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

1 files changed, 3027 insertions, 2306 deletions

diff --git a/src/nvim/option.c b/src/nvim/option.c
index 01a5c7677f..96d6d8e01e 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -1,6 +1,3 @@
-// This is an open source non-commercial project. Dear PVS-Studio, please check
-// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
-
 // User-settable options. Checklist for adding a new option:
 // - Put it in options.lua
 // - For a global option: Add a variable for it in option_defs.h.
@@ -13,15 +10,13 @@
 //     add some code to didset_window_options().
 //   - For a buffer option, add some code to buf_copy_options().
 //   - For a buffer string option, add code to check_buf_options().
-// - If it's a numeric option, add any necessary bounds checks to
-//   set_num_option().
+// - If it's a numeric option, add any necessary bounds checks to check_num_option_bounds().
 // - If it's a list of flags, add some code in do_set(), search for WW_ALL.
 // - Add documentation! doc/options.txt, and any other related places.
 // - Add an entry in runtime/optwin.vim.
 
 #define IN_OPTION_C
 #include <assert.h>
-#include <ctype.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <stdbool.h>
@@ -30,38 +25,43 @@
 #include <string.h>
 
 #include "auto/config.h"
+#include "klib/kvec.h"
+#include "nvim/api/extmark.h"
 #include "nvim/api/private/defs.h"
-#include "nvim/ascii.h"
+#include "nvim/api/private/helpers.h"
+#include "nvim/api/private/validate.h"
+#include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
 #include "nvim/change.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand.h"
+#include "nvim/cmdexpand_defs.h"
 #include "nvim/cursor_shape.h"
 #include "nvim/decoration_provider.h"
 #include "nvim/diff.h"
 #include "nvim/drawscreen.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
-#include "nvim/eval/typval_defs.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
 #include "nvim/ex_session.h"
 #include "nvim/fold.h"
+#include "nvim/func_attr.h"
 #include "nvim/garray.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/grid_defs.h"
 #include "nvim/highlight.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/locale.h"
 #include "nvim/log.h"
-#include "nvim/macros.h"
+#include "nvim/lua/executor.h"
+#include "nvim/macros_defs.h"
 #include "nvim/mapping.h"
 #include "nvim/mbyte.h"
 #include "nvim/memfile.h"
@@ -74,47 +74,46 @@
 #include "nvim/ops.h"
 #include "nvim/option.h"
 #include "nvim/option_defs.h"
+#include "nvim/option_vars.h"
 #include "nvim/optionstr.h"
+#include "nvim/os/input.h"
+#include "nvim/os/lang.h"
 #include "nvim/os/os.h"
 #include "nvim/path.h"
 #include "nvim/popupmenu.h"
-#include "nvim/pos.h"
+#include "nvim/pos_defs.h"
 #include "nvim/regexp.h"
 #include "nvim/runtime.h"
-#include "nvim/screen.h"
 #include "nvim/search.h"
 #include "nvim/sign_defs.h"
 #include "nvim/spell.h"
 #include "nvim/spellfile.h"
 #include "nvim/spellsuggest.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
 #include "nvim/terminal.h"
-#include "nvim/types.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
-#include "nvim/vim.h"
+#include "nvim/vim_defs.h"
 #include "nvim/window.h"
-#ifdef MSWIN
-# include "nvim/os/pty_conpty_win.h"
+
+#ifdef BACKSLASH_IN_FILENAME
+# include "nvim/arglist.h"
 #endif
-#include "nvim/api/extmark.h"
-#include "nvim/api/private/helpers.h"
-#include "nvim/lua/executor.h"
-#include "nvim/os/input.h"
-#include "nvim/os/lang.h"
 
-static char e_unknown_option[]
+static const char e_unknown_option[]
   = N_("E518: Unknown option");
-static char e_not_allowed_in_modeline[]
+static const char e_not_allowed_in_modeline[]
   = N_("E520: Not allowed in a modeline");
-static char e_not_allowed_in_modeline_when_modelineexpr_is_off[]
+static const char e_not_allowed_in_modeline_when_modelineexpr_is_off[]
   = N_("E992: Not allowed in a modeline when 'modelineexpr' is off");
-static char e_key_code_not_set[]
+static const char e_key_code_not_set[]
   = N_("E846: Key code not set");
-static char e_number_required_after_equal[]
+static const char e_number_required_after_equal[]
   = N_("E521: Number required after =");
-static char e_preview_window_already_exists[]
+static const char e_preview_window_already_exists[]
   = N_("E590: A preview window already exists");
 
 static char *p_term = NULL;
@@ -123,17 +122,30 @@ static char *p_ttytype = NULL;
 // Saved values for when 'bin' is set.
 static int p_et_nobin;
 static int p_ml_nobin;
-static long p_tw_nobin;
-static long p_wm_nobin;
+static OptInt p_tw_nobin;
+static OptInt p_wm_nobin;
 
 // Saved values for when 'paste' is set.
 static int p_ai_nopaste;
 static int p_et_nopaste;
-static long p_sts_nopaste;
-static long p_tw_nopaste;
-static long p_wm_nopaste;
+static OptInt p_sts_nopaste;
+static OptInt p_tw_nopaste;
+static OptInt p_wm_nopaste;
 static char *p_vsts_nopaste;
 
+#define OPTION_COUNT ARRAY_SIZE(options)
+
+/// :set boolean option prefix
+typedef enum {
+  PREFIX_NO = 0,  ///< "no" prefix
+  PREFIX_NONE,    ///< no prefix
+  PREFIX_INV,     ///< "inv" prefix
+} set_prefix_T;
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "option.c.generated.h"
+#endif
+
 // options[] is initialized here.
 // The order of the options MUST be alphabetic for ":set all" and findoption().
 // All option names MUST start with a lowercase letter (for findoption()).
@@ -145,141 +157,190 @@ static char *p_vsts_nopaste;
 # include "options.generated.h"
 #endif
 
-#define OPTION_COUNT ARRAY_SIZE(options)
-
-typedef enum {
-  OP_NONE = 0,
-  OP_ADDING,      ///< "opt+=arg"
-  OP_PREPENDING,  ///< "opt^=arg"
-  OP_REMOVING,    ///< "opt-=arg"
-} set_op_T;
-
-#ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "option.c.generated.h"
-#endif
+static char *(p_bin_dep_opts[]) = {
+  "textwidth", "wrapmargin", "modeline", "expandtab", NULL
+};
+static char *(p_paste_dep_opts[]) = {
+  "autoindent", "expandtab", "ruler", "showmatch", "smarttab",
+  "softtabstop", "textwidth", "wrapmargin", "revins", "varsofttabstop", NULL
+};
 
 void set_init_tablocal(void)
 {
   // susy baka: cmdheight calls itself OPT_GLOBAL but is really tablocal!
   int ch_idx = findoption("cmdheight");
-  p_ch = (long)options[ch_idx].def_val;
+  p_ch = (OptInt)(intptr_t)options[ch_idx].def_val;
 }
 
-/// Initialize the options, first part.
-///
-/// Called only once from main(), just after creating the first buffer.
-/// If "clean_arg" is true, Nvim was started with --clean.
-///
-/// NOTE: ELOG() etc calls are not allowed here, as log location depends on
-/// env var expansion which depends on expression evaluation and other
-/// editor state initialized here. Do logging in set_init_2 or later.
-void set_init_1(bool clean_arg)
+/// Initialize the 'shell' option to a default value.
+static void set_init_default_shell(void)
 {
-  langmap_init();
-
   // Find default value for 'shell' option.
   // Don't use it if it is empty.
-  {
-    const char *shell = os_getenv("SHELL");
-    if (shell != NULL) {
-      if (vim_strchr(shell, ' ') != NULL) {
-        const size_t len = strlen(shell) + 3;  // two quotes and a trailing NUL
-        char *const cmd = xmalloc(len);
-        snprintf(cmd, len, "\"%s\"", shell);
-        set_string_default("sh", cmd, true);
-      } else {
-        set_string_default("sh", (char *)shell, false);
-      }
+  const char *shell = os_getenv("SHELL");
+  if (shell != NULL) {
+    if (vim_strchr(shell, ' ') != NULL) {
+      const size_t len = strlen(shell) + 3;  // two quotes and a trailing NUL
+      char *const cmd = xmalloc(len);
+      snprintf(cmd, len, "\"%s\"", shell);
+      set_string_default("sh", cmd, true);
+    } else {
+      set_string_default("sh", (char *)shell, false);
     }
   }
+}
 
