Merge remote-tracking branch 'upstream/master' into userreg

1 files changed, 1183 insertions, 886 deletions

diff --git a/src/nvim/optionstr.c b/src/nvim/optionstr.c
index 1da6fa15d7..a5a708600f 100644
--- a/src/nvim/optionstr.c
+++ b/src/nvim/optionstr.c
@@ -2,14 +2,14 @@
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
 #include <assert.h>
-#include <inttypes.h>
 #include <stdbool.h>
-#include <stdlib.h>
+#include <stdint.h>
 #include <string.h>
 
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
 #include "nvim/cursor_shape.h"
@@ -17,27 +17,40 @@
 #include "nvim/digraph.h"
 #include "nvim/drawscreen.h"
 #include "nvim/eval.h"
+#include "nvim/eval/typval_defs.h"
+#include "nvim/eval/userfunc.h"
 #include "nvim/eval/vars.h"
 #include "nvim/ex_getln.h"
-#include "nvim/hardcopy.h"
+#include "nvim/fold.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
 #include "nvim/highlight_group.h"
 #include "nvim/indent.h"
 #include "nvim/indent_c.h"
 #include "nvim/insexpand.h"
 #include "nvim/keycodes.h"
+#include "nvim/macros.h"
 #include "nvim/mapping.h"
+#include "nvim/mbyte.h"
 #include "nvim/memline.h"
+#include "nvim/memory.h"
+#include "nvim/message.h"
 #include "nvim/mouse.h"
 #include "nvim/move.h"
 #include "nvim/ops.h"
 #include "nvim/option.h"
+#include "nvim/option_defs.h"
 #include "nvim/optionstr.h"
+#include "nvim/os/os.h"
+#include "nvim/pos.h"
 #include "nvim/quickfix.h"
 #include "nvim/runtime.h"
+#include "nvim/screen.h"
 #include "nvim/spell.h"
 #include "nvim/spellfile.h"
 #include "nvim/spellsuggest.h"
 #include "nvim/strings.h"
+#include "nvim/tag.h"
 #include "nvim/ui.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
@@ -78,7 +91,7 @@ static char *(p_swb_values[]) = { "useopen", "usetab", "split", "newtab", "vspli
 static char *(p_spk_values[]) = { "cursor", "screen", "topline", NULL };
 static char *(p_tc_values[]) = { "followic", "ignore", "match", "followscs", "smart", NULL };
 static char *(p_ve_values[]) = { "block", "insert", "all", "onemore", "none", "NONE", NULL };
-static char *(p_wop_values[]) = { "tagfile", "pum", NULL };
+static char *(p_wop_values[]) = { "tagfile", "pum", "fuzzy", NULL };
 static char *(p_wak_values[]) = { "yes", "menu", "no", NULL };
 static char *(p_mousem_values[]) = { "extend", "popup", "popup_setpos", "mac", NULL };
 static char *(p_sel_values[]) = { "inclusive", "exclusive", "old", NULL };
@@ -113,12 +126,14 @@ static char *(p_icm_values[]) = { "nosplit", "split", NULL };
 static char *(p_jop_values[]) = { "stack", "view", NULL };
 static char *(p_tpf_values[]) = { "BS", "HT", "FF", "ESC", "DEL", "C0", "C1", NULL };
 static char *(p_rdb_values[]) = { "compositor", "nothrottle", "invalid", "nodelta", NULL };
+static char *(p_sloc_values[]) = { "last", "statusline", "tabline", NULL };
 
 /// All possible flags for 'shm'.
 static char SHM_ALL[] = { SHM_RO, SHM_MOD, SHM_FILE, SHM_LAST, SHM_TEXT, SHM_LINES, SHM_NEW,
                           SHM_WRI, SHM_ABBREVIATIONS, SHM_WRITE, SHM_TRUNC, SHM_TRUNCALL,
                           SHM_OVER, SHM_OVERALL, SHM_SEARCH, SHM_ATTENTION, SHM_INTRO,
-                          SHM_COMPLETIONMENU, SHM_RECORDING, SHM_FILEINFO, SHM_SEARCHCOUNT, 0, };
+                          SHM_COMPLETIONMENU, SHM_COMPLETIONSCAN, SHM_RECORDING, SHM_FILEINFO,
+                          SHM_SEARCHCOUNT, 0, };
 
 /// After setting various option values: recompute variables that depend on
 /// option values.
@@ -148,40 +163,41 @@ void didset_string_options(void)
 /// "oldval_l"  the old local value (only non-NULL if global and local value are set)
 /// "oldval_g"  the old global value (only non-NULL if global and local value are set)
 /// "newval"    the new value
-void trigger_optionsset_string(int opt_idx, int opt_flags, char *oldval, char *oldval_l,
-                               char *oldval_g, char *newval)
+void trigger_optionset_string(int opt_idx, int opt_flags, char *oldval, char *oldval_l,
+                              char *oldval_g, char *newval)
 {
   // Don't do this recursively.
-  if (oldval != NULL
-      && newval != NULL
-      && *get_vim_var_str(VV_OPTION_TYPE) == NUL) {
-    char buf_type[7];
+  if (oldval == NULL || newval == NULL
+      || *get_vim_var_str(VV_OPTION_TYPE) != NUL) {
+    return;
+  }
 
-    vim_snprintf(buf_type, ARRAY_SIZE(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, "setlocal", -1);
-      set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
-    }
-    if (opt_flags & OPT_GLOBAL) {
-      set_vim_var_string(VV_OPTION_COMMAND, "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, "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, "modeline", -1);
-      set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
-    }
-    apply_autocmds(EVENT_OPTIONSET, get_option(opt_idx)->fullname, NULL, false, NULL);
-    reset_v_option_vars();
+  char buf_type[7];
+
+  vim_snprintf(buf_type, ARRAY_SIZE(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, "setlocal", -1);
+    set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
+  }
+  if (opt_flags & OPT_GLOBAL) {
+    set_vim_var_string(VV_OPTION_COMMAND, "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, "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, "modeline", -1);
+    set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
   }
+  apply_autocmds(EVENT_OPTIONSET, get_option(opt_idx)->fullname, NULL, false, NULL);
+  reset_v_option_vars();
 }
 
 static char *illegal_char(char *errbuf, size_t errbuflen, int c)
@@ -190,7 +206,7 @@ static char *illegal_char(char *errbuf, size_t errbuflen, int c)
     return "";
   }
   vim_snprintf(errbuf, errbuflen, _("E539: Illegal character <%s>"),
-               (char *)transchar(c));
+               transchar(c));
   return errbuf;
 }
 
@@ -227,6 +243,7 @@ void check_buf_options(buf_T *buf)
   check_string_option(&buf->b_p_cink);
   check_string_option(&buf->b_p_cino);
   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_cinsd);
@@ -434,8 +451,8 @@ char *set_string_option(const int opt_idx, const char *const value, const int op
   // call autocommand after handling side effects
   if (errmsg == NULL) {
     if (!starting) {
-      trigger_optionsset_string(opt_idx, opt_flags, saved_oldval, saved_oldval_l, saved_oldval_g,
-                                saved_newval);
+      trigger_optionset_string(opt_idx, opt_flags, saved_oldval, saved_oldval_l, saved_oldval_g,
+                               saved_newval);
     }
     if (opt->flags & P_UI_OPTION) {
       ui_call_option_set(cstr_as_string(opt->fullname),
@@ -536,7 +553,7 @@ static int check_signcolumn(char *val)
 
   // check for 'auto:<NUMBER>-<NUMBER>'
   if (strlen(val) == 8
-      && !STRNCMP(val, "auto:", 5)
+      && !strncmp(val, "auto:", 5)
       && ascii_isdigit(val[5])
       && val[6] == '-'
       && ascii_isdigit(val[7])) {
@@ -597,7 +614,7 @@ char *check_stl_option(char *s)
       groupdepth++;
       continue;
     }
-    if (vim_strchr(STL_ALL, *s) == NULL) {
+    if (vim_strchr(STL_ALL, (uint8_t)(*s)) == NULL) {
       return illegal_char(errbuf, sizeof(errbuf), *s);
     }
     if (*s == '{') {
@@ -623,6 +640,952 @@ char *check_stl_option(char *s)
 
 static int shada_idx = -1;
 
