view src/optionstr.c @ 35308:22c03485f222 v9.1.0456

patch 9.1.0456: Left shift is incorrect with vartabstop and shiftwidth=0 Commit: https://github.com/vim/vim/commit/88d4f255b7b7a19bb4f6489e0ad0956e47d51fed Author: Gary Johnson <garyjohn@spocom.com> Date: Sat Jun 1 20:51:33 2024 +0200 patch 9.1.0456: Left shift is incorrect with vartabstop and shiftwidth=0 Problem: Left shift is incorrect with vartabstop and shiftwidth=0 Solution: make tabstop_at() function aware of shift direction (Gary Johnson) The problem was that with 'vartabstop' set and 'shiftwidth' equal 0, left shifts using << were shifting the line to the wrong column. The tabstop to the right of the first character in the line was being used as the shift amount instead of the tabstop to the left of that first character. The reason was that the tabstop_at() function always returned the value of the tabstop to the right of the given column and was not accounting for the direction of the shift. The solution was to make tabstop_at() aware of the direction of the shift and to choose the tabtop accordingly. A test was added to check this behavior and make sure it doesn't regress. While at it, also fix a few indentation/alignment issues. fixes: #14864 closes: #14887 Signed-off-by: Gary Johnson <garyjohn@spocom.com> Signed-off-by: Christian Brabandt <cb@256bit.org>
author Christian Brabandt <cb@256bit.org>
date Sat, 01 Jun 2024 21:00:03 +0200
parents 159d598e6781
children f0aeb83d01b5
line wrap: on
line source

/* 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_u shm_buf[SHM_LEN];
static int set_shm_recursive = 0;

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", "term", "wildmode", NULL};
#if defined(FEAT_LINEBREAK)
// Note: Keep this in sync with briopt_check()
static char *(p_briopt_values[]) = {"shift:", "min:", "sbr", "list:", "column:", NULL};
#endif
#if defined(FEAT_DIFF)
// Note: Keep this in sync with diffopt_changed()
static char *(p_dip_values[]) = {"filler", "context:", "iblank", "icase", "iwhite", "iwhiteall", "iwhiteeol", "horizontal", "vertical", "closeoff", "hiddenoff", "foldcolumn:", "followwrap", "internal", "indent-heuristic", "algorithm:", NULL};
static char *(p_dip_algorithm_values[]) = {"myers", "minimal", "patience", "histogram", NULL};
#endif
static char *(p_nf_values[]) = {"bin", "octal", "hex", "alpha", "unsigned", NULL};
static char *(p_ff_values[]) = {FF_UNIX, FF_DOS, FF_MAC, NULL};
#ifdef FEAT_CLIPBOARD
// Note: Keep this in sync with did_set_clipboard()
static char *(p_cb_values[]) = {"unnamed", "unnamedplus", "autoselect", "autoselectplus", "autoselectml", "html", "exclude:", NULL};
#endif
#ifdef FEAT_CRYPT
static char *(p_cm_values[]) = {"zip", "blowfish", "blowfish2",
 # ifdef FEAT_SODIUM
    "xchacha20", "xchacha20v2",
 # endif
    NULL};
#endif
static char *(p_cmp_values[]) = {"internal", "keepascii", NULL};
#ifdef FEAT_SYN_HL
// Note: Keep this in sync with fill_culopt_flags()
static char *(p_culopt_values[]) = {"line", "screenline", "number", "both", NULL};
#endif
static char *(p_dy_values[]) = {"lastline", "truncate", "uhex", NULL};
static char *(p_jop_values[]) = {"stack", NULL};
#ifdef FEAT_FOLDING
static char *(p_fdo_values[]) = {"all", "block", "hor", "mark", "percent",
				 "quickfix", "search", "tag", "insert",
				 "undo", "jump", NULL};
#endif
// Note: Keep this in sync with match_keyprotocol()
static char *(p_kpc_protocol_values[]) = {"none", "mok2", "kitty", NULL};
#ifdef FEAT_PROP_POPUP
// Note: Keep this in sync with parse_popup_option()
static char *(p_popup_option_values[]) = {"height:", "width:", "highlight:", "border:", "align:", NULL};
static char *(p_popup_option_border_values[]) = {"on", "off", NULL};
static char *(p_popup_option_align_values[]) = {"item", "menu", NULL};
#endif
#if defined(FEAT_SPELL)
// Note: Keep this in sync with spell_check_sps()
static char *(p_sps_values[]) = {"best", "fast", "double", "expr:", "file:", "timeout:", NULL};
#endif
#ifdef FEAT_SESSION
// Also used for 'viewoptions'!  Keep in sync with SSOP_ flags.
static char *(p_ssop_values[]) = {"buffers", "winpos", "resize", "winsize",
    "localoptions", "options", "help", "blank", "globals", "slash", "unix",
    "sesdir", "curdir", "folds", "cursor", "tabpages", "terminal", "skiprtp",
    NULL};
#endif
// Keep in sync with SWB_ flags in option.h
static char *(p_swb_values[]) = {"useopen", "usetab", "split", "newtab", "vsplit", "uselast", NULL};
static char *(p_spk_values[]) = {"cursor", "screen", "topline", 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(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", "none", "NONE", NULL};
// Note: Keep this in sync with check_opt_wim()
static char *(p_wim_values[]) = {"full", "longest", "list", "lastused", NULL};
static char *(p_wop_values[]) = {"fuzzy", "tagfile", "pum", 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", "nostop", 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", "popuphidden", "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 char *(p_sloc_values[]) = {"last", "statusline", "tabline", NULL};
static char *(p_sws_values[]) = {"fsync", "sync", NULL};

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_jop, p_jop_values, &jop_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(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
    (void)opt_strings_flags(p_swb, p_swb_values, &swb_flags, TRUE);
}

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * 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_optionset_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)
	return;

    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,
	    get_option_fullname(opt_idx), NULL, FALSE,
	    NULL);
    reset_v_option_vars();
}
#endif

    static char *
illegal_char(char *errbuf, size_t errbuflen, int c)
{
    if (errbuf == NULL)
	return "";
    vim_snprintf(errbuf, errbuflen, _(e_illegal_character_str),
		    (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_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);
    check_string_option(&buf->b_p_com);
#ifdef FEAT_FOLDING
    check_string_option(&buf->b_p_cms);
#endif
    check_string_option(&buf->b_p_nf);
    check_string_option(&buf->b_p_qe);
#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);
    check_string_option(&buf->b_s.b_p_spo);
#endif
    check_string_option(&buf->b_p_sua);
    check_string_option(&buf->b_p_cink);
    check_string_option(&buf->b_p_cino);
    check_string_option(&buf->b_p_cinsd);
    parse_cino(buf);
    check_string_option(&buf->b_p_lop);
    check_string_option(&buf->b_p_ft);
    check_string_option(&buf->b_p_cinw);
    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);
    check_string_option(&buf->b_p_tsrfu);
#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);
    check_string_option(&buf->b_p_lw);
    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_internal_error_str), "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)
	return;

    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
}

#if defined(FEAT_PROP_POPUP) || \
    (defined(FEAT_DIFF) && defined(FEAT_FOLDING)) || defined(PROTO)
/*
 * 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();
}
#endif

#if defined(FEAT_PROP_POPUP) || defined(PROTO)
/*
 * 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();
}
#endif

/*
 * Set a string option to a new value, and handle the effects.
 *
 * Returns NULL on success or an untranslated error message on error.
 */
    char *
set_string_option(
    int		opt_idx,
    char_u	*value,
    int		opt_flags,	// OPT_LOCAL and/or OPT_GLOBAL
    char	*errbuf,
    size_t	errbuflen)
{
    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	*errmsg = NULL;
    int		value_checked = FALSE;

    if (is_hidden_option(opt_idx))	// don't set hidden option
	return NULL;

    s = vim_strsave(value == NULL ? (char_u *)"" : value);
    if (s == NULL)
	return 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 ((errmsg = did_set_string_option(opt_idx, varp, oldval, value, errbuf,
		    errbuflen, opt_flags, OP_NONE, &value_checked)) == NULL)
	did_set_option(opt_idx, opt_flags, TRUE, value_checked);

#if defined(FEAT_EVAL)
    // call autocommand after handling side effects
    if (errmsg == NULL)
	trigger_optionset_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 errmsg;
}

/*
 * 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 an untranslated error message or NULL.
 */
    static char *
check_stl_option(char_u *s)
{
    int		groupdepth = 0;
    static char errbuf[ERR_BUFLEN];
    int		errbuflen = ERR_BUFLEN;

    while (*s)
    {
	// Check for valid keys after % sequences
	while (*s && *s != '%')
	    s++;
	if (!*s)
	    break;
	s++;
	if (*s == '%' || *s == STL_TRUNCMARK || *s == STL_SEPARATE)
	{
	    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, errbuflen, *s);
	}
	if (*s == '{')
	{
	    int reevaluate = (*++s == '%');

	    if (reevaluate && *++s == '}')
		// "}" is not allowed immediately after "%{%"
		return illegal_char(errbuf, errbuflen, '}');
	    while ((*s != '}' || (reevaluate && s[-1] != '%')) && *s)
		s++;
	    if (*s != '}')
		return e_unclosed_expression_sequence;
	}
    }
    if (groupdepth != 0)
	return e_unbalanced_groups;
    return NULL;
}
#endif

/*
 * 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.
 */
    static int
check_illegal_path_names(int opt_idx, char_u **varp)
{
    return (((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));
}

/*
 * An option that accepts a list of flags is changed.
 * e.g. 'viewoptions', 'switchbuf', 'casemap', etc.
 */
    static char *
did_set_opt_flags(char_u *val, char **values, unsigned *flagp, int list)
{
    if (opt_strings_flags(val, values, flagp, list) == FAIL)
	return e_invalid_argument;

    return NULL;
}

/*
 * An option that accepts a list of string values is changed.
 * e.g. 'nrformats', 'scrollopt', 'wildoptions', etc.
 */
    static char *
did_set_opt_strings(char_u *val, char **values, int list)
{
    return did_set_opt_flags(val, values, NULL, list);
}

/*
 * An option which is a list of flags is set.  Valid values are in 'flags'.
 */
    static char *
did_set_option_listflag(
	char_u *val,
	char_u *flags,
	char *errbuf,
	size_t errbuflen)
{
    char_u	*s;

    for (s = val; *s; ++s)
	if (vim_strchr(flags, *s) == NULL)
	    return illegal_char(errbuf, errbuflen, *s);

    return NULL;
}

/*
 * Expand an option that accepts a list of fixed string values with known
 * number of items.
 */
    static int
expand_set_opt_string(
	optexpand_T *args,
	char **values,
	size_t numValues,
	int *numMatches,
	char_u ***matches)
{
    char_u	*p;
    regmatch_T	*regmatch = args->oe_regmatch;
    int		include_orig_val = args->oe_include_orig_val;
    char_u	*option_val = args->oe_opt_value;