-  // Set the default for 'backupskip' to include environment variables for
-  // temp files.
-  {
+/// Set the default for 'backupskip' to include environment variables for
+/// temp files.
+static void set_init_default_backupskip(void)
+{
 #ifdef UNIX
-    static char *(names[4]) = { "", "TMPDIR", "TEMP", "TMP" };
+  static char *(names[4]) = { "", "TMPDIR", "TEMP", "TMP" };
 #else
-    static char *(names[3]) = { "TMPDIR", "TEMP", "TMP" };
+  static char *(names[3]) = { "TMPDIR", "TEMP", "TMP" };
 #endif
-    garray_T ga;
-    int opt_idx = findoption("backupskip");
+  garray_T ga;
+  int opt_idx = findoption("backupskip");
 
-    ga_init(&ga, 1, 100);
-    for (size_t n = 0; n < ARRAY_SIZE(names); n++) {
-      bool mustfree = true;
-      char *p;
+  ga_init(&ga, 1, 100);
+  for (size_t n = 0; n < ARRAY_SIZE(names); n++) {
+    bool mustfree = true;
+    char *p;
 #ifdef UNIX
-      if (*names[n] == NUL) {
+    if (*names[n] == NUL) {
 # ifdef __APPLE__
-        p = "/private/tmp";
+      p = "/private/tmp";
 # else
-        p = "/tmp";
+      p = "/tmp";
 # endif
-        mustfree = false;
-      } else  // NOLINT(readability/braces)
+      mustfree = false;
+    } else  // NOLINT(readability/braces)
 #endif
-      {
-        p = vim_getenv(names[n]);
-      }
-      if (p != NULL && *p != NUL) {
-        // First time count the NUL, otherwise count the ','.
-        const size_t len = strlen(p) + 3;
-        char *item = xmalloc(len);
-        xstrlcpy(item, p, len);
-        add_pathsep(item);
-        xstrlcat(item, "*", len);
-        if (find_dup_item(ga.ga_data, item, options[opt_idx].flags)
-            == NULL) {
-          ga_grow(&ga, (int)len);
-          if (!GA_EMPTY(&ga)) {
-            STRCAT(ga.ga_data, ",");
-          }
-          STRCAT(ga.ga_data, p);
-          add_pathsep(ga.ga_data);
-          STRCAT(ga.ga_data, "*");
-          ga.ga_len += (int)len;
+    {
+      p = vim_getenv(names[n]);
+    }
+    if (p != NULL && *p != NUL) {
+      // First time count the NUL, otherwise count the ','.
+      const size_t len = strlen(p) + 3;
+      char *item = xmalloc(len);
+      xstrlcpy(item, p, len);
+      add_pathsep(item);
+      xstrlcat(item, "*", len);
+      if (find_dup_item(ga.ga_data, item, options[opt_idx].flags)
+          == NULL) {
+        ga_grow(&ga, (int)len);
+        if (!GA_EMPTY(&ga)) {
+          STRCAT(ga.ga_data, ",");
         }
-        xfree(item);
-      }
-      if (mustfree) {
-        xfree(p);
+        STRCAT(ga.ga_data, p);
+        add_pathsep(ga.ga_data);
+        STRCAT(ga.ga_data, "*");
+        ga.ga_len += (int)len;
       }
+      xfree(item);
+    }
+    if (mustfree) {
+      xfree(p);
     }
-    if (ga.ga_data != NULL) {
-      set_string_default("bsk", ga.ga_data, true);
+  }
+  if (ga.ga_data != NULL) {
+    set_string_default("bsk", ga.ga_data, true);
+  }
+}
+
+/// Initialize the 'cdpath' option to a default value.
+static void set_init_default_cdpath(void)
+{
+  char *cdpath = vim_getenv("CDPATH");
+  if (cdpath == NULL) {
+    return;
+  }
+
+  char *buf = xmalloc(2 * strlen(cdpath) + 2);
+  buf[0] = ',';               // start with ",", current dir first
+  int j = 1;
+  for (int i = 0; cdpath[i] != NUL; i++) {
+    if (vim_ispathlistsep(cdpath[i])) {
+      buf[j++] = ',';
+    } else {
+      if (cdpath[i] == ' ' || cdpath[i] == ',') {
+        buf[j++] = '\\';
+      }
+      buf[j++] = cdpath[i];
     }
   }
+  buf[j] = NUL;
+  int opt_idx = findoption("cdpath");
+  if (opt_idx >= 0) {
+    options[opt_idx].def_val = buf;
+    options[opt_idx].flags |= P_DEF_ALLOCED;
+  } else {
+    xfree(buf);           // cannot happen
+  }
+  xfree(cdpath);
+}
 
-  {
-    // Initialize the 'cdpath' option's default value.
-    char *cdpath = vim_getenv("CDPATH");
-    if (cdpath != NULL) {
-      char *buf = xmalloc(2 * strlen(cdpath) + 2);
-      {
-        buf[0] = ',';               // start with ",", current dir first
-        int j = 1;
-        for (int i = 0; cdpath[i] != NUL; i++) {
-          if (vim_ispathlistsep(cdpath[i])) {
-            buf[j++] = ',';
-          } else {
-            if (cdpath[i] == ' ' || cdpath[i] == ',') {
-              buf[j++] = '\\';
-            }
-            buf[j++] = cdpath[i];
-          }
-        }
-        buf[j] = NUL;
-        int opt_idx = findoption("cdpath");
-        if (opt_idx >= 0) {
-          options[opt_idx].def_val = buf;
-          options[opt_idx].flags |= P_DEF_ALLOCED;
-        } else {
-          xfree(buf);           // cannot happen
-        }
+/// Expand environment variables and things like "~" for the defaults.
+/// If option_expand() returns non-NULL the variable is expanded.  This can
+/// only happen for non-indirect options.
+/// Also set the default to the expanded value, so ":set" does not list
+/// them.
+/// Don't set the P_ALLOCED flag, because we don't want to free the
+/// default.
+static void set_init_expand_env(void)
+{
+  for (int opt_idx = 0; options[opt_idx].fullname; opt_idx++) {
+    vimoption_T *opt = &options[opt_idx];
+    if (opt->flags & P_NO_DEF_EXP) {
+      continue;
+    }
+    char *p;
+    if ((opt->flags & P_GETTEXT) && opt->var != NULL) {
+      p = _(*(char **)opt->var);
+    } else {
+      p = option_expand(opt_idx, NULL);
+    }
+    if (p != NULL) {
+      p = xstrdup(p);
+      *(char **)opt->var = p;
+      if (opt->flags & P_DEF_ALLOCED) {
+        xfree(opt->def_val);
       }
-      xfree(cdpath);
+      opt->def_val = p;
+      opt->flags |= P_DEF_ALLOCED;
     }
   }
+}
+
+/// Initialize the encoding used for "default" in 'fileencodings'.
+static void set_init_fenc_default(void)
+{
+  // enc_locale() will try to find the encoding of the current locale.
+  // This will be used when "default" is used as encoding specifier
+  // in 'fileencodings'.
+  char *p = enc_locale();
+  if (p == NULL) {
+    // Use utf-8 as "default" if locale encoding can't be detected.
+    p = xmemdupz(S_LEN("utf-8"));
+  }
+  fenc_default = p;
+}
+
+/// Initialize the options, first part.
+///
+/// Called only once from main(), just after creating the first buffer.
+/// If "clean_arg" is true, Nvim was started with --clean.
+///
+/// NOTE: ELOG() etc calls are not allowed here, as log location depends on
+/// env var expansion which depends on expression evaluation and other
+/// editor state initialized here. Do logging in set_init_2 or later.
+void set_init_1(bool clean_arg)
+{
+  langmap_init();
+
+  set_init_default_shell();
+  set_init_default_backupskip();
+  set_init_default_cdpath();
 
   char *backupdir = stdpaths_user_state_subpath("backup", 2, true);
   const size_t backupdir_len = strlen(backupdir);
@@ -328,33 +389,7 @@ void set_init_1(bool clean_arg)
   init_spell_chartab();
 