+static bool check_illegal_path_names(char *val, uint32_t flags)
+{
+  // 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.
+  return (((flags & P_NFNAME)
+           && strpbrk(val, (secure ? "/\\*?[|;&<>\r\n" : "/\\*?[<>\r\n")) != NULL)
+          || ((flags & P_NDNAME)
+              && strpbrk(val, "*?[|;&<>\r\n") != NULL));
+}
+
+static void did_set_backupcopy(buf_T *buf, char *oldval, int opt_flags, char **errmsg)
+{
+  char *bkc = p_bkc;
+  unsigned int *flags = &bkc_flags;
+
+  if (opt_flags & OPT_LOCAL) {
+    bkc = buf->b_p_bkc;
+    flags = &buf->b_bkc_flags;
+  }
+
+  if ((opt_flags & OPT_LOCAL) && *bkc == NUL) {
+    // make the local value empty: use the global value
+    *flags = 0;
+  } else {
+    if (opt_strings_flags(bkc, p_bkc_values, flags, true) != OK) {
+      *errmsg = e_invarg;
+    }
+
+    if (((*flags & BKC_AUTO) != 0)
+        + ((*flags & BKC_YES) != 0)
+        + ((*flags & BKC_NO) != 0) != 1) {
+      // Must have exactly one of "auto", "yes"  and "no".
+      (void)opt_strings_flags(oldval, p_bkc_values, flags, true);
+      *errmsg = e_invarg;
+    }
+  }
+}
+
+static void did_set_backupext_or_patchmode(char **errmsg)
+{
+  if (strcmp(*p_bex == '.' ? p_bex + 1 : p_bex,
+             *p_pm == '.' ? p_pm + 1 : p_pm) == 0) {
+    *errmsg = e_backupext_and_patchmode_are_equal;
+  }
+}
+
+static void did_set_breakindentopt(win_T *win, char **errmsg)
+{
+  if (briopt_check(win) == FAIL) {
+    *errmsg = e_invarg;
+  }
+  // list setting requires a redraw
+  if (win == curwin && win->w_briopt_list) {
+    redraw_all_later(UPD_NOT_VALID);
+  }
+}
+
+static void did_set_isopt(buf_T *buf, bool *did_chartab, char **errmsg)
+{
+  // '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 (buf_init_chartab(buf, true) == FAIL) {
+    *did_chartab = true;           // need to restore it below
+    *errmsg = e_invarg;            // error in value
+  }
+}
+
+static void did_set_helpfile(void)
+{
+  // May compute new values for $VIM and $VIMRUNTIME
+  if (didset_vim) {
+    vim_unsetenv_ext("VIM");
+  }
+  if (didset_vimruntime) {
+    vim_unsetenv_ext("VIMRUNTIME");
+  }
+}
+
+static void did_set_cursorlineopt(win_T *win, char **varp, char **errmsg)
+{
+  if (**varp == NUL || fill_culopt_flags(*varp, win) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_helplang(char **errmsg)
+{
+  // Check for "", "ab", "ab,cd", etc.
+  for (char *s = p_hlg; *s != NUL; s += 3) {
+    if (s[1] == NUL || ((s[2] != ',' || s[3] == NUL) && s[2] != NUL)) {
+      *errmsg = e_invarg;
+      break;
+    }
+    if (s[2] == NUL) {
+      break;
+    }
+  }
+}
+
+static void did_set_highlight(char **varp, char **errmsg)
+{
+  if (strcmp(*varp, HIGHLIGHT_INIT) != 0) {
+    *errmsg = e_unsupportedoption;
+  }
+}
+
+static void did_set_opt_flags(char *val, char **values, unsigned *flagp, bool list, char **errmsg)
+{
+  if (opt_strings_flags(val, values, flagp, list) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_opt_strings(char *val, char **values, bool list, char **errmsg)
+{
+  did_set_opt_flags(val, values, NULL, list, errmsg);
+}
+
+static void did_set_sessionoptions(char *oldval, char **errmsg)
+{
+  if (opt_strings_flags(p_ssop, p_ssop_values, &ssop_flags, true) != OK) {
+    *errmsg = e_invarg;
+  }
+  if ((ssop_flags & SSOP_CURDIR) && (ssop_flags & SSOP_SESDIR)) {
+    // Don't allow both "sesdir" and "curdir".
+    (void)opt_strings_flags(oldval, p_ssop_values, &ssop_flags, true);
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_ambiwidth(char **errmsg)
+{
+  if (check_opt_strings(p_ambw, p_ambw_values, false) != OK) {
+    *errmsg = e_invarg;
+  } else {
+    *errmsg = check_chars_options();
+  }
+}
+
+static void did_set_background(char **errmsg)
+{
+  if (check_opt_strings(p_bg, p_bg_values, false) != OK) {
+    *errmsg = e_invarg;
+    return;
+  }
+
+  int dark = (*p_bg == 'd');
+
+  init_highlight(false, false);
+
+  if (dark != (*p_bg == 'd') && get_var_value("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(S_LEN("g:colors_name"), true);
+    free_string_option(p_bg);
+    p_bg = xstrdup((dark ? "dark" : "light"));
+    check_string_option(&p_bg);
+    init_highlight(false, false);
+  }
+}
+
+static void did_set_wildmode(char **errmsg)
+{
+  if (check_opt_wim() == FAIL) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_winaltkeys(char **errmsg)
+{
+  if (*p_wak == NUL || check_opt_strings(p_wak, p_wak_values, false) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_eventignore(char **errmsg)
+{
+  if (check_ei() == FAIL) {
+    *errmsg = e_invarg;
+  }
+}
+
+// 'encoding', 'fileencoding' and 'makeencoding'
+static void did_set_encoding(buf_T *buf, char **varp, char **gvarp, int opt_flags, char **errmsg)
+{
+  if (gvarp == &p_fenc) {
+    if (!MODIFIABLE(buf) && opt_flags != OPT_GLOBAL) {
+      *errmsg = e_modifiable;
+      return;
+    }
+
+    if (vim_strchr(*varp, ',') != NULL) {
+      // No comma allowed in 'fileencoding'; catches confusing it
+      // with 'fileencodings'.
+      *errmsg = e_invarg;
+      return;
+    }
+
+    // May show a "+" in the title now.
+    redraw_titles();
+    // Add 'fileencoding' to the swap file.
+    ml_setflags(buf);
+  }
+
+  // canonize the value, so that strcmp() can be used on it
+  char *p = enc_canonize(*varp);
+  xfree(*varp);
+  *varp = p;
+  if (varp == &p_enc) {
+    // only encoding=utf-8 allowed
+    if (strcmp(p_enc, "utf-8") != 0) {
+      *errmsg = e_unsupportedoption;
+      return;
+    }
+    spell_reload();
+  }
+}
+
+static void did_set_keymap(buf_T *buf, char **varp, int opt_flags, int *value_checked,
+                           char **errmsg)
+{
+  if (!valid_filetype(*varp)) {
+    *errmsg = e_invarg;
+    return;
+  }
+
+  int secure_save = secure;
+
+  // Reset the secure flag, since the value of 'keymap' has
+  // been checked to be safe.
+  secure = 0;
+
+  // load or unload key mapping tables
+  *errmsg = keymap_init();
+
+  secure = secure_save;
+
+  // Since we check the value, there is no need to set P_INSECURE,
+  // even when the value comes from a modeline.
+  *value_checked = true;
+
+  if (*errmsg == NULL) {
+    if (*buf->b_p_keymap != NUL) {
+      // Installed a new keymap, switch on using it.
+      buf->b_p_iminsert = B_IMODE_LMAP;
+      if (buf->b_p_imsearch != B_IMODE_USE_INSERT) {
+        buf->b_p_imsearch = B_IMODE_LMAP;
+      }
+    } else {
+      // Cleared the keymap, may reset 'iminsert' and 'imsearch'.
+      if (buf->b_p_iminsert == B_IMODE_LMAP) {
+        buf->b_p_iminsert = B_IMODE_NONE;
+      }
+      if (buf->b_p_imsearch == B_IMODE_LMAP) {
+        buf->b_p_imsearch = B_IMODE_USE_INSERT;
+      }
+    }
+    if ((opt_flags & OPT_LOCAL) == 0) {
+      set_iminsert_global(buf);
+      set_imsearch_global(buf);
+    }
+    status_redraw_buf(buf);
+  }
+}
+
+static void did_set_fileformat(buf_T *buf, char **varp, const char *oldval, int opt_flags,
+                               char **errmsg)
+{
+  if (!MODIFIABLE(buf) && !(opt_flags & OPT_GLOBAL)) {
+    *errmsg = e_modifiable;
+  } else if (check_opt_strings(*varp, p_ff_values, false) != OK) {
+    *errmsg = e_invarg;
+  } else {
+    redraw_titles();
+    // update flag in swap file
+    ml_setflags(buf);
+    // Redraw needed when switching to/from "mac": a CR in the text
+    // will be displayed differently.
+    if (get_fileformat(buf) == EOL_MAC || *oldval == 'm') {
+      redraw_buf_later(buf, UPD_NOT_VALID);
+    }
+  }
+}
+
+static void did_set_matchpairs(char **varp, char **errmsg)
+{
+  for (char *p = *varp; *p != NUL; p++) {
+    int x2 = -1;
+    int x3 = -1;
+
+    p += utfc_ptr2len(p);
+    if (*p != NUL) {
+      x2 = (unsigned char)(*p++);
+    }
+    if (*p != NUL) {
+      x3 = utf_ptr2char(p);
+      p += utfc_ptr2len(p);
+    }
+    if (x2 != ':' || x3 == -1 || (*p != NUL && *p != ',')) {
+      *errmsg = e_invarg;
+      break;
+    }
+    if (*p == NUL) {
+      break;
+    }
+  }
+}
+
+static void did_set_comments(char **varp, char *errbuf, size_t errbuflen, char **errmsg)
+{
+  for (char *s = *varp; *s;) {
+    while (*s && *s != ':') {
+      if (vim_strchr(COM_ALL, (uint8_t)(*s)) == NULL
+          && !ascii_isdigit(*s) && *s != '-') {
+        *errmsg = illegal_char(errbuf, errbuflen, *s);
+        break;
+      }
+      s++;
+    }
+    if (*s++ == NUL) {
+      *errmsg = N_("E524: Missing colon");
+    } else if (*s == ',' || *s == NUL) {
+      *errmsg = N_("E525: Zero length string");
+    }
+    if (*errmsg != NULL) {
+      break;
+    }
+    while (*s && *s != ',') {
+      if (*s == '\\' && s[1] != NUL) {
+        s++;
+      }
+      s++;
+    }
+    s = skip_to_option_part(s);
+  }
+}
+
+static void did_set_global_listfillchars(win_T *win, char **varp, int opt_flags, char **errmsg)
+{
+  char **local_ptr = varp == &p_lcs ? &win->w_p_lcs : &win->w_p_fcs;
+  // only apply the global value to "win" when it does not have a local value
+  *errmsg = set_chars_option(win, varp, **local_ptr == NUL || !(opt_flags & OPT_GLOBAL));
+  if (*errmsg == NULL) {
+    // 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.
+      local_ptr = varp == &p_lcs ? &wp->w_p_lcs : &wp->w_p_fcs;
+      if (**local_ptr == NUL) {
+        (void)set_chars_option(wp, local_ptr, true);
+      }
+    }
+    redraw_all_later(UPD_NOT_VALID);
+  }
+}
+
+static void did_set_verbosefile(char **errmsg)
+{
+  verbose_stop();
+  if (*p_vfile != NUL && verbose_open() == FAIL) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_shada(vimoption_T **opt, int *opt_idx, bool *free_oldval, char *errbuf,
+                          size_t errbuflen, char **errmsg)
+{
+  // TODO(ZyX-I): Remove this code in the future, alongside with &viminfo
+  //              option.
+  *opt_idx = (((*opt)->fullname[0] == 'v')
+              ? (shada_idx == -1 ? ((shada_idx = findoption("shada"))) : shada_idx)
+              : *opt_idx);
+  *opt = get_option(*opt_idx);
+  // Update free_oldval now that we have the opt_idx for 'shada', otherwise
+  // there would be a disconnect between the check for P_ALLOCED at the start
+  // of the function and the set of P_ALLOCED at the end of the function.
+  *free_oldval = ((*opt)->flags & P_ALLOCED);
+  for (char *s = p_shada; *s;) {
+    // Check it's a valid character
+    if (vim_strchr("!\"%'/:<@cfhnrs", (uint8_t)(*s)) == NULL) {
+      *errmsg = illegal_char(errbuf, 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 (ascii_isdigit(*++s)) {}
+    } else if (*s == '!' || *s == 'h' || *s == 'c') {
+      s++;                    // no extra chars
+    } else {                    // must have a number
+      while (ascii_isdigit(*++s)) {}
+
+      if (!ascii_isdigit(*(s - 1))) {
+        if (errbuf != NULL) {
+          vim_snprintf(errbuf, errbuflen,
+                       _("E526: Missing number after <%s>"),
+                       transchar_byte((uint8_t)(*(s - 1))));
+          *errmsg = errbuf;
+        } else {
+          *errmsg = "";
+        }
+        break;
+      }
+    }
+    if (*s == ',') {
+      s++;
+    } else if (*s) {
+      if (errbuf != NULL) {
+        *errmsg = N_("E527: Missing comma");
+      } else {
+        *errmsg = "";
+      }
+      break;
+    }
+  }
+  if (*p_shada && *errmsg == NULL && get_shada_parameter('\'') < 0) {
+    *errmsg = N_("E528: Must specify a ' value");
+  }
+}
+
+static void did_set_showbreak(char **varp, char **errmsg)
+{
+  for (char *s = *varp; *s;) {
+    if (ptr2cells(s) != 1) {
+      *errmsg = e_showbreak_contains_unprintable_or_wide_character;
+    }
+    MB_PTR_ADV(s);
+  }
+}
+
+static void did_set_titleiconstring(char **varp)
+{
+  // 'titlestring' and 'iconstring'
+  int flagval = (varp == &p_titlestring) ? STL_IN_TITLE : STL_IN_ICON;
+
+  // NULL => statusline syntax
+  if (vim_strchr(*varp, '%') && check_stl_option(*varp) == NULL) {
+    stl_syntax |= flagval;
+  } else {
+    stl_syntax &= ~flagval;
+  }
+  did_set_title();
+}
+
+static void did_set_selection(char **errmsg)
+{
+  if (*p_sel == NUL || check_opt_strings(p_sel, p_sel_values, false) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_keymodel(char **errmsg)
+{
+  if (check_opt_strings(p_km, p_km_values, true) != OK) {
+    *errmsg = e_invarg;
+    return;
+  }
+  km_stopsel = (vim_strchr(p_km, 'o') != NULL);