    // Assume numValues is small since they are fixed enums, so just allocate
    // upfront instead of needing two passes to calculate output size.
    *matches = ALLOC_MULT(char_u *, numValues + 1);
    if (*matches == NULL)
	return FAIL;

    int count = 0;

    if (include_orig_val && *option_val != NUL)
    {
	p = vim_strsave(option_val);
	if (p == NULL)
	{
	    VIM_CLEAR(*matches);
	    return FAIL;
	}
	(*matches)[count++] = p;
    }

    for (char **val = values; *val != NULL; val++)
    {
	if (include_orig_val && *option_val != NUL)
	{
	    if (STRCMP((char_u*)*val, option_val) == 0)
		continue;
	}
	if (vim_regexec(regmatch, (char_u*)(*val), (colnr_T)0))
	{
	    p = vim_strsave((char_u*)*val);
	    if (p == NULL)
	    {
		if (count == 0)
		{
		    VIM_CLEAR(*matches);
		    return FAIL;
		}
		else
		    break;
	    }
	    (*matches)[count++] = p;
	}
    }
    if (count == 0)
    {
	VIM_CLEAR(*matches);
	return FAIL;
    }
    *numMatches = count;
    return OK;
}

static char_u *set_opt_callback_orig_option = NULL;
static char_u *((*set_opt_callback_func)(expand_T *, int));

/*
 * Callback used by expand_set_opt_generic to also include the original value
 * as the first item.
 */
    static char_u *
expand_set_opt_generic_cb(expand_T *xp, int idx)
{
    if (idx == 0)
    {
	if (set_opt_callback_orig_option != NULL)
	    return set_opt_callback_orig_option;
	else
	    return (char_u *)""; // empty strings are ignored
    }
    return set_opt_callback_func(xp, idx - 1);
}

/*
 * Expand an option with a callback that iterates through a list of possible
 * names using an index.
 */
    static int
expand_set_opt_generic(
	optexpand_T *args,
	char_u *((*func)(expand_T *, int)),
	int *numMatches,
	char_u ***matches)
{
    int ret;

    set_opt_callback_orig_option = args->oe_include_orig_val ?
	args->oe_opt_value : NULL;
    set_opt_callback_func = func;

    ret = ExpandGeneric(
	    (char_u*)"", // not using fuzzy as currently EXPAND_STRING_SETTING doesn't use it
	    args->oe_xp,
	    args->oe_regmatch,
	    matches,
	    numMatches,
	    expand_set_opt_generic_cb,
	    FALSE);

    set_opt_callback_orig_option = NULL;
    set_opt_callback_func = NULL;
    return ret;
}

# if defined(FEAT_GUI_MSWIN) || defined(FEAT_GUI_GTK)
static garray_T *expand_cb_ga;
static optexpand_T *expand_cb_args;

/*
 * Callback provided to a function in expand_set_opt_callback. Will perform
 * regex matching against the value and add to the list.
 *
 * Returns OK usually. Returns FAIL if it failed to allocate memory, and the
 * caller should terminate the enumeration.
 */
    static int
expand_set_opt_callback_cb(char_u *val)
{
    regmatch_T	*regmatch = expand_cb_args->oe_regmatch;
    expand_T	*xp = expand_cb_args->oe_xp;
    garray_T	*ga = expand_cb_ga;
    char_u	*str;

    if (val == NULL || *val == NUL)
	return OK;

    if (xp->xp_pattern[0] != NUL &&
	    !vim_regexec(regmatch, val, (colnr_T)0))
	return OK;

    str = vim_strsave_escaped(val, (char_u *)" \t\\");

    if (str == NULL)
	return FAIL;

    if (ga_grow(ga, 1) == FAIL)
    {
	vim_free(str);
	return FAIL;
    }

    ((char_u **)ga->ga_data)[ga->ga_len] = str;
    ++ga->ga_len;
    return OK;
}

/*
 * Expand an option with a provided function that takes a callback. The
 * function will enumerate through all options and call the callback to add it
 * to the list.
 *
 * "func" is the enumerator function that will generate the list of options.
 * "func_params" is a single parameter that will be passed to func.
 */
    static int
expand_set_opt_callback(
	optexpand_T *args,
	void (*func)(optexpand_T *, void* params, int (*cb)(char_u *val)),
	void *func_params,
	int *numMatches,
	char_u ***matches)
{
    garray_T	ga;
    int		include_orig_val = args->oe_include_orig_val;
    char_u	*option_val = args->oe_opt_value;

    ga_init2(&ga, sizeof(char *), 30);

    if (include_orig_val && *option_val != NUL)
    {
	char_u *p = vim_strsave(option_val);
	if (p == NULL)
	    return FAIL;
	if (ga_grow(&ga, 1) == FAIL)
	{
	    vim_free(p);
	    return FAIL;
	}
	((char_u **)ga.ga_data)[ga.ga_len] = p;
	++ga.ga_len;
    }

    expand_cb_ga = &ga;
    expand_cb_args = args;

    func(args, func_params, expand_set_opt_callback_cb);

    expand_cb_ga = NULL;
    expand_cb_args = NULL;

    *matches = ga.ga_data;
    *numMatches = ga.ga_len;
    return OK;
}
#endif

/*
 * Expand an option which is a list of flags.
 */
    static int
expand_set_opt_listflag(
	optexpand_T *args,
	char_u *flags,
	int *numMatches,
	char_u ***matches)
{
    char_u  *p;
    char_u  *option_val = args->oe_opt_value;
    char_u  *cmdline_val = args->oe_set_arg;
    int	    append = args->oe_append;
    int	    include_orig_val = args->oe_include_orig_val && (*option_val != NUL);

    size_t num_flags = STRLEN(flags);

    // Assume we only have small number of flags, so just allocate max size.
    *matches = ALLOC_MULT(char_u *, num_flags + 1);
    if (*matches == NULL)
	return FAIL;

    int count = 0;

    if (include_orig_val)
    {
	p = vim_strsave(option_val);
	if (p == NULL)
	{
	    VIM_CLEAR(*matches);
	    return FAIL;
	}
	(*matches)[count++] = p;
    }

    for (char_u *flag = flags; *flag != NUL; flag++)
    {
	if (append && vim_strchr(option_val, *flag) != NULL)
	    continue;

	if (vim_strchr(cmdline_val, *flag) == NULL)
	{
	    if (include_orig_val
		    && option_val[1] == NUL
		    && *flag == option_val[0])
	    {
		// This value is already used as the first choice as it's the
		// existing flag. Just skip it to avoid duplicate.
		continue;
	    }
	    p = vim_strnsave(flag, 1);
	    if (p == NULL)
	    {
		if (count == 0)
		{
		    VIM_CLEAR(*matches);
		    return FAIL;
		}
		else
		    break;
	    }
	    (*matches)[count++] = p;
	}
    }

    if (count == 0)
    {
	VIM_CLEAR(*matches);
	return FAIL;
    }
    *numMatches = count;
    return OK;
}

/*
 * The 'ambiwidth' option is changed.
 */
    char *
did_set_ambiwidth(optset_T *args UNUSED)
{
    if (check_opt_strings(p_ambw, p_ambw_values, FALSE) != OK)
	return e_invalid_argument;

    return check_chars_options();
}

    int
expand_set_ambiwidth(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_ambw_values,
	    ARRAY_LENGTH(p_ambw_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'background' option is changed.
 */
    char *
did_set_background(optset_T *args)
{
    if (check_opt_strings(p_bg, p_bg_values, FALSE) == FAIL)
	return e_invalid_argument;

    if (args->os_oldval.string != NULL && args->os_oldval.string[0] == *p_bg)
	// Value was not changed
	return NULL;

#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
#ifdef FEAT_TERMINAL
    term_update_colors_all();
#endif

    return NULL;
}

    int
expand_set_background(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_bg_values,
	    ARRAY_LENGTH(p_bg_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'backspace' option is changed.
 */
    char *
did_set_backspace(optset_T *args UNUSED)
{
    if (VIM_ISDIGIT(*p_bs))
    {
	if (*p_bs > '3' || p_bs[1] != NUL)
	    return e_invalid_argument;
    }
    else if (check_opt_strings(p_bs, p_bs_values, TRUE) != OK)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_backspace(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_bs_values,
	    ARRAY_LENGTH(p_bs_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'backupcopy' option is changed.
 */
    char *
did_set_backupcopy(optset_T *args)
{
    char_u		*bkc = p_bkc;
    unsigned int	*flags = &bkc_flags;
    char		*errmsg = NULL;

    if (args->os_flags & OPT_LOCAL)
    {
	bkc = curbuf->b_p_bkc;
	flags = &curbuf->b_bkc_flags;
    }

    if ((args->os_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_invalid_argument;
	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(args->os_oldval.string, p_bkc_values,
								  flags, TRUE);
	    errmsg = e_invalid_argument;
	}
    }

    return errmsg;
}

    int
expand_set_backupcopy(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_bkc_values,
	    ARRAY_LENGTH(p_bkc_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'backupext' or the 'patchmode' option is changed.
 */
    char *
did_set_backupext_or_patchmode(optset_T *args UNUSED)
{
    if (STRCMP(*p_bex == '.' ? p_bex + 1 : p_bex,
		*p_pm == '.' ? p_pm + 1 : p_pm) == 0)
	return e_backupext_and_patchmode_are_equal;

    return NULL;
}

/*
 * The 'belloff' option is changed.
 */
    char *
did_set_belloff(optset_T *args UNUSED)
{
    return did_set_opt_flags(p_bo, p_bo_values, &bo_flags, TRUE);
}

    int
expand_set_belloff(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_bo_values,
	    ARRAY_LENGTH(p_bo_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_LINEBREAK) || defined(PROTO)
/*
 * The 'breakat' option is changed.
 */
    char *
did_set_breakat(optset_T *args UNUSED)
{
    char_u	*p;
    int		i;

    for (i = 0; i < 256; i++)
	breakat_flags[i] = FALSE;

    if (p_breakat != NULL)
	for (p = p_breakat; *p; p++)
	    breakat_flags[*p] = TRUE;

    return NULL;
}

/*
 * The 'breakindentopt' option is changed.
 */
    char *
did_set_breakindentopt(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (briopt_check(curwin) == FAIL)
	errmsg = e_invalid_argument;
    // list setting requires a redraw
    if (curwin->w_briopt_list)
	redraw_all_later(UPD_NOT_VALID);

    return errmsg;
}

    int
expand_set_breakindentopt(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_briopt_values,
	    ARRAY_LENGTH(p_briopt_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if defined(FEAT_BROWSE) || defined(PROTO)
/*
 * The 'browsedir' option is changed.
 */
    char *
did_set_browsedir(optset_T *args UNUSED)
{
    if (check_opt_strings(p_bsdir, p_bsdir_values, FALSE) != OK
	    && !mch_isdir(p_bsdir))
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_browsedir(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_bsdir_values,
	    ARRAY_LENGTH(p_bsdir_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The 'bufhidden' option is changed.
 */
    char *
did_set_bufhidden(optset_T *args UNUSED)
{
    return did_set_opt_strings(curbuf->b_p_bh, p_bufhidden_values, FALSE);
}