   // Expand environment variables and things like "~" for the defaults.
-  // If option_expand() returns non-NULL the variable is expanded.  This can
-  // only happen for non-indirect options.
-  // Also set the default to the expanded value, so ":set" does not list
-  // them.
-  // Don't set the P_ALLOCED flag, because we don't want to free the
-  // default.
-  for (int opt_idx = 0; options[opt_idx].fullname; opt_idx++) {
-    vimoption_T *opt = &options[opt_idx];
-    if (opt->flags & P_NO_DEF_EXP) {
-      continue;
-    }
-    char *p;
-    if ((opt->flags & P_GETTEXT) && opt->var != NULL) {
-      p = _(*(char **)opt->var);
-    } else {
-      p = option_expand(opt_idx, NULL);
-    }
-    if (p != NULL) {
-      p = xstrdup(p);
-      *(char **)opt->var = p;
-      if (opt->flags & P_DEF_ALLOCED) {
-        xfree(opt->def_val);
-      }
-      opt->def_val = p;
-      opt->flags |= P_DEF_ALLOCED;
-    }
-  }
+  set_init_expand_env();
 
   save_file_ff(curbuf);         // Buffer is unchanged
 
@@ -364,22 +399,13 @@ void set_init_1(bool clean_arg)
   // NOTE: mlterm's author is being asked to 'set' a variable
   //       instead of an environment variable due to inheritance.
   if (os_env_exists("MLTERM")) {
-    set_option_value_give_err("tbidi", 1L, NULL, 0);
+    set_option_value_give_err("tbidi", BOOLEAN_OPTVAL(true), 0);
   }
 
   didset_options2();
 
   lang_init();
-
-  // enc_locale() will try to find the encoding of the current locale.
-  // This will be used when 'default' is used as encoding specifier
-  // in 'fileencodings'
-  char *p = enc_locale();
-  if (p == NULL) {
-    // use utf-8 as 'default' if locale encoding can't be detected.
-    p = xmemdupz(S_LEN("utf-8"));
-  }
-  fenc_default = p;
+  set_init_fenc_default();
 
 #ifdef HAVE_WORKING_LIBINTL
   // GNU gettext 0.10.37 supports this feature: set the codeset used for
@@ -401,7 +427,7 @@ static void set_option_default(const int opt_idx, int opt_flags)
 
   // pointer to variable for current option
   vimoption_T *opt = &options[opt_idx];
-  char_u *varp = (char_u *)get_varp_scope(opt, both ? OPT_LOCAL : opt_flags);
+  void *varp = get_varp_scope(opt, both ? OPT_LOCAL : opt_flags);
   uint32_t flags = opt->flags;
   if (varp != NULL) {       // skip hidden option, nothing to do for it
     if (flags & P_STRING) {
@@ -420,19 +446,18 @@ static void set_option_default(const int opt_idx, int opt_flags)
       if (opt->indir == PV_SCROLL) {
         win_comp_scroll(curwin);
       } else {
-        long def_val = (long)opt->def_val;
-        if ((long *)varp == &curwin->w_p_so
-            || (long *)varp == &curwin->w_p_siso) {
+        OptInt def_val = (OptInt)(intptr_t)opt->def_val;
+        if ((OptInt *)varp == &curwin->w_p_so
+            || (OptInt *)varp == &curwin->w_p_siso) {
           // 'scrolloff' and 'sidescrolloff' local values have a
           // different default value than the global default.
-          *(long *)varp = -1;
+          *(OptInt *)varp = -1;
         } else {
-          *(long *)varp = def_val;
+          *(OptInt *)varp = def_val;
         }
         // May also set global value for local option.
         if (both) {
-          *(long *)get_varp_scope(opt, OPT_GLOBAL) =
-            def_val;
+          *(OptInt *)get_varp_scope(opt, OPT_GLOBAL) = def_val;
         }
       }
     } else {  // P_BOOL
@@ -531,11 +556,11 @@ static char *find_dup_item(char *origval, const char *newval, uint32_t flags)
 
 /// Set the Vi-default value of a number option.
 /// Used for 'lines' and 'columns'.
-void set_number_default(char *name, long val)
+void set_number_default(char *name, OptInt val)
 {
   int opt_idx = findoption(name);
   if (opt_idx >= 0) {
-    options[opt_idx].def_val = (char *)(intptr_t)val;
+    options[opt_idx].def_val = (void *)(intptr_t)val;
   }
 }
 
@@ -547,14 +572,14 @@ void free_all_options(void)
     if (options[i].indir == PV_NONE) {
       // global option: free value and default value.
       if ((options[i].flags & P_ALLOCED) && options[i].var != NULL) {
-        free_string_option(*(char **)options[i].var);
+        optval_free(optval_from_varp(i, options[i].var));
       }
       if (options[i].flags & P_DEF_ALLOCED) {
-        free_string_option(options[i].def_val);
+        optval_free(optval_from_varp(i, &options[i].def_val));
       }
-    } else if (options[i].var != VAR_WIN && (options[i].flags & P_STRING)) {
+    } else if (options[i].var != VAR_WIN) {
       // buffer-local option: free global value
-      clear_string_option((char **)options[i].var);
+      optval_free(optval_from_varp(i, options[i].var));
     }
   }
   free_operatorfunc_option();
@@ -594,16 +619,16 @@ void set_init_3(void)
   // set, but only if they have not been set before.
   int idx_srr = findoption("srr");
   int do_srr = (idx_srr < 0)
-    ? false
-    : !(options[idx_srr].flags & P_WAS_SET);
+               ? false
+               : !(options[idx_srr].flags & P_WAS_SET);
   int idx_sp = findoption("sp");
   int do_sp = (idx_sp < 0)
-    ? false
-    : !(options[idx_sp].flags & P_WAS_SET);
+              ? false
+              : !(options[idx_sp].flags & P_WAS_SET);
 
   size_t len = 0;
   char *p = (char *)invocation_path_tail(p_sh, &len);
-  p = xstrnsave(p, len);
+  p = xmemdupz(p, len);
 
   {
     //
@@ -726,69 +751,187 @@ void ex_set(exarg_T *eap)
   (void)do_set(eap->arg, flags);
 }
 
-/// Part of do_set() for string options.
-/// @return  FAIL on failure, do not process further options.
-static int do_set_string(int opt_idx, int opt_flags, char **argp, int nextchar, set_op_T op_arg,
-                         uint32_t flags, char *varp_arg, char *errbuf, size_t errbuflen,
-                         int *value_checked, char **errmsg)
+/// Get the default value for a string option.
+static char *stropt_get_default_val(int opt_idx, uint64_t flags)
+{
+  char *newval = options[opt_idx].def_val;
+  // expand environment variables and ~ since the default value was
+  // already expanded, only required when an environment variable was set
+  // later
+  if (newval == NULL) {
+    newval = empty_string_option;
+  } else if (!(options[opt_idx].flags & P_NO_DEF_EXP)) {
+    char *s = option_expand(opt_idx, newval);
+    if (s == NULL) {
+      s = newval;
+    }
+    newval = xstrdup(s);
+  } else {
+    newval = xstrdup(newval);
+  }
+  return newval;
+}
+
+/// Copy the new string value into allocated memory for the option.
+/// Can't use set_string_option_direct(), because we need to remove the
+/// backslashes.
+static char *stropt_copy_value(char *origval, char **argp, set_op_T op,
+                               uint32_t flags FUNC_ATTR_UNUSED)
 {
   char *arg = *argp;
-  set_op_T op = op_arg;
-  char *varp = varp_arg;
-  char *save_arg = NULL;
-  char *s = NULL;
-  char_u *origval_l = NULL;
-  char_u *origval_g = NULL;
-  char whichwrap[80];
 