+  km_startsel = (vim_strchr(p_km, 'a') != NULL);
+}
+
+static void did_set_display(char **errmsg)
+{
+  if (opt_strings_flags(p_dy, p_dy_values, &dy_flags, true) != OK) {
+    *errmsg = e_invarg;
+    return;
+  }
+  (void)init_chartab();
+  msg_grid_validate();
+}
+
+static void did_set_spellfile(char **varp, char **errmsg)
+{
+  // When there is a window for this buffer in which 'spell'
+  // is set load the wordlists.
+
+  if ((!valid_spellfile(*varp))) {
+    *errmsg = e_invarg;
+  } else {
+    *errmsg = did_set_spell_option(true);
+  }
+}
+
+static void did_set_spell(char **varp, char **errmsg)
+{
+  // When there is a window for this buffer in which 'spell'
+  // is set load the wordlists.
+  if (!valid_spelllang(*varp)) {
+    *errmsg = e_invarg;
+  } else {
+    *errmsg = did_set_spell_option(false);
+  }
+}
+
+static void did_set_spellcapcheck(win_T *win, char **errmsg)
+{
+  // When 'spellcapcheck' is set compile the regexp program.
+  *errmsg = compile_cap_prog(win->w_s);
+}
+
+static void did_set_spelloptions(win_T *win, char **errmsg)
+{
+  if (opt_strings_flags(win->w_s->b_p_spo, p_spo_values, &(win->w_s->b_p_spo_flags),
+                        true) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_spellsuggest(char **errmsg)
+{
+  if (spell_check_sps() != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_mkspellmem(char **errmsg)
+{
+  if (spell_check_msm() != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_buftype(buf_T *buf, win_T *win, char **errmsg)
+{
+  // When 'buftype' is set, check for valid value.
+  if ((buf->terminal && buf->b_p_bt[0] != 't')
+      || (!buf->terminal && buf->b_p_bt[0] == 't')
+      || check_opt_strings(buf->b_p_bt, p_buftype_values, false) != OK) {
+    *errmsg = e_invarg;
+  } else {
+    if (win->w_status_height || global_stl_height()) {
+      win->w_redr_status = true;
+      redraw_later(win, UPD_VALID);
+    }
+    buf->b_help = (buf->b_p_bt[0] == 'h');
+    redraw_titles();
+  }
+}
+
+// 'statusline', 'winbar', 'tabline', 'rulerformat' or 'statuscolumn'
+static void did_set_statusline(win_T *win, char **varp, char **gvarp, char **errmsg)
+{
+  if (varp == &p_ruf) {       // reset ru_wid first
+    ru_wid = 0;
+  } else if (varp == &win->w_p_stc) {
+    win->w_nrwidth_line_count = 0;
+  }
+  char *s = *varp;
+  if (varp == &p_ruf && *s == '%') {
+    // set ru_wid if 'ruf' starts with "%99("
+    if (*++s == '-') {        // ignore a '-'
+      s++;
+    }
+    int wid = getdigits_int(&s, true, 0);
+    if (wid && *s == '(' && (*errmsg = check_stl_option(p_ruf)) == NULL) {
+      ru_wid = wid;
+    } else {
+      *errmsg = check_stl_option(p_ruf);
+    }
+  } else if (varp == &p_ruf || s[0] != '%' || s[1] != '!') {
+    // check 'statusline', 'winbar', 'tabline' or 'statuscolumn'
+    // only if it doesn't start with "%!"
+    *errmsg = check_stl_option(s);
+  }
+  if (varp == &p_ruf && *errmsg == NULL) {
+    comp_col();
+  }
+  // add / remove window bars for 'winbar'
+  if (gvarp == &p_wbr) {
+    set_winbar(true);
+  }
+}
+
+static void did_set_complete(char **varp, char *errbuf, size_t errbuflen, char **errmsg)
+{
+  // check if it is a valid value for 'complete' -- Acevedo
+  for (char *s = *varp; *s;) {
+    while (*s == ',' || *s == ' ') {
+      s++;
+    }
+    if (!*s) {
+      break;
+    }
+    if (vim_strchr(".wbuksid]tU", (uint8_t)(*s)) == NULL) {
+      *errmsg = illegal_char(errbuf, errbuflen, *s);
+      break;
+    }
+    if (*++s != NUL && *s != ',' && *s != ' ') {
+      if (s[-1] == 'k' || s[-1] == 's') {
+        // skip optional filename after 'k' and 's'
+        while (*s && *s != ',' && *s != ' ') {
+          if (*s == '\\' && s[1] != NUL) {
+            s++;
+          }
+          s++;
+        }
+      } else {
+        if (errbuf != NULL) {
+          vim_snprintf(errbuf, errbuflen,
+                       _("E535: Illegal character after <%c>"),
+                       *--s);
+          *errmsg = errbuf;
+        } else {
+          *errmsg = "";
+        }
+        break;
+      }
+    }
+  }
+}
+
+static void did_set_completeopt(char **errmsg)
+{
+  if (check_opt_strings(p_cot, p_cot_values, true) != OK) {
+    *errmsg = e_invarg;
+  } else {
+    completeopt_was_set();
+  }
+}
+
+static void did_set_signcolumn(win_T *win, char **varp, const char *oldval, char **errmsg)
+{
+  if (check_signcolumn(*varp) != OK) {
+    *errmsg = e_invarg;
+  }
+  // When changing the 'signcolumn' to or from 'number', recompute the
+  // width of the number column if 'number' or 'relativenumber' is set.
+  if (((*oldval == 'n' && *(oldval + 1) == 'u')
+       || (*win->w_p_scl == 'n' && *(win->w_p_scl + 1) == 'u'))
+      && (win->w_p_nu || win->w_p_rnu)) {
+    win->w_nrwidth_line_count = 0;
+  }
+}
+
+static void did_set_foldcolumn(char **varp, char **errmsg)
+{
+  if (**varp == NUL || check_opt_strings(*varp, p_fdc_values, false) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_pastetoggle(void)
+{
+  // 'pastetoggle': translate key codes like in a mapping
+  if (*p_pt) {
+    char *p = NULL;
+    (void)replace_termcodes(p_pt,
+                            strlen(p_pt),
+                            &p, REPTERM_FROM_PART | REPTERM_DO_LT, NULL,
+                            CPO_TO_CPO_FLAGS);
+    if (p != NULL) {
+      free_string_option(p_pt);
+      p_pt = p;
+    }
+  }
+}
+
+static void did_set_backspace(char **errmsg)
+{
+  if (ascii_isdigit(*p_bs)) {
+    if (*p_bs > '3' || p_bs[1] != NUL) {
+      *errmsg = e_invarg;
+    }
+  } else if (check_opt_strings(p_bs, p_bs_values, true) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_tagcase(buf_T *buf, int opt_flags, char **errmsg)
+{
+  unsigned int *flags;
+  char *p;
+
+  if (opt_flags & OPT_LOCAL) {
+    p = buf->b_p_tc;
+    flags = &buf->b_tc_flags;
+  } else {
+    p = p_tc;
+    flags = &tc_flags;
+  }
+
+  if ((opt_flags & OPT_LOCAL) && *p == NUL) {
+    // make the local value empty: use the global value
+    *flags = 0;
+  } else if (*p == NUL
+             || opt_strings_flags(p, p_tc_values, flags, false) != OK) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_diffopt(char **errmsg)
+{
+  if (diffopt_changed() == FAIL) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_foldmethod(win_T *win, char **varp, char **errmsg)
+{
+  if (check_opt_strings(*varp, p_fdm_values, false) != OK
+      || *win->w_p_fdm == NUL) {
+    *errmsg = e_invarg;
+  } else {
+    foldUpdateAll(win);
+    if (foldmethodIsDiff(win)) {
+      newFoldLevel();
+    }
+  }
+}
+
+static void did_set_foldmarker(win_T *win, char **varp, char **errmsg)
+{
+  char *p = vim_strchr(*varp, ',');
+  if (p == NULL) {
+    *errmsg = N_("E536: comma required");
+  } else if (p == *varp || p[1] == NUL) {
+    *errmsg = e_invarg;
+  } else if (foldmethodIsMarker(win)) {
+    foldUpdateAll(win);
+  }
+}
+
+static void did_set_commentstring(char **varp, char **errmsg)
+{
+  if (**varp != NUL && strstr(*varp, "%s") == NULL) {
+    *errmsg = N_("E537: 'commentstring' must be empty or contain %s");
+  }
+}
+
+static void did_set_foldignore(win_T *win)
+{
+  if (foldmethodIsIndent(win)) {
+    foldUpdateAll(win);
+  }
+}
+
+static void did_set_virtualedit(win_T *win, int opt_flags, char *oldval, char **errmsg)
+{
+  char *ve = p_ve;
+  unsigned int *flags = &ve_flags;
+
+  if (opt_flags & OPT_LOCAL) {
+    ve = win->w_p_ve;
+    flags = &win->w_ve_flags;
+  }
+
+  if ((opt_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) {
+      *errmsg = e_invarg;
+    } else if (strcmp(p_ve, oldval) != 0) {
+      // Recompute cursor position in case the new 've' setting
+      // changes something.
+      validate_virtcol_win(win);
+      coladvance(win->w_virtcol);
+    }
+  }
+}
+
+static void did_set_lispoptions(char **varp, char **errmsg)
+{
+  if (**varp != NUL && strcmp(*varp, "expr:0") != 0 && strcmp(*varp, "expr:1") != 0) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_filetype_or_syntax(char **varp, char *oldval, int *value_checked,
+                                       bool *value_changed, char **errmsg)
+{
+  if (!valid_filetype(*varp)) {
+    *errmsg = e_invarg;
+    return;
+  }
+
+  *value_changed = strcmp(oldval, *varp) != 0;
+
+  // Since we check the value, there is no need to set P_INSECURE,
+  // even when the value comes from a modeline.
+  *value_checked = true;
+}
+
+static void did_set_winhl(win_T *win, char **errmsg)
+{
+  if (!parse_winhl_opt(win)) {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_varsoftabstop(buf_T *buf, char **varp, char **errmsg)
+{
+  if (!(*varp)[0] || ((*varp)[0] == '0' && !(*varp)[1])) {
+    XFREE_CLEAR(buf->b_p_vsts_array);
+    return;
+  }
+
+  for (char *cp = *varp; *cp; cp++) {
+    if (ascii_isdigit(*cp)) {
+      continue;
+    }
+    if (*cp == ',' && cp > *varp && *(cp - 1) != ',') {
+      continue;
+    }
+    *errmsg = e_invarg;
+    return;
+  }
+
+  long *oldarray = buf->b_p_vsts_array;
+  if (tabstop_set(*varp, &(buf->b_p_vsts_array))) {
+    xfree(oldarray);
+  } else {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_vartabstop(buf_T *buf, win_T *win, char **varp, char **errmsg)
+{
+  if (!(*varp)[0] || ((*varp)[0] == '0' && !(*varp)[1])) {
+    XFREE_CLEAR(buf->b_p_vts_array);
+    return;
+  }
+
+  for (char *cp = *varp; *cp; cp++) {
+    if (ascii_isdigit(*cp)) {
+      continue;
+    }
+    if (*cp == ',' && cp > *varp && *(cp - 1) != ',') {
+      continue;
+    }
+    *errmsg = e_invarg;
+    return;
+  }
+
+  long *oldarray = buf->b_p_vts_array;
+  if (tabstop_set(*varp, &(buf->b_p_vts_array))) {
+    xfree(oldarray);
+    if (foldmethodIsIndent(win)) {
+      foldUpdateAll(win);
+    }
+  } else {
+    *errmsg = e_invarg;
+  }
+}
+
+static void did_set_optexpr(win_T *win, char **p_opt, char **varp, char **gvarp)
+{
+  char *name = get_scriptlocal_funcname(*p_opt);
+  if (name != NULL) {
+    free_string_option(*p_opt);
+    *p_opt = name;
+  }
+}
+
+// handle option that is a list of flags.
+static void did_set_option_listflag(char **varp, char *flags, char *errbuf, size_t errbuflen,
+                                    char **errmsg)
+{
+  for (char *s = *varp; *s; s++) {
+    if (vim_strchr(flags, *s) == NULL) {
+      *errmsg = illegal_char(errbuf, errbuflen, *s);
+      break;
+    }
+  }
+}
+
+// When 'syntax' is set, load the syntax of that name
+static void do_syntax_autocmd(buf_T *buf, bool 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, buf->b_p_syn, buf->b_fname,
+                 value_changed || syn_recursive == 1, buf);
+  buf->b_flags |= BF_SYN_SET;
+  syn_recursive--;
+}
+
+static void do_filetype_autocmd(buf_T *buf, char **varp, int opt_flags, bool value_changed)
+{
+  // 'filetype' is set, trigger the FileType autocommand
+  // Skip this when called from a modeline and the filetype was
+  // already set to this value.
+  if (!(opt_flags & OPT_MODELINE) || value_changed) {
+    static int ft_recursive = 0;
+    int secure_save = secure;
+
+    // Reset the secure flag, since the value of 'filetype' has
+    // been checked to be safe.
+    secure = 0;
+
+    ft_recursive++;
+    did_filetype = true;
+    // Only pass true for "force" when the value changed or not
+    // used recursively, to avoid endless recurrence.
+    apply_autocmds(EVENT_FILETYPE, buf->b_p_ft, buf->b_fname,
+                   value_changed || ft_recursive == 1, buf);
+    ft_recursive--;
+    // Just in case the old "buf" is now invalid
+    if (varp != &(buf->b_p_ft)) {
+      varp = NULL;
+    }
+    secure = secure_save;
+  }
+}
+
+static void did_set_spelllang_source(win_T *win)
+{
+  char fname[200];
+  char *q = win->w_s->b_p_spl;
+
+  // Skip the first name if it is "cjk".
+  if (strncmp(q, "cjk,", 4) == 0) {
+    q += 4;
+  }
+
+  // Source the spell/LANG.vim in 'runtimepath'.
+  // They could set 'spellcapcheck' depending on the language.
+  // Use the first name in 'spelllang' up to '_region' or
+  // '.encoding'.
+  char *p;
+  for (p = q; *p != NUL; p++) {
+    if (!ASCII_ISALNUM(*p) && *p != '-') {
+      break;
+    }
+  }
+  if (p > q) {
+    vim_snprintf(fname, sizeof(fname), "spell/%.*s.vim", (int)(p - q), q);
+    source_runtime(fname, DIP_ALL);
+  }
+}
+
 /// Handle string options that need some action to perform when changed.