    int
expand_set_bufhidden(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_bufhidden_values,
	    ARRAY_LENGTH(p_bufhidden_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'buftype' option is changed.
 */
    char *
did_set_buftype(optset_T *args UNUSED)
{
    if (check_opt_strings(curbuf->b_p_bt, p_buftype_values, FALSE) != OK)
	return e_invalid_argument;

    if (curwin->w_status_height)
    {
	curwin->w_redr_status = TRUE;
	redraw_later(UPD_VALID);
    }
    curbuf->b_help = (curbuf->b_p_bt[0] == 'h');
    redraw_titles();

    return NULL;
}

    int
expand_set_buftype(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_buftype_values,
	    ARRAY_LENGTH(p_buftype_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'casemap' option is changed.
 */
    char *
did_set_casemap(optset_T *args UNUSED)
{
    return did_set_opt_flags(p_cmp, p_cmp_values, &cmp_flags, TRUE);
}

    int
expand_set_casemap(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_cmp_values,
	    ARRAY_LENGTH(p_cmp_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_CLIPBOARD) || defined(PROTO)
    int
expand_set_clipboard(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_cb_values,
	    ARRAY_LENGTH(p_cb_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The global 'listchars' or 'fillchars' option is changed.
 */
    static char *
did_set_global_listfillchars(char_u *val, int opt_lcs, int opt_flags,
						char *errbuf, size_t errbuflen)
{
    char	*errmsg = NULL;
    char_u	**local_ptr = opt_lcs ? &curwin->w_p_lcs : &curwin->w_p_fcs;

    // only apply the global value to "curwin" when it does not have a
    // local value
    if (opt_lcs)
	errmsg = set_listchars_option(curwin, val,
		**local_ptr == NUL || !(opt_flags & OPT_GLOBAL),
							    errbuf, errbuflen);
    else
	errmsg = set_fillchars_option(curwin, val,
		**local_ptr == NUL || !(opt_flags & OPT_GLOBAL),
							    errbuf, errbuflen);
    if (errmsg != NULL)
	return errmsg;

    tabpage_T	*tp;
    win_T	*wp;

    // If the current window is set to use the global
    // 'listchars'/'fillchars' value, clear the window-local value.
    if (!(opt_flags & OPT_GLOBAL))
	clear_string_option(local_ptr);
    FOR_ALL_TAB_WINDOWS(tp, wp)
    {
	// If the current window has a local value need to apply it
	// again, it was changed when setting the global value.
	// If no error was returned above, we don't expect an error
	// here, so ignore the return value.
	if (opt_lcs)
	{
	    if (*wp->w_p_lcs == NUL)
		(void)set_listchars_option(wp, wp->w_p_lcs, TRUE, NULL, 0);
	}
	else
	{
	    if (*wp->w_p_fcs == NUL)
		(void)set_fillchars_option(wp, wp->w_p_fcs, TRUE, NULL, 0);
	}
    }

    redraw_all_later(UPD_NOT_VALID);

    return NULL;
}

/*
 * The 'fillchars' option or the 'listchars' option is changed.
 */
    char *
did_set_chars_option(optset_T *args)
{
    char_u **varp = (char_u **)args->os_varp;
    char *errmsg = NULL;

    if (   varp == &p_lcs		// global 'listchars'
	|| varp == &p_fcs)		// global 'fillchars'
	errmsg = did_set_global_listfillchars(*varp, varp == &p_lcs,
			  args->os_flags, args->os_errbuf, args->os_errbuflen);
    else if (varp == &curwin->w_p_lcs)	// local 'listchars'
	errmsg = set_listchars_option(curwin, *varp, TRUE,
					  args->os_errbuf, args->os_errbuflen);
    else if (varp == &curwin->w_p_fcs)	// local 'fillchars'
	errmsg = set_fillchars_option(curwin, *varp, TRUE,
					  args->os_errbuf, args->os_errbuflen);

    return errmsg;
}

/*
 * Expand 'fillchars' or 'listchars' option value.
 */
    int
expand_set_chars_option(optexpand_T *args, int *numMatches, char_u ***matches)
{
    char_u **varp = (char_u **)args->oe_varp;
    int is_lcs = (varp == &p_lcs || varp == &curwin->w_p_lcs);
    return expand_set_opt_generic(
	    args,
	    is_lcs ? get_listchars_name : get_fillchars_name,
	    numMatches,
	    matches);
}

/*
 * The 'cinoptions' option is changed.
 */
    char *
did_set_cinoptions(optset_T *args UNUSED)
{
    // TODO: recognize errors
    parse_cino(curbuf);

    return NULL;
}

#if defined(FEAT_SYN_HL) || defined(PROTO)
/*
 * The 'colorcolumn' option is changed.
 */
    char *
did_set_colorcolumn(optset_T *args UNUSED)
{
    return check_colorcolumn(curwin);
}
#endif

/*
 * The 'comments' option is changed.
 */
    char *
did_set_comments(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u	*s;
    char	*errmsg = NULL;

    for (s = *varp; *s; )
    {
	while (*s && *s != ':')
	{
	    if (vim_strchr((char_u *)COM_ALL, *s) == NULL
		    && !VIM_ISDIGIT(*s) && *s != '-')
	    {
		errmsg = illegal_char(args->os_errbuf, args->os_errbuflen, *s);
		break;
	    }
	    ++s;
	}
	if (*s++ == NUL)
	    errmsg = e_missing_colon;
	else if (*s == ',' || *s == NUL)
	    errmsg = e_zero_length_string;
	if (errmsg != NULL)
	    break;
	while (*s && *s != ',')
	{
	    if (*s == '\\' && s[1] != NUL)
		++s;
	    ++s;
	}
	s = skip_to_option_part(s);
    }

    return errmsg;
}

#if defined(FEAT_FOLDING) || defined(PROTO)
/*
 * The 'commentstring' option is changed.
 */
    char *
did_set_commentstring(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (**varp != NUL && strstr((char *)*varp, "%s") == NULL)
	return e_commentstring_must_be_empty_or_contain_str;

    return NULL;
}
#endif

/*
 * The 'complete' option is changed.
 */
    char *
did_set_complete(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u	*s;

    // check if it is a valid value for 'complete' -- Acevedo
    for (s = *varp; *s;)
    {
	while (*s == ',' || *s == ' ')
	    s++;
	if (!*s)
	    break;
	if (vim_strchr((char_u *)".wbuksid]tU", *s) == NULL)
	    return illegal_char(args->os_errbuf, args->os_errbuflen, *s);
	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 (args->os_errbuf != NULL)
		{
		    vim_snprintf((char *)args->os_errbuf, args->os_errbuflen,
			    _(e_illegal_character_after_chr), *--s);
		    return args->os_errbuf;
		}
		return "";
	    }
	}
    }

    return NULL;
}

    int
expand_set_complete(optexpand_T *args, int *numMatches, char_u ***matches)
{
    static char *(p_cpt_values[]) = {
	".", "w", "b", "u", "k", "kspell", "s", "i", "d", "]", "t", "U",
	NULL};
    return expand_set_opt_string(
	    args,
	    p_cpt_values,
	    ARRAY_LENGTH(p_cpt_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'completeopt' option is changed.
 */
    char *
did_set_completeopt(optset_T *args UNUSED)
{
    if (check_opt_strings(p_cot, p_cot_values, TRUE) != OK)
	return e_invalid_argument;

    completeopt_was_set();
    return NULL;
}

    int
expand_set_completeopt(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_cot_values,
	    ARRAY_LENGTH(p_cot_values) - 1,
	    numMatches,
	    matches);
}

#if (defined(FEAT_PROP_POPUP) && defined(FEAT_QUICKFIX)) || defined(PROTO)
/*
 * The 'completepopup' option is changed.
 */
    char *
did_set_completepopup(optset_T *args UNUSED)
{
    if (parse_completepopup(NULL) == FAIL)
	return e_invalid_argument;

    popup_close_info();
    return NULL;
}
#endif

#if defined(BACKSLASH_IN_FILENAME) || defined(PROTO)
/*
 * The 'completeslash' option is changed.
 */
    char *
did_set_completeslash(optset_T *args UNUSED)
{
    if (check_opt_strings(p_csl, p_csl_values, FALSE) != OK
	    || check_opt_strings(curbuf->b_p_csl, p_csl_values, FALSE) != OK)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_completeslash(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_csl_values,
	    ARRAY_LENGTH(p_csl_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if defined(FEAT_CONCEAL) || defined(PROTO)
/*
 * The 'concealcursor' option is changed.
 */
    char *
did_set_concealcursor(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    return did_set_option_listflag(*varp, (char_u *)COCU_ALL, args->os_errbuf,
		    args->os_errbuflen);
}

    int
expand_set_concealcursor(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_listflag(args, (char_u*)COCU_ALL, numMatches, matches);
}
#endif

/*
 * The 'cpoptions' option is changed.
 */
    char *
did_set_cpoptions(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    return did_set_option_listflag(*varp, (char_u *)CPO_ALL, args->os_errbuf,
		    args->os_errbuflen);
}

    int
expand_set_cpoptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_listflag(args, (char_u*)CPO_ALL, numMatches, matches);
}

#if defined(FEAT_CRYPT) || defined(PROTO)
/*
 * The 'cryptkey' option is changed.
 */
    char *
did_set_cryptkey(optset_T *args)
{
    // Make sure the ":set" command doesn't show the new value in the
    // history.
    remove_key_from_history();

    if (args->os_op != OP_NONE)
	// Don't allow set+=/-=/^= as they can allow for substring guessing
	return e_invalid_argument;

    if (STRCMP(curbuf->b_p_key, args->os_oldval.string) != 0)
    {
	// Need to update the swapfile.
	ml_set_crypt_key(curbuf, args->os_oldval.string,
		*curbuf->b_p_cm == NUL ? p_cm : curbuf->b_p_cm);
	changed_internal();
    }
# ifdef FEAT_SODIUM
    if (crypt_method_is_sodium(crypt_get_method_nr(curbuf)))
       crypt_sodium_lock_key(args->os_newval.string);
# endif

    return NULL;
}

/*
 * The 'cryptmethod' option is changed.
 */
    char *
did_set_cryptmethod(optset_T *args)
{
    char_u  *p;
    char_u  *s;

    if (args->os_flags & OPT_LOCAL)
	p = curbuf->b_p_cm;
    else
	p = p_cm;
    if (check_opt_strings(p, p_cm_values, TRUE) != OK)
	return e_invalid_argument;
    else if (crypt_self_test() == FAIL)
	return e_invalid_argument;

