diff --git a/src/optionstr.c b/src/optionstr.c
new file mode 100644
index 0000000..44f0759
--- /dev/null
+++ b/src/optionstr.c
@@ -0,0 +1,2491 @@
+/* vi:set ts=8 sts=4 sw=4 noet:
+ *
+ * VIM - Vi IMproved	by Bram Moolenaar
+ *
+ * Do ":help uganda"  in Vim to read copying and usage conditions.
+ * Do ":help credits" in Vim to see a list of people who contributed.
+ * See README.txt for an overview of the Vim source code.
+ */
+
+/*
+ * optionstr.c: Functions related to string options
+ */
+
+#include "vim.h"
+
+static char *(p_ambw_values[]) = {"single", "double", NULL};
+static char *(p_bg_values[]) = {"light", "dark", NULL};
+static char *(p_bkc_values[]) = {"yes", "auto", "no", "breaksymlink", "breakhardlink", NULL};
+static char *(p_bo_values[]) = {"all", "backspace", "cursor", "complete",
+				 "copy", "ctrlg", "error", "esc", "ex",
+				 "hangul", "insertmode", "lang", "mess",
+				 "showmatch", "operator", "register", "shell",
+				 "spell", "wildmode", NULL};
+static char *(p_nf_values[]) = {"bin", "octal", "hex", "alpha", NULL};
+static char *(p_ff_values[]) = {FF_UNIX, FF_DOS, FF_MAC, NULL};
+#ifdef FEAT_CRYPT
+static char *(p_cm_values[]) = {"zip", "blowfish", "blowfish2", NULL};
+#endif
+static char *(p_cmp_values[]) = {"internal", "keepascii", NULL};
+static char *(p_dy_values[]) = {"lastline", "truncate", "uhex", NULL};
+#ifdef FEAT_FOLDING
+static char *(p_fdo_values[]) = {"all", "block", "hor", "mark", "percent",
+				 "quickfix", "search", "tag", "insert",
+				 "undo", "jump", NULL};
+#endif
+#ifdef FEAT_SESSION
+// Also used for 'viewoptions'!
+static char *(p_ssop_values[]) = {"buffers", "winpos", "resize", "winsize",
+    "localoptions", "options", "help", "blank", "globals", "slash", "unix",
+    "sesdir", "curdir", "folds", "cursor", "tabpages", "terminal", NULL};
+#endif
+static char *(p_swb_values[]) = {"useopen", "usetab", "split", "newtab", "vsplit", NULL};
+static char *(p_tc_values[]) = {"followic", "ignore", "match", "followscs", "smart", NULL};
+#if defined(FEAT_TOOLBAR) && !defined(FEAT_GUI_MSWIN)
+static char *(p_toolbar_values[]) = {"text", "icons", "tooltips", "horiz", NULL};
+#endif
+#if defined(FEAT_TOOLBAR) && defined(FEAT_GUI_GTK)
+static char *(p_tbis_values[]) = {"tiny", "small", "medium", "large", "huge", "giant", NULL};
+#endif
+#if defined(FEAT_MOUSE) && (defined(UNIX) || defined(VMS))
+static char *(p_ttym_values[]) = {"xterm", "xterm2", "dec", "netterm", "jsbterm", "pterm", "urxvt", "sgr", NULL};
+#endif
+static char *(p_ve_values[]) = {"block", "insert", "all", "onemore", NULL};
+static char *(p_wop_values[]) = {"tagfile", NULL};
+#ifdef FEAT_WAK
+static char *(p_wak_values[]) = {"yes", "menu", "no", NULL};
+#endif
+static char *(p_mousem_values[]) = {"extend", "popup", "popup_setpos", "mac", NULL};
+static char *(p_sel_values[]) = {"inclusive", "exclusive", "old", NULL};
+static char *(p_slm_values[]) = {"mouse", "key", "cmd", NULL};
+static char *(p_km_values[]) = {"startsel", "stopsel", NULL};
+#ifdef FEAT_BROWSE
+static char *(p_bsdir_values[]) = {"current", "last", "buffer", NULL};
+#endif
+static char *(p_scbopt_values[]) = {"ver", "hor", "jump", NULL};
+static char *(p_debug_values[]) = {"msg", "throw", "beep", NULL};
+static char *(p_ead_values[]) = {"both", "ver", "hor", NULL};
+static char *(p_buftype_values[]) = {"nofile", "nowrite", "quickfix", "help", "terminal", "acwrite", "prompt", "popup", NULL};
+static char *(p_bufhidden_values[]) = {"hide", "unload", "delete", "wipe", NULL};
+static char *(p_bs_values[]) = {"indent", "eol", "start", NULL};
+#ifdef FEAT_FOLDING
+static char *(p_fdm_values[]) = {"manual", "expr", "marker", "indent", "syntax",
+# ifdef FEAT_DIFF
+				"diff",
+# endif
+				NULL};
+static char *(p_fcl_values[]) = {"all", NULL};
+#endif
+static char *(p_cot_values[]) = {"menu", "menuone", "longest", "preview", "popup", "noinsert", "noselect", NULL};
+#ifdef BACKSLASH_IN_FILENAME
+static char *(p_csl_values[]) = {"slash", "backslash", NULL};
+#endif
+#ifdef FEAT_SIGNS
+static char *(p_scl_values[]) = {"yes", "no", "auto", "number", NULL};
+#endif
+#if defined(MSWIN) && defined(FEAT_TERMINAL)
+static char *(p_twt_values[]) = {"winpty", "conpty", "", NULL};
+#endif
+
+static int check_opt_strings(char_u *val, char **values, int list);
+static int opt_strings_flags(char_u *val, char **values, unsigned *flagp, int list);
+
+/*
+ * After setting various option values: recompute variables that depend on
+ * option values.
+ */
+    void
+didset_string_options(void)
+{
+    (void)opt_strings_flags(p_cmp, p_cmp_values, &cmp_flags, TRUE);
+    (void)opt_strings_flags(p_bkc, p_bkc_values, &bkc_flags, TRUE);
+    (void)opt_strings_flags(p_bo, p_bo_values, &bo_flags, TRUE);
+#ifdef FEAT_SESSION
+    (void)opt_strings_flags(p_ssop, p_ssop_values, &ssop_flags, TRUE);
+    (void)opt_strings_flags(p_vop, p_ssop_values, &vop_flags, TRUE);
+#endif
+#ifdef FEAT_FOLDING
+    (void)opt_strings_flags(p_fdo, p_fdo_values, &fdo_flags, TRUE);
+#endif
+    (void)opt_strings_flags(p_dy, p_dy_values, &dy_flags, TRUE);
+    (void)opt_strings_flags(p_tc, p_tc_values, &tc_flags, FALSE);
+    (void)opt_strings_flags(p_ve, p_ve_values, &ve_flags, TRUE);
+#if defined(FEAT_MOUSE) && (defined(UNIX) || defined(VMS))
+    (void)opt_strings_flags(p_ttym, p_ttym_values, &ttym_flags, FALSE);
+#endif
+#if defined(FEAT_TOOLBAR) && !defined(FEAT_GUI_MSWIN)
+    (void)opt_strings_flags(p_toolbar, p_toolbar_values, &toolbar_flags, TRUE);
+#endif
+#if defined(FEAT_TOOLBAR) && defined(FEAT_GUI_GTK)
+    (void)opt_strings_flags(p_tbis, p_tbis_values, &tbis_flags, FALSE);
+#endif
+}
+
+#if defined(FEAT_EVAL)
+/*
+ * Trigger the OptionSet autocommand.
+ * "opt_idx"	is the index of the option being set.
+ * "opt_flags"	can be OPT_LOCAL etc.
+ * "oldval"	the old value
+ *  "oldval_l"  the old local value (only non-NULL if global and local value
+ *		are set)
+ * "oldval_g"   the old global value (only non-NULL if global and local value
+ *		are set)
+ * "newval"	the new value
+ */
+    void
+trigger_optionsset_string(
+	int	opt_idx,
+	int	opt_flags,
+	char_u  *oldval,
+	char_u  *oldval_l,
+	char_u  *oldval_g,
+	char_u  *newval)
+{
+    // Don't do this recursively.
+    if (oldval != NULL && newval != NULL
+				    && *get_vim_var_str(VV_OPTION_TYPE) == NUL)
+    {
+	char_u buf_type[7];
+
+	sprintf((char *)buf_type, "%s",
+	    (opt_flags & OPT_LOCAL) ? "local" : "global");
+	set_vim_var_string(VV_OPTION_OLD, oldval, -1);
+	set_vim_var_string(VV_OPTION_NEW, newval, -1);
+	set_vim_var_string(VV_OPTION_TYPE, buf_type, -1);
+	if (opt_flags & OPT_LOCAL)
+	{
+	    set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"setlocal", -1);
+	    set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
+	}
+	if (opt_flags & OPT_GLOBAL)
+	{
+	    set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"setglobal", -1);
+	    set_vim_var_string(VV_OPTION_OLDGLOBAL, oldval, -1);
+	}
+	if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
+	{
+	    set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"set", -1);
+	    set_vim_var_string(VV_OPTION_OLDLOCAL, oldval_l, -1);
+	    set_vim_var_string(VV_OPTION_OLDGLOBAL, oldval_g, -1);
+	}
+	if (opt_flags & OPT_MODELINE)
+	{
+	    set_vim_var_string(VV_OPTION_COMMAND, (char_u *)"modeline", -1);
+	    set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
+	}
+	apply_autocmds(EVENT_OPTIONSET,
+		       (char_u *)get_option_fullname(opt_idx), NULL, FALSE,
+		       NULL);
+	reset_v_option_vars();
+    }
+}
+#endif
+
+    static char *
+illegal_char(char *errbuf, int c)
+{
+    if (errbuf == NULL)
+	return "";
+    sprintf((char *)errbuf, _("E539: Illegal character <%s>"),
+							(char *)transchar(c));
+    return errbuf;
+}
+
+/*
+ * Check string options in a buffer for NULL value.