 /// The new value must be allocated.
 ///
@@ -635,12 +1598,12 @@ static int shada_idx = -1;
 /// @param value_checked  value was checked to be safe, no need to set P_INSECURE
 ///
 /// @return  NULL for success, or an untranslated error message for an error
-char *did_set_string_option(int opt_idx, char **varp, char *oldval, char *errbuf, size_t errbuflen,
-                            int opt_flags, int *value_checked)
+static char *did_set_string_option_for(buf_T *buf, win_T *win, int opt_idx, char **varp,
+                                       char *oldval, char *errbuf, size_t errbuflen, int opt_flags,
+                                       int *value_checked)
 {
   char *errmsg = NULL;
-  char *s, *p;
-  int did_chartab = false;
+  bool did_chartab = false;
   vimoption_T *opt = get_option(opt_idx);
   bool free_oldval = (opt->flags & P_ALLOCED);
   bool value_changed = false;
@@ -653,864 +1616,244 @@ char *did_set_string_option(int opt_idx, char **varp, char *oldval, char *errbuf
   if ((secure || sandbox != 0)
       && (opt->flags & P_SECURE)) {
     errmsg = e_secure;
-  } else if (((opt->flags & P_NFNAME)
-              && strpbrk(*varp, (secure ? "/\\*?[|;&<>\r\n" : "/\\*?[<>\r\n")) != NULL)
-             || ((opt->flags & P_NDNAME)
-                 && strpbrk(*varp, "*?[|;&<>\r\n") != NULL)) {
-    // Check for a "normal" directory or file name in some options.  Disallow a
-    // path separator (slash and/or backslash), wildcards and characters that
-    // are often illegal in a file name. Be more permissive if "secure" is off.
+  } else if (check_illegal_path_names(*varp, opt->flags)) {
+    // Check for a "normal" directory or file name in some options.
     errmsg = e_invarg;
   } else if (gvarp == &p_bkc) {  // 'backupcopy'
-    char *bkc = p_bkc;
-    unsigned int *flags = &bkc_flags;
-
-    if (opt_flags & OPT_LOCAL) {
-      bkc = curbuf->b_p_bkc;
-      flags = &curbuf->b_bkc_flags;
-    }
-
-    if ((opt_flags & OPT_LOCAL) && *bkc == NUL) {
-      // make the local value empty: use the global value
-      *flags = 0;
-    } else {
-      if (opt_strings_flags(bkc, p_bkc_values, flags, true) != OK) {
-        errmsg = e_invarg;
-      }
-
-      if (((*flags & BKC_AUTO) != 0)
-          + ((*flags & BKC_YES) != 0)
-          + ((*flags & BKC_NO) != 0) != 1) {
-        // Must have exactly one of "auto", "yes"  and "no".
-        (void)opt_strings_flags(oldval, p_bkc_values, flags, true);
-        errmsg = e_invarg;
-      }
-    }
+    did_set_backupcopy(buf, oldval, opt_flags, &errmsg);
   } else if (varp == &p_bex || varp == &p_pm) {  // 'backupext' and 'patchmode'
-    if (strcmp(*p_bex == '.' ? p_bex + 1 : p_bex,
-               *p_pm == '.' ? p_pm + 1 : p_pm) == 0) {
-      errmsg = e_backupext_and_patchmode_are_equal;
-    }
-  } else if (varp == &curwin->w_p_briopt) {  // 'breakindentopt'
-    if (briopt_check(curwin) == FAIL) {
-      errmsg = e_invarg;
-    }
+    did_set_backupext_or_patchmode(&errmsg);
+  } else if (varp == &win->w_p_briopt) {  // 'breakindentopt'
+    did_set_breakindentopt(win, &errmsg);
   } else if (varp == &p_isi
-             || varp == &(curbuf->b_p_isk)
+             || varp == &buf->b_p_isk
              || varp == &p_isp
              || varp == &p_isf) {
-    // '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) {
-      did_chartab = true;           // need to restore it below
-      errmsg = e_invarg;            // error in value
-    }
+    // 'isident', 'iskeyword', 'isprint or 'isfname' option
+    did_set_isopt(buf, &did_chartab, &errmsg);
   } else if (varp == &p_hf) {  // 'helpfile'
-    // May compute new values for $VIM and $VIMRUNTIME
-    if (didset_vim) {
-      vim_unsetenv_ext("VIM");
-    }
-    if (didset_vimruntime) {
-      vim_unsetenv_ext("VIMRUNTIME");
-    }
+    did_set_helpfile();
   } else if (varp == &p_rtp || varp == &p_pp) {  // 'runtimepath' 'packpath'
     runtime_search_path_invalidate();
-  } else if (varp == &curwin->w_p_culopt
-             || gvarp == &curwin->w_allbuf_opt.wo_culopt) {  // 'cursorlineopt'
-    if (**varp == NUL || fill_culopt_flags(*varp, curwin) != OK) {
-      errmsg = e_invarg;
-    }
-  } else if (varp == &curwin->w_p_cc) {  // 'colorcolumn'
-    errmsg = check_colorcolumn(curwin);
-  } else if (varp == (char **)&p_hlg) {  // 'helplang'
-    // Check for "", "ab", "ab,cd", etc.
-    for (s = (char *)p_hlg; *s != NUL; s += 3) {
-      if (s[1] == NUL || ((s[2] != ',' || s[3] == NUL) && s[2] != NUL)) {
-        errmsg = e_invarg;
-        break;
-      }
-      if (s[2] == NUL) {
-        break;
-      }
-    }
+  } else if (varp == &win->w_p_culopt
+             || gvarp == &win->w_allbuf_opt.wo_culopt) {  // 'cursorlineopt'
+    did_set_cursorlineopt(win, varp, &errmsg);
+  } else if (varp == &win->w_p_cc) {  // 'colorcolumn'
+    errmsg = check_colorcolumn(win);
+  } else if (varp == &p_hlg) {  // 'helplang'
+    did_set_helplang(&errmsg);
   } else if (varp == &p_hl) {  // 'highlight'
-    if (strcmp(*varp, HIGHLIGHT_INIT) != 0) {
-      errmsg = e_unsupportedoption;
-    }
+    did_set_highlight(varp, &errmsg);
   } else if (varp == &p_jop) {  // 'jumpoptions'
-    if (opt_strings_flags(p_jop, p_jop_values, &jop_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_jop, p_jop_values, &jop_flags, true, &errmsg);
   } else if (gvarp == &p_nf) {  // 'nrformats'
-    if (check_opt_strings(*varp, p_nf_values, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(*varp, p_nf_values, true, &errmsg);
   } else if (varp == &p_ssop) {  // 'sessionoptions'
-    if (opt_strings_flags(p_ssop, p_ssop_values, &ssop_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
-    if ((ssop_flags & SSOP_CURDIR) && (ssop_flags & SSOP_SESDIR)) {
-      // Don't allow both "sesdir" and "curdir".
-      (void)opt_strings_flags(oldval, p_ssop_values, &ssop_flags, true);
-      errmsg = e_invarg;
-    }
+    did_set_sessionoptions(oldval, &errmsg);
   } else if (varp == &p_vop) {  // 'viewoptions'
-    if (opt_strings_flags(p_vop, p_ssop_values, &vop_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_vop, p_ssop_values, &vop_flags, true, &errmsg);
   } else if (varp == &p_rdb) {  // 'redrawdebug'
-    if (opt_strings_flags(p_rdb, p_rdb_values, &rdb_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_rdb, p_rdb_values, &rdb_flags, true, &errmsg);
   } else if (varp == &p_sbo) {  // 'scrollopt'
-    if (check_opt_strings(p_sbo, p_scbopt_values, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(p_sbo, p_scbopt_values, true, &errmsg);
   } else if (varp == &p_ambw || (int *)varp == &p_emoji) {  // 'ambiwidth'
-    if (check_opt_strings(p_ambw, p_ambw_values, false) != OK) {
-      errmsg = e_invarg;
-    } else {
-      errmsg = check_chars_options();
-    }
+    did_set_ambiwidth(&errmsg);
   } else if (varp == &p_bg) {  // 'background'
-    if (check_opt_strings(p_bg, p_bg_values, false) == OK) {
-      int dark = (*p_bg == 'd');
-
-      init_highlight(false, false);
-
-      if (dark != (*p_bg == 'd') && get_var_value("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(S_LEN("g:colors_name"), true);
-        free_string_option(p_bg);
-        p_bg = xstrdup((dark ? "dark" : "light"));
-        check_string_option(&p_bg);
-        init_highlight(false, false);
-      }
-    } else {
-      errmsg = e_invarg;
-    }
+    did_set_background(&errmsg);
   } else if (varp == &p_wim) {  // 'wildmode'
-    if (check_opt_wim() == FAIL) {
-      errmsg = e_invarg;
-    }
+    did_set_wildmode(&errmsg);
   } else if (varp == &p_wop) {  // 'wildoptions'
-    if (opt_strings_flags(p_wop, p_wop_values, &wop_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_wop, p_wop_values, &wop_flags, true, &errmsg);
   } else if (varp == &p_wak) {  // 'winaltkeys'
-    if (*p_wak == NUL
-        || check_opt_strings(p_wak, p_wak_values, false) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_winaltkeys(&errmsg);
   } else if (varp == &p_ei) {  // 'eventignore'
-    if (check_ei() == FAIL) {
-      errmsg = e_invarg;
-    }
+    did_set_eventignore(&errmsg);
   } else if (varp == &p_enc || gvarp == &p_fenc || gvarp == &p_menc) {
     // 'encoding', 'fileencoding' and 'makeencoding'
-    if (gvarp == &p_fenc) {
-      if (!MODIFIABLE(curbuf) && opt_flags != OPT_GLOBAL) {
-        errmsg = e_modifiable;
-      } else if (vim_strchr(*varp, ',') != NULL) {
-        // No comma allowed in 'fileencoding'; catches confusing it
-        // with 'fileencodings'.
-        errmsg = e_invarg;
-      } else {
-        // 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);
-      xfree(*varp);
-      *varp = p;
-      if (varp == &p_enc) {
-        // only encoding=utf-8 allowed
-        if (strcmp(p_enc, "utf-8") != 0) {
-          errmsg = e_unsupportedoption;
-        } else {
-          spell_reload();
-        }
-      }
-    }
-  } else if (varp == &p_penc) {
-    // Canonize printencoding if VIM standard one
-    p = enc_canonize(p_penc);
-    xfree(p_penc);
-    p_penc = p;
-  } else if (varp == &curbuf->b_p_keymap) {
-    if (!valid_filetype(*varp)) {
-      errmsg = e_invarg;
-    } else {
-      int secure_save = secure;
-
-      // Reset the secure flag, since the value of 'keymap' has
-      // been checked to be safe.
-      secure = 0;
-
-      // load or unload key mapping tables
-      errmsg = keymap_init();
-
-      secure = secure_save;
-
-      // Since we check the value, there is no need to set P_INSECURE,
-      // even when the value comes from a modeline.
-      *value_checked = true;
-    }
-
-    if (errmsg == NULL) {
-      if (*curbuf->b_p_keymap != NUL) {
-        // Installed a new keymap, switch on using it.
-        curbuf->b_p_iminsert = B_IMODE_LMAP;
-        if (curbuf->b_p_imsearch != B_IMODE_USE_INSERT) {
-          curbuf->b_p_imsearch = B_IMODE_LMAP;
-        }
-      } else {
-        // Cleared the keymap, may reset 'iminsert' and 'imsearch'.
-        if (curbuf->b_p_iminsert == B_IMODE_LMAP) {
-          curbuf->b_p_iminsert = B_IMODE_NONE;
-        }
-        if (curbuf->b_p_imsearch == B_IMODE_LMAP) {
-          curbuf->b_p_imsearch = B_IMODE_USE_INSERT;
-        }
-      }
-      if ((opt_flags & OPT_LOCAL) == 0) {
-        set_iminsert_global();
-        set_imsearch_global();
-      }
-      status_redraw_curbuf();
-    }
+    did_set_encoding(buf, varp, gvarp, opt_flags, &errmsg);
+  } else if (varp == &buf->b_p_keymap) {
+    did_set_keymap(buf, varp, opt_flags, value_checked, &errmsg);
   } else if (gvarp == &p_ff) {  // 'fileformat'
-    if (!MODIFIABLE(curbuf) && !(opt_flags & OPT_GLOBAL)) {
-      errmsg = e_modifiable;
-    } else if (check_opt_strings(*varp, p_ff_values, false) != OK) {
-      errmsg = e_invarg;
-    } else {
-      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 || *oldval == 'm') {
-        redraw_curbuf_later(UPD_NOT_VALID);
-      }
-    }
+    did_set_fileformat(buf, varp, oldval, opt_flags, &errmsg);
   } else if (varp == &p_ffs) {  // 'fileformats'
-    if (check_opt_strings(p_ffs, p_ff_values, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(p_ffs, p_ff_values, true, &errmsg);
   } else if (gvarp == &p_mps) {  // 'matchpairs'
-    for (p = *varp; *p != NUL; p++) {
-      int x2 = -1;
-      int x3 = -1;
-
-      p += utfc_ptr2len(p);
-      if (*p != NUL) {
-        x2 = (unsigned char)(*p++);
-      }
-      if (*p != NUL) {
-        x3 = utf_ptr2char(p);
-        p += utfc_ptr2len(p);
-      }
-      if (x2 != ':' || x3 == -1 || (*p != NUL && *p != ',')) {
-        errmsg = e_invarg;
-        break;
-      }
-      if (*p == NUL) {
-        break;
-      }
-    }
+    did_set_matchpairs(varp, &errmsg);
   } else if (gvarp == &p_com) {  // 'comments'
-    for (s = *varp; *s;) {
-      while (*s && *s != ':') {
-        if (vim_strchr(COM_ALL, *s) == NULL
-            && !ascii_isdigit(*s) && *s != '-') {
-          errmsg = illegal_char(errbuf, errbuflen, *s);
-          break;
-        }
-        s++;
-      }
-      if (*s++ == NUL) {
-        errmsg = N_("E524: Missing colon");
-      } else if (*s == ',' || *s == NUL) {
-        errmsg = N_("E525: Zero length string");
-      }
-      if (errmsg != NULL) {
-        break;
-      }
-      while (*s && *s != ',') {
-        if (*s == '\\' && s[1] != NUL) {