    // When setting the global value to empty, make it "zip".
    if (*p_cm == NUL)
    {
	free_string_option(p_cm);
	p_cm = vim_strsave((char_u *)"zip");
    }
    // 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 ((args->os_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 ((args->os_flags & OPT_LOCAL) && *args->os_oldval.string == NUL)
	s = p_cm;  // was previously using the global value
    else
	s = args->os_oldval.string;
    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 ((args->os_flags & OPT_GLOBAL)
	    && STRCMP(p_cm, args->os_oldval.string) != 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, args->os_oldval.string);
    }
    return NULL;
}

    int
expand_set_cryptmethod(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_cm_values,
	    ARRAY_LENGTH(p_cm_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if (defined(FEAT_CSCOPE) && defined(FEAT_QUICKFIX)) || defined(PROTO)
/*
 * The 'cscopequickfix' option is changed.
 */
    char *
did_set_cscopequickfix(optset_T *args UNUSED)
{
    char_u	*p;

    if (p_csqf == NULL)
	return 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] != ','))
	    return e_invalid_argument;
	else if (p[2] == NUL)
	    break;
	else
	    p += 3;
    }

    return NULL;
}
#endif

#if defined(FEAT_SYN_HL) || defined(PROTO)
/*
 * The 'cursorlineopt' option is changed.
 */
    char *
did_set_cursorlineopt(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    // This could be changed to use opt_strings_flags() instead.
    if (**varp == NUL || fill_culopt_flags(*varp, curwin) != OK)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_cursorlineopt(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_culopt_values,
	    ARRAY_LENGTH(p_culopt_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The 'debug' option is changed.
 */
    char *
did_set_debug(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_debug, p_debug_values, TRUE);
}

    int
expand_set_debug(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_debug_values,
	    ARRAY_LENGTH(p_debug_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_DIFF) || defined(PROTO)
/*
 * The 'diffopt' option is changed.
 */
    char *
did_set_diffopt(optset_T *args UNUSED)
{
    if (diffopt_changed() == FAIL)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_diffopt(optexpand_T *args, int *numMatches, char_u ***matches)
{
    expand_T *xp = args->oe_xp;

    if (xp->xp_pattern > args->oe_set_arg && *(xp->xp_pattern-1) == ':')
    {
	// Within "algorithm:", we have a subgroup of possible options.
	int algo_len = (int)STRLEN("algorithm:");
	if (xp->xp_pattern - args->oe_set_arg >= algo_len &&
		STRNCMP(xp->xp_pattern - algo_len, "algorithm:", algo_len) == 0)
	{
	    return expand_set_opt_string(
		    args,
		    p_dip_algorithm_values,
		    ARRAY_LENGTH(p_dip_algorithm_values) - 1,
		    numMatches,
		    matches);
	}
	return FAIL;
    }

    return expand_set_opt_string(
	    args,
	    p_dip_values,
	    ARRAY_LENGTH(p_dip_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The 'display' option is changed.
 */
    char *
did_set_display(optset_T *args UNUSED)
{
    if (opt_strings_flags(p_dy, p_dy_values, &dy_flags, TRUE) != OK)
	return e_invalid_argument;

    (void)init_chartab();
    return NULL;
}

    int
expand_set_display(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_dy_values,
	    ARRAY_LENGTH(p_dy_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'eadirection' option is changed.
 */
    char *
did_set_eadirection(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_ead, p_ead_values, FALSE);
}

    int
expand_set_eadirection(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_ead_values,
	    ARRAY_LENGTH(p_ead_values) - 1,
	    numMatches,
	    matches);
}

/*
 * One of the 'encoding', 'fileencoding', 'termencoding' or 'makeencoding'
 * options is changed.
 */
    char *
did_set_encoding(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u	**gvarp;
    char	*errmsg = NULL;
    char_u	*p;

    // 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(args->os_idx, OPT_GLOBAL);

    if (gvarp == &p_fenc)
    {
	if (!curbuf->b_p_ma && args->os_flags != OPT_GLOBAL)
	    errmsg = e_cannot_make_changes_modifiable_is_off;
	else if (vim_strchr(*varp, ',') != NULL)
	    // No comma allowed in 'fileencoding'; catches confusing it
	    // with 'fileencodings'.
	    errmsg = e_invalid_argument;
	else
	{
	    // May show a "+" in the title now.
	    redraw_titles();
	    // 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();
	    redraw_titles();
	}
    }

#if defined(FEAT_GUI_GTK)
    if (errmsg == NULL && varp == &p_tenc && gui.in_use)
    {
	// GTK uses only a single encoding, and that is UTF-8.
	if (STRCMP(p_tenc, "utf-8") != 0)
	    errmsg = e_cannot_be_changed_in_gtk_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(_(e_cannot_convert_between_str_and_str),
			p_tenc, p_enc);
		errmsg = e_invalid_argument;
	    }
	}

#if defined(MSWIN)
	// $HOME, $VIM and $VIMRUNTIME may have characters in active code page.
	if (varp == &p_enc)
	{
	    init_homedir();
	    init_vimdir();
	}
#endif
    }

    return errmsg;
}

    int
expand_set_encoding(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_generic(
	    args,
	    get_encoding_name,
	    numMatches,
	    matches);
}

/*
 * The 'eventignore' option is changed.
 */
    char *
did_set_eventignore(optset_T *args UNUSED)
{
    if (check_ei() == FAIL)
	return e_invalid_argument;
    return NULL;
}

    static char_u *
get_eventignore_name(expand_T *xp, int idx)
{
    // 'eventignore' allows special keyword "all" in addition to
    // all event names.
    if (idx == 0)
	return (char_u *)"all";
    return get_event_name_no_group(xp, idx - 1);
}

    int
expand_set_eventignore(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_generic(
	    args,
	    get_eventignore_name,
	    numMatches,
	    matches);
}

/*
 * The 'fileformat' option is changed.
 */
    char *
did_set_fileformat(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (!curbuf->b_p_ma && !(args->os_flags & OPT_GLOBAL))
	return e_cannot_make_changes_modifiable_is_off;
    else if (check_opt_strings(*varp, p_ff_values, FALSE) != OK)
	return e_invalid_argument;

    // may also change 'textmode'
    if (get_fileformat(curbuf) == EOL_DOS)
	curbuf->b_p_tx = TRUE;
    else
	curbuf->b_p_tx = FALSE;
    redraw_titles();
    // 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 || *args->os_oldval.string == 'm')
	redraw_curbuf_later(UPD_NOT_VALID);

    return NULL;
}

    int
expand_set_fileformat(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_ff_values,
	    ARRAY_LENGTH(p_ff_values) - 1,
	    numMatches,
	    matches);
}

/*
 * Function given to ExpandGeneric() to obtain the possible arguments of the
 * fileformat options.
 */
    char_u *
get_fileformat_name(expand_T *xp UNUSED, int idx)
{
    if (idx >= (int)ARRAY_LENGTH(p_ff_values))
	return NULL;

    return (char_u*)p_ff_values[idx];
}

/*
 * The 'fileformats' option is changed.
 */
    char *
did_set_fileformats(optset_T *args UNUSED)
{
    if (check_opt_strings(p_ffs, p_ff_values, TRUE) != OK)
	return e_invalid_argument;

    // also change 'textauto'
    if (*p_ffs == NUL)
	p_ta = FALSE;
    else
	p_ta = TRUE;

    return NULL;
}

/*
 * The 'filetype' or the 'syntax' option is changed.
 */
    char *
did_set_filetype_or_syntax(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (!valid_filetype(*varp))
	return e_invalid_argument;

    args->os_value_changed = STRCMP(args->os_oldval.string, *varp) != 0;

    // Since we check the value, there is no need to set P_INSECURE,
    // even when the value comes from a modeline.
    args->os_value_checked = TRUE;

    return NULL;
}

#if defined(FEAT_FOLDING) || defined(PROTO)
/*
 * The 'foldclose' option is changed.
 */
    char *
did_set_foldclose(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_fcl, p_fcl_values, TRUE);
}

    int
expand_set_foldclose(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_fcl_values,
	    ARRAY_LENGTH(p_fcl_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if (defined(FEAT_EVAL) && defined(FEAT_FOLDING)) || defined(PROTO)
/*
 * The 'foldexpr' option is changed.
 */
    char *
did_set_foldexpr(optset_T *args)
{
    (void)did_set_optexpr(args);
    if (foldmethodIsExpr(curwin))
	foldUpdateAll(curwin);
    return NULL;
}
#endif

#if defined(FEAT_FOLDING) || defined(PROTO)
/*
 * The 'foldignore' option is changed.
 */
    char *
did_set_foldignore(optset_T *args UNUSED)
{
    if (foldmethodIsIndent(curwin))
	foldUpdateAll(curwin);
    return NULL;
}

/*
 * The 'foldmarker' option is changed.
 */
    char *
did_set_foldmarker(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u	*p;

    p = vim_strchr(*varp, ',');
    if (p == NULL)
	return e_comma_required;
    else if (p == *varp || p[1] == NUL)
	return e_invalid_argument;
    else if (foldmethodIsMarker(curwin))
	foldUpdateAll(curwin);

    return NULL;
}

/*
 * The 'foldmethod' option is changed.
 */
    char *
did_set_foldmethod(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (check_opt_strings(*varp, p_fdm_values, FALSE) != OK
	    || *curwin->w_p_fdm == NUL)
	return e_invalid_argument;

    foldUpdateAll(curwin);
    if (foldmethodIsDiff(curwin))
	newFoldLevel();
    return NULL;
}

    int
expand_set_foldmethod(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_fdm_values,
	    ARRAY_LENGTH(p_fdm_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'foldopen' option is changed.
 */
    char *
did_set_foldopen(optset_T *args UNUSED)
{
    return did_set_opt_flags(p_fdo, p_fdo_values, &fdo_flags, TRUE);
}

    int
expand_set_foldopen(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_fdo_values,
	    ARRAY_LENGTH(p_fdo_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The 'formatoptions' option is changed.
 */
    char *
did_set_formatoptions(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    return did_set_option_listflag(*varp, (char_u *)FO_ALL, args->os_errbuf,
		    args->os_errbuflen);
}

    int
expand_set_formatoptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_listflag(args, (char_u*)FO_ALL, numMatches, matches);
}

#if defined(CURSOR_SHAPE) || defined(PROTO)
/*
 * The 'guicursor' option is changed.
 */
    char *
did_set_guicursor(optset_T *args UNUSED)
{
    return parse_shape_opt(SHAPE_CURSOR);
}
#endif

#if defined(FEAT_GUI) || defined(PROTO)
/*
 * The 'guifont' option is changed.
 */
    char *
did_set_guifont(optset_T *args UNUSED)
{
    char_u	*p;
    char	*errmsg = NULL;

    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(args->os_oldval.string);
	    free_string_option(p_guifont);
	    p_guifont = (p != NULL) ? p : vim_strsave(args->os_oldval.string);
	}
# 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.
		free_string_option(p_guifont);
		p_guifont = vim_strsave(args->os_oldval.string);
	    }
	    else
# endif
		errmsg = e_invalid_fonts;
	}
    }

    return errmsg;
}

/*
 * Expand the 'guifont' option. Only when GUI is being used. Each platform has
 * specific behaviors.
 */
    int
expand_set_guifont(optexpand_T *args, int *numMatches, char_u ***matches)
{
    if (!gui.in_use)
	return FAIL;