+ */
+    void
+check_buf_options(buf_T *buf)
+{
+    check_string_option(&buf->b_p_bh);
+    check_string_option(&buf->b_p_bt);
+    check_string_option(&buf->b_p_fenc);
+    check_string_option(&buf->b_p_ff);
+#ifdef FEAT_FIND_ID
+    check_string_option(&buf->b_p_def);
+    check_string_option(&buf->b_p_inc);
+# ifdef FEAT_EVAL
+    check_string_option(&buf->b_p_inex);
+# endif
+#endif
+#if defined(FEAT_CINDENT) && defined(FEAT_EVAL)
+    check_string_option(&buf->b_p_inde);
+    check_string_option(&buf->b_p_indk);
+#endif
+#if defined(FEAT_BEVAL) && defined(FEAT_EVAL)
+    check_string_option(&buf->b_p_bexpr);
+#endif
+#if defined(FEAT_CRYPT)
+    check_string_option(&buf->b_p_cm);
+#endif
+    check_string_option(&buf->b_p_fp);
+#if defined(FEAT_EVAL)
+    check_string_option(&buf->b_p_fex);
+#endif
+#ifdef FEAT_CRYPT
+    check_string_option(&buf->b_p_key);
+#endif
+    check_string_option(&buf->b_p_kp);
+    check_string_option(&buf->b_p_mps);
+    check_string_option(&buf->b_p_fo);
+    check_string_option(&buf->b_p_flp);
+    check_string_option(&buf->b_p_isk);
+#ifdef FEAT_COMMENTS
+    check_string_option(&buf->b_p_com);
+#endif
+#ifdef FEAT_FOLDING
+    check_string_option(&buf->b_p_cms);
+#endif
+    check_string_option(&buf->b_p_nf);
+#ifdef FEAT_TEXTOBJ
+    check_string_option(&buf->b_p_qe);
+#endif
+#ifdef FEAT_SYN_HL
+    check_string_option(&buf->b_p_syn);
+    check_string_option(&buf->b_s.b_syn_isk);
+#endif
+#ifdef FEAT_SPELL
+    check_string_option(&buf->b_s.b_p_spc);
+    check_string_option(&buf->b_s.b_p_spf);
+    check_string_option(&buf->b_s.b_p_spl);
+#endif
+#ifdef FEAT_SEARCHPATH
+    check_string_option(&buf->b_p_sua);
+#endif
+#ifdef FEAT_CINDENT
+    check_string_option(&buf->b_p_cink);
+    check_string_option(&buf->b_p_cino);
+    parse_cino(buf);
+#endif
+    check_string_option(&buf->b_p_ft);
+#if defined(FEAT_SMARTINDENT) || defined(FEAT_CINDENT)
+    check_string_option(&buf->b_p_cinw);
+#endif
+    check_string_option(&buf->b_p_cpt);
+#ifdef FEAT_COMPL_FUNC
+    check_string_option(&buf->b_p_cfu);
+    check_string_option(&buf->b_p_ofu);
+#endif
+#ifdef FEAT_EVAL
+    check_string_option(&buf->b_p_tfu);
+#endif
+#ifdef FEAT_KEYMAP
+    check_string_option(&buf->b_p_keymap);
+#endif
+#ifdef FEAT_QUICKFIX
+    check_string_option(&buf->b_p_gp);
+    check_string_option(&buf->b_p_mp);
+    check_string_option(&buf->b_p_efm);
+#endif
+    check_string_option(&buf->b_p_ep);
+    check_string_option(&buf->b_p_path);
+    check_string_option(&buf->b_p_tags);
+    check_string_option(&buf->b_p_tc);
+    check_string_option(&buf->b_p_dict);
+    check_string_option(&buf->b_p_tsr);
+#ifdef FEAT_LISP
+    check_string_option(&buf->b_p_lw);
+#endif
+    check_string_option(&buf->b_p_bkc);
+    check_string_option(&buf->b_p_menc);
+#ifdef FEAT_VARTABS
+    check_string_option(&buf->b_p_vsts);
+    check_string_option(&buf->b_p_vts);
+#endif
+}
+
+/*
+ * Free the string allocated for an option.
+ * Checks for the string being empty_option. This may happen if we're out of
+ * memory, vim_strsave() returned NULL, which was replaced by empty_option by
+ * check_options().
+ * Does NOT check for P_ALLOCED flag!
+ */
+    void
+free_string_option(char_u *p)
+{
+    if (p != empty_option)
+	vim_free(p);
+}
+
+    void
+clear_string_option(char_u **pp)
+{
+    if (*pp != empty_option)
+	vim_free(*pp);
+    *pp = empty_option;
+}
+
+    void
+check_string_option(char_u **pp)
+{
+    if (*pp == NULL)
+	*pp = empty_option;
+}
+
+/*
+ * Set global value for string option when it's a local option.
+ */
+    static void
+set_string_option_global(
+    int		opt_idx,	// option index
+    char_u	**varp)		// pointer to option variable
+{
+    char_u	**p, *s;
+
+    // the global value is always allocated
+    if (is_window_local_option(opt_idx))
+	p = (char_u **)GLOBAL_WO(varp);
+    else
+	p = (char_u **)get_option_var(opt_idx);
+    if (!is_global_option(opt_idx)
+	    && p != varp
+	    && (s = vim_strsave(*varp)) != NULL)
+    {
+	free_string_option(*p);
+	*p = s;
+    }
+}
+
+/*
+ * Set a string option to a new value (without checking the effect).
+ * The string is copied into allocated memory.
+ * if ("opt_idx" == -1) "name" is used, otherwise "opt_idx" is used.
+ * When "set_sid" is zero set the scriptID to current_sctx.sc_sid.  When
+ * "set_sid" is SID_NONE don't set the scriptID.  Otherwise set the scriptID to
+ * "set_sid".
+ */
+    void
+set_string_option_direct(
+    char_u	*name,
+    int		opt_idx,
+    char_u	*val,
+    int		opt_flags,	// OPT_FREE, OPT_LOCAL and/or OPT_GLOBAL
+    int		set_sid UNUSED)
+{
+    char_u	*s;
+    char_u	**varp;
+    int		both = (opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0;
+    int		idx = opt_idx;
+
+    if (idx == -1)		// use name
+    {
+	idx = findoption(name);
+	if (idx < 0)	// not found (should not happen)
+	{
+	    semsg(_(e_intern2), "set_string_option_direct()");
+	    siemsg(_("For option %s"), name);
+	    return;
+	}
+    }
+
+    if (is_hidden_option(idx))		// can't set hidden option
+	return;
+
+    s = vim_strsave(val);
+    if (s != NULL)
+    {
+	varp = (char_u **)get_option_varp_scope(idx,
+					       both ? OPT_LOCAL : opt_flags);
+	if ((opt_flags & OPT_FREE) && (get_option_flags(idx) & P_ALLOCED))
+	    free_string_option(*varp);
+	*varp = s;
+
+	// For buffer/window local option may also set the global value.
+	if (both)
+	    set_string_option_global(idx, varp);
+
+	set_option_flag(idx, P_ALLOCED);
+
+	// When setting both values of a global option with a local value,
+	// make the local value empty, so that the global value is used.
+	if (is_global_local_option(idx) && both)
+	{
+	    free_string_option(*varp);
+	    *varp = empty_option;
+	}
+# ifdef FEAT_EVAL
+	if (set_sid != SID_NONE)
+	{
+	    sctx_T script_ctx;
+
+	    if (set_sid == 0)
+		script_ctx = current_sctx;
+	    else
+	    {
+		script_ctx.sc_sid = set_sid;
+		script_ctx.sc_seq = 0;
+		script_ctx.sc_lnum = 0;
+		script_ctx.sc_version = 1;
+	    }
+	    set_option_sctx_idx(idx, opt_flags, script_ctx);
+	}
+# endif
+    }
+}
+
+/*
+ * Like set_string_option_direct(), but for a window-local option in "wp".
+ * Blocks autocommands to avoid the old curwin becoming invalid.
+ */
+    void
+set_string_option_direct_in_win(
+	win_T		*wp,
+	char_u		*name,
+	int		opt_idx,
+	char_u		*val,
+	int		opt_flags,
+	int		set_sid)
+{
+    win_T	*save_curwin = curwin;
+
+    block_autocmds();
+    curwin = wp;
+    curbuf = curwin->w_buffer;
+    set_string_option_direct(name, opt_idx, val, opt_flags, set_sid);
+    curwin = save_curwin;
+    curbuf = curwin->w_buffer;
+    unblock_autocmds();
+}
+
+/*
+ * Like set_string_option_direct(), but for a buffer-local option in "buf".
+ * Blocks autocommands to avoid the old curbuf becoming invalid.
+ */
+    void
+set_string_option_direct_in_buf(
+	buf_T		*buf,
+	char_u		*name,
+	int		opt_idx,
+	char_u		*val,
+	int		opt_flags,
+	int		set_sid)
+{
+    buf_T	*save_curbuf = curbuf;
+
+    block_autocmds();
+    curbuf = buf;
+    curwin->w_buffer = curbuf;
+    set_string_option_direct(name, opt_idx, val, opt_flags, set_sid);
+    curbuf = save_curbuf;
+    curwin->w_buffer = curbuf;
+    unblock_autocmds();
+}
+
+/*
+ * Set a string option to a new value, and handle the effects.
+ *
+ * Returns NULL on success or error message on error.
+ */
+    char *
+set_string_option(
+    int		opt_idx,
+    char_u	*value,
+    int		opt_flags)	// OPT_LOCAL and/or OPT_GLOBAL
+{
+    char_u	*s;
+    char_u	**varp;
+    char_u	*oldval;
+#if defined(FEAT_EVAL)
+    char_u	*oldval_l = NULL;
+    char_u	*oldval_g = NULL;
+    char_u	*saved_oldval = NULL;
+    char_u	*saved_oldval_l = NULL;
+    char_u	*saved_oldval_g = NULL;
+    char_u	*saved_newval = NULL;
+#endif
+    char	*r = NULL;
+    int		value_checked = FALSE;
+
+    if (is_hidden_option(opt_idx))	// don't set hidden option
+	return NULL;
+
+    s = vim_strsave(value);
+    if (s != NULL)
+    {
+	varp = (char_u **)get_option_varp_scope(opt_idx,
+		(opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0
+		    ? (is_global_local_option(opt_idx)
+			? OPT_GLOBAL : OPT_LOCAL)
+		    : opt_flags);
+	oldval = *varp;
+#if defined(FEAT_EVAL)
+	if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
+	{
+	    oldval_l = *(char_u **)get_option_varp_scope(opt_idx, OPT_LOCAL);
+	    oldval_g = *(char_u **)get_option_varp_scope(opt_idx, OPT_GLOBAL);
+	}
+#endif
+	*varp = s;
+
+#if defined(FEAT_EVAL)
+	if (!starting
+# ifdef FEAT_CRYPT
+		&& !is_crypt_key_option(opt_idx)
+# endif
+		)
+	{
+	    if (oldval_l != NULL)
+		saved_oldval_l = vim_strsave(oldval_l);
+	    if (oldval_g != NULL)
+		saved_oldval_g = vim_strsave(oldval_g);
+	    saved_oldval = vim_strsave(oldval);
+	    saved_newval = vim_strsave(s);
+	}
+#endif
+	if ((r = did_set_string_option(opt_idx, varp, TRUE, oldval, NULL,
+					   opt_flags, &value_checked)) == NULL)
+	    did_set_option(opt_idx, opt_flags, TRUE, value_checked);
+
+#if defined(FEAT_EVAL)
+	// call autocommand after handling side effects
+	if (r == NULL)
+	    trigger_optionsset_string(opt_idx, opt_flags,
+				   saved_oldval, saved_oldval_l,
+				   saved_oldval_g, saved_newval);
+	vim_free(saved_oldval);
+	vim_free(saved_oldval_l);
+	vim_free(saved_oldval_g);
+	vim_free(saved_newval);
+#endif
+    }
+    return r;
+}
+
+/*
+ * Return TRUE if "val" is a valid 'filetype' name.