-  // When using ":set opt=val" for a global option
-  // with a local value the local value will be
-  // reset, use the global value here.
-  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0
-      && ((int)options[opt_idx].indir & PV_BOTH)) {
-    varp = (char *)options[opt_idx].var;
+  // get a bit too much
+  size_t newlen = strlen(arg) + 1;
+  if (op != OP_NONE) {
+    newlen += strlen(origval) + 1;
+  }
+  char *newval = xmalloc(newlen);
+  char *s = newval;
+
+  // Copy the string, skip over escaped chars.
+  // For MS-Windows backslashes before normal file name characters
+  // are not removed, and keep backslash at start, for "\\machine\path",
+  // but do remove it for "\\\\machine\\path".
+  // The reverse is found in escape_option_str_cmdline().
+  while (*arg != NUL && !ascii_iswhite(*arg)) {
+    if (*arg == '\\' && arg[1] != NUL
+#ifdef BACKSLASH_IN_FILENAME
+        && !((flags & P_EXPAND)
+             && vim_isfilec((uint8_t)arg[1])
+             && !ascii_iswhite(arg[1])
+             && (arg[1] != '\\'
+                 || (s == newval && arg[2] != '\\')))
+#endif
+        ) {
+      arg++;  // remove backslash
+    }
+    int i = utfc_ptr2len(arg);
+    if (i > 1) {
+      // copy multibyte char
+      memmove(s, arg, (size_t)i);
+      arg += i;
+      s += i;
+    } else {
+      *s++ = *arg++;
+    }
   }
+  *s = NUL;
 
-  // The old value is kept until we are sure that the new value is valid.
-  char *oldval = *(char **)varp;
+  *argp = arg;
+  return newval;
+}
 
-  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
-    origval_l = *(char_u **)get_varp_scope(&(options[opt_idx]), OPT_LOCAL);
-    origval_g = *(char_u **)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
+/// Expand environment variables and ~ in string option value 'newval'.
+static char *stropt_expand_envvar(int opt_idx, char *origval, char *newval, set_op_T op)
+{
+  char *s = option_expand(opt_idx, newval);
+  if (s == NULL) {
+    return newval;
+  }
 
-    // A global-local string option might have an empty option as value to
-    // indicate that the global value should be used.
-    if (((int)options[opt_idx].indir & PV_BOTH) && origval_l == (char_u *)empty_option) {
-      origval_l = origval_g;
-    }
+  xfree(newval);
+  uint32_t newlen = (unsigned)strlen(s) + 1;
+  if (op != OP_NONE) {
+    newlen += (unsigned)strlen(origval) + 1;
   }
+  newval = xmalloc(newlen);
+  STRCPY(newval, s);
 
-  char *origval;
-  // When setting the local value of a global option, the old value may be
-  // the global value.
-  if (((int)options[opt_idx].indir & PV_BOTH) && (opt_flags & OPT_LOCAL)) {
-    origval = *(char **)get_varp(&options[opt_idx]);
+  return newval;
+}
+
+/// Concatenate the original and new values of a string option, adding a "," if
+/// needed.
+static void stropt_concat_with_comma(char *origval, char *newval, set_op_T op, uint32_t flags)
+{
+  int len = 0;
+  int comma = ((flags & P_COMMA) && *origval != NUL && *newval != NUL);
+  if (op == OP_ADDING) {
+    len = (int)strlen(origval);
+    // Strip a trailing comma, would get 2.
+    if (comma && len > 1
+        && (flags & P_ONECOMMA) == P_ONECOMMA
+        && origval[len - 1] == ','
+        && origval[len - 2] != '\\') {
+      len--;
+    }
+    memmove(newval + len + comma, newval, strlen(newval) + 1);
+    memmove(newval, origval, (size_t)len);
   } else {
-    origval = oldval;
+    len = (int)strlen(newval);
+    STRMOVE(newval + len + comma, origval);
   }
+  if (comma) {
+    newval[len] = ',';
+  }
+}
 
-  char *newval;
-  if (nextchar == '&') {  // set to default val
-    newval = options[opt_idx].def_val;
-    // expand environment variables and ~ since the default value was
-    // already expanded, only required when an environment variable was set
-    // later
-    if (newval == NULL) {
-      newval = empty_option;
-    } else if (!(options[opt_idx].flags & P_NO_DEF_EXP)) {
-      s = option_expand(opt_idx, newval);
-      if (s == NULL) {
-        s = newval;
+/// Remove a value from a string option.  Copy string option value in "origval"
+/// to "newval" and then remove the string "strval" of length "len".
+static void stropt_remove_val(char *origval, char *newval, uint32_t flags, char *strval, int len)
+{
+  // Remove newval[] from origval[]. (Note: "len" has been set above
+  // and is used here).
+  STRCPY(newval, origval);
+  if (*strval) {
+    // may need to remove a comma
+    if (flags & P_COMMA) {
+      if (strval == origval) {
+        // include comma after string
+        if (strval[len] == ',') {
+          len++;
+        }
+      } else {
+        // include comma before string
+        strval--;
+        len++;
+      }
+    }
+    STRMOVE(newval + (strval - origval), strval + len);
+  }
+}
+
+/// Remove flags that appear twice in the string option value 'newval'.
+static void stropt_remove_dupflags(char *newval, uint32_t flags)
+{
+  char *s = newval;
+  // Remove flags that appear twice.
+  for (s = newval; *s;) {
+    // if options have P_FLAGLIST and P_ONECOMMA such as 'whichwrap'
+    if (flags & P_ONECOMMA) {
+      if (*s != ',' && *(s + 1) == ','
+          && vim_strchr(s + 2, (uint8_t)(*s)) != NULL) {
+        // Remove the duplicated value and the next comma.
+        STRMOVE(s, s + 2);
+        continue;
       }
-      newval = xstrdup(s);
     } else {
-      newval = xstrdup(newval);
+      if ((!(flags & P_COMMA) || *s != ',')
+          && vim_strchr(s + 1, (uint8_t)(*s)) != NULL) {
+        STRMOVE(s, s + 1);
+        continue;
+      }
     }
+    s++;
+  }
+}
+
+/// Get the string value specified for a ":set" command.  The following set
+/// options are supported:
+///     set {opt}&
+///     set {opt}<
+///     set {opt}={val}
+///     set {opt}:{val}
+static char *stropt_get_newval(int nextchar, int opt_idx, char **argp, void *varp, char *origval,
+                               set_op_T *op_arg, uint32_t flags)
+{
+  char *arg = *argp;
+  set_op_T op = *op_arg;
+  char *save_arg = NULL;
+  char *newval;
+  char *s = NULL;
+  if (nextchar == '&') {  // set to default val
+    newval = stropt_get_default_val(opt_idx, flags);
   } else if (nextchar == '<') {  // set to global val
     newval = xstrdup(*(char **)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL));
   } else {
@@ -796,123 +939,18 @@ static int do_set_string(int opt_idx, int opt_flags, char **argp, int nextchar,
 