# if defined(FEAT_GUI_MSWIN) || defined(FEAT_GUI_GTK)
    char_u **varp = (char_u **)args->oe_varp;
    int wide = (varp == &p_guifontwide);

    return expand_set_opt_callback(
	    args, gui_mch_expand_font, &wide, numMatches, matches);
# else
    return FAIL;
# endif
}

# if defined(FEAT_XFONTSET) || defined(PROTO)
/*
 * The 'guifontset' option is changed.
 */
    char *
did_set_guifontset(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (STRCMP(p_guifontset, "*") == 0)
	errmsg = e_cant_select_fontset;
    else if (gui.in_use && gui_init_font(p_guifontset, TRUE) != OK)
	errmsg = e_invalid_fontset;

    return errmsg;
}
# endif

/*
 * The 'guifontwide' option is changed.
 */
    char *
did_set_guifontwide(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (STRCMP(p_guifontwide, "*") == 0)
	errmsg = e_cant_select_wide_font;
    else if (gui_get_wide_font() == FAIL)
	errmsg = e_invalid_wide_font;

    return errmsg;
}
#endif

#if defined(FEAT_GUI_GTK) || defined(FEAT_GUI_MSWIN) || defined(PROTO)
/*
 * The 'guiligatures' option is changed.
 */
    char *
did_set_guiligatures(optset_T *args UNUSED)
{
    gui_set_ligatures();
    return NULL;
}
#endif

#if defined(FEAT_GUI) || defined(PROTO)
/*
 * The 'guioptions' option is changed.
 */
    char *
did_set_guioptions(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char *errmsg;

    errmsg = did_set_option_listflag(*varp, (char_u *)GO_ALL, args->os_errbuf,
		    args->os_errbuflen);
    if (errmsg != NULL)
	return errmsg;

    gui_init_which_components(args->os_oldval.string);
    return NULL;
}

    int
expand_set_guioptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_listflag(args, (char_u*)GO_ALL, numMatches, matches);
}
#endif

#if defined(FEAT_GUI_TABLINE) || defined(PROTO)
/*
 * The 'guitablabel' option is changed.
 */
    char *
did_set_guitablabel(optset_T *args UNUSED)
{
    redraw_tabline = TRUE;
    return NULL;
}
#endif

/*
 * The 'helpfile' option is changed.
 */
    char *
did_set_helpfile(optset_T *args UNUSED)
{
    // May compute new values for $VIM and $VIMRUNTIME
    if (didset_vim)
	vim_unsetenv_ext((char_u *)"VIM");
    if (didset_vimruntime)
	vim_unsetenv_ext((char_u *)"VIMRUNTIME");
    return NULL;
}

#if defined(FEAT_MULTI_LANG) || defined(PROTO)
/*
 * The 'helplang' option is changed.
 */
    char *
did_set_helplang(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    // Check for "", "ab", "ab,cd", etc.
    for (char_u *s = p_hlg; *s != NUL; s += 3)
    {
	if (s[1] == NUL || ((s[2] != ',' || s[3] == NUL) && s[2] != NUL))
	{
	    errmsg = e_invalid_argument;
	    break;
	}
	if (s[2] == NUL)
	    break;
    }

    return errmsg;
}
#endif

/*
 * The 'highlight' option is changed.
 */
    char *
did_set_highlight(optset_T *args UNUSED)
{
    if (highlight_changed() == FAIL)
	return e_invalid_argument;	// invalid flags

    return NULL;
}

/*
 * Expand 'highlight' option.
 */
    int
expand_set_highlight(optexpand_T *args, int *numMatches, char_u ***matches)
{
    char_u	    *p;
    expand_T	    *xp = args->oe_xp;
    static char_u   hl_flags[HLF_COUNT] = HL_FLAGS;
    size_t	    i;
    int		    count = 0;

    if (xp->xp_pattern > args->oe_set_arg && *(xp->xp_pattern-1) == ':')
    {
	// Right after a ':', meaning we just return all highlight names.
	return expand_set_opt_generic(
		args,
		get_highlight_name,
		numMatches,
		matches);
    }

    if (*xp->xp_pattern == NUL)
    {
	// At beginning of a comma-separated list. Return the specific list of
	// supported occasions.
	*matches = ALLOC_MULT(char_u *, HLF_COUNT + 1);
	if (*matches == NULL)
	    return FAIL;

	// We still want to return the full option if it's requested.
	if (args->oe_include_orig_val)
	{
	    p = vim_strsave(args->oe_opt_value);
	    if (p == NULL)
	    {
		VIM_CLEAR(*matches);
		return FAIL;
	    }
	    (*matches)[count++] = p;
	}

	for (i = 0; i < HLF_COUNT; i++)
	{
	    p = vim_strnsave(&hl_flags[i], 1);
	    if (p == NULL)
	    {
		if (count == 0)
		{
		    VIM_CLEAR(*matches);
		    return FAIL;
		}
		else
		    break;
	    }
	    (*matches)[count++] = p;
	}

	if (count == 0)
	{
	    VIM_CLEAR(*matches);
	    return FAIL;
	}
	*numMatches = count;
	return OK;
    }

    // We are after the initial character (which indicates the occasion). We
    // already made sure we are not matching after a ':' above, so now we want
    // to match against display mode modifiers.
    // Since the xp_pattern starts from the beginning, we need to include it in
    // the returned match.

    // Note: Keep this in sync with highlight_changed()
    static char_u p_hl_mode_values[] =
	{':', 'b', 'i', '-', 'n', 'r', 's', 'u', 'c', '2', 'd', '=', 't'};
    size_t num_hl_modes = ARRAY_LENGTH(p_hl_mode_values);

    *matches = ALLOC_MULT(char_u *, num_hl_modes);
    if (*matches == NULL)
	return FAIL;

    int pattern_len = xp->xp_pattern_len;

    for (i = 0; i < num_hl_modes; i++)
    {
	// Don't allow duplicates as these are unique flags
	char_u *dup = vim_strchr(xp->xp_pattern + 1, p_hl_mode_values[i]);
	if (dup != NULL && (int)(dup - xp->xp_pattern) < pattern_len)
	    continue;

	// ':' only works by itself, not with other flags.
	if (pattern_len > 1 && p_hl_mode_values[i] == ':')
	    continue;

	p = vim_strnsave(xp->xp_pattern, pattern_len + 1);
	if (p == NULL)
	{
	    if (i == 0)
	    {
		VIM_CLEAR(*matches);
		return FAIL;
	    }
	    else
		break;
	}
	p[pattern_len] = p_hl_mode_values[i];
	p[pattern_len + 1] = NUL;
	(*matches)[count++] = p;
    }
    if (count == 0)
    {
	VIM_CLEAR(*matches);
	return FAIL;
    }
    *numMatches = count;

    return OK;
}

/*
 * The 'titlestring' or the 'iconstring' option is changed.
 */
    static char *
parse_titleiconstring(optset_T *args UNUSED, int flagval UNUSED)
{
#ifdef FEAT_STL_OPT
    char_u	**varp = (char_u **)args->os_varp;

    // NULL => statusline syntax
    if (vim_strchr(*varp, '%') && check_stl_option(*varp) == NULL)
	stl_syntax |= flagval;
    else
	stl_syntax &= ~flagval;
#endif
    did_set_title();

    return NULL;
}

/*
 * The 'iconstring' option is changed.
 */
    char *
did_set_iconstring(optset_T *args)
{
    int flagval = 0;

#ifdef FEAT_STL_OPT
    flagval = STL_IN_ICON;
#endif

    return parse_titleiconstring(args, flagval);
}

#if (defined(FEAT_XIM) && defined(FEAT_GUI_GTK)) || defined(PROTO)
/*
 * The 'imactivatekey' option is changed.
 */
    char *
did_set_imactivatekey(optset_T *args UNUSED)
{
    if (!im_xim_isvalid_imactivate())
	return e_invalid_argument;
    return NULL;
}
#endif

/*
 * The 'isident' or the 'iskeyword' or the 'isprint' or the 'isfname' option is
 * changed.
 */
    char *
did_set_isopt(optset_T *args)
{
    // '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.
    if (init_chartab() == FAIL)
    {
	args->os_restore_chartab = TRUE;// need to restore the chartab.
	return e_invalid_argument;	// error in value
    }

    return NULL;
}

/*
 * The 'jumpoptions' option is changed.
 */
    char *
did_set_jumpoptions(optset_T *args UNUSED)
{
    if (opt_strings_flags(p_jop, p_jop_values, &jop_flags, TRUE) != OK)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_jumpoptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_jop_values,
	    ARRAY_LENGTH(p_jop_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_KEYMAP) || defined(PROTO)
/*
 * The 'keymap' option is changed.
 */
    char *
did_set_keymap(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char *errmsg = NULL;

    if (!valid_filetype(*varp))
	errmsg = e_invalid_argument;
    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.
	args->os_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 ((args->os_flags & OPT_LOCAL) == 0)
	{
	    set_iminsert_global();
	    set_imsearch_global();
	}
	status_redraw_curbuf();
    }

    return errmsg;
}
#endif

/*
 * The 'keymodel' option is changed.
 */
    char *
did_set_keymodel(optset_T *args UNUSED)
{
    if (check_opt_strings(p_km, p_km_values, TRUE) != OK)
	return e_invalid_argument;

    km_stopsel = (vim_strchr(p_km, 'o') != NULL);
    km_startsel = (vim_strchr(p_km, 'a') != NULL);
    return NULL;
}

    int
expand_set_keymodel(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_km_values,
	    ARRAY_LENGTH(p_km_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'keyprotocol' option is changed.
 */
    char *
did_set_keyprotocol(optset_T *args UNUSED)
{
    char_u *term = T_NAME;
    keyprot_T kpc = match_keyprotocol(term);
    if (kpc == KEYPROTOCOL_FAIL)
	return e_invalid_argument;

    apply_keyprotocol(term, kpc);

    return NULL;
}

    int
expand_set_keyprotocol(optexpand_T *args, int *numMatches, char_u ***matches)
{
    expand_T *xp = args->oe_xp;
    if (xp->xp_pattern > args->oe_set_arg && *(xp->xp_pattern-1) == ':')
    {
	// 'keyprotocol' only has well-defined terms for completion for the
	// protocol part after the colon.
	return expand_set_opt_string(
		args,
		p_kpc_protocol_values,
		ARRAY_LENGTH(p_kpc_protocol_values) - 1,
		numMatches,
		matches);
    }
    // Use expand_set_opt_string instead of returning FAIL so that we can
    // include the original value if args->oe_include_orig_val is set.
    static char *(empty[]) = {NULL};
    return expand_set_opt_string(args, empty, 0, numMatches, matches);
}