+ * Also used for 'syntax' and 'keymap'.
+ */
+    static int
+valid_filetype(char_u *val)
+{
+    return valid_name(val, ".-_");
+}
+
+#ifdef FEAT_STL_OPT
+/*
+ * Check validity of options with the 'statusline' format.
+ * Return error message or NULL.
+ */
+    static char *
+check_stl_option(char_u *s)
+{
+    int		itemcnt = 0;
+    int		groupdepth = 0;
+    static char errbuf[80];
+
+    while (*s && itemcnt < STL_MAX_ITEM)
+    {
+	// Check for valid keys after % sequences
+	while (*s && *s != '%')
+	    s++;
+	if (!*s)
+	    break;
+	s++;
+	if (*s != '%' && *s != ')')
+	    ++itemcnt;
+	if (*s == '%' || *s == STL_TRUNCMARK || *s == STL_MIDDLEMARK)
+	{
+	    s++;
+	    continue;
+	}
+	if (*s == ')')
+	{
+	    s++;
+	    if (--groupdepth < 0)
+		break;
+	    continue;
+	}
+	if (*s == '-')
+	    s++;
+	while (VIM_ISDIGIT(*s))
+	    s++;
+	if (*s == STL_USER_HL)
+	    continue;
+	if (*s == '.')
+	{
+	    s++;
+	    while (*s && VIM_ISDIGIT(*s))
+		s++;
+	}
+	if (*s == '(')
+	{
+	    groupdepth++;
+	    continue;
+	}
+	if (vim_strchr(STL_ALL, *s) == NULL)
+	{
+	    return illegal_char(errbuf, *s);
+	}
+	if (*s == '{')
+	{
+	    s++;
+	    while (*s != '}' && *s)
+		s++;
+	    if (*s != '}')
+		return N_("E540: Unclosed expression sequence");
+	}
+    }
+    if (itemcnt >= STL_MAX_ITEM)
+	return N_("E541: too many items");
+    if (groupdepth != 0)
+	return N_("E542: unbalanced groups");
+    return NULL;
+}
+#endif
+
+/*
+ * Handle string options that need some action to perform when changed.
+ * Returns NULL for success, or an error message for an error.
+ */
+    char *
+did_set_string_option(
+    int		opt_idx,		// index in options[] table
+    char_u	**varp,			// pointer to the option variable
+    int		new_value_alloced,	// new value was allocated
+    char_u	*oldval,		// previous value of the option
+    char	*errbuf,		// buffer for errors, or NULL
+    int		opt_flags,		// OPT_LOCAL and/or OPT_GLOBAL
+    int		*value_checked)		// value was checked to be save, no
+					// need to set P_INSECURE
+{
+    char	*errmsg = NULL;
+    char_u	*s, *p;
+    int		did_chartab = FALSE;
+    char_u	**gvarp;
+    long_u	free_oldval = (get_option_flags(opt_idx) & P_ALLOCED);
+#ifdef FEAT_GUI
+    // set when changing an option that only requires a redraw in the GUI
+    int		redraw_gui_only = FALSE;
+#endif
+    int		value_changed = FALSE;
+#if defined(FEAT_VTP) && defined(FEAT_TERMGUICOLORS)
+    int		did_swaptcap = FALSE;
+#endif
+
+    // Get the global option to compare with, otherwise we would have to check
+    // two values for all local options.
+    gvarp = (char_u **)get_option_varp_scope(opt_idx, OPT_GLOBAL);
+
+    // Disallow changing some options from secure mode
+    if ((secure
+#ifdef HAVE_SANDBOX
+		|| sandbox != 0
+#endif
+		) && (get_option_flags(opt_idx) & P_SECURE))
+	errmsg = e_secure;
+
+    // Check for a "normal" directory or file name in some options.  Disallow a
+    // path separator (slash and/or backslash), wildcards and characters that
+    // are often illegal in a file name. Be more permissive if "secure" is off.
+    else if (((get_option_flags(opt_idx) & P_NFNAME)
+		    && vim_strpbrk(*varp, (char_u *)(secure
+			    ? "/\\*?[|;&<>\r\n" : "/\\*?[<>\r\n")) != NULL)
+	  || ((get_option_flags(opt_idx) & P_NDNAME)
+		    && vim_strpbrk(*varp, (char_u *)"*?[|;&<>\r\n") != NULL))
+	errmsg = e_invarg;
+
+    // 'term'
+    else if (varp == &T_NAME)
+    {
+	if (T_NAME[0] == NUL)
+	    errmsg = N_("E529: Cannot set 'term' to empty string");
+#ifdef FEAT_GUI
+	if (gui.in_use)
+	    errmsg = N_("E530: Cannot change term in GUI");
+	else if (term_is_gui(T_NAME))
+	    errmsg = N_("E531: Use \":gui\" to start the GUI");
+#endif
+	else if (set_termname(T_NAME) == FAIL)
+	    errmsg = N_("E522: Not found in termcap");
+	else
+	{
+	    // Screen colors may have changed.
+	    redraw_later_clear();
+
+	    // Both 'term' and 'ttytype' point to T_NAME, only set the
+	    // P_ALLOCED flag on 'term'.
+	    opt_idx = findoption((char_u *)"term");
+	    free_oldval = (get_option_flags(opt_idx) & P_ALLOCED);
+	}
+    }
+
+    // 'backupcopy'
+    else if (gvarp == &p_bkc)
+    {
+	char_u		*bkc = p_bkc;
+	unsigned int	*flags = &bkc_flags;
+
+	if (opt_flags & OPT_LOCAL)
+	{
+	    bkc = curbuf->b_p_bkc;
+	    flags = &curbuf->b_bkc_flags;
+	}
+
+	if ((opt_flags & OPT_LOCAL) && *bkc == NUL)
+	    // make the local value empty: use the global value
+	    *flags = 0;
+	else
+	{
+	    if (opt_strings_flags(bkc, p_bkc_values, flags, TRUE) != OK)
+		errmsg = e_invarg;
+	    if ((((int)*flags & BKC_AUTO) != 0)
+		    + (((int)*flags & BKC_YES) != 0)
+		    + (((int)*flags & BKC_NO) != 0) != 1)
+	    {
+		// Must have exactly one of "auto", "yes"  and "no".
+		(void)opt_strings_flags(oldval, p_bkc_values, flags, TRUE);
+		errmsg = e_invarg;
+	    }
+	}
+    }
+
+    // 'backupext' and 'patchmode'
+    else if (varp == &p_bex || varp == &p_pm)
+    {
+	if (STRCMP(*p_bex == '.' ? p_bex + 1 : p_bex,
+		     *p_pm == '.' ? p_pm + 1 : p_pm) == 0)
+	    errmsg = N_("E589: 'backupext' and 'patchmode' are equal");
+    }
+#ifdef FEAT_LINEBREAK
+    // 'breakindentopt'
+    else if (varp == &curwin->w_p_briopt)
+    {
+	if (briopt_check(curwin) == FAIL)
+	    errmsg = e_invarg;
+    }
+#endif
+
+    // 'isident', 'iskeyword', 'isprint or 'isfname' option: refill g_chartab[]
+    // If the new option is invalid, use old value.  'lisp' option: refill
+    // g_chartab[] for '-' char
+    else if (  varp == &p_isi
+	    || varp == &(curbuf->b_p_isk)
+	    || varp == &p_isp
+	    || varp == &p_isf)
+    {
+	if (init_chartab() == FAIL)
+	{
+	    did_chartab = TRUE;	    // need to restore it below
+	    errmsg = e_invarg;	    // error in value
+	}
+    }
+
+    // 'helpfile'
+    else if (varp == &p_hf)
+    {
+	// May compute new values for $VIM and $VIMRUNTIME
+	if (didset_vim)
+	{
+	    vim_setenv((char_u *)"VIM", (char_u *)"");
+	    didset_vim = FALSE;
+	}
+	if (didset_vimruntime)
+	{
+	    vim_setenv((char_u *)"VIMRUNTIME", (char_u *)"");
+	    didset_vimruntime = FALSE;
+	}
+    }
+
+#ifdef FEAT_SYN_HL
+    // 'cursorlineopt'
+    else if (varp == &curwin->w_p_culopt
+				  || gvarp == &curwin->w_allbuf_opt.wo_culopt)
+    {
+	if (**varp == NUL || fill_culopt_flags(*varp, curwin) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // 'colorcolumn'
+    else if (varp == &curwin->w_p_cc)
+	errmsg = check_colorcolumn(curwin);
+#endif
+
+#ifdef FEAT_MULTI_LANG
+    // 'helplang'
+    else if (varp == &p_hlg)
+    {
+	// Check for "", "ab", "ab,cd", etc.
+	for (s = p_hlg; *s != NUL; s += 3)
+	{
+	    if (s[1] == NUL || ((s[2] != ',' || s[3] == NUL) && s[2] != NUL))
+	    {
+		errmsg = e_invarg;
+		break;
+	    }
+	    if (s[2] == NUL)
+		break;
+	}
+    }
+#endif
+
+    // 'highlight'
+    else if (varp == &p_hl)
+    {
+	if (highlight_changed() == FAIL)
+	    errmsg = e_invarg;	// invalid flags
+    }
+
+    // 'nrformats'
+    else if (gvarp == &p_nf)
+    {
+	if (check_opt_strings(*varp, p_nf_values, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+#ifdef FEAT_SESSION
+    // 'sessionoptions'
+    else if (varp == &p_ssop)
+    {
+	if (opt_strings_flags(p_ssop, p_ssop_values, &ssop_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+	if ((ssop_flags & SSOP_CURDIR) && (ssop_flags & SSOP_SESDIR))
+	{
+	    // Don't allow both "sesdir" and "curdir".