-          s++;
-        }
-        s++;
-      }
-      s = skip_to_option_part(s);
-    }
+    did_set_comments(varp, errbuf, errbuflen, &errmsg);
   } else if (varp == &p_lcs || varp == &p_fcs) {  // global 'listchars' or 'fillchars'
-    char **local_ptr = varp == &p_lcs ? &curwin->w_p_lcs : &curwin->w_p_fcs;
-    // only apply the global value to "curwin" when it does not have a local value
-    errmsg =
-      set_chars_option(curwin, varp, **local_ptr == NUL || !(opt_flags & OPT_GLOBAL));
-    if (errmsg == NULL) {
-      // 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.
-        local_ptr = varp == &p_lcs ? &wp->w_p_lcs : &wp->w_p_fcs;
-        if (**local_ptr == NUL) {
-          (void)set_chars_option(wp, local_ptr, true);
-        }
-      }
-      redraw_all_later(UPD_NOT_VALID);
-    }
-  } else if (varp == &curwin->w_p_lcs) {  // local 'listchars'
-    errmsg = set_chars_option(curwin, varp, true);
-  } else if (varp == &curwin->w_p_fcs) {  // local 'fillchars'
-    errmsg = set_chars_option(curwin, varp, true);
+    did_set_global_listfillchars(win, varp, opt_flags, &errmsg);
+  } else if (varp == &win->w_p_lcs) {  // local 'listchars'
+    errmsg = set_chars_option(win, varp, true);
+  } else if (varp == &win->w_p_fcs) {  // local 'fillchars'
+    errmsg = set_chars_option(win, varp, true);
   } else if (varp == &p_cedit) {  // 'cedit'
     errmsg = check_cedit();
   } else if (varp == &p_vfile) {  // 'verbosefile'
-    verbose_stop();
-    if (*p_vfile != NUL && verbose_open() == FAIL) {
-      errmsg = e_invarg;
-    }
+    did_set_verbosefile(&errmsg);
   } else if (varp == &p_shada) {  // 'shada'
-    // TODO(ZyX-I): Remove this code in the future, alongside with &viminfo
-    //              option.
-    opt_idx = ((opt->fullname[0] == 'v')
-               ? (shada_idx == -1 ? ((shada_idx = findoption("shada"))) : shada_idx)
-               : opt_idx);
-    opt = get_option(opt_idx);
-    // Update free_oldval now that we have the opt_idx for 'shada', otherwise
-    // there would be a disconnect between the check for P_ALLOCED at the start
-    // of the function and the set of P_ALLOCED at the end of the function.
-    free_oldval = (opt->flags & P_ALLOCED);
-    for (s = p_shada; *s;) {
-      // Check it's a valid character
-      if (vim_strchr("!\"%'/:<@cfhnrs", *s) == NULL) {
-        errmsg = illegal_char(errbuf, 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 (ascii_isdigit(*++s)) {}
-      } else if (*s == '!' || *s == 'h' || *s == 'c') {
-        s++;                    // no extra chars
-      } else {                    // must have a number
-        while (ascii_isdigit(*++s)) {}
-
-        if (!ascii_isdigit(*(s - 1))) {
-          if (errbuf != NULL) {
-            vim_snprintf(errbuf, errbuflen,
-                         _("E526: Missing number after <%s>"),
-                         transchar_byte(*(s - 1)));
-            errmsg = errbuf;
-          } else {
-            errmsg = "";
-          }
-          break;
-        }
-      }
-      if (*s == ',') {
-        s++;
-      } else if (*s) {
-        if (errbuf != NULL) {
-          errmsg = N_("E527: Missing comma");
-        } else {
-          errmsg = "";
-        }
-        break;
-      }
-    }
-    if (*p_shada && errmsg == NULL && get_shada_parameter('\'') < 0) {
-      errmsg = N_("E528: Must specify a ' value");
-    }
+    did_set_shada(&opt, &opt_idx, &free_oldval, errbuf, errbuflen, &errmsg);
   } else if (gvarp == &p_sbr) {  // 'showbreak'
-    for (s = *varp; *s;) {
-      if (ptr2cells(s) != 1) {
-        errmsg = e_showbreak_contains_unprintable_or_wide_character;
-      }
-      MB_PTR_ADV(s);
-    }
+    did_set_showbreak(varp, &errmsg);
   } else if (varp == &p_guicursor) {  // 'guicursor'
     errmsg = parse_shape_opt(SHAPE_CURSOR);
-  } else if (varp == &p_popt) {
-    errmsg = parse_printoptions();
-  } else if (varp == &p_pmfn) {
-    errmsg = parse_printmbfont();
   } else if (varp == &p_langmap) {  // 'langmap'
     langmap_set();
   } else if (varp == &p_breakat) {  // 'breakat'
     fill_breakat_flags();
   } else if (varp == &p_titlestring || varp == &p_iconstring) {
     // 'titlestring' and 'iconstring'
-    int flagval = (varp == &p_titlestring) ? STL_IN_TITLE : STL_IN_ICON;
-
-    // NULL => statusline syntax
-    if (vim_strchr(*varp, '%') && check_stl_option(*varp) == NULL) {
-      stl_syntax |= flagval;
-    } else {
-      stl_syntax &= ~flagval;
-    }
-    did_set_title();
+    did_set_titleiconstring(varp);
   } else if (varp == &p_sel) {  // 'selection'
-    if (*p_sel == NUL
-        || check_opt_strings(p_sel, p_sel_values, false) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_selection(&errmsg);
   } else if (varp == &p_slm) {  // 'selectmode'
-    if (check_opt_strings(p_slm, p_slm_values, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(p_slm, p_slm_values, true, &errmsg);
   } else if (varp == &p_km) {  // 'keymodel'
-    if (check_opt_strings(p_km, p_km_values, true) != OK) {
-      errmsg = e_invarg;
-    } else {
-      km_stopsel = (vim_strchr(p_km, 'o') != NULL);
-      km_startsel = (vim_strchr(p_km, 'a') != NULL);
-    }
+    did_set_keymodel(&errmsg);
   } else if (varp == &p_mousem) {  // 'mousemodel'
-    if (check_opt_strings(p_mousem, p_mousem_values, false) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(p_mousem, p_mousem_values, false, &errmsg);
   } else if (varp == &p_mousescroll) {  // 'mousescroll'
     errmsg = check_mousescroll(p_mousescroll);
   } else if (varp == &p_swb) {  // 'switchbuf'
-    if (opt_strings_flags(p_swb, p_swb_values, &swb_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_swb, p_swb_values, &swb_flags, true, &errmsg);
   } else if (varp == &p_spk) {  // 'splitkeep'
-    if (check_opt_strings(p_spk, p_spk_values, false) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(p_spk, p_spk_values, false, &errmsg);
   } else if (varp == &p_debug) {  // 'debug'
-    if (check_opt_strings(p_debug, p_debug_values, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(p_debug, p_debug_values, true, &errmsg);
   } else if (varp == &p_dy) {  // 'display'
-    if (opt_strings_flags(p_dy, p_dy_values, &dy_flags, true) != OK) {
-      errmsg = e_invarg;
-    } else {
-      (void)init_chartab();
-      msg_grid_validate();
-    }
+    did_set_display(&errmsg);
   } else if (varp == &p_ead) {  // 'eadirection'
-    if (check_opt_strings(p_ead, p_ead_values, false) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(p_ead, p_ead_values, false, &errmsg);
   } else if (varp == &p_cb) {  // 'clipboard'
-    if (opt_strings_flags(p_cb, p_cb_values, &cb_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
-  } else if (varp == &(curwin->w_s->b_p_spl)  // 'spell'
-             || varp == &(curwin->w_s->b_p_spf)) {
-    // When 'spelllang' or 'spellfile' is set and there is a window for this
-    // buffer in which 'spell' is set load the wordlists.
-    const bool is_spellfile = varp == &(curwin->w_s->b_p_spf);
-
-    if ((is_spellfile && !valid_spellfile(*varp))
-        || (!is_spellfile && !valid_spelllang(*varp))) {
-      errmsg = e_invarg;
-    } else {
-      errmsg = did_set_spell_option(is_spellfile);
-    }
-  } else if (varp == &(curwin->w_s->b_p_spc)) {
-    // When 'spellcapcheck' is set compile the regexp program.
-    errmsg = compile_cap_prog(curwin->w_s);
-  } else if (varp == &(curwin->w_s->b_p_spo)) {  // 'spelloptions'
-    if (opt_strings_flags(curwin->w_s->b_p_spo, p_spo_values, &(curwin->w_s->b_p_spo_flags),
-                          true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_cb, p_cb_values, &cb_flags, true, &errmsg);
+  } else if (varp == &win->w_s->b_p_spf) {
+    did_set_spellfile(varp, &errmsg);
+  } else if (varp == &win->w_s->b_p_spl) {  // 'spell'
+    did_set_spell(varp, &errmsg);
+  } else if (varp == &win->w_s->b_p_spc) {
+    did_set_spellcapcheck(win, &errmsg);
+  } else if (varp == &win->w_s->b_p_spo) {  // 'spelloptions'
+    did_set_spelloptions(win, &errmsg);
   } else if (varp == &p_sps) {  // 'spellsuggest'
-    if (spell_check_sps() != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_spellsuggest(&errmsg);
   } else if (varp == &p_msm) {  // 'mkspellmem'
-    if (spell_check_msm() != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_mkspellmem(&errmsg);
   } else if (gvarp == &p_bh) {
-    // When 'bufhidden' is set, check for valid value.
-    if (check_opt_strings(curbuf->b_p_bh, p_bufhidden_values, false) != OK) {
-      errmsg = e_invarg;
-    }
-  } else if (gvarp == &p_bt) {
-    // When 'buftype' is set, check for valid value.
-    if ((curbuf->terminal && curbuf->b_p_bt[0] != 't')
-        || (!curbuf->terminal && curbuf->b_p_bt[0] == 't')
-        || check_opt_strings(curbuf->b_p_bt, p_buftype_values, false) != OK) {
-      errmsg = e_invarg;
-    } else {
-      if (curwin->w_status_height || global_stl_height()) {
-        curwin->w_redr_status = true;
-        redraw_later(curwin, UPD_VALID);
-      }
-      curbuf->b_help = (curbuf->b_p_bt[0] == 'h');
-      redraw_titles();
-    }
+    did_set_opt_strings(buf->b_p_bh, p_bufhidden_values, false, &errmsg);
+  } else if (gvarp == &p_bt) {  // 'buftype'
+    did_set_buftype(buf, win, &errmsg);
   } else if (gvarp == &p_stl || gvarp == &p_wbr || varp == &p_tal
-             || varp == &p_ruf) {
-    // 'statusline', 'winbar', 'tabline' or 'rulerformat'
-    int wid;
-
-    if (varp == &p_ruf) {       // reset ru_wid first
-      ru_wid = 0;
-    }
-    s = *varp;
-    if (varp == &p_ruf && *s == '%') {
-      // set ru_wid if 'ruf' starts with "%99("
-      if (*++s == '-') {        // ignore a '-'
-        s++;
-      }
-      wid = getdigits_int(&s, true, 0);
-      if (wid && *s == '(' && (errmsg = check_stl_option(p_ruf)) == NULL) {
-        ru_wid = wid;
-      } else {
-        errmsg = check_stl_option(p_ruf);
-      }
-    } else if (varp == &p_ruf || s[0] != '%' || s[1] != '!') {
-      // check 'statusline', 'winbar' or 'tabline' only if it doesn't start with "%!"
-      errmsg = check_stl_option(s);
-    }
-    if (varp == &p_ruf && errmsg == NULL) {
-      comp_col();
-    }
-    // add / remove window bars for 'winbar'
-    if (gvarp == &p_wbr) {
-      set_winbar(true);
-    }
-  } else if (gvarp == &p_cpt) {
-    // check if it is a valid value for 'complete' -- Acevedo
-    for (s = *varp; *s;) {
-      while (*s == ',' || *s == ' ') {
-        s++;
-      }
-      if (!*s) {
-        break;
-      }
-      if (vim_strchr(".wbuksid]tU", *s) == NULL) {
-        errmsg = illegal_char(errbuf, errbuflen, *s);
-        break;
-      }
-      if (*++s != NUL && *s != ',' && *s != ' ') {
-        if (s[-1] == 'k' || s[-1] == 's') {
-          // skip optional filename after 'k' and 's'
-          while (*s && *s != ',' && *s != ' ') {
-            if (*s == '\\' && s[1] != NUL) {
-              s++;
-            }
-            s++;
-          }
-        } else {
-          if (errbuf != NULL) {
-            vim_snprintf(errbuf, errbuflen,
-                         _("E535: Illegal character after <%c>"),
-                         *--s);
-            errmsg = errbuf;
-          } else {
-            errmsg = "";
-          }
-          break;
-        }
-      }
-    }
+             || varp == &p_ruf || varp == &win->w_p_stc) {
+    // 'statusline', 'winbar', 'tabline', 'rulerformat' or 'statuscolumn'
+    did_set_statusline(win, varp, gvarp, &errmsg);
+  } else if (gvarp == &p_cpt) {  // 'complete'
+    did_set_complete(varp, errbuf, errbuflen, &errmsg);
   } else if (varp == &p_cot) {  // 'completeopt'
-    if (check_opt_strings(p_cot, p_cot_values, true) != OK) {
-      errmsg = e_invarg;
-    } else {
-      completeopt_was_set();
-    }
+    did_set_completeopt(&errmsg);
 #ifdef BACKSLASH_IN_FILENAME
   } else if (gvarp == &p_csl) {  // 'completeslash'
     if (check_opt_strings(p_csl, p_csl_values, false) != OK
-        || check_opt_strings(curbuf->b_p_csl, p_csl_values, false) != OK) {
+        || check_opt_strings(buf->b_p_csl, p_csl_values, false) != OK) {
       errmsg = e_invarg;
     }
 #endif
-  } else if (varp == &curwin->w_p_scl) {  // 'signcolumn'
-    if (check_signcolumn(*varp) != OK) {