     // Set 'keywordprg' to ":help" if an empty
     // value was passed to :set by the user.
-    if (varp == (char *)&p_kp && (*arg == NUL || *arg == ' ')) {
+    if (varp == &p_kp && (*arg == NUL || *arg == ' ')) {
       save_arg = arg;
       arg = ":help";
-    } else if (varp == (char *)&p_bs && ascii_isdigit(**(char_u **)varp)) {
-      // Convert 'backspace' number to string, for
-      // adding, prepending and removing string.
-      int i = getdigits_int((char **)varp, true, 0);
-      switch (i) {
-      case 0:
-        *(char **)varp = empty_option;
-        break;
-      case 1:
-        *(char_u **)varp = (char_u *)xstrdup("indent,eol");
-        break;
-      case 2:
-        *(char_u **)varp = (char_u *)xstrdup("indent,eol,start");
-        break;
-      case 3:
-        *(char_u **)varp = (char_u *)xstrdup("indent,eol,nostop");
-        break;
-      }
-      xfree(oldval);
-      if (origval == oldval) {
-        origval = *(char **)varp;
-      }
-      if (origval_l == (char_u *)oldval) {
-        origval_l = *(char_u **)varp;
-      }
-      if (origval_g == (char_u *)oldval) {
-        origval_g = *(char_u **)varp;
-      }
-      oldval = *(char **)varp;
-    } else if (varp == (char *)&p_ww && ascii_isdigit(*arg)) {
-      // Convert 'whichwrap' number to string, for backwards compatibility
-      // with Vim 3.0.
-      *whichwrap = NUL;
-      int i = getdigits_int(&arg, true, 0);
-      if (i & 1) {
-        xstrlcat(whichwrap, "b,", sizeof(whichwrap));
-      }
-      if (i & 2) {
-        xstrlcat(whichwrap, "s,", sizeof(whichwrap));
-      }
-      if (i & 4) {
-        xstrlcat(whichwrap, "h,l,", sizeof(whichwrap));
-      }
-      if (i & 8) {
-        xstrlcat(whichwrap, "<,>,", sizeof(whichwrap));
-      }
-      if (i & 16) {
-        xstrlcat(whichwrap, "[,],", sizeof(whichwrap));
-      }
-      if (*whichwrap != NUL) {  // remove trailing ,
-        whichwrap[strlen(whichwrap) - 1] = NUL;
-      }
-      save_arg = arg;
-      arg = whichwrap;
-    } else if (*arg == '>' && (varp == (char *)&p_dir || varp == (char *)&p_bdir)) {
-      // Remove '>' before 'dir' and 'bdir', for backwards compatibility with
-      // version 3.0
-      arg++;
     }
 
     // Copy the new string into allocated memory.
-    // Can't use set_string_option_direct(), because we need to remove the
-    // backslashes.
-
-    // get a bit too much
-    size_t newlen = strlen(arg) + 1;
-    if (op != OP_NONE) {
-      newlen += strlen(origval) + 1;
-    }
-    newval = xmalloc(newlen);
-    s = newval;
-
-    // Copy the string, skip over escaped chars.
-    // For MS-Windows backslashes before normal file name characters
-    // are not removed, and keep backslash at start, for "\\machine\path",
-    // but do remove it for "\\\\machine\\path".
-    // The reverse is found in ExpandOldSetting().
-    while (*arg != NUL && !ascii_iswhite(*arg)) {
-      if (*arg == '\\' && arg[1] != NUL
-#ifdef BACKSLASH_IN_FILENAME
-          && !((flags & P_EXPAND)
-               && vim_isfilec((uint8_t)arg[1])
-               && !ascii_iswhite(arg[1])
-               && (arg[1] != '\\'
-                   || (s == newval && arg[2] != '\\')))
-#endif
-          ) {
-        arg++;  // remove backslash
-      }
-      int i = utfc_ptr2len(arg);
-      if (i > 1) {
-        // copy multibyte char
-        memmove(s, arg, (size_t)i);
-        arg += i;
-        s += i;
-      } else {
-        *s++ = *arg++;
-      }
-    }
-    *s = NUL;
+    newval = stropt_copy_value(origval, &arg, op, flags);
 
     // Expand environment variables and ~.
     // Don't do it when adding without inserting a comma.
     if (op == OP_NONE || (flags & P_COMMA)) {
-      s = option_expand(opt_idx, newval);
-      if (s != NULL) {
-        xfree(newval);
-        newlen = (unsigned)strlen(s) + 1;
-        if (op != OP_NONE) {
-          newlen += (unsigned)strlen(origval) + 1;
-        }
-        newval = xmalloc(newlen);
-        STRCPY(newval, s);
-      }
+      newval = stropt_expand_envvar(opt_idx, origval, newval, op);
     }
 
     // locate newval[] in origval[] when removing it
@@ -936,130 +974,439 @@ static int do_set_string(int opt_idx, int opt_flags, char **argp, int nextchar,
 
     // concatenate the two strings; add a ',' if needed
     if (op == OP_ADDING || op == OP_PREPENDING) {
-      int comma = ((flags & P_COMMA) && *origval != NUL && *newval != NUL);
-      if (op == OP_ADDING) {
-        len = (int)strlen(origval);
-        // Strip a trailing comma, would get 2.
-        if (comma && len > 1
-            && (flags & P_ONECOMMA) == P_ONECOMMA
-            && origval[len - 1] == ','
-            && origval[len - 2] != '\\') {
-          len--;
-        }
-        memmove(newval + len + comma, newval, strlen(newval) + 1);
-        memmove(newval, origval, (size_t)len);
-      } else {
-        len = (int)strlen(newval);
-        STRMOVE(newval + len + comma, origval);
+      stropt_concat_with_comma(origval, newval, op, flags);
+    } else if (op == OP_REMOVING) {
+      // Remove newval[] from origval[]. (Note: "len" has been set above
+      // and is used here).
+      stropt_remove_val(origval, newval, flags, s, len);
+    }
+
+    if (flags & P_FLAGLIST) {
+      // Remove flags that appear twice.
+      stropt_remove_dupflags(newval, flags);
+    }
+  }
+
+  if (save_arg != NULL) {
+    arg = save_arg;  // arg was temporarily changed, restore it
+  }
+  *argp = arg;
+  *op_arg = op;
+
+  return newval;
+}
+
+static set_op_T get_op(const char *arg)
+{
+  set_op_T op = OP_NONE;
+  if (*arg != NUL && *(arg + 1) == '=') {
+    if (*arg == '+') {
+      op = OP_ADDING;          // "+="
+    } else if (*arg == '^') {
+      op = OP_PREPENDING;      // "^="
+    } else if (*arg == '-') {
+      op = OP_REMOVING;        // "-="
+    }
+  }
+  return op;
+}
+
+static set_prefix_T get_option_prefix(char **argp)
+{
+  if (strncmp(*argp, "no", 2) == 0) {
+    *argp += 2;
+    return PREFIX_NO;
+  } else if (strncmp(*argp, "inv", 3) == 0) {
+    *argp += 3;
+    return PREFIX_INV;
+  }
+
+  return PREFIX_NONE;
+}
+
+/// @param[in]   arg       Pointer to start option name
+/// @param[out]  opt_idxp  Option index in options[] table.
+/// @param[out]  keyp
+/// @param[out]  len       Length of option name
+/// @return  FAIL if an error is detected, OK otherwise
+static int parse_option_name(char *arg, int *keyp, int *lenp, int *opt_idxp)
+{
+  // find end of name
+  int key = 0;
+  int len;
+  int opt_idx;
+
+  if (*arg == '<') {
+    opt_idx = -1;
+    // look out for <t_>;>
+    if (arg[1] == 't' && arg[2] == '_' && arg[3] && arg[4]) {
+      len = 5;
+    } else {
+      len = 1;
+      while (arg[len] != NUL && arg[len] != '>') {
+        len++;
       }
-      if (comma) {
-        newval[len] = ',';
+    }
+    if (arg[len] != '>') {
+      return FAIL;
+    }
+    if (arg[1] == 't' && arg[2] == '_') {  // could be term code
+      opt_idx = findoption_len(arg + 1, (size_t)(len - 1));
+    }
+    len++;
+    if (opt_idx == -1) {
+      key = find_key_option(arg + 1, true);
+    }
+  } else {
+    // The two characters after "t_" may not be alphanumeric.
+    if (arg[0] == 't' && arg[1] == '_' && arg[2] && arg[3]) {
+      len = 4;
+    } else {
+      len = 0;
+      while (ASCII_ISALNUM(arg[len]) || arg[len] == '_') {
+        len++;
       }
     }
+    opt_idx = findoption_len(arg, (size_t)len);
+    if (opt_idx == -1) {
+      key = find_key_option(arg, false);
+    }
+  }
 