+	    (void)opt_strings_flags(oldval, p_ssop_values, &ssop_flags, TRUE);
+	    errmsg = e_invarg;
+	}
+    }
+    // 'viewoptions'
+    else if (varp == &p_vop)
+    {
+	if (opt_strings_flags(p_vop, p_ssop_values, &vop_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+#endif
+
+    // 'scrollopt'
+    else if (varp == &p_sbo)
+    {
+	if (check_opt_strings(p_sbo, p_scbopt_values, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // 'ambiwidth'
+    else if (varp == &p_ambw || varp == &p_emoji)
+    {
+	if (check_opt_strings(p_ambw, p_ambw_values, FALSE) != OK)
+	    errmsg = e_invarg;
+	else if (set_chars_option(&p_lcs) != NULL)
+	    errmsg = _("E834: Conflicts with value of 'listchars'");
+	else if (set_chars_option(&p_fcs) != NULL)
+	    errmsg = _("E835: Conflicts with value of 'fillchars'");
+    }
+
+    // 'background'
+    else if (varp == &p_bg)
+    {
+	if (check_opt_strings(p_bg, p_bg_values, FALSE) == OK)
+	{
+#ifdef FEAT_EVAL
+	    int dark = (*p_bg == 'd');
+#endif
+
+	    init_highlight(FALSE, FALSE);
+
+#ifdef FEAT_EVAL
+	    if (dark != (*p_bg == 'd')
+			  && get_var_value((char_u *)"g:colors_name") != NULL)
+	    {
+		// The color scheme must have set 'background' back to another
+		// value, that's not what we want here.  Disable the color
+		// scheme and set the colors again.
+		do_unlet((char_u *)"g:colors_name", TRUE);
+		free_string_option(p_bg);
+		p_bg = vim_strsave((char_u *)(dark ? "dark" : "light"));
+		check_string_option(&p_bg);
+		init_highlight(FALSE, FALSE);
+	    }
+#endif
+	}
+	else
+	    errmsg = e_invarg;
+    }
+
+    // 'wildmode'
+    else if (varp == &p_wim)
+    {
+	if (check_opt_wim() == FAIL)
+	    errmsg = e_invarg;
+    }
+
+    // 'wildoptions'
+    else if (varp == &p_wop)
+    {
+	if (check_opt_strings(p_wop, p_wop_values, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+#ifdef FEAT_WAK
+    // 'winaltkeys'
+    else if (varp == &p_wak)
+    {
+	if (*p_wak == NUL
+		|| check_opt_strings(p_wak, p_wak_values, FALSE) != OK)
+	    errmsg = e_invarg;
+# ifdef FEAT_MENU
+#  ifdef FEAT_GUI_MOTIF
+	else if (gui.in_use)
+	    gui_motif_set_mnemonics(p_wak[0] == 'y' || p_wak[0] == 'm');
+#  else
+#   ifdef FEAT_GUI_GTK
+	else if (gui.in_use)
+	    gui_gtk_set_mnemonics(p_wak[0] == 'y' || p_wak[0] == 'm');
+#   endif
+#  endif
+# endif
+    }
+#endif
+
+    // 'eventignore'
+    else if (varp == &p_ei)
+    {
+	if (check_ei() == FAIL)
+	    errmsg = e_invarg;
+    }
+
+    // 'encoding', 'fileencoding', 'termencoding' and 'makeencoding'
+    else if (varp == &p_enc || gvarp == &p_fenc || varp == &p_tenc
+							   || gvarp == &p_menc)
+    {
+	if (gvarp == &p_fenc)
+	{
+	    if (!curbuf->b_p_ma && opt_flags != OPT_GLOBAL)
+		errmsg = e_modifiable;
+	    else if (vim_strchr(*varp, ',') != NULL)
+		// No comma allowed in 'fileencoding'; catches confusing it
+		// with 'fileencodings'.
+		errmsg = e_invarg;
+	    else
+	    {
+#ifdef FEAT_TITLE
+		// May show a "+" in the title now.
+		redraw_titles();
+#endif
+		// Add 'fileencoding' to the swap file.
+		ml_setflags(curbuf);
+	    }
+	}
+	if (errmsg == NULL)
+	{
+	    // canonize the value, so that STRCMP() can be used on it
+	    p = enc_canonize(*varp);
+	    if (p != NULL)
+	    {
+		vim_free(*varp);
+		*varp = p;
+	    }
+	    if (varp == &p_enc)
+	    {
+		errmsg = mb_init();
+#ifdef FEAT_TITLE
+		redraw_titles();
+#endif
+	    }
+	}
+
+#if defined(FEAT_GUI_GTK)
+	if (errmsg == NULL && varp == &p_tenc && gui.in_use)
+	{
+	    // GTK+ 2 uses only a single encoding, and that is UTF-8.
+	    if (STRCMP(p_tenc, "utf-8") != 0)
+		errmsg = N_("E617: Cannot be changed in the GTK+ 2 GUI");
+	}
+#endif
+
+	if (errmsg == NULL)
+	{
+#ifdef FEAT_KEYMAP
+	    // When 'keymap' is used and 'encoding' changes, reload the keymap
+	    // (with another encoding).
+	    if (varp == &p_enc && *curbuf->b_p_keymap != NUL)
+		(void)keymap_init();
+#endif
+
+	    // When 'termencoding' is not empty and 'encoding' changes or when
+	    // 'termencoding' changes, need to setup for keyboard input and
+	    // display output conversion.
+	    if (((varp == &p_enc && *p_tenc != NUL) || varp == &p_tenc))
+	    {
+		if (convert_setup(&input_conv, p_tenc, p_enc) == FAIL
+			|| convert_setup(&output_conv, p_enc, p_tenc) == FAIL)
+		{
+		    semsg(_("E950: Cannot convert between %s and %s"),
+			    p_tenc, p_enc);
+		    errmsg = e_invarg;
+		}
+	    }
+
+#if defined(MSWIN)
+	    // $HOME may have characters in active code page.
+	    if (varp == &p_enc)
+		init_homedir();
+#endif
+	}
+    }
+
+#if defined(FEAT_POSTSCRIPT)
+    else if (varp == &p_penc)
+    {
+	// Canonize printencoding if VIM standard one
+	p = enc_canonize(p_penc);
+	if (p != NULL)
+	{
+	    vim_free(p_penc);
+	    p_penc = p;
+	}
+	else
+	{
+	    // Ensure lower case and '-' for '_'
+	    for (s = p_penc; *s != NUL; s++)
+	    {
+		if (*s == '_')
+		    *s = '-';
+		else
+		    *s = TOLOWER_ASC(*s);
+	    }
+	}
+    }
+#endif
+
+#if defined(FEAT_XIM) && defined(FEAT_GUI_GTK)
+    else if (varp == &p_imak)
+    {
+	if (!im_xim_isvalid_imactivate())
+	    errmsg = e_invarg;
+    }
+#endif
+
+#ifdef FEAT_KEYMAP
+    else if (varp == &curbuf->b_p_keymap)
+    {
+	if (!valid_filetype(*varp))
+	    errmsg = e_invarg;
+	else
+	{
+	    int	    secure_save = secure;
+
+	    // Reset the secure flag, since the value of 'keymap' has
+	    // been checked to be safe.
+	    secure = 0;
+
+	    // load or unload key mapping tables
+	    errmsg = keymap_init();
+
+	    secure = secure_save;
+
+	    // Since we check the value, there is no need to set P_INSECURE,
+	    // even when the value comes from a modeline.
+	    *value_checked = TRUE;
+	}
+
+	if (errmsg == NULL)
+	{
+	    if (*curbuf->b_p_keymap != NUL)
+	    {
+		// Installed a new keymap, switch on using it.
+		curbuf->b_p_iminsert = B_IMODE_LMAP;
+		if (curbuf->b_p_imsearch != B_IMODE_USE_INSERT)
+		    curbuf->b_p_imsearch = B_IMODE_LMAP;
+	    }
+	    else
+	    {
+		// Cleared the keymap, may reset 'iminsert' and 'imsearch'.
+		if (curbuf->b_p_iminsert == B_IMODE_LMAP)
+		    curbuf->b_p_iminsert = B_IMODE_NONE;
+		if (curbuf->b_p_imsearch == B_IMODE_LMAP)
+		    curbuf->b_p_imsearch = B_IMODE_USE_INSERT;
+	    }
+	    if ((opt_flags & OPT_LOCAL) == 0)
+	    {
+		set_iminsert_global();
+		set_imsearch_global();
+	    }
+	    status_redraw_curbuf();
+	}
+    }
+#endif
+
+    // 'fileformat'
+    else if (gvarp == &p_ff)
+    {
+	if (!curbuf->b_p_ma && !(opt_flags & OPT_GLOBAL))
+	    errmsg = e_modifiable;
+	else if (check_opt_strings(*varp, p_ff_values, FALSE) != OK)
+	    errmsg = e_invarg;
+	else
+	{
+	    // may also change 'textmode'
+	    if (get_fileformat(curbuf) == EOL_DOS)
+		curbuf->b_p_tx = TRUE;
+	    else
+		curbuf->b_p_tx = FALSE;
+#ifdef FEAT_TITLE
+	    redraw_titles();
+#endif
+	    // update flag in swap file
+	    ml_setflags(curbuf);
+	    // Redraw needed when switching to/from "mac": a CR in the text
+	    // will be displayed differently.
+	    if (get_fileformat(curbuf) == EOL_MAC || *oldval == 'm')
+		redraw_curbuf_later(NOT_VALID);
+	}
+    }
+
+    // 'fileformats'
+    else if (varp == &p_ffs)
+    {
+	if (check_opt_strings(p_ffs, p_ff_values, TRUE) != OK)
+	    errmsg = e_invarg;
+	else
+	{
+	    // also change 'textauto'
+	    if (*p_ffs == NUL)
+		p_ta = FALSE;
+	    else
+		p_ta = TRUE;
+	}
+    }
+
+#if defined(FEAT_CRYPT)
+    // 'cryptkey'
+    else if (gvarp == &p_key)
+    {
+	// Make sure the ":set" command doesn't show the new value in the
+	// history.