/*
 * The 'lispoptions' option is changed.
 */
    char *
did_set_lispoptions(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (**varp != NUL
	    && STRCMP(*varp, "expr:0") != 0
	    && STRCMP(*varp, "expr:1") != 0)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_lispoptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    static char *(p_lop_values[]) = {"expr:0", "expr:1", NULL};
    return expand_set_opt_string(
	    args,
	    p_lop_values,
	    ARRAY_LENGTH(p_lop_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'matchpairs' option is changed.
 */
    char *
did_set_matchpairs(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u	*p;

    if (has_mbyte)
    {
	for (p = *varp; *p != NUL; ++p)
	{
	    int x2 = -1;
	    int x3 = -1;

	    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 != ','))
		return e_invalid_argument;
	    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] != ','))
		return e_invalid_argument;
	    if (p[3] == NUL)
		break;
	}
    }

    return NULL;
}

#if defined(FEAT_SPELL) || defined(PROTO)
/*
 * The 'mkspellmem' option is changed.
 */
    char *
did_set_mkspellmem(optset_T *args UNUSED)
{
    if (spell_check_msm() != OK)
	return e_invalid_argument;

    return NULL;
}
#endif

/*
 * The 'mouse' option is changed.
 */
    char *
did_set_mouse(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    return did_set_option_listflag(*varp, (char_u *)MOUSE_ALL, args->os_errbuf,
		    args->os_errbuflen);
}

    int
expand_set_mouse(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_listflag(args, (char_u*)MOUSE_ALL, numMatches, matches);
}

/*
 * The 'mousemodel' option is changed.
 */
    char *
did_set_mousemodel(optset_T *args UNUSED)
{
    if (check_opt_strings(p_mousem, p_mousem_values, FALSE) != OK)
	return e_invalid_argument;
#if defined(FEAT_GUI_MOTIF) && defined(FEAT_MENU) && (XmVersion <= 1002)
    else if (*p_mousem != *args->os_oldval.string)
	// 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

    return NULL;
}

    int
expand_set_mousemodel(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_mousem_values,
	    ARRAY_LENGTH(p_mousem_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_MOUSESHAPE) || defined(PROTO)
    char *
did_set_mouseshape(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    errmsg = parse_shape_opt(SHAPE_MOUSE);
    update_mouseshape(-1);

    return errmsg;
}
#endif

/*
 * The 'nrformats' option is changed.
 */
    char *
did_set_nrformats(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    return did_set_opt_strings(*varp, p_nf_values, TRUE);
}

    int
expand_set_nrformats(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_nf_values,
	    ARRAY_LENGTH(p_nf_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_EVAL) || defined(PROTO)
/*
 * One of the '*expr' options is changed: 'balloonexpr', 'diffexpr',
 * 'foldexpr', 'foldtext', 'formatexpr', 'includeexpr', 'indentexpr',
 * 'patchexpr', 'printexpr' and 'charconvert'.
 *
 */
    char *
did_set_optexpr(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    // If the option value starts with <SID> or s:, then replace that with
    // the script identifier.
    char_u *name = get_scriptlocal_funcname(*varp);
    if (name != NULL)
    {
	free_string_option(*varp);
	*varp = name;
    }

    return NULL;
}
#endif

/*
 * The 'pastetoggle' option is changed.
 */
    char *
did_set_pastetoggle(optset_T *args UNUSED)
{
    char_u	*p;

    // translate key codes like in a mapping
    if (*p_pt)
    {
	(void)replace_termcodes(p_pt, &p, 0,
		REPTERM_FROM_PART | REPTERM_DO_LT, NULL);
	if (p != NULL)
	{
	    free_string_option(p_pt);
	    p_pt = p;
	}
    }

    return NULL;
}

#if defined(FEAT_PROP_POPUP) || defined(PROTO)
/*
 * The 'previewpopup' option is changed.
 */
    char *
did_set_previewpopup(optset_T *args UNUSED)
{
    if (parse_previewpopup(NULL) == FAIL)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_popupoption(optexpand_T *args, int *numMatches, char_u ***matches)
{
    expand_T *xp = args->oe_xp;

    if (xp->xp_pattern > args->oe_set_arg && *(xp->xp_pattern-1) == ':')
    {
	// Within "highlight:"/"border:"/"align:", we have a subgroup of possible options.
	int border_len = (int)STRLEN("border:");
	if (xp->xp_pattern - args->oe_set_arg >= border_len &&
		STRNCMP(xp->xp_pattern - border_len, "border:", border_len) == 0)
	{
	    return expand_set_opt_string(
		    args,
		    p_popup_option_border_values,
		    ARRAY_LENGTH(p_popup_option_border_values) - 1,
		    numMatches,
		    matches);
	}
	int align_len = (int)STRLEN("align:");
	if (xp->xp_pattern - args->oe_set_arg >= align_len &&
		STRNCMP(xp->xp_pattern - align_len, "align:", align_len) == 0)
	{
	    return expand_set_opt_string(
		    args,
		    p_popup_option_align_values,
		    ARRAY_LENGTH(p_popup_option_align_values) - 1,
		    numMatches,
		    matches);
	}
	int highlight_len = (int)STRLEN("highlight:");
	if (xp->xp_pattern - args->oe_set_arg >= highlight_len &&
		STRNCMP(xp->xp_pattern - highlight_len, "highlight:", highlight_len) == 0)
	{
	    // Return the list of all highlight names
	    return expand_set_opt_generic(
		    args,
		    get_highlight_name,
		    numMatches,
		    matches);
	}
	return FAIL;
    }

    return expand_set_opt_string(
	    args,
	    p_popup_option_values,
	    ARRAY_LENGTH(p_popup_option_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if defined(FEAT_POSTSCRIPT) || defined(PROTO)
/*
 * The 'printencoding' option is changed.
 */
    char *
did_set_printencoding(optset_T *args UNUSED)
{
    char_u	*s, *p;

    // 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);
	}
    }

    return NULL;
}
#endif

#if defined(FEAT_PRINTER) || defined(PROTO)

    static char_u *
get_printoptions_names(expand_T *xp UNUSED, int idx)
{
    if (idx >= (int)ARRAY_LENGTH(printer_opts))
	return NULL;
    return (char_u*)printer_opts[idx].name;
}

/*
 * Expand 'printoptions' option
 */
    int
expand_set_printoptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_generic(
	    args,
	    get_printoptions_names,
	    numMatches,
	    matches);
}
#endif

#if defined(FEAT_STL_OPT) || defined(PROTO)
/*
 * The 'statusline' or the 'tabline' or the 'rulerformat' option is changed.
 * "rulerformat" is TRUE if the 'rulerformat' option is changed.
 */
    static char *
parse_statustabline_rulerformat(optset_T *args, int rulerformat)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u	*s;
    char	*errmsg = NULL;
    int		wid;

    if (rulerformat)	// reset ru_wid first
	ru_wid = 0;
    s = *varp;
    if (rulerformat && *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' or 'tabline' only if it doesn't start with "%!"
    else if (rulerformat || s[0] != '%' || s[1] != '!')
	errmsg = check_stl_option(s);
    if (rulerformat && errmsg == NULL)
	comp_col();

    return errmsg;
}
#endif

#if defined(FEAT_RENDER_OPTIONS) || defined(PROTO)
/*
 * The 'renderoptions' option is changed.
 */
    char *
did_set_renderoptions(optset_T *args UNUSED)
{
    if (!gui_mch_set_rendering_options(p_rop))
	return e_invalid_argument;

    return NULL;
}
#endif

#if defined(FEAT_RIGHTLEFT) || defined(PROTO)
/*
 * The 'rightleftcmd' option is changed.
 */
    char *
did_set_rightleftcmd(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    // Currently only "search" is a supported value.
    if (**varp != NUL && STRCMP(*varp, "search") != 0)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_rightleftcmd(optexpand_T *args, int *numMatches, char_u ***matches)
{
    static char *(p_rlc_values[]) = {"search", NULL};
    return expand_set_opt_string(
	    args,
	    p_rlc_values,
	    ARRAY_LENGTH(p_rlc_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if defined(FEAT_STL_OPT) || defined(PROTO)
/*
 * The 'rulerformat' option is changed.
 */
    char *
did_set_rulerformat(optset_T *args)
{
    return parse_statustabline_rulerformat(args, TRUE);
}
#endif

/*
 * The 'scrollopt' option is changed.
 */
    char *
did_set_scrollopt(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_sbo, p_scbopt_values, TRUE);
}

    int
expand_set_scrollopt(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_scbopt_values,
	    ARRAY_LENGTH(p_scbopt_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'selection' option is changed.
 */
    char *
did_set_selection(optset_T *args UNUSED)
{
    if (*p_sel == NUL || check_opt_strings(p_sel, p_sel_values, FALSE) != OK)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_selection(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_sel_values,
	    ARRAY_LENGTH(p_sel_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'selectmode' option is changed.
 */
    char *
did_set_selectmode(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_slm, p_slm_values, TRUE);
}

    int
expand_set_selectmode(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_slm_values,
	    ARRAY_LENGTH(p_slm_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_SESSION) || defined(PROTO)
/*
 * The 'sessionoptions' option is changed.
 */
    char *
did_set_sessionoptions(optset_T *args)
{
    if (opt_strings_flags(p_ssop, p_ssop_values, &ssop_flags, TRUE) != OK)
	return e_invalid_argument;
    if ((ssop_flags & SSOP_CURDIR) && (ssop_flags & SSOP_SESDIR))
    {
	// Don't allow both "sesdir" and "curdir".
	(void)opt_strings_flags(args->os_oldval.string, p_ssop_values,
							&ssop_flags, TRUE);
	return e_invalid_argument;
    }

    return NULL;
}

    int
expand_set_sessionoptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_ssop_values,
	    ARRAY_LENGTH(p_ssop_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The 'shortmess' option is changed.
 */
    char *
did_set_shortmess(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    return did_set_option_listflag(*varp, (char_u *)SHM_ALL, args->os_errbuf,
		    args->os_errbuflen);
}

    int
expand_set_shortmess(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_listflag(args, (char_u*)SHM_ALL, numMatches, matches);
}

#if defined(FEAT_LINEBREAK) || defined(PROTO)
/*
 * The 'showbreak' option is changed.
 */
    char *
did_set_showbreak(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u	*s;

    for (s = *varp; *s; )
    {
	if (ptr2cells(s) != 1)
	    return e_showbreak_contains_unprintable_or_wide_character;
	MB_PTR_ADV(s);
    }

    return NULL;
}
#endif

/*
 * The 'showcmdloc' option is changed.
 */
    char *
did_set_showcmdloc(optset_T *args UNUSED)
{
    char	*errmsg = did_set_opt_strings(p_sloc, p_sloc_values, FALSE);

    if (errmsg == NULL)
	comp_col();

    return errmsg;
}

    int
expand_set_showcmdloc(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_sloc_values,
	    ARRAY_LENGTH(p_sloc_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_SIGNS) || defined(PROTO)
/*
 * The 'signcolumn' option is changed.
 */
    char *
did_set_signcolumn(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (check_opt_strings(*varp, p_scl_values, FALSE) != OK)
	return e_invalid_argument;
    // When changing the 'signcolumn' to or from 'number', recompute the
    // width of the number column if 'number' or 'relativenumber' is set.
    if (((*args->os_oldval.string == 'n' && args->os_oldval.string[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;

    return NULL;
}

    int
expand_set_signcolumn(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_scl_values,
	    ARRAY_LENGTH(p_scl_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if defined(FEAT_SPELL) || defined(PROTO)
/*
 * The 'spellcapcheck' option is changed.
 */
    char *
did_set_spellcapcheck(optset_T *args UNUSED)
{
    // compile the regexp program.
    return compile_cap_prog(curwin->w_s);
}