-    // Remove newval[] from origval[]. (Note: "len" has been set above and
-    // is used here).
-    if (op == OP_REMOVING) {
-      STRCPY(newval, origval);
-      if (*s) {
-        // may need to remove a comma
-        if (flags & P_COMMA) {
-          if (s == origval) {
-            // include comma after string
-            if (s[len] == ',') {
-              len++;
-            }
-          } else {
-            // include comma before string
-            s--;
-            len++;
-          }
-        }
-        STRMOVE(newval + (s - origval), s + len);
+  *keyp = key;
+  *lenp = len;
+  *opt_idxp = opt_idx;
+
+  return OK;
+}
+
+static int validate_opt_idx(win_T *win, int opt_idx, int opt_flags, uint32_t flags,
+                            set_prefix_T prefix, const char **errmsg)
+{
+  // Only bools can have a prefix of 'inv' or 'no'
+  if (!(flags & P_BOOL) && prefix != PREFIX_NONE) {
+    *errmsg = e_invarg;
+    return FAIL;
+  }
+
+  // Skip all options that are not window-local (used when showing
+  // an already loaded buffer in a window).
+  if ((opt_flags & OPT_WINONLY)
+      && (opt_idx < 0 || options[opt_idx].var != VAR_WIN)) {
+    return FAIL;
+  }
+
+  // Skip all options that are window-local (used for :vimgrep).
+  if ((opt_flags & OPT_NOWIN) && opt_idx >= 0
+      && options[opt_idx].var == VAR_WIN) {
+    return FAIL;
+  }
+
+  // Disallow changing some options from modelines.
+  if (opt_flags & OPT_MODELINE) {
+    if (flags & (P_SECURE | P_NO_ML)) {
+      *errmsg = e_not_allowed_in_modeline;
+      return FAIL;
+    }
+    if ((flags & P_MLE) && !p_mle) {
+      *errmsg = e_not_allowed_in_modeline_when_modelineexpr_is_off;
+      return FAIL;
+    }
+    // In diff mode some options are overruled.  This avoids that
+    // 'foldmethod' becomes "marker" instead of "diff" and that
+    // "wrap" gets set.
+    if (win->w_p_diff
+        && opt_idx >= 0              // shut up coverity warning
+        && (options[opt_idx].indir == PV_FDM
+            || options[opt_idx].indir == PV_WRAP)) {
+      return FAIL;
+    }
+  }
+
+  // Disallow changing some options in the sandbox
+  if (sandbox != 0 && (flags & P_SECURE)) {
+    *errmsg = e_sandbox;
+    return FAIL;
+  }
+
+  return OK;
+}
+
+/// Get new option value from argp. Allocated OptVal must be freed by caller.
+static OptVal get_option_newval(int opt_idx, int opt_flags, set_prefix_T prefix, char **argp,
+                                int nextchar, set_op_T op, uint32_t flags, void *varp, char *errbuf,
+                                const size_t errbuflen, const char **errmsg)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  assert(varp != NULL);
+
+  vimoption_T *opt = &options[opt_idx];
+  char *arg = *argp;
+  // When setting the local value of a global option, the old value may be the global value.
+  const bool oldval_is_global = ((int)opt->indir & PV_BOTH) && (opt_flags & OPT_LOCAL);
+  OptVal oldval = optval_from_varp(opt_idx, oldval_is_global ? get_varp(opt) : varp);
+  OptVal newval = NIL_OPTVAL;
+
+  switch (oldval.type) {
+  case kOptValTypeNil:
+    abort();
+  case kOptValTypeBoolean: {
+    TriState newval_bool;
+
+    // ":set opt!": invert
+    // ":set opt&": reset to default value
+    // ":set opt<": reset to global value
+    if (nextchar == '!') {
+      switch (oldval.data.boolean) {
+      case kNone:
+        newval_bool = kNone;
+        break;
+      case kTrue:
+        newval_bool = kFalse;
+        break;
+      case kFalse:
+        newval_bool = kTrue;
+        break;
+      }
+    } else if (nextchar == '&') {
+      newval_bool = TRISTATE_FROM_INT((int)(intptr_t)options[opt_idx].def_val);
+    } else if (nextchar == '<') {
+      // For 'autoread', kNone means to use global value.
+      if ((int *)varp == &curbuf->b_p_ar && opt_flags == OPT_LOCAL) {
+        newval_bool = kNone;
+      } else {
+        newval_bool = TRISTATE_FROM_INT(*(int *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL));
+      }
+    } else {
+      // ":set invopt": invert
+      // ":set opt" or ":set noopt": set or reset
+      if (prefix == PREFIX_INV) {
+        newval_bool = *(int *)varp ^ 1;
+      } else {
+        newval_bool = prefix == PREFIX_NO ? 0 : 1;
       }
     }
 
-    if (flags & P_FLAGLIST) {
-      // Remove flags that appear twice.
-      for (s = newval; *s;) {
-        // if options have P_FLAGLIST and P_ONECOMMA such as
-        // 'whichwrap'
-        if (flags & P_ONECOMMA) {
-          if (*s != ',' && *(s + 1) == ','
-              && vim_strchr(s + 2, (uint8_t)(*s)) != NULL) {
-            // Remove the duplicated value and the next comma.
-            STRMOVE(s, s + 2);
-            continue;
-          }
-        } else {
-          if ((!(flags & P_COMMA) || *s != ',')
-              && vim_strchr(s + 1, (uint8_t)(*s)) != NULL) {
-            STRMOVE(s, s + 1);
-            continue;
-          }
-        }
-        s++;
+    newval = BOOLEAN_OPTVAL(newval_bool);
+    break;
+  }
+  case kOptValTypeNumber: {
+    OptInt oldval_num = oldval.data.number;
+    OptInt newval_num;
+
+    // Different ways to set a number option:
+    // &            set to default value
+    // <            set to global value
+    // <xx>         accept special key codes for 'wildchar'
+    // c            accept any non-digit for 'wildchar'
+    // [-]0-9       set number
+    // other        error
+    arg++;
+    if (nextchar == '&') {
+      newval_num = (OptInt)(intptr_t)options[opt_idx].def_val;
+    } else if (nextchar == '<') {
+      if ((OptInt *)varp == &curbuf->b_p_ul && opt_flags == OPT_LOCAL) {
+        // for 'undolevels' NO_LOCAL_UNDOLEVEL means using the global newval_num
+        newval_num = NO_LOCAL_UNDOLEVEL;
+      } else if (opt_flags == OPT_LOCAL
+                 && ((OptInt *)varp == &curwin->w_p_siso || (OptInt *)varp == &curwin->w_p_so)) {
+        // for 'scrolloff'/'sidescrolloff' -1 means using the global newval_num
+        newval_num = -1;
+      } else {
+        newval_num = *(OptInt *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
+      }
+    } else if (((OptInt *)varp == &p_wc || (OptInt *)varp == &p_wcm)
+               && (*arg == '<' || *arg == '^'
+                   || (*arg != NUL && (!arg[1] || ascii_iswhite(arg[1]))
+                       && !ascii_isdigit(*arg)))) {
+      newval_num = string_to_key(arg);
+      if (newval_num == 0 && (OptInt *)varp != &p_wcm) {
+        *errmsg = e_invarg;
+        return newval;
       }
+    } else if (*arg == '-' || ascii_isdigit(*arg)) {
+      int i;
+      // Allow negative, octal and hex numbers.
+      vim_str2nr(arg, NULL, &i, STR2NR_ALL, &newval_num, NULL, 0, true, NULL);
+      if (i == 0 || (arg[i] != NUL && !ascii_iswhite(arg[i]))) {
+        *errmsg = e_number_required_after_equal;
+        return newval;
+      }
+    } else {
+      *errmsg = e_number_required_after_equal;
+      return newval;
     }
 