+	remove_key_from_history();
+
+	if (STRCMP(curbuf->b_p_key, oldval) != 0)
+	    // Need to update the swapfile.
+	    ml_set_crypt_key(curbuf, oldval,
+			      *curbuf->b_p_cm == NUL ? p_cm : curbuf->b_p_cm);
+    }
+
+    else if (gvarp == &p_cm)
+    {
+	if (opt_flags & OPT_LOCAL)
+	    p = curbuf->b_p_cm;
+	else
+	    p = p_cm;
+	if (check_opt_strings(p, p_cm_values, TRUE) != OK)
+	    errmsg = e_invarg;
+	else if (crypt_self_test() == FAIL)
+	    errmsg = e_invarg;
+	else
+	{
+	    // When setting the global value to empty, make it "zip".
+	    if (*p_cm == NUL)
+	    {
+		if (new_value_alloced)
+		    free_string_option(p_cm);
+		p_cm = vim_strsave((char_u *)"zip");
+		new_value_alloced = TRUE;
+	    }
+	    // When using ":set cm=name" the local value is going to be empty.
+	    // Do that here, otherwise the crypt functions will still use the
+	    // local value.
+	    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0)
+	    {
+		free_string_option(curbuf->b_p_cm);
+		curbuf->b_p_cm = empty_option;
+	    }
+
+	    // Need to update the swapfile when the effective method changed.
+	    // Set "s" to the effective old value, "p" to the effective new
+	    // method and compare.
+	    if ((opt_flags & OPT_LOCAL) && *oldval == NUL)
+		s = p_cm;  // was previously using the global value
+	    else
+		s = oldval;
+	    if (*curbuf->b_p_cm == NUL)
+		p = p_cm;  // is now using the global value
+	    else
+		p = curbuf->b_p_cm;
+	    if (STRCMP(s, p) != 0)
+		ml_set_crypt_key(curbuf, curbuf->b_p_key, s);
+
+	    // If the global value changes need to update the swapfile for all
+	    // buffers using that value.
+	    if ((opt_flags & OPT_GLOBAL) && STRCMP(p_cm, oldval) != 0)
+	    {
+		buf_T	*buf;
+
+		FOR_ALL_BUFFERS(buf)
+		    if (buf != curbuf && *buf->b_p_cm == NUL)
+			ml_set_crypt_key(buf, buf->b_p_key, oldval);
+	    }
+	}
+    }
+#endif
+
+    // 'matchpairs'
+    else if (gvarp == &p_mps)
+    {
+	if (has_mbyte)
+	{
+	    for (p = *varp; *p != NUL; ++p)
+	    {
+		int x2 = -1;
+		int x3 = -1;
+
+		if (*p != NUL)
+		    p += mb_ptr2len(p);
+		if (*p != NUL)
+		    x2 = *p++;
+		if (*p != NUL)
+		{
+		    x3 = mb_ptr2char(p);
+		    p += mb_ptr2len(p);
+		}
+		if (x2 != ':' || x3 == -1 || (*p != NUL && *p != ','))
+		{
+		    errmsg = e_invarg;
+		    break;
+		}
+		if (*p == NUL)
+		    break;
+	    }
+	}
+	else
+	{
+	    // Check for "x:y,x:y"
+	    for (p = *varp; *p != NUL; p += 4)
+	    {
+		if (p[1] != ':' || p[2] == NUL || (p[3] != NUL && p[3] != ','))
+		{
+		    errmsg = e_invarg;
+		    break;
+		}
+		if (p[3] == NUL)
+		    break;
+	    }
+	}
+    }
+
+#ifdef FEAT_COMMENTS
+    // 'comments'
+    else if (gvarp == &p_com)
+    {
+	for (s = *varp; *s; )
+	{
+	    while (*s && *s != ':')
+	    {
+		if (vim_strchr((char_u *)COM_ALL, *s) == NULL
+					     && !VIM_ISDIGIT(*s) && *s != '-')
+		{
+		    errmsg = illegal_char(errbuf, *s);
+		    break;
+		}
+		++s;
+	    }
+	    if (*s++ == NUL)
+		errmsg = N_("E524: Missing colon");
+	    else if (*s == ',' || *s == NUL)
+		errmsg = N_("E525: Zero length string");
+	    if (errmsg != NULL)
+		break;
+	    while (*s && *s != ',')
+	    {
+		if (*s == '\\' && s[1] != NUL)
+		    ++s;
+		++s;
+	    }
+	    s = skip_to_option_part(s);
+	}
+    }
+#endif
+
+    // 'listchars'
+    else if (varp == &p_lcs)
+    {
+	errmsg = set_chars_option(varp);
+    }
+
+    // 'fillchars'
+    else if (varp == &p_fcs)
+    {
+	errmsg = set_chars_option(varp);
+    }
+
+#ifdef FEAT_CMDWIN
+    // 'cedit'
+    else if (varp == &p_cedit)
+    {
+	errmsg = check_cedit();
+    }
+#endif
+
+    // 'verbosefile'
+    else if (varp == &p_vfile)
+    {
+	verbose_stop();
+	if (*p_vfile != NUL && verbose_open() == FAIL)
+	    errmsg = e_invarg;
+    }
+
+#ifdef FEAT_VIMINFO
+    // 'viminfo'
+    else if (varp == &p_viminfo)
+    {
+	for (s = p_viminfo; *s;)
+	{
+	    // Check it's a valid character
+	    if (vim_strchr((char_u *)"!\"%'/:<@cfhnrs", *s) == NULL)
+	    {
+		errmsg = illegal_char(errbuf, *s);
+		break;
+	    }
+	    if (*s == 'n')	// name is always last one
+		break;
+	    else if (*s == 'r') // skip until next ','
+	    {
+		while (*++s && *s != ',')
+		    ;
+	    }
+	    else if (*s == '%')
+	    {
+		// optional number
+		while (vim_isdigit(*++s))
+		    ;
+	    }
+	    else if (*s == '!' || *s == 'h' || *s == 'c')
+		++s;		// no extra chars
+	    else		// must have a number
+	    {
+		while (vim_isdigit(*++s))
+		    ;
+
+		if (!VIM_ISDIGIT(*(s - 1)))
+		{
+		    if (errbuf != NULL)
+		    {
+			sprintf(errbuf, _("E526: Missing number after <%s>"),
+						    transchar_byte(*(s - 1)));
+			errmsg = errbuf;
+		    }
+		    else
+			errmsg = "";
+		    break;
+		}
+	    }
+	    if (*s == ',')
+		++s;
+	    else if (*s)
+	    {
+		if (errbuf != NULL)
+		    errmsg = N_("E527: Missing comma");
+		else
+		    errmsg = "";
+		break;
+	    }
+	}
+	if (*p_viminfo && errmsg == NULL && get_viminfo_parameter('\'') < 0)
+	    errmsg = N_("E528: Must specify a ' value");
+    }
+#endif // FEAT_VIMINFO
+
+    // terminal options
+    else if (istermoption_idx(opt_idx) && full_screen)
+    {
+	// ":set t_Co=0" and ":set t_Co=1" do ":set t_Co="
+	if (varp == &T_CCO)
+	{
+	    int colors = atoi((char *)T_CCO);
+
+	    // Only reinitialize colors if t_Co value has really changed to
+	    // avoid expensive reload of colorscheme if t_Co is set to the
+	    // same value multiple times.
+	    if (colors != t_colors)
+	    {
+		t_colors = colors;
+		if (t_colors <= 1)
+		{
+		    if (new_value_alloced)
+			vim_free(T_CCO);
+		    T_CCO = empty_option;
+		}
+#if defined(FEAT_VTP) && defined(FEAT_TERMGUICOLORS)
+		if (is_term_win32())
+		{
+		    swap_tcap();
+		    did_swaptcap = TRUE;
+		}
+#endif
+		// We now have a different color setup, initialize it again.
+		init_highlight(TRUE, FALSE);
+	    }
+	}
+	ttest(FALSE);
+	if (varp == &T_ME)
+	{
+	    out_str(T_ME);
+	    redraw_later(CLEAR);
+#if defined(MSWIN) && (!defined(FEAT_GUI_MSWIN) || defined(VIMDLL))
+	    // Since t_me has been set, this probably means that the user
+	    // wants to use this as default colors.  Need to reset default
+	    // background/foreground colors.
+# ifdef VIMDLL
+	    if (!gui.in_use && !gui.starting)
+# endif
+		mch_set_normal_colors();
+#endif
+	}
+	if (varp == &T_BE && termcap_active)
+	{
+	    if (*T_BE == NUL)
+		// When clearing t_BE we assume the user no longer wants
+		// bracketed paste, thus disable it by writing t_BD.
+		out_str(T_BD);
+	    else
+		out_str(T_BE);
+	}
+    }
+
+#ifdef FEAT_LINEBREAK
+    // 'showbreak'
+    else if (varp == &p_sbr)
+    {
+	for (s = p_sbr; *s; )
+	{
+	    if (ptr2cells(s) != 1)
+		errmsg = N_("E595: contains unprintable or wide character");
+	    MB_PTR_ADV(s);
+	}
+    }
+#endif
+
+#ifdef FEAT_GUI
+    // 'guifont'
+    else if (varp == &p_guifont)
+    {
+	if (gui.in_use)
+	{
+	    p = p_guifont;
+# if defined(FEAT_GUI_GTK)
+	    // Put up a font dialog and let the user select a new value.
+	    // If this is cancelled go back to the old value but don't
+	    // give an error message.
+	    if (STRCMP(p, "*") == 0)
+	    {
+		p = gui_mch_font_dialog(oldval);
+
+		if (new_value_alloced)
+		    free_string_option(p_guifont);
+
+		p_guifont = (p != NULL) ? p : vim_strsave(oldval);
+		new_value_alloced = TRUE;
+	    }
+# endif
+	    if (p != NULL && gui_init_font(p_guifont, FALSE) != OK)
+	    {
+# if defined(FEAT_GUI_MSWIN) || defined(FEAT_GUI_PHOTON)
+		if (STRCMP(p_guifont, "*") == 0)
+		{
+		    // Dialog was cancelled: Keep the old value without giving
+		    // an error message.