-      errmsg = e_invarg;
-    }
-    // When changing the 'signcolumn' to or from 'number', recompute the
-    // width of the number column if 'number' or 'relativenumber' is set.
-    if (((*oldval == 'n' && *(oldval + 1) == 'u')
-         || (*curwin->w_p_scl == 'n' && *(curwin->w_p_scl + 1) == 'u'))
-        && (curwin->w_p_nu || curwin->w_p_rnu)) {
-      curwin->w_nrwidth_line_count = 0;
-    }
-  } else if (varp == &curwin->w_p_fdc
-             || varp == &curwin->w_allbuf_opt.wo_fdc) {
+  } else if (varp == &win->w_p_scl) {  // 'signcolumn'
+    did_set_signcolumn(win, varp, oldval, &errmsg);
+  } else if (varp == &p_sloc) {  // 'showcmdloc'
+    did_set_opt_strings(*varp, p_sloc_values, false, &errmsg);
+  } else if (varp == &win->w_p_fdc
+             || varp == &win->w_allbuf_opt.wo_fdc) {
     // 'foldcolumn'
-    if (**varp == NUL || check_opt_strings(*varp, p_fdc_values, false) != OK) {
-      errmsg = e_invarg;
-    }
-  } else if (varp == &p_pt) {
-    // 'pastetoggle': translate key codes like in a mapping
-    if (*p_pt) {
-      p = NULL;
-      (void)replace_termcodes(p_pt,
-                              strlen(p_pt),
-                              &p, REPTERM_FROM_PART | REPTERM_DO_LT, NULL,
-                              CPO_TO_CPO_FLAGS);
-      if (p != NULL) {
-        free_string_option(p_pt);
-        p_pt = p;
-      }
-    }
+    did_set_foldcolumn(varp, &errmsg);
+  } else if (varp == &p_pt) {  // 'pastetoggle'
+    did_set_pastetoggle();
   } else if (varp == &p_bs) {  // 'backspace'
-    if (ascii_isdigit(*p_bs)) {
-      if (*p_bs > '3' || p_bs[1] != NUL) {
-        errmsg = e_invarg;
-      }
-    } else if (check_opt_strings(p_bs, p_bs_values, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_backspace(&errmsg);
   } else if (varp == &p_bo) {
-    if (opt_strings_flags(p_bo, p_bo_values, &bo_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_bo, p_bo_values, &bo_flags, true, &errmsg);
   } else if (gvarp == &p_tc) {  // 'tagcase'
-    unsigned int *flags;
-
-    if (opt_flags & OPT_LOCAL) {
-      p = curbuf->b_p_tc;
-      flags = &curbuf->b_tc_flags;
-    } else {
-      p = p_tc;
-      flags = &tc_flags;
-    }
-
-    if ((opt_flags & OPT_LOCAL) && *p == NUL) {
-      // make the local value empty: use the global value
-      *flags = 0;
-    } else if (*p == NUL
-               || opt_strings_flags(p, p_tc_values, flags, false) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_tagcase(buf, opt_flags, &errmsg);
   } else if (varp == &p_cmp) {  // 'casemap'
-    if (opt_strings_flags(p_cmp, p_cmp_values, &cmp_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_cmp, p_cmp_values, &cmp_flags, true, &errmsg);
   } else if (varp == &p_dip) {  // 'diffopt'
-    if (diffopt_changed() == FAIL) {
-      errmsg = e_invarg;
-    }
-  } else if (gvarp == &curwin->w_allbuf_opt.wo_fdm) {  // 'foldmethod'
-    if (check_opt_strings(*varp, p_fdm_values, false) != OK
-        || *curwin->w_p_fdm == NUL) {
-      errmsg = e_invarg;
-    } else {
-      foldUpdateAll(curwin);
-      if (foldmethodIsDiff(curwin)) {
-        newFoldLevel();
-      }
-    }
-  } else if (varp == &curwin->w_p_fde) {  // 'foldexpr'
-    if (foldmethodIsExpr(curwin)) {
-      foldUpdateAll(curwin);
-    }
-  } else if (gvarp == &curwin->w_allbuf_opt.wo_fmr) {  // 'foldmarker'
-    p = vim_strchr(*varp, ',');
-    if (p == NULL) {
-      errmsg = N_("E536: comma required");
-    } else if (p == *varp || p[1] == NUL) {
-      errmsg = e_invarg;
-    } else if (foldmethodIsMarker(curwin)) {
-      foldUpdateAll(curwin);
-    }
+    did_set_diffopt(&errmsg);
+  } else if (gvarp == &win->w_allbuf_opt.wo_fdm) {  // 'foldmethod'
+    did_set_foldmethod(win, varp, &errmsg);
+  } else if (gvarp == &win->w_allbuf_opt.wo_fmr) {  // 'foldmarker'
+    did_set_foldmarker(win, varp, &errmsg);
   } else if (gvarp == &p_cms) {  // 'commentstring'
-    if (**varp != NUL && strstr(*varp, "%s") == NULL) {
-      errmsg = N_("E537: 'commentstring' must be empty or contain %s");
-    }
+    did_set_commentstring(varp, &errmsg);
   } else if (varp == &p_fdo) {  // 'foldopen'
-    if (opt_strings_flags(p_fdo, p_fdo_values, &fdo_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_flags(p_fdo, p_fdo_values, &fdo_flags, true, &errmsg);
   } else if (varp == &p_fcl) {  // 'foldclose'
-    if (check_opt_strings(p_fcl, p_fcl_values, true) != OK) {
-      errmsg = e_invarg;
-    }
-  } else if (gvarp == &curwin->w_allbuf_opt.wo_fdi) {  // 'foldignore'
-    if (foldmethodIsIndent(curwin)) {
-      foldUpdateAll(curwin);
-    }
+    did_set_opt_strings(*varp, p_fcl_values, true, &errmsg);
+  } else if (gvarp == &win->w_allbuf_opt.wo_fdi) {  // 'foldignore'
+    did_set_foldignore(win);
   } else if (gvarp == &p_ve) {  // 'virtualedit'
-    char *ve = p_ve;
-    unsigned int *flags = &ve_flags;
-
-    if (opt_flags & OPT_LOCAL) {
-      ve = curwin->w_p_ve;
-      flags = &curwin->w_ve_flags;
-    }
-
-    if ((opt_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) {
-        errmsg = e_invarg;
-      } else if (strcmp(p_ve, oldval) != 0) {
-        // Recompute cursor position in case the new 've' setting
-        // changes something.
-        validate_virtcol();
-        coladvance(curwin->w_virtcol);
-      }
-    }
-  } else if (varp == &p_csqf) {
-    if (p_csqf != NULL) {
-      p = p_csqf;
-      while (*p != NUL) {
-        if (vim_strchr(CSQF_CMDS, *p) == NULL
-            || p[1] == NUL
-            || vim_strchr(CSQF_FLAGS, p[1]) == NULL
-            || (p[2] != NUL && p[2] != ',')) {
-          errmsg = e_invarg;
-          break;
-        } else if (p[2] == NUL) {
-          break;
-        } else {
-          p += 3;
-        }
-      }
-    }
+    did_set_virtualedit(win, opt_flags, oldval, &errmsg);
   } else if (gvarp == &p_cino) {  // 'cinoptions'
     // TODO(vim): recognize errors
-    parse_cino(curbuf);
+    parse_cino(buf);
+  } else if (gvarp == &p_lop) {  // 'lispoptions'
+    did_set_lispoptions(varp, &errmsg);
   } else if (varp == &p_icm) {  // 'inccommand'
-    if (check_opt_strings(p_icm, p_icm_values, false) != OK) {
-      errmsg = e_invarg;
-    }
-  } else if (gvarp == &p_ft) {
-    if (!valid_filetype(*varp)) {
-      errmsg = e_invarg;
-    } else {
-      value_changed = strcmp(oldval, *varp) != 0;
-
-      // Since we check the value, there is no need to set P_INSECURE,
-      // even when the value comes from a modeline.
-      *value_checked = true;
-    }
-  } else if (gvarp == &p_syn) {
-    if (!valid_filetype(*varp)) {
-      errmsg = e_invarg;
-    } else {
-      value_changed = strcmp(oldval, *varp) != 0;
-
-      // Since we check the value, there is no need to set P_INSECURE,
-      // even when the value comes from a modeline.
-      *value_checked = true;
-    }
-  } else if (varp == &curwin->w_p_winhl) {
-    if (!parse_winhl_opt(curwin)) {
-      errmsg = e_invarg;
-    }
+    did_set_opt_strings(*varp, p_icm_values, false, &errmsg);
+  } else if (gvarp == &p_ft || gvarp == &p_syn) {
+    did_set_filetype_or_syntax(varp, oldval, value_checked, &value_changed, &errmsg);
+  } else if (varp == &win->w_p_winhl) {
+    did_set_winhl(win, &errmsg);
   } else if (varp == &p_tpf) {
-    if (opt_strings_flags(p_tpf, p_tpf_values, &tpf_flags, true) != OK) {
-      errmsg = e_invarg;
-    }
-  } else if (varp == &(curbuf->b_p_vsts)) {  // 'varsofttabstop'
-    char *cp;
-
-    if (!(*varp)[0] || ((*varp)[0] == '0' && !(*varp)[1])) {
-      XFREE_CLEAR(curbuf->b_p_vsts_array);
-    } else {
-      for (cp = *varp; *cp; cp++) {
-        if (ascii_isdigit(*cp)) {
-          continue;
-        }
-        if (*cp == ',' && cp > *varp && *(cp - 1) != ',') {
-          continue;
-        }
-        errmsg = e_invarg;
-        break;
-      }
-      if (errmsg == NULL) {
-        long *oldarray = curbuf->b_p_vsts_array;
-        if (tabstop_set(*varp, &(curbuf->b_p_vsts_array))) {
-          xfree(oldarray);
-        } else {
-          errmsg = e_invarg;
-        }
-      }
-    }
-  } else if (varp == &(curbuf->b_p_vts)) {  // 'vartabstop'
-    char *cp;
-
-    if (!(*varp)[0] || ((*varp)[0] == '0' && !(*varp)[1])) {
-      XFREE_CLEAR(curbuf->b_p_vts_array);
-    } else {
-      for (cp = *varp; *cp; cp++) {
-        if (ascii_isdigit(*cp)) {
-          continue;
-        }
-        if (*cp == ',' && cp > *varp && *(cp - 1) != ',') {
-          continue;
-        }
-        errmsg = e_invarg;
-        break;
-      }
-      if (errmsg == NULL) {
-        long *oldarray = curbuf->b_p_vts_array;
-        if (tabstop_set(*varp, &(curbuf->b_p_vts_array))) {
-          xfree(oldarray);
-          if (foldmethodIsIndent(curwin)) {
-            foldUpdateAll(curwin);
-          }
-        } else {
-          errmsg = e_invarg;
-        }
-      }
-    }
+    did_set_opt_flags(p_tpf, p_tpf_values, &tpf_flags, true, &errmsg);
+  } else if (varp == &buf->b_p_vsts) {  // 'varsofttabstop'
+    did_set_varsoftabstop(buf, varp, &errmsg);
+  } else if (varp == &buf->b_p_vts) {  // 'vartabstop'
+    did_set_vartabstop(buf, win, varp, &errmsg);
+  } else if (varp == &p_dex) {  // 'diffexpr'
+    did_set_optexpr(win, &p_dex, varp, gvarp);
+  } else if (varp == &win->w_p_fde) {  // 'foldexpr'
+    did_set_optexpr(win, &win->w_p_fde, varp, gvarp);
+    if (foldmethodIsExpr(win)) {
+      foldUpdateAll(win);
+    }
+  } else if (varp == &win->w_p_fdt) {  // 'foldtext'
+    did_set_optexpr(win, &win->w_p_fdt, varp, gvarp);
+  } else if (varp == &p_pex) {  // 'patchexpr'
+    did_set_optexpr(win, &p_pex, varp, gvarp);
+  } else if (gvarp == &p_fex) {  // 'formatexpr'
+    did_set_optexpr(win, &buf->b_p_fex, varp, gvarp);
+  } else if (gvarp == &p_inex) {  // 'includeexpr'
+    did_set_optexpr(win, &buf->b_p_inex, varp, gvarp);
+  } else if (gvarp == &p_inde) {  // 'indentexpr'
+    did_set_optexpr(win, &buf->b_p_inde, varp, gvarp);
+  } else if (gvarp == &p_cfu) {  // 'completefunc'
+    set_completefunc_option(&errmsg);
+  } else if (gvarp == &p_ofu) {  // 'omnifunc'
+    set_omnifunc_option(buf, &errmsg);
+  } else if (gvarp == &p_tsrfu) {  // 'thesaurusfunc'
+    set_thesaurusfunc_option(&errmsg);
   } else if (varp == &p_opfunc) {  // 'operatorfunc'
-    if (set_operatorfunc_option() == FAIL) {
-      errmsg = e_invarg;
-    }
+    set_operatorfunc_option(&errmsg);
   } else if (varp == &p_qftf) {  // 'quickfixtextfunc'
-    if (qf_process_qftf_option() == FAIL) {
-      errmsg = e_invarg;
-    }
-  } else {
-    // Options that are a list of flags.
-    p = NULL;
-    if (varp == &p_ww) {  // 'whichwrap'
-      p = WW_ALL;
-    }
-    if (varp == &p_shm) {  // 'shortmess'
-      p = SHM_ALL;
-    } else if (varp == &(p_cpo)) {  // 'cpoptions'
-      p = CPO_VI;
-    } else if (varp == &(curbuf->b_p_fo)) {  // 'formatoptions'
-      p = FO_ALL;
-    } else if (varp == &curwin->w_p_cocu) {  // 'concealcursor'
-      p = COCU_ALL;
-    } else if (varp == &p_mouse) {  // 'mouse'
-      p = MOUSE_ALL;
-    }
-    if (p != NULL) {
-      for (s = *varp; *s; s++) {
-        if (vim_strchr(p, *s) == NULL) {
-          errmsg = illegal_char(errbuf, errbuflen, *s);
-          break;
-        }
-      }
+    qf_process_qftf_option(&errmsg);
+  } else if (gvarp == &p_tfu) {  // 'tagfunc'
+    set_tagfunc_option(&errmsg);
+  } else if (varp == &p_ww) {  // 'whichwrap'
+    did_set_option_listflag(varp, WW_ALL, errbuf, errbuflen, &errmsg);
+  } else if (varp == &p_shm) {  // 'shortmess'
+    did_set_option_listflag(varp, SHM_ALL, errbuf, errbuflen, &errmsg);
+  } else if (varp == &p_cpo) {  // 'cpoptions'
+    did_set_option_listflag(varp, CPO_VI, errbuf, errbuflen, &errmsg);
+  } else if (varp == &buf->b_p_fo) {  // 'formatoptions'
+    did_set_option_listflag(varp, FO_ALL, errbuf, errbuflen, &errmsg);
+  } else if (varp == &win->w_p_cocu) {  // 'concealcursor'
+    did_set_option_listflag(varp, COCU_ALL, errbuf, errbuflen, &errmsg);
+  } else if (varp == &p_mouse) {  // 'mouse'
+    did_set_option_listflag(varp, MOUSE_ALL, errbuf, errbuflen, &errmsg);
+  } else if (gvarp == &p_flp) {
+    if (win->w_briopt_list) {
+      // Changing Formatlistpattern when briopt includes the list setting:
+      // redraw
+      redraw_all_later(UPD_NOT_VALID);
     }
   }
 