-    if (save_arg != NULL) {
-      arg = save_arg;  // arg was temporarily changed, restore it
+    if (op == OP_ADDING) {
+      newval_num = oldval_num + newval_num;
     }
+    if (op == OP_PREPENDING) {
+      newval_num = oldval_num * newval_num;
+    }
+    if (op == OP_REMOVING) {
+      newval_num = oldval_num - newval_num;
+    }
+
+    newval = NUMBER_OPTVAL(newval_num);
+    break;
+  }
+  case kOptValTypeString: {
+    char *oldval_str = oldval.data.string.data;
+    // Get the new value for the option
+    char *newval_str = stropt_get_newval(nextchar, opt_idx, argp, varp, oldval_str, &op, flags);
+    newval = CSTR_AS_OPTVAL(newval_str);
+    break;
+  }
   }
 
-  // Set the new value.
-  *(char_u **)(varp) = (char_u *)newval;
+  return newval;
+}
 
-  // origval may be freed by did_set_string_option(), make a copy.
-  char *saved_origval = (origval != NULL) ? xstrdup(origval) : NULL;
-  char *saved_origval_l = (origval_l != NULL) ? xstrdup((char *)origval_l) : NULL;
-  char *saved_origval_g = (origval_g != NULL) ? xstrdup((char *)origval_g) : NULL;
+static void do_one_set_option(int opt_flags, char **argp, bool *did_show, char *errbuf,
+                              size_t errbuflen, const char **errmsg)
+{
+  // 1: nothing, 0: "no", 2: "inv" in front of name
+  set_prefix_T prefix = get_option_prefix(argp);
 
-  // newval (and varp) may become invalid if the buffer is closed by
-  // autocommands.
-  char *saved_newval = (newval != NULL) ? xstrdup(newval) : NULL;
+  char *arg = *argp;
 
-  {
-    uint32_t *p = insecure_flag(curwin, opt_idx, opt_flags);
-    const int secure_saved = secure;
+  // find end of name
+  int key = 0;
+  int len;
+  int opt_idx;
+  if (parse_option_name(arg, &key, &len, &opt_idx) == FAIL) {
+    *errmsg = e_invarg;
+    return;
+  }
+
+  // remember character after option name
+  int afterchar = (uint8_t)arg[len];
 
-    // When an option is set in the sandbox, from a modeline or in secure
-    // mode, then deal with side effects in secure mode.  Also when the
-    // value was set with the P_INSECURE flag and is not completely
-    // replaced.
-    if ((opt_flags & OPT_MODELINE)
-        || sandbox != 0
-        || (op != OP_NONE && (*p & P_INSECURE))) {
-      secure = 1;
+  // skip white space, allow ":set ai  ?"
+  while (ascii_iswhite(arg[len])) {
+    len++;
+  }
+
+  set_op_T op = get_op(arg + len);
+  if (op != OP_NONE) {
+    len++;
+  }
+
+  uint8_t nextchar = (uint8_t)arg[len];  // next non-white char after option name
+
+  if (opt_idx == -1 && key == 0) {          // found a mismatch: skip
+    *errmsg = e_unknown_option;
+    return;
+  }
+
+  uint32_t flags;  // flags for current option
+  void *varp = NULL;  // pointer to variable for current option
+
+  if (opt_idx >= 0) {
+    if (options[opt_idx].var == NULL) {         // hidden option: skip
+      // Only give an error message when requesting the value of
+      // a hidden option, ignore setting it.
+      if (vim_strchr("=:!&<", nextchar) == NULL
+          && (!(options[opt_idx].flags & P_BOOL)
+              || nextchar == '?')) {
+        *errmsg = e_unsupportedoption;
+      }
+      return;
     }
 
-    // Handle side effects, and set the global value for ":set" on local
-    // options. Note: when setting 'syntax' or 'filetype' autocommands may
-    // be triggered that can cause havoc.
-    *errmsg = did_set_string_option(opt_idx, (char **)varp, oldval,
-                                    errbuf, errbuflen,
-                                    opt_flags, value_checked);
+    flags = options[opt_idx].flags;
+    varp = get_varp_scope(&(options[opt_idx]), opt_flags);
+  } else {
+    flags = P_STRING;
+  }
 
-    secure = secure_saved;
+  if (validate_opt_idx(curwin, opt_idx, opt_flags, flags, prefix, errmsg) == FAIL) {
+    return;
   }
 
-  if (*errmsg == NULL) {
-    if (!starting) {
-      trigger_optionset_string(opt_idx, opt_flags, saved_origval, saved_origval_l,
-                               saved_origval_g, saved_newval);
+  if (vim_strchr("?=:!&<", nextchar) != NULL) {
+    *argp += len;
+    if (nextchar == '&' && (*argp)[1] == 'v' && (*argp)[2] == 'i') {
+      if ((*argp)[3] == 'm') {  // "opt&vim": set to Vim default
+        *argp += 3;
+      } else {  // "opt&vi": set to Vi default
+        *argp += 2;
+      }
     }
-    if (options[opt_idx].flags & P_UI_OPTION) {
-      ui_call_option_set(cstr_as_string(options[opt_idx].fullname),
-                         STRING_OBJ(cstr_as_string(saved_newval)));
+    if (vim_strchr("?!&<", nextchar) != NULL
+        && (*argp)[1] != NUL && !ascii_iswhite((*argp)[1])) {
+      *errmsg = e_trailing;
+      return;
     }
   }
-  xfree(saved_origval);
-  xfree(saved_origval_l);
-  xfree(saved_origval_g);
-  xfree(saved_newval);
 
-  *argp = arg;
-  return *errmsg == NULL ? OK : FAIL;
+  //
+  // allow '=' and ':' as MS-DOS command.com allows only one
+  // '=' character per "set" command line. grrr. (jw)
+  //
+  if (nextchar == '?'
+      || (prefix == PREFIX_NONE
+          && vim_strchr("=:&<", nextchar) == NULL
+          && !(flags & P_BOOL))) {
+    // print value
+    if (*did_show) {
+      msg_putchar('\n');                // cursor below last one
+    } else {
+      gotocmdline(true);                // cursor at status line
+      *did_show = true;                 // remember that we did a line
+    }
+    if (opt_idx >= 0) {
+      showoneopt(&options[opt_idx], opt_flags);
+      if (p_verbose > 0) {
+        // Mention where the option was last set.
+        if (varp == options[opt_idx].var) {
+          option_last_set_msg(options[opt_idx].last_set);
+        } else if ((int)options[opt_idx].indir & PV_WIN) {
+          option_last_set_msg(curwin->w_p_script_ctx[(int)options[opt_idx].indir & PV_MASK]);
+        } else if ((int)options[opt_idx].indir & PV_BUF) {
+          option_last_set_msg(curbuf->b_p_script_ctx[(int)options[opt_idx].indir & PV_MASK]);
+        }
+      }
+    } else {
+      *errmsg = e_key_code_not_set;
+      return;
+    }
+    if (nextchar != '?' && nextchar != NUL && !ascii_iswhite(afterchar)) {
+      *errmsg = e_trailing;
+    }
+    return;
+  }
+
+  if (flags & P_BOOL) {
+    if (vim_strchr("=:", nextchar) != NULL) {
+      *errmsg = e_invarg;
+      return;
+    }
+
+    if (vim_strchr("!&<", nextchar) == NULL && nextchar != NUL && !ascii_iswhite(afterchar)) {
+      *errmsg = e_trailing;
+      return;
+    }
+  } else {
+    if (vim_strchr("=:&<", nextchar) == NULL) {
+      *errmsg = e_invarg;
+      return;
+    }
+  }
+
+  // Don't try to change hidden option.
+  if (varp == NULL) {
+    return;
+  }
+
+  OptVal newval = get_option_newval(opt_idx, opt_flags, prefix, argp, nextchar, op, flags, varp,
+                                    errbuf, errbuflen, errmsg);
+
+  if (newval.type == kOptValTypeNil || *errmsg != NULL) {
+    return;
+  }
+
+  *errmsg = set_option(opt_idx, varp, newval, opt_flags, op == OP_NONE, errbuf, errbuflen);
 }
 