/*
 * The 'spellfile' option is changed.
 */
    char *
did_set_spellfile(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (!valid_spellfile(*varp))
	return e_invalid_argument;

    // If there is a window for this buffer in which 'spell' is set load the
    // wordlists.
    return did_set_spell_option(TRUE);
}

/*
 * The 'spell' option is changed.
 */
    char *
did_set_spelllang(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (!valid_spelllang(*varp))
	return e_invalid_argument;

    // If there is a window for this buffer in which 'spell' is set load the
    // wordlists.
    return did_set_spell_option(FALSE);
}

/*
 * The 'spelloptions' option is changed.
 */
    char *
did_set_spelloptions(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (**varp != NUL && STRCMP(*varp, "camel") != 0)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_spelloptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    static char *(p_spo_values[]) = {"camel", NULL};
    return expand_set_opt_string(
	    args,
	    p_spo_values,
	    ARRAY_LENGTH(p_spo_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'spellsuggest' option is changed.
 */
    char *
did_set_spellsuggest(optset_T *args UNUSED)
{
    if (spell_check_sps() != OK)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_spellsuggest(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_sps_values,
	    ARRAY_LENGTH(p_sps_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The 'splitkeep' option is changed.
 */
    char *
did_set_splitkeep(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_spk, p_spk_values, FALSE);
}

    int
expand_set_splitkeep(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_spk_values,
	    ARRAY_LENGTH(p_spk_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_STL_OPT) || defined(PROTO)
/*
 * The 'statusline' option is changed.
 */
    char *
did_set_statusline(optset_T *args)
{
    return parse_statustabline_rulerformat(args, FALSE);
}
#endif

/*
 * The 'swapsync' option is changed.
 */
    char *
did_set_swapsync(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_sws, p_sws_values, FALSE);
}

    int
expand_set_swapsync(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_sws_values,
	    ARRAY_LENGTH(p_sws_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'switchbuf' option is changed.
 */
    char *
did_set_switchbuf(optset_T *args UNUSED)
{
    return did_set_opt_flags(p_swb, p_swb_values, &swb_flags, TRUE);
}

    int
expand_set_switchbuf(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_swb_values,
	    ARRAY_LENGTH(p_swb_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_STL_OPT) || defined(PROTO)
/*
 * The 'tabline' option is changed.
 */
    char *
did_set_tabline(optset_T *args)
{
    return parse_statustabline_rulerformat(args, FALSE);
}
#endif

/*
 * The 'tagcase' option is changed.
 */
    char *
did_set_tagcase(optset_T *args)
{
    unsigned int	*flags;
    char_u		*p;

    if (args->os_flags & OPT_LOCAL)
    {
	p = curbuf->b_p_tc;
	flags = &curbuf->b_tc_flags;
    }
    else
    {
	p = p_tc;
	flags = &tc_flags;
    }

    if ((args->os_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)
	return e_invalid_argument;

    return NULL;
}

    int
expand_set_tagcase(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_tc_values,
	    ARRAY_LENGTH(p_tc_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'term' option is changed.
 */
    char *
did_set_term(optset_T *args UNUSED)
{
    if (T_NAME[0] == NUL)
	return e_cannot_set_term_to_empty_string;
#ifdef FEAT_GUI
    if (gui.in_use)
	return e_cannot_change_term_in_GUI;
    if (term_is_gui(T_NAME))
	return e_use_gui_to_start_GUI;
#endif
    if (set_termname(T_NAME) == FAIL)
	return e_not_found_in_termcap;

    // Screen colors may have changed.
    redraw_later_clear();

    return NULL;
}

/*
 * Some terminal option (t_xxx) is changed
 */
    char *
did_set_term_option(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    if (!full_screen)
	return NULL;

    // ":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)
	    {
		vim_free(T_CCO);
		T_CCO = empty_option;
	    }
#if defined(FEAT_VTP) && defined(FEAT_TERMGUICOLORS)
	    if (is_term_win32())
	    {
		swap_tcap();
		args->os_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(UPD_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)
    {
	MAY_WANT_TO_LOG_THIS;

	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);
    }

    return NULL;
}

#if defined(FEAT_TERMINAL) || defined(PROTO)
/*
 * The 'termwinkey' option is changed.
 */
    char *
did_set_termwinkey(optset_T *args UNUSED)
{
    if (*curwin->w_p_twk != NUL && string_to_key(curwin->w_p_twk, TRUE) == 0)
	return e_invalid_argument;

    return NULL;
}

/*
 * The 'termwinsize' option is changed.
 */
    char *
did_set_termwinsize(optset_T *args UNUSED)
{
    char_u	*p;

    if (*curwin->w_p_tws == NUL)
	return NULL;

    p = skipdigits(curwin->w_p_tws);
    if (p == curwin->w_p_tws
	    || (*p != 'x' && *p != '*')
	    || *skipdigits(p + 1) != NUL)
	return e_invalid_argument;

    return NULL;
}

# if defined(MSWIN) || defined(PROTO)
/*
 * The 'termwintype' option is changed.
 */
    char *
did_set_termwintype(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_twt, p_twt_values, FALSE);
}

    int
expand_set_termwintype(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_twt_values,
	    ARRAY_LENGTH(p_twt_values) - 1,
	    numMatches,
	    matches);
}
# endif
#endif

/*
 * The 'titlestring' option is changed.
 */
    char *
did_set_titlestring(optset_T *args)
{
    int flagval = 0;

#ifdef FEAT_STL_OPT
    flagval = STL_IN_TITLE;
#endif
    return parse_titleiconstring(args, flagval);
}

#if (defined(FEAT_TOOLBAR) && !defined(FEAT_GUI_MSWIN)) || defined(PROTO)
/*
 * The 'toolbar' option is changed.
 */
    char *
did_set_toolbar(optset_T *args UNUSED)
{
    if (opt_strings_flags(p_toolbar, p_toolbar_values, &toolbar_flags,
								TRUE) != OK)
	return e_invalid_argument;

    out_flush();
    gui_mch_show_toolbar((toolbar_flags &
		(TOOLBAR_TEXT | TOOLBAR_ICONS)) != 0);
    return NULL;
}

    int
expand_set_toolbar(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_toolbar_values,
	    ARRAY_LENGTH(p_toolbar_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if (defined(FEAT_TOOLBAR) && defined(FEAT_GUI_GTK)) || defined(PROTO)
/*
 * The 'toolbariconsize' option is changed.  GTK+ 2 only.
 */
    char *
did_set_toolbariconsize(optset_T *args UNUSED)
{
    if (opt_strings_flags(p_tbis, p_tbis_values, &tbis_flags, FALSE) != OK)
	return e_invalid_argument;

    out_flush();
    gui_mch_show_toolbar((toolbar_flags &
		(TOOLBAR_TEXT | TOOLBAR_ICONS)) != 0);
    return NULL;
}

    int
expand_set_toolbariconsize(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_tbis_values,
	    ARRAY_LENGTH(p_tbis_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if defined(UNIX) || defined(VMS) || defined(PROTO)
/*
 * The 'ttymouse' option is changed.
 */
    char *
did_set_ttymouse(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    // 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_invalid_argument;
    else
	check_mouse_termcode();
    if (termcap_active)
	setmouse();		// may switch it on again

    return errmsg;
}

    int
expand_set_ttymouse(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_ttym_values,
	    ARRAY_LENGTH(p_ttym_values) - 1,
	    numMatches,
	    matches);
}
#endif

#if defined(FEAT_VARTABS) || defined(PROTO)
/*
 * The 'varsofttabstop' option is changed.
 */
    char *
did_set_varsofttabstop(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u *cp;

    if (!((*varp)[0]) || ((*varp)[0] == '0' && !((*varp)[1])))
	VIM_CLEAR(curbuf->b_p_vsts_array);
    else
    {
	for (cp = *varp; *cp; ++cp)
	{
	    if (vim_isdigit(*cp))
		continue;
	    if (*cp == ',' && cp > *varp && *(cp-1) != ',')
		continue;
	    return e_invalid_argument;
	}

	int *oldarray = curbuf->b_p_vsts_array;
	if (tabstop_set(*varp, &(curbuf->b_p_vsts_array)) == OK)
	{
	    if (oldarray)
		vim_free(oldarray);
	}
	else
	    return e_invalid_argument;
    }

    return NULL;
}

/*
 * The 'vartabstop' option is changed.
 */
    char *
did_set_vartabstop(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;
    char_u *cp;

    if (!((*varp)[0]) || ((*varp)[0] == '0' && !((*varp)[1])))
	VIM_CLEAR(curbuf->b_p_vts_array);
    else
    {
	for (cp = *varp; *cp; ++cp)
	{
	    if (vim_isdigit(*cp))
		continue;
	    if (*cp == ',' && cp > *varp && *(cp-1) != ',')
		continue;
	    return e_invalid_argument;
	}

	int *oldarray = curbuf->b_p_vts_array;

	if (tabstop_set(*varp, &(curbuf->b_p_vts_array)) == OK)
	{
	    vim_free(oldarray);
# ifdef FEAT_FOLDING
	    if (foldmethodIsIndent(curwin))
		foldUpdateAll(curwin);
# endif
	}
	else
	    return e_invalid_argument;
    }

    return NULL;
}
#endif

/*
 * The 'verbosefile' option is changed.
 */
    char *
did_set_verbosefile(optset_T *args UNUSED)
{
    verbose_stop();
    if (*p_vfile != NUL && verbose_open() == FAIL)
	return e_invalid_argument;

    return NULL;
}

#if defined(FEAT_SESSION) || defined(PROTO)
/*
 * The 'viewoptions' option is changed.
 */
    char *
did_set_viewoptions(optset_T *args UNUSED)
{
    return did_set_opt_flags(p_vop, p_ssop_values, &vop_flags, TRUE);
}
#endif