+		    if (new_value_alloced)
+			free_string_option(p_guifont);
+		    p_guifont = vim_strsave(oldval);
+		    new_value_alloced = TRUE;
+		}
+		else
+# endif
+		    errmsg = N_("E596: Invalid font(s)");
+	    }
+	}
+	redraw_gui_only = TRUE;
+    }
+# ifdef FEAT_XFONTSET
+    else if (varp == &p_guifontset)
+    {
+	if (STRCMP(p_guifontset, "*") == 0)
+	    errmsg = N_("E597: can't select fontset");
+	else if (gui.in_use && gui_init_font(p_guifontset, TRUE) != OK)
+	    errmsg = N_("E598: Invalid fontset");
+	redraw_gui_only = TRUE;
+    }
+# endif
+    else if (varp == &p_guifontwide)
+    {
+	if (STRCMP(p_guifontwide, "*") == 0)
+	    errmsg = N_("E533: can't select wide font");
+	else if (gui_get_wide_font() == FAIL)
+	    errmsg = N_("E534: Invalid wide font");
+	redraw_gui_only = TRUE;
+    }
+#endif
+
+#ifdef CURSOR_SHAPE
+    // 'guicursor'
+    else if (varp == &p_guicursor)
+	errmsg = parse_shape_opt(SHAPE_CURSOR);
+#endif
+
+#ifdef FEAT_MOUSESHAPE
+    // 'mouseshape'
+    else if (varp == &p_mouseshape)
+    {
+	errmsg = parse_shape_opt(SHAPE_MOUSE);
+	update_mouseshape(-1);
+    }
+#endif
+
+#ifdef FEAT_PRINTER
+    else if (varp == &p_popt)
+	errmsg = parse_printoptions();
+# if defined(FEAT_POSTSCRIPT)
+    else if (varp == &p_pmfn)
+	errmsg = parse_printmbfont();
+# endif
+#endif
+
+#ifdef FEAT_LANGMAP
+    // 'langmap'
+    else if (varp == &p_langmap)
+	langmap_set();
+#endif
+
+#ifdef FEAT_LINEBREAK
+    // 'breakat'
+    else if (varp == &p_breakat)
+	fill_breakat_flags();
+#endif
+
+#ifdef FEAT_TITLE
+    // 'titlestring' and 'iconstring'
+    else if (varp == &p_titlestring || varp == &p_iconstring)
+    {
+# ifdef FEAT_STL_OPT
+	int	flagval = (varp == &p_titlestring) ? STL_IN_TITLE : STL_IN_ICON;
+
+	// NULL => statusline syntax
+	if (vim_strchr(*varp, '%') && check_stl_option(*varp) == NULL)
+	    stl_syntax |= flagval;
+	else
+	    stl_syntax &= ~flagval;
+# endif
+	did_set_title();
+    }
+#endif
+
+#ifdef FEAT_GUI
+    // 'guioptions'
+    else if (varp == &p_go)
+    {
+	gui_init_which_components(oldval);
+	redraw_gui_only = TRUE;
+    }
+#endif
+
+#if defined(FEAT_GUI_TABLINE)
+    // 'guitablabel'
+    else if (varp == &p_gtl)
+    {
+	redraw_tabline = TRUE;
+	redraw_gui_only = TRUE;
+    }
+    // 'guitabtooltip'
+    else if (varp == &p_gtt)
+    {
+	redraw_gui_only = TRUE;
+    }
+#endif
+
+#if defined(FEAT_MOUSE_TTY) && (defined(UNIX) || defined(VMS))
+    // 'ttymouse'
+    else if (varp == &p_ttym)
+    {
+	// Switch the mouse off before changing the escape sequences used for
+	// that.
+	mch_setmouse(FALSE);
+	if (opt_strings_flags(p_ttym, p_ttym_values, &ttym_flags, FALSE) != OK)
+	    errmsg = e_invarg;
+	else
+	    check_mouse_termcode();
+	if (termcap_active)
+	    setmouse();		// may switch it on again
+    }
+#endif
+
+    // 'selection'
+    else if (varp == &p_sel)
+    {
+	if (*p_sel == NUL
+		|| check_opt_strings(p_sel, p_sel_values, FALSE) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // 'selectmode'
+    else if (varp == &p_slm)
+    {
+	if (check_opt_strings(p_slm, p_slm_values, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+#ifdef FEAT_BROWSE
+    // 'browsedir'
+    else if (varp == &p_bsdir)
+    {
+	if (check_opt_strings(p_bsdir, p_bsdir_values, FALSE) != OK
+		&& !mch_isdir(p_bsdir))
+	    errmsg = e_invarg;
+    }
+#endif
+
+    // 'keymodel'
+    else if (varp == &p_km)
+    {
+	if (check_opt_strings(p_km, p_km_values, TRUE) != OK)
+	    errmsg = e_invarg;
+	else
+	{
+	    km_stopsel = (vim_strchr(p_km, 'o') != NULL);
+	    km_startsel = (vim_strchr(p_km, 'a') != NULL);
+	}
+    }
+
+    // 'mousemodel'
+    else if (varp == &p_mousem)
+    {
+	if (check_opt_strings(p_mousem, p_mousem_values, FALSE) != OK)
+	    errmsg = e_invarg;
+#if defined(FEAT_GUI_MOTIF) && defined(FEAT_MENU) && (XmVersion <= 1002)
+	else if (*p_mousem != *oldval)
+	    // Changed from "extend" to "popup" or "popup_setpos" or vv: need
+	    // to create or delete the popup menus.
+	    gui_motif_update_mousemodel(root_menu);
+#endif
+    }
+
+    // 'switchbuf'
+    else if (varp == &p_swb)
+    {
+	if (opt_strings_flags(p_swb, p_swb_values, &swb_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // 'debug'
+    else if (varp == &p_debug)
+    {
+	if (check_opt_strings(p_debug, p_debug_values, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // 'display'
+    else if (varp == &p_dy)
+    {
+	if (opt_strings_flags(p_dy, p_dy_values, &dy_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+	else
+	    (void)init_chartab();
+
+    }
+
+    // 'eadirection'
+    else if (varp == &p_ead)
+    {
+	if (check_opt_strings(p_ead, p_ead_values, FALSE) != OK)
+	    errmsg = e_invarg;
+    }
+
+#ifdef FEAT_CLIPBOARD
+    // 'clipboard'
+    else if (varp == &p_cb)
+	errmsg = check_clipboard_option();
+#endif
+
+#ifdef FEAT_SPELL
+    // When 'spelllang' or 'spellfile' is set and there is a window for this
+    // buffer in which 'spell' is set load the wordlists.
+    else if (varp == &(curwin->w_s->b_p_spl)
+	    || varp == &(curwin->w_s->b_p_spf))
+    {
+	int	is_spellfile = varp == &(curwin->w_s->b_p_spf);
+
+	if ((is_spellfile && !valid_spellfile(*varp))
+	    || (!is_spellfile && !valid_spellang(*varp)))
+	    errmsg = e_invarg;
+	else
+	    errmsg = did_set_spell_option(is_spellfile);
+    }
+    // When 'spellcapcheck' is set compile the regexp program.
+    else if (varp == &(curwin->w_s->b_p_spc))
+    {
+	errmsg = compile_cap_prog(curwin->w_s);
+    }
+    // 'spellsuggest'
+    else if (varp == &p_sps)
+    {
+	if (spell_check_sps() != OK)
+	    errmsg = e_invarg;
+    }
+    // 'mkspellmem'
+    else if (varp == &p_msm)
+    {
+	if (spell_check_msm() != OK)
+	    errmsg = e_invarg;
+    }
+#endif
+
+    // When 'bufhidden' is set, check for valid value.
+    else if (gvarp == &p_bh)
+    {
+	if (check_opt_strings(curbuf->b_p_bh, p_bufhidden_values, FALSE) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // When 'buftype' is set, check for valid value.
+    else if (gvarp == &p_bt)
+    {
+	if (check_opt_strings(curbuf->b_p_bt, p_buftype_values, FALSE) != OK)
+	    errmsg = e_invarg;
+	else
+	{
+	    if (curwin->w_status_height)
+	    {
+		curwin->w_redr_status = TRUE;
+		redraw_later(VALID);
+	    }
+	    curbuf->b_help = (curbuf->b_p_bt[0] == 'h');
+#ifdef FEAT_TITLE
+	    redraw_titles();
+#endif
+	}
+    }
+
+#ifdef FEAT_STL_OPT
+    // 'statusline' or 'rulerformat'
+    else if (gvarp == &p_stl || varp == &p_ruf)
+    {
+	int wid;
+
+	if (varp == &p_ruf)	// reset ru_wid first
+	    ru_wid = 0;
+	s = *varp;
+	if (varp == &p_ruf && *s == '%')
+	{
+	    // set ru_wid if 'ruf' starts with "%99("
+	    if (*++s == '-')	// ignore a '-'
+		s++;
+	    wid = getdigits(&s);
+	    if (wid && *s == '(' && (errmsg = check_stl_option(p_ruf)) == NULL)
+		ru_wid = wid;
+	    else
+		errmsg = check_stl_option(p_ruf);
+	}
+	// check 'statusline' only if it doesn't start with "%!"
+	else if (varp == &p_ruf || s[0] != '%' || s[1] != '!')
+	    errmsg = check_stl_option(s);
+	if (varp == &p_ruf && errmsg == NULL)
+	    comp_col();
+    }
+#endif
+
+    // check if it is a valid value for 'complete' -- Acevedo
+    else if (gvarp == &p_cpt)
+    {
+	for (s = *varp; *s;)
+	{
+	    while (*s == ',' || *s == ' ')
+		s++;
+	    if (!*s)
+		break;
+	    if (vim_strchr((char_u *)".wbuksid]tU", *s) == NULL)
+	    {
+		errmsg = illegal_char(errbuf, *s);
+		break;
+	    }
+	    if (*++s != NUL && *s != ',' && *s != ' ')
+	    {
+		if (s[-1] == 'k' || s[-1] == 's')
+		{
+		    // skip optional filename after 'k' and 's'
+		    while (*s && *s != ',' && *s != ' ')
+		    {
+			if (*s == '\\' && s[1] != NUL)
+			    ++s;
+			++s;
+		    }
+		}
+		else
+		{
+		    if (errbuf != NULL)
+		    {
+			sprintf((char *)errbuf,
+				     _("E535: Illegal character after <%c>"),
+				     *--s);
+			errmsg = errbuf;
+		    }
+		    else
+			errmsg = "";
+		    break;
+		}
+	    }
+	}
+    }
+
+    // 'completeopt'
+    else if (varp == &p_cot)
+    {
+	if (check_opt_strings(p_cot, p_cot_values, TRUE) != OK)
+	    errmsg = e_invarg;
+	else
+	    completeopt_was_set();
+    }
+
+#ifdef BACKSLASH_IN_FILENAME
+    // 'completeslash'
+    else if (gvarp == &p_csl)
+    {
+	if (check_opt_strings(p_csl, p_csl_values, FALSE) != OK
+		|| check_opt_strings(curbuf->b_p_csl, p_csl_values, FALSE) != OK)
+	    errmsg = e_invarg;
+    }
+#endif
+
+#ifdef FEAT_SIGNS
+    // 'signcolumn'
+    else if (varp == &curwin->w_p_scl)
+    {
+	if (check_opt_strings(*varp, p_scl_values, FALSE) != OK)
+	    errmsg = e_invarg;
+	// When changing the 'signcolumn' to or from 'number', recompute the
+	// width of the number column if 'number' or 'relativenumber' is set.