@@ -1520,7 +1863,7 @@ char *did_set_string_option(int opt_idx, char **varp, char *oldval, char *errbuf
     *varp = oldval;
     // When resetting some values, need to act on it.
     if (did_chartab) {
-      (void)init_chartab();
+      (void)buf_init_chartab(buf, true);
     }
   } else {
     // Remember where the option was set.
@@ -1537,7 +1880,7 @@ char *did_set_string_option(int opt_idx, char **varp, char *oldval, char *errbuf
         && (opt->indir & PV_BOTH)) {
       // global option with local value set to use global value; free
       // the local value and make it empty
-      p = get_varp_scope(opt, OPT_LOCAL);
+      char *p = get_varp_scope(opt, OPT_LOCAL);
       free_string_option(*(char **)p);
       *(char **)p = empty_option;
     } else if (!(opt_flags & OPT_LOCAL) && opt_flags != OPT_GLOBAL) {
@@ -1546,65 +1889,12 @@ char *did_set_string_option(int opt_idx, char **varp, char *oldval, char *errbuf
     }
 
     // Trigger the autocommand only after setting the flags.
-    // When 'syntax' is set, load the syntax of that name
-    if (varp == &(curbuf->b_p_syn)) {
-      static int syn_recursive = 0;
-
-      syn_recursive++;
-      // Only pass true for "force" when the value changed or not used
-      // recursively, to avoid endless recurrence.
-      apply_autocmds(EVENT_SYNTAX, curbuf->b_p_syn, curbuf->b_fname,
-                     value_changed || syn_recursive == 1, curbuf);
-      curbuf->b_flags |= BF_SYN_SET;
-      syn_recursive--;
-    } else if (varp == &(curbuf->b_p_ft)) {
-      // 'filetype' is set, trigger the FileType autocommand
-      // Skip this when called from a modeline and the filetype was
-      // already set to this value.
-      if (!(opt_flags & OPT_MODELINE) || value_changed) {
-        static int ft_recursive = 0;
-        int secure_save = secure;
-
-        // Reset the secure flag, since the value of 'filetype' has
-        // been checked to be safe.
-        secure = 0;
-
-        ft_recursive++;
-        did_filetype = true;
-        // Only pass true for "force" when the value changed or not
-        // used recursively, to avoid endless recurrence.
-        apply_autocmds(EVENT_FILETYPE, curbuf->b_p_ft, curbuf->b_fname,
-                       value_changed || ft_recursive == 1, curbuf);
-        ft_recursive--;
-        // Just in case the old "curbuf" is now invalid
-        if (varp != &(curbuf->b_p_ft)) {
-          varp = NULL;
-        }
-        secure = secure_save;
-      }
-    }
-    if (varp == &(curwin->w_s->b_p_spl)) {
-      char fname[200];
-      char *q = curwin->w_s->b_p_spl;
-
-      // Skip the first name if it is "cjk".
-      if (STRNCMP(q, "cjk,", 4) == 0) {
-        q += 4;
-      }
-
-      // Source the spell/LANG.vim in 'runtimepath'.
-      // They could set 'spellcapcheck' depending on the language.
-      // Use the first name in 'spelllang' up to '_region' or
-      // '.encoding'.
-      for (p = q; *p != NUL; p++) {
-        if (!ASCII_ISALNUM(*p) && *p != '-') {
-          break;
-        }
-      }
-      if (p > q) {
-        vim_snprintf(fname, sizeof(fname), "spell/%.*s.vim", (int)(p - q), q);
-        source_runtime(fname, DIP_ALL);
-      }
+    if (varp == &buf->b_p_syn) {
+      do_syntax_autocmd(buf, value_changed);
+    } else if (varp == &buf->b_p_ft) {
+      do_filetype_autocmd(buf, varp, opt_flags, value_changed);
+    } else if (varp == &win->w_s->b_p_spl) {
+      did_set_spelllang_source(win);
     }
   }
 