#if defined(FEAT_VIMINFO) || defined(PROTO)
/*
 * The 'viminfo' option is changed.
 */
    char *
did_set_viminfo(optset_T *args)
{
    char_u	*s;
    char	*errmsg = NULL;

    for (s = p_viminfo; *s;)
    {
	// Check it's a valid character
	if (vim_strchr((char_u *)"!\"%'/:<@cfhnrs", *s) == NULL)
	{
	    errmsg = illegal_char(args->os_errbuf, args->os_errbuflen, *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 (args->os_errbuf != NULL)
		{
		    vim_snprintf(args->os_errbuf, args->os_errbuflen,
			    _(e_missing_number_after_angle_str_angle),
			    transchar_byte(*(s - 1)));
		    errmsg = args->os_errbuf;
		}
		else
		    errmsg = "";
		break;
	    }
	}
	if (*s == ',')
	    ++s;
	else if (*s)
	{
	    if (args->os_errbuf != NULL)
		errmsg = e_missing_comma;
	    else
		errmsg = "";
	    break;
	}
    }
    if (*p_viminfo && errmsg == NULL && get_viminfo_parameter('\'') < 0)
	errmsg = e_must_specify_a_value;

    return errmsg;
}
#endif

/*
 * The 'virtualedit' option is changed.
 */
    char *
did_set_virtualedit(optset_T *args)
{
    char_u		*ve = p_ve;
    unsigned int	*flags = &ve_flags;

    if (args->os_flags & OPT_LOCAL)
    {
	ve = curwin->w_p_ve;
	flags = &curwin->w_ve_flags;
    }

    if ((args->os_flags & OPT_LOCAL) && *ve == NUL)
	// make the local value empty: use the global value
	*flags = 0;
    else
    {
	if (opt_strings_flags(ve, p_ve_values, flags, TRUE) != OK)
	    return e_invalid_argument;
	else if (STRCMP(ve, args->os_oldval.string) != 0)
	{
	    // Recompute cursor position in case the new 've' setting
	    // changes something.
	    validate_virtcol();
	    coladvance(curwin->w_virtcol);
	}
    }

    return NULL;
}

    int
expand_set_virtualedit(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_ve_values,
	    ARRAY_LENGTH(p_ve_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'whichwrap' option is changed.
 */
    char *
did_set_whichwrap(optset_T *args)
{
    char_u	**varp = (char_u **)args->os_varp;

    // Add ',' to the list flags because 'whichwrap' is a flag
    // list that is comma-separated.
    return did_set_option_listflag(*varp, (char_u *)(WW_ALL ","),
		    args->os_errbuf, args->os_errbuflen);
}

    int
expand_set_whichwrap(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_listflag(args, (char_u*)WW_ALL, numMatches, matches);
}

/*
 * The 'wildmode' option is changed.
 */
    char *
did_set_wildmode(optset_T *args UNUSED)
{
    if (check_opt_wim() == FAIL)
	return e_invalid_argument;
    return NULL;
}

    int
expand_set_wildmode(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_wim_values,
	    ARRAY_LENGTH(p_wim_values) - 1,
	    numMatches,
	    matches);
}

/*
 * The 'wildoptions' option is changed.
 */
    char *
did_set_wildoptions(optset_T *args UNUSED)
{
    return did_set_opt_strings(p_wop, p_wop_values, TRUE);
}

    int
expand_set_wildoptions(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_wop_values,
	    ARRAY_LENGTH(p_wop_values) - 1,
	    numMatches,
	    matches);
}

#if defined(FEAT_WAK) || defined(PROTO)
/*
 * The 'winaltkeys' option is changed.
 */
    char *
did_set_winaltkeys(optset_T *args UNUSED)
{
    char *errmsg = NULL;

    if (*p_wak == NUL || check_opt_strings(p_wak, p_wak_values, FALSE) != OK)
	errmsg = e_invalid_argument;
# ifdef FEAT_MENU
#  if defined(FEAT_GUI_MOTIF)
    else if (gui.in_use)
	gui_motif_set_mnemonics(p_wak[0] == 'y' || p_wak[0] == 'm');
#  elif defined(FEAT_GUI_GTK)
    else if (gui.in_use)
	gui_gtk_set_mnemonics(p_wak[0] == 'y' || p_wak[0] == 'm');
#  endif
# endif
    return errmsg;
}

    int
expand_set_winaltkeys(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_string(
	    args,
	    p_wak_values,
	    ARRAY_LENGTH(p_wak_values) - 1,
	    numMatches,
	    matches);
}
#endif

/*
 * The 'wincolor' option is changed.
 */
    char *
did_set_wincolor(optset_T *args UNUSED)
{
#ifdef FEAT_TERMINAL
    term_update_wincolor(curwin);
#endif
    return NULL;
}

    int
expand_set_wincolor(optexpand_T *args, int *numMatches, char_u ***matches)
{
    return expand_set_opt_generic(
	    args,
	    get_highlight_name,
	    numMatches,
	    matches);
}

#ifdef FEAT_SYN_HL
/*
 * When the 'syntax' option is set, load the syntax of that name.
 */
    static void
do_syntax_autocmd(int value_changed)
{
    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

/*
 * When the 'filetype' option is set, trigger the FileType autocommand.
 */
    static void
do_filetype_autocmd(char_u **varp, int opt_flags, int value_changed)
{
    // Skip this when called from a modeline and the filetype was already set
    // to this value.
    if ((opt_flags & OPT_MODELINE) && !value_changed)
	return;

    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;
    curbuf->b_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
/*
 * When the 'spelllang' option is set, source the spell/LANG.vim file in
 * 'runtimepath'.
 */
    static void
do_spelllang_source(void)
{
    char_u	fname[200];
    char_u	*p;
    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;

    // 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

/*
 * Handle string options that need some action to perform when changed.
 * The new value must be allocated.
 * Returns NULL for success, or an untranslated 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
    char_u	*oldval,		// previous value of the option
    char_u	*value,			// new value of the option
    char	*errbuf,		// buffer for errors, or NULL
    size_t	errbuflen,		// length of error buffer
    int		opt_flags,		// OPT_LOCAL and/or OPT_GLOBAL
    set_op_T    op,			// OP_ADDING/OP_PREPENDING/OP_REMOVING
    int		*value_checked)		// value was checked to be safe, no
					// need to set P_INSECURE
{
    char	*errmsg = NULL;
    long_u	free_oldval = (get_option_flags(opt_idx) & P_ALLOCED);
    opt_did_set_cb_T did_set_cb = get_option_did_set_cb(opt_idx);
    optset_T	args;

    // 'ttytype' is an alias for 'term'.  Both 'term' and 'ttytype' point to
    // T_NAME.  If 'term' or 'ttytype' is modified, then use the index for the
    // 'term' option.  Only set the P_ALLOCED flag on 'term'.
    if (varp == &T_NAME)
    {
	opt_idx = findoption((char_u *)"term");
	if (opt_idx >= 0)
	{
	    free_oldval = (get_option_flags(opt_idx) & P_ALLOCED);
	    did_set_cb = get_option_did_set_cb(opt_idx);
	}
    }

    CLEAR_FIELD(args);

    // Disallow changing some options from secure mode
    if ((secure
#ifdef HAVE_SANDBOX
		|| sandbox != 0
#endif
		) && (get_option_flags(opt_idx) & P_SECURE))
	errmsg = e_not_allowed_here;
    // Check for a "normal" directory or file name in some options.
    else if (check_illegal_path_names(opt_idx, varp))
	errmsg = e_invalid_argument;
    else if (did_set_cb != NULL)
    {
	args.os_varp = (char_u *)varp;
	args.os_idx = opt_idx;
	args.os_flags = opt_flags;
	args.os_op = op;
	args.os_oldval.string = oldval;
	args.os_newval.string = value;
	args.os_errbuf = errbuf;
	args.os_errbuflen = errbuflen;
	// Invoke the option specific callback function to validate and apply
	// the new option value.
	errmsg = did_set_cb(&args);

	// The 'keymap', 'filetype' and 'syntax' option callback functions
	// may change the os_value_checked field.
	*value_checked = args.os_value_checked;
    }

    // If an error is detected, restore the previous value.
    if (errmsg != NULL)
    {
	free_string_option(*varp);
	*varp = oldval;
	// When resetting some values, need to act on it.
	if (args.os_restore_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);
	set_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
	    char_u *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
	if (varp == &(curbuf->b_p_syn))
	    do_syntax_autocmd(args.os_value_changed);
#endif
	else if (varp == &(curbuf->b_p_ft))
	    do_filetype_autocmd(varp, opt_flags, args.os_value_changed);
#ifdef FEAT_SPELL
	if (varp == &(curwin->w_s->b_p_spl))
	    do_spelllang_source();
#endif
    }

    if (varp == &p_mouse)
    {
	if (*p_mouse == NUL)
	    mch_setmouse(FALSE);    // switch mouse off
	else
	    setmouse();		    // in case 'mouse' changed
    }

#if defined(FEAT_LUA) || defined(PROTO)
    if (varp == &p_rtp)
	update_package_paths_in_lua();
#endif

#if defined(FEAT_LINEBREAK)
    // Changing Formatlistpattern when briopt includes the list setting:
    // redraw
    if ((varp == &p_flp || varp == &(curbuf->b_p_flp))
	    && curwin->w_briopt_list)
	redraw_all_later(UPD_NOT_VALID);
#endif

    if (curwin->w_curswant != MAXCOL
		   && (get_option_flags(opt_idx) & (P_CURSWANT | P_RALL)) != 0
				&& (get_option_flags(opt_idx) & P_HLONLY) == 0)
	curwin->w_set_curswant = TRUE;

    if ((opt_flags & OPT_NO_REDRAW) == 0)
    {
#ifdef FEAT_GUI
	// set when changing an option that only requires a redraw in the GUI
	int	redraw_gui_only = FALSE;

	if (varp == &p_go			// 'guioptions'
		|| varp == &p_guifont		// 'guifont'
# ifdef FEAT_GUI_TABLINE
		|| varp == &p_gtl		// 'guitablabel'
		|| varp == &p_gtt		// 'guitabtooltip'
# endif
# ifdef FEAT_XFONTSET
		|| varp == &p_guifontset	// 'guifontset'
# endif
		|| varp == &p_guifontwide	// 'guifontwide'
# if defined(FEAT_GUI_GTK) || defined(FEAT_GUI_MSWIN)
		|| varp == &p_guiligatures	// 'guiligatures'
# endif
	    )
	    redraw_gui_only = TRUE;

	// 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 (args.os_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);
}

/*
 * Save the actual shortmess Flags and clear them temporarily to avoid that
 * file messages overwrites any output from the following commands.
 *
 * Caller must make sure to first call save_clear_shm_value() and then
 * restore_shm_value() exactly the same number of times.
 */
    void
save_clear_shm_value(void)
{
    if (STRLEN(p_shm) >= SHM_LEN)
    {
	iemsg(e_internal_error_shortmess_too_long);
	return;
    }

    if (++set_shm_recursive == 1)
    {
	STRCPY(shm_buf, p_shm);
	set_option_value_give_err((char_u *)"shm", 0L, (char_u *)"", 0);
    }
}

/*
 * Restore the shortmess Flags set from the save_clear_shm_value() function.
 */
    void
restore_shm_value(void)
{
    if (--set_shm_recursive == 0)
    {
	set_option_value_give_err((char_u *)"shm", 0L, shm_buf, 0);
	vim_memset(shm_buf, 0, SHM_LEN);
    }
}