+	if (((*oldval == 'n' && *(oldval + 1) == 'u')
+		|| (*curwin->w_p_scl == 'n' && *(curwin->w_p_scl + 1) =='u'))
+		&& (curwin->w_p_nu || curwin->w_p_rnu))
+	    curwin->w_nrwidth_line_count = 0;
+    }
+#endif
+
+
+#if defined(FEAT_TOOLBAR) && !defined(FEAT_GUI_MSWIN)
+    // 'toolbar'
+    else if (varp == &p_toolbar)
+    {
+	if (opt_strings_flags(p_toolbar, p_toolbar_values,
+			      &toolbar_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+	else
+	{
+	    out_flush();
+	    gui_mch_show_toolbar((toolbar_flags &
+				  (TOOLBAR_TEXT | TOOLBAR_ICONS)) != 0);
+	}
+    }
+#endif
+
+#if defined(FEAT_TOOLBAR) && defined(FEAT_GUI_GTK)
+    // 'toolbariconsize': GTK+ 2 only
+    else if (varp == &p_tbis)
+    {
+	if (opt_strings_flags(p_tbis, p_tbis_values, &tbis_flags, FALSE) != OK)
+	    errmsg = e_invarg;
+	else
+	{
+	    out_flush();
+	    gui_mch_show_toolbar((toolbar_flags &
+				  (TOOLBAR_TEXT | TOOLBAR_ICONS)) != 0);
+	}
+    }
+#endif
+
+    // 'pastetoggle': translate key codes like in a mapping
+    else if (varp == &p_pt)
+    {
+	if (*p_pt)
+	{
+	    (void)replace_termcodes(p_pt, &p, TRUE, TRUE, FALSE);
+	    if (p != NULL)
+	    {
+		if (new_value_alloced)
+		    free_string_option(p_pt);
+		p_pt = p;
+		new_value_alloced = TRUE;
+	    }
+	}
+    }
+
+    // 'backspace'
+    else if (varp == &p_bs)
+    {
+	if (VIM_ISDIGIT(*p_bs))
+	{
+	    if (*p_bs > '2' || p_bs[1] != NUL)
+		errmsg = e_invarg;
+	}
+	else if (check_opt_strings(p_bs, p_bs_values, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+    else if (varp == &p_bo)
+    {
+	if (opt_strings_flags(p_bo, p_bo_values, &bo_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // 'tagcase'
+    else if (gvarp == &p_tc)
+    {
+	unsigned int	*flags;
+
+	if (opt_flags & OPT_LOCAL)
+	{
+	    p = curbuf->b_p_tc;
+	    flags = &curbuf->b_tc_flags;
+	}
+	else
+	{
+	    p = p_tc;
+	    flags = &tc_flags;
+	}
+
+	if ((opt_flags & OPT_LOCAL) && *p == NUL)
+	    // make the local value empty: use the global value
+	    *flags = 0;
+	else if (*p == NUL
+		|| opt_strings_flags(p, p_tc_values, flags, FALSE) != OK)
+	    errmsg = e_invarg;
+    }
+
+    // 'casemap'
+    else if (varp == &p_cmp)
+    {
+	if (opt_strings_flags(p_cmp, p_cmp_values, &cmp_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+
+#ifdef FEAT_DIFF
+    // 'diffopt'
+    else if (varp == &p_dip)
+    {
+	if (diffopt_changed() == FAIL)
+	    errmsg = e_invarg;
+    }
+#endif
+
+#ifdef FEAT_FOLDING
+    // 'foldmethod'
+    else if (gvarp == &curwin->w_allbuf_opt.wo_fdm)
+    {
+	if (check_opt_strings(*varp, p_fdm_values, FALSE) != OK
+		|| *curwin->w_p_fdm == NUL)
+	    errmsg = e_invarg;
+	else
+	{
+	    foldUpdateAll(curwin);
+	    if (foldmethodIsDiff(curwin))
+		newFoldLevel();
+	}
+    }
+# ifdef FEAT_EVAL
+    // 'foldexpr'
+    else if (varp == &curwin->w_p_fde)
+    {
+	if (foldmethodIsExpr(curwin))
+	    foldUpdateAll(curwin);
+    }
+# endif
+    // 'foldmarker'
+    else if (gvarp == &curwin->w_allbuf_opt.wo_fmr)
+    {
+	p = vim_strchr(*varp, ',');
+	if (p == NULL)
+	    errmsg = N_("E536: comma required");
+	else if (p == *varp || p[1] == NUL)
+	    errmsg = e_invarg;
+	else if (foldmethodIsMarker(curwin))
+	    foldUpdateAll(curwin);
+    }
+    // 'commentstring'
+    else if (gvarp == &p_cms)
+    {
+	if (**varp != NUL && strstr((char *)*varp, "%s") == NULL)
+	    errmsg = N_("E537: 'commentstring' must be empty or contain %s");
+    }
+    // 'foldopen'
+    else if (varp == &p_fdo)
+    {
+	if (opt_strings_flags(p_fdo, p_fdo_values, &fdo_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+    // 'foldclose'
+    else if (varp == &p_fcl)
+    {
+	if (check_opt_strings(p_fcl, p_fcl_values, TRUE) != OK)
+	    errmsg = e_invarg;
+    }
+    // 'foldignore'
+    else if (gvarp == &curwin->w_allbuf_opt.wo_fdi)
+    {
+	if (foldmethodIsIndent(curwin))
+	    foldUpdateAll(curwin);
+    }
+#endif
+
+    // 'virtualedit'
+    else if (varp == &p_ve)
+    {
+	if (opt_strings_flags(p_ve, p_ve_values, &ve_flags, TRUE) != OK)
+	    errmsg = e_invarg;
+	else if (STRCMP(p_ve, oldval) != 0)
+	{
+	    // Recompute cursor position in case the new 've' setting
+	    // changes something.
+	    validate_virtcol();
+	    coladvance(curwin->w_virtcol);
+	}
+    }
+
+#if defined(FEAT_CSCOPE) && defined(FEAT_QUICKFIX)
+    else if (varp == &p_csqf)
+    {
+	if (p_csqf != NULL)
+	{
+	    p = p_csqf;
+	    while (*p != NUL)
+	    {
+		if (vim_strchr((char_u *)CSQF_CMDS, *p) == NULL
+			|| p[1] == NUL
+			|| vim_strchr((char_u *)CSQF_FLAGS, p[1]) == NULL
+			|| (p[2] != NUL && p[2] != ','))
+		{
+		    errmsg = e_invarg;
+		    break;
+		}
+		else if (p[2] == NUL)
+		    break;
+		else
+		    p += 3;
+	    }
+	}
+    }
+#endif
+
+#ifdef FEAT_CINDENT
+    // 'cinoptions'
+    else if (gvarp == &p_cino)
+    {
+	// TODO: recognize errors
+	parse_cino(curbuf);
+    }
+#endif
+
+#if defined(FEAT_RENDER_OPTIONS)
+    // 'renderoptions'
+    else if (varp == &p_rop)
+    {
+	if (!gui_mch_set_rendering_options(p_rop))
+	    errmsg = e_invarg;
+    }
+#endif
+
+    else if (gvarp == &p_ft)
+    {
+	if (!valid_filetype(*varp))
+	    errmsg = e_invarg;
+	else
+	{
+	    value_changed = STRCMP(oldval, *varp) != 0;
+
+	    // Since we check the value, there is no need to set P_INSECURE,
+	    // even when the value comes from a modeline.
+	    *value_checked = TRUE;
+	}
+    }
+
+#ifdef FEAT_SYN_HL
+    else if (gvarp == &p_syn)
+    {
+	if (!valid_filetype(*varp))
+	    errmsg = e_invarg;
+	else
+	{
+	    value_changed = STRCMP(oldval, *varp) != 0;
+
+	    // Since we check the value, there is no need to set P_INSECURE,
+	    // even when the value comes from a modeline.
