);
	    COPY_OPT_SCTX(buf, BV_QE);
#endif
#if defined(FEAT_BEVAL) && defined(FEAT_EVAL)
	    buf->b_p_bexpr = empty_option;
#endif
#if defined(FEAT_CRYPT)
	    buf->b_p_cm = empty_option;
#endif
#ifdef FEAT_PERSISTENT_UNDO
	    buf->b_p_udf = p_udf;
	    COPY_OPT_SCTX(buf, BV_UDF);
#endif
#ifdef FEAT_LISP
	    buf->b_p_lw = empty_option;
#endif
	    buf->b_p_menc = empty_option;

	    /*
	     * Don't copy the options set by ex_help(), use the saved values,
	     * when going from a help buffer to a non-help buffer.
	     * Don't touch these at all when BCO_NOHELP is used and going from
	     * or to a help buffer.
	     */
	    if (dont_do_help)
	    {
		buf->b_p_isk = save_p_isk;
#ifdef FEAT_VARTABS
		if (p_vts && p_vts != empty_option && !buf->b_p_vts_array)
		    tabstop_set(p_vts, &buf->b_p_vts_array);
		else
		    buf->b_p_vts_array = NULL;
#endif
	    }
	    else
	    {
		buf->b_p_isk = vim_strsave(p_isk);
		COPY_OPT_SCTX(buf, BV_ISK);
		did_isk = TRUE;
		buf->b_p_ts = p_ts;
#ifdef FEAT_VARTABS
		buf->b_p_vts = vim_strsave(p_vts);
		COPY_OPT_SCTX(buf, BV_VTS);
		if (p_vts && p_vts != empty_option && !buf->b_p_vts_array)
		    tabstop_set(p_vts, &buf->b_p_vts_array);
		else
		    buf->b_p_vts_array = NULL;
#endif
		buf->b_help = FALSE;
		if (buf->b_p_bt[0] == 'h')
		    clear_string_option(&buf->b_p_bt);
		buf->b_p_ma = p_ma;
		COPY_OPT_SCTX(buf, BV_MA);
	    }
	}

	/*
	 * When the options should be copied (ignoring BCO_ALWAYS), set the
	 * flag that indicates that the options have been initialized.
	 */
	if (should_copy)
	    buf->b_p_initialized = TRUE;
    }

    check_buf_options(buf);	    // make sure we don't have NULLs
    if (did_isk)
	(void)buf_init_chartab(buf, FALSE);
}