@@ -1612,16 +1902,23 @@ char *did_set_string_option(int opt_idx, char **varp, char *oldval, char *errbuf
     setmouse();  // in case 'mouse' changed
   }
 
-  if (curwin->w_curswant != MAXCOL
+  if (win->w_curswant != MAXCOL
       && (opt->flags & (P_CURSWANT | P_RALL)) != 0) {
-    curwin->w_set_curswant = true;
+    win->w_set_curswant = true;
   }
 
-  check_redraw(opt->flags);
+  check_redraw_for(buf, win, opt->flags);
 
   return errmsg;
 }
 
+char *did_set_string_option(int opt_idx, char **varp, char *oldval, char *errbuf, size_t errbuflen,
+                            int opt_flags, int *value_checked)
+{
+  return did_set_string_option_for(curbuf, curwin, opt_idx, varp, oldval, errbuf, errbuflen,
+                                   opt_flags, value_checked);
+}
+
 /// Check an option that can be a range of string values.
 ///
 /// @param list  when true: accept a list of values
@@ -1651,7 +1948,7 @@ static int opt_strings_flags(char *val, char **values, unsigned *flagp, bool lis
       }
 
       size_t len = strlen(values[i]);
-      if (STRNCMP(values[i], val, len) == 0
+      if (strncmp(values[i], val, len) == 0
           && ((list && val[len] == ',') || val[len] == NUL)) {
         val += len + (val[len] == ',');
         assert(i < sizeof(1U) * 8);