+	    *value_checked = TRUE;
+	}
+    }
+#endif
+
+#ifdef FEAT_TERMINAL
+    // 'termwinkey'
+    else if (varp == &curwin->w_p_twk)
+    {
+	if (*curwin->w_p_twk != NUL
+				  && string_to_key(curwin->w_p_twk, TRUE) == 0)
+	    errmsg = e_invarg;
+    }
+    // 'termwinsize'
+    else if (varp == &curwin->w_p_tws)
+    {
+	if (*curwin->w_p_tws != NUL)
+	{
+	    p = skipdigits(curwin->w_p_tws);
+	    if (p == curwin->w_p_tws
+		    || (*p != 'x' && *p != '*')
+		    || *skipdigits(p + 1) != NUL)
+		errmsg = e_invarg;
+	}
+    }
+# if defined(MSWIN)
+    // 'termwintype'
+    else if (varp == &p_twt)
+    {
+	if (check_opt_strings(*varp, p_twt_values, FALSE) != OK)
+	    errmsg = e_invarg;
+    }
+# endif
+#endif
+
+#ifdef FEAT_VARTABS
+    // 'varsofttabstop'
+    else if (varp == &(curbuf->b_p_vsts))
+    {
+	char_u *cp;
+
+	if (!(*varp)[0] || ((*varp)[0] == '0' && !(*varp)[1]))
+	{
+	    if (curbuf->b_p_vsts_array)
+	    {
+		vim_free(curbuf->b_p_vsts_array);
+		curbuf->b_p_vsts_array = 0;
+	    }
+	}
+	else
+	{
+	    for (cp = *varp; *cp; ++cp)
+	    {
+		if (vim_isdigit(*cp))
+		    continue;
+		if (*cp == ',' && cp > *varp && *(cp-1) != ',')
+		    continue;
+		errmsg = e_invarg;
+		break;
+	    }
+	    if (errmsg == NULL)
+	    {
+		int *oldarray = curbuf->b_p_vsts_array;
+		if (tabstop_set(*varp, &(curbuf->b_p_vsts_array)))
+		{
+		    if (oldarray)
+			vim_free(oldarray);
+		}
+		else
+		    errmsg = e_invarg;
+	    }
+	}
+    }
+
+    // 'vartabstop'
+    else if (varp == &(curbuf->b_p_vts))
+    {
+	char_u *cp;
+
+	if (!(*varp)[0] || ((*varp)[0] == '0' && !(*varp)[1]))
+	{
+	    if (curbuf->b_p_vts_array)
+	    {
+		vim_free(curbuf->b_p_vts_array);
+		curbuf->b_p_vts_array = NULL;
+	    }
+	}
+	else
+	{
+	    for (cp = *varp; *cp; ++cp)
+	    {
+		if (vim_isdigit(*cp))
+		    continue;
+		if (*cp == ',' && cp > *varp && *(cp-1) != ',')
+		    continue;
+		errmsg = e_invarg;
+		break;
+	    }
+	    if (errmsg == NULL)
+	    {
+		int *oldarray = curbuf->b_p_vts_array;
+
+		if (tabstop_set(*varp, &(curbuf->b_p_vts_array)))
+		{
+		    vim_free(oldarray);
+#ifdef FEAT_FOLDING
+		    if (foldmethodIsIndent(curwin))
+			foldUpdateAll(curwin);
+#endif
+		}
+		else
+		    errmsg = e_invarg;
+	    }
+	}
+    }
+#endif
+
+#ifdef FEAT_TEXT_PROP
+    // 'previewpopup'
+    else if (varp == &p_pvp)
+    {
+	if (parse_previewpopup(NULL) == FAIL)
+	    errmsg = e_invarg;
+    }
+# ifdef FEAT_QUICKFIX
+    // 'completepopup'
+    else if (varp == &p_cpp)
+    {
+	if (parse_completepopup(NULL) == FAIL)
+	    errmsg = e_invarg;
+    }
+# endif
+#endif
+
+    // Options that are a list of flags.
+    else
+    {
+	p = NULL;
+	if (varp == &p_ww) // 'whichwrap'
+	    p = (char_u *)WW_ALL;
+	if (varp == &p_shm) // 'shortmess'
+	    p = (char_u *)SHM_ALL;
+	else if (varp == &(p_cpo)) // 'cpoptions'
+	    p = (char_u *)CPO_ALL;
+	else if (varp == &(curbuf->b_p_fo)) // 'formatoptions'
+	    p = (char_u *)FO_ALL;
+#ifdef FEAT_CONCEAL
+	else if (varp == &curwin->w_p_cocu) // 'concealcursor'
+	    p = (char_u *)COCU_ALL;
+#endif
+	else if (varp == &p_mouse) // 'mouse'
+	{
+#ifdef FEAT_MOUSE
+	    p = (char_u *)MOUSE_ALL;
+#else
+	    if (*p_mouse != NUL)
+		errmsg = N_("E538: No mouse support");
+#endif
+	}
+#if defined(FEAT_GUI)
+	else if (varp == &p_go) // 'guioptions'
+	    p = (char_u *)GO_ALL;
+#endif
+	if (p != NULL)
+	{
+	    for (s = *varp; *s; ++s)
+		if (vim_strchr(p, *s) == NULL)
+		{
+		    errmsg = illegal_char(errbuf, *s);
+		    break;
+		}
+	}
+    }
+
+    // If error detected, restore the previous value.
+    if (errmsg != NULL)
+    {
+	if (new_value_alloced)
+	    free_string_option(*varp);
+	*varp = oldval;
+	// When resetting some values, need to act on it.
+	if (did_chartab)
+	    (void)init_chartab();
+	if (varp == &p_hl)
+	    (void)highlight_changed();
+    }
+    else
+    {
+#ifdef FEAT_EVAL
+	// Remember where the option was set.
+	set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
+#endif
+	// Free string options that are in allocated memory.
+	// Use "free_oldval", because recursiveness may change the flags under
+	// our fingers (esp. init_highlight()).
+	if (free_oldval)
+	    free_string_option(oldval);
+	if (new_value_alloced)
+	    set_option_flag(opt_idx, P_ALLOCED);
+	else
+	    clear_option_flag(opt_idx, P_ALLOCED);
+
+	if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0
+		&& is_global_local_option(opt_idx))
+	{
+	    // global option with local value set to use global value; free
+	    // the local value and make it empty
+	    p = get_option_varp_scope(opt_idx, OPT_LOCAL);
+	    free_string_option(*(char_u **)p);
+	    *(char_u **)p = empty_option;
+	}
+
+	// May set global value for local option.
+	else if (!(opt_flags & OPT_LOCAL) && opt_flags != OPT_GLOBAL)
+	    set_string_option_global(opt_idx, varp);
+
+	// Trigger the autocommand only after setting the flags.
+#ifdef FEAT_SYN_HL
+	// When 'syntax' is set, load the syntax of that name
+	if (varp == &(curbuf->b_p_syn))
+	{
+	    static int syn_recursive = 0;
+
+	    ++syn_recursive;
+	    // Only pass TRUE for "force" when the value changed or not used
+	    // recursively, to avoid endless recurrence.
+	    apply_autocmds(EVENT_SYNTAX, curbuf->b_p_syn, curbuf->b_fname,
+		    value_changed || syn_recursive == 1, curbuf);
+	    curbuf->b_flags |= BF_SYN_SET;
+	    --syn_recursive;
+	}
+#endif
+	else if (varp == &(curbuf->b_p_ft))
+	{
+	    // 'filetype' is set, trigger the FileType autocommand.
+	    // Skip this when called from a modeline and the filetype was
+	    // already set to this value.
+	    if (!(opt_flags & OPT_MODELINE) || value_changed)
+	    {
+		static int  ft_recursive = 0;
+		int	    secure_save = secure;
+
+		// Reset the secure flag, since the value of 'filetype' has
+		// been checked to be safe.
+		secure = 0;
+
+		++ft_recursive;
+		did_filetype = TRUE;
+		// Only pass TRUE for "force" when the value changed or not
+		// used recursively, to avoid endless recurrence.
+		apply_autocmds(EVENT_FILETYPE, curbuf->b_p_ft, curbuf->b_fname,
+				   value_changed || ft_recursive == 1, curbuf);
+		--ft_recursive;
+		// Just in case the old "curbuf" is now invalid.
+		if (varp != &(curbuf->b_p_ft))
+		    varp = NULL;
+
+		secure = secure_save;
+	    }
+	}
+#ifdef FEAT_SPELL
+	if (varp == &(curwin->w_s->b_p_spl))
+	{
+	    char_u	fname[200];
+	    char_u	*q = curwin->w_s->b_p_spl;
+
+	    // Skip the first name if it is "cjk".
+	    if (STRNCMP(q, "cjk,", 4) == 0)
+		q += 4;
+
+	    // Source the spell/LANG.vim in 'runtimepath'.
+	    // They could set 'spellcapcheck' depending on the language.
+	    // Use the first name in 'spelllang' up to '_region' or
+	    // '.encoding'.
+	    for (p = q; *p != NUL; ++p)
+		if (!ASCII_ISALNUM(*p) && *p != '-')
+		    break;
+	    if (p > q)
+	    {
+		vim_snprintf((char *)fname, 200, "spell/%.*s.vim",
+							      (int)(p - q), q);
+		source_runtime(fname, DIP_ALL);
+	    }
+	}
+#endif
+    }
+
+#ifdef FEAT_MOUSE
+    if (varp == &p_mouse)
+    {
+# ifdef FEAT_MOUSE_TTY
+	if (*p_mouse == NUL)
+	    mch_setmouse(FALSE);    // switch mouse off
+	else
+# endif
+	    setmouse();		    // in case 'mouse' changed
+    }
+#endif
+
+    if (curwin->w_curswant != MAXCOL
+		     && (get_option_flags(opt_idx) & (P_CURSWANT | P_RALL)) != 0)
+	curwin->w_set_curswant = TRUE;
+
+#ifdef FEAT_GUI
+    // check redraw when it's not a GUI option or the GUI is active.
+    if (!redraw_gui_only || gui.in_use)
+#endif
+	check_redraw(get_option_flags(opt_idx));
+
+#if defined(FEAT_VTP) && defined(FEAT_TERMGUICOLORS)
+    if (did_swaptcap)
+    {
+	set_termname((char_u *)"win32");
+	init_highlight(TRUE, FALSE);
+    }
+#endif
+
+    return errmsg;
+}
+
+/*
+ * Check an option that can be a range of string values.
+ *
+ * Return OK for correct value, FAIL otherwise.
+ * Empty is always OK.
+ */
+    static int
+check_opt_strings(
+    char_u	*val,
+    char	**values,
+    int		list)	    // when TRUE: accept a list of values
+{
+    return opt_strings_flags(val, values, NULL, list);
+}
+
+/*
+ * Handle an option that can be a range of string values.
+ * Set a flag in "*flagp" for each string present.
+ *
+ * Return OK for correct value, FAIL otherwise.
+ * Empty is always OK.
+ */
+    static int
+opt_strings_flags(
+    char_u	*val,		// new value
+    char	**values,	// array of valid string values
+    unsigned	*flagp,
+    int		list)		// when TRUE: accept a list of values
+{
+    int		i;
+    int		len;
+    unsigned	new_flags = 0;
+
+    while (*val)
+    {
+	for (i = 0; ; ++i)
+	{
+	    if (values[i] == NULL)	// val not found in values[]
+		return FAIL;
+
+	    len = (int)STRLEN(values[i]);
+	    if (STRNCMP(values[i], val, len) == 0
+		    && ((list && val[len] == ',') || val[len] == NUL))
+	    {
+		val += len + (val[len] == ',');
+		new_flags |= (1 << i);
+		break;		// check next item in val list
+	    }
+	}
+    }
+    if (flagp != NULL)
+	*flagp = new_flags;
+
+    return OK;
+}
+
+/*
+ * return OK if "p" is a valid fileformat name, FAIL otherwise.
+ */
+    int
+check_ff_value(char_u *p)
+{
+    return check_opt_strings(p, p_ff_values, FALSE);
+}