 /// Parse 'arg' for option settings.
@@ -1079,402 +1426,79 @@ static int do_set_string(int opt_idx, int opt_flags, char **argp, int nextchar,
 /// @return  FAIL if an error is detected, OK otherwise
 int do_set(char *arg, int opt_flags)
 {
-  int did_show = false;             // already showed one value
+  bool did_show = false;             // already showed one value
 
   if (*arg == NUL) {
-    showoptions(0, opt_flags);
+    showoptions(false, opt_flags);
     did_show = true;
-    goto theend;
-  }
-
-  char errbuf[80];
-
-  while (*arg != NUL) {         // loop to process all options
-    char *errmsg = NULL;
-    char *startarg = arg;             // remember for error message
-
-    if (strncmp(arg, "all", 3) == 0 && !ASCII_ISALPHA(arg[3])
-        && !(opt_flags & OPT_MODELINE)) {
-      // ":set all"  show all options.
-      // ":set all&" set all options to their default value.
-      arg += 3;
-      if (*arg == '&') {
-        arg++;
-        // Only for :set command set global value of local options.
-        set_options_default(OPT_FREE | opt_flags);
-        didset_options();
-        didset_options2();
-        ui_refresh_options();
-        redraw_all_later(UPD_CLEAR);
-      } else {
-        showoptions(1, opt_flags);
-        did_show = true;
-      }
-    } else {
-      int prefix = 1;  // 1: nothing, 0: "no", 2: "inv" in front of name
-      if (strncmp(arg, "no", 2) == 0) {
-        prefix = 0;
-        arg += 2;
-      } else if (strncmp(arg, "inv", 3) == 0) {
-        prefix = 2;
+  } else {
+    while (*arg != NUL) {         // loop to process all options
+      if (strncmp(arg, "all", 3) == 0 && !ASCII_ISALPHA(arg[3])
+          && !(opt_flags & OPT_MODELINE)) {
+        // ":set all"  show all options.
+        // ":set all&" set all options to their default value.
         arg += 3;
-      }
-
-      // find end of name
-      int key = 0;
-      int len;
-      int opt_idx;
-      if (*arg == '<') {
-        opt_idx = -1;
-        // look out for <t_>;>
-        if (arg[1] == 't' && arg[2] == '_' && arg[3] && arg[4]) {
-          len = 5;
+        if (*arg == '&') {
+          arg++;
+          // Only for :set command set global value of local options.
+          set_options_default(OPT_FREE | opt_flags);
+          didset_options();
+          didset_options2();
+          ui_refresh_options();
+          redraw_all_later(UPD_CLEAR);
         } else {
-          len = 1;
-          while (arg[len] != NUL && arg[len] != '>') {
-            len++;
-          }
-        }
-        if (arg[len] != '>') {
-          errmsg = e_invarg;
-          goto skip;
-        }
-        if (arg[1] == 't' && arg[2] == '_') {  // could be term code
-          opt_idx = findoption_len((const char *)arg + 1, (size_t)(len - 1));
-        }
-        len++;
-        if (opt_idx == -1) {
-          key = find_key_option(arg + 1, true);
+          showoptions(true, opt_flags);
+          did_show = true;
         }
       } else {
-        len = 0;
-        // The two characters after "t_" may not be alphanumeric.
-        if (arg[0] == 't' && arg[1] == '_' && arg[2] && arg[3]) {
-          len = 4;
-        } else {
-          while (ASCII_ISALNUM(arg[len]) || arg[len] == '_') {
-            len++;
+        char *startarg = arg;             // remember for error message
+        const char *errmsg = NULL;
+        char errbuf[80];
+
+        do_one_set_option(opt_flags, &arg, &did_show, errbuf, sizeof(errbuf), &errmsg);
+
+        // Advance to next argument.
+        // - skip until a blank found, taking care of backslashes
+        // - skip blanks
+        // - skip one "=val" argument (for hidden options ":set gfn =xx")
+        for (int i = 0; i < 2; i++) {
+          arg = skiptowhite_esc(arg);
+          arg = skipwhite(arg);
+          if (*arg != '=') {
+            break;
           }
         }
-        opt_idx = findoption_len((const char *)arg, (size_t)len);
-        if (opt_idx == -1) {
-          key = find_key_option(arg, false);
-        }
-      }
-
-      // remember character after option name
-      int afterchar = (uint8_t)arg[len];
-
-      // skip white space, allow ":set ai  ?"
-      while (ascii_iswhite(arg[len])) {
-        len++;
-      }
-
-      set_op_T op = OP_NONE;
-      if (arg[len] != NUL && arg[len + 1] == '=') {
-        if (arg[len] == '+') {
-          op = OP_ADDING;                       // "+="
-          len++;
-        } else if (arg[len] == '^') {
-          op = OP_PREPENDING;                   // "^="
-          len++;
-        } else if (arg[len] == '-') {
-          op = OP_REMOVING;                     // "-="
-          len++;
-        }
-      }
-      char_u nextchar = (uint8_t)arg[len];  // next non-white char after option name
 
-      if (opt_idx == -1 && key == 0) {          // found a mismatch: skip
-        errmsg = e_unknown_option;
-        goto skip;
-      }
-
-      uint32_t flags;  // flags for current option
-      char *varp = NULL;  // pointer to variable for current option
-
-      if (opt_idx >= 0) {
-        if (options[opt_idx].var == NULL) {         // hidden option: skip
-          // Only give an error message when requesting the value of
-          // a hidden option, ignore setting it.
-          if (vim_strchr("=:!&<", (uint8_t)nextchar) == NULL
-              && (!(options[opt_idx].flags & P_BOOL)
-                  || nextchar == '?')) {
-            errmsg = e_unsupportedoption;
+        if (errmsg != NULL) {
+          xstrlcpy(IObuff, _(errmsg), IOSIZE);
+          int i = (int)strlen(IObuff) + 2;
+          if (i + (arg - startarg) < IOSIZE) {
+            // append the argument with the error
+            xstrlcat(IObuff, ": ", IOSIZE);
+            assert(arg >= startarg);
+            memmove(IObuff + i, startarg, (size_t)(arg - startarg));
+            IObuff[i + (arg - startarg)] = NUL;
           }
-          goto skip;
-        }
+          // make sure all characters are printable
+          trans_characters(IObuff, IOSIZE);
 
-        flags = options[opt_idx].flags;
-        varp = get_varp_scope(&(options[opt_idx]), opt_flags);
-      } else {
-        flags = P_STRING;
-      }
-
-      // Skip all options that are not window-local (used when showing
-      // an already loaded buffer in a window).
-      if ((opt_flags & OPT_WINONLY)
-          && (opt_idx < 0 || options[opt_idx].var != VAR_WIN)) {
-        goto skip;
-      }
+          no_wait_return++;         // wait_return() done later
+          emsg(IObuff);             // show error highlighted
+          no_wait_return--;
 
-      // Skip all options that are window-local (used for :vimgrep).
-      if ((opt_flags & OPT_NOWIN) && opt_idx >= 0
-          && options[opt_idx].var == VAR_WIN) {
-        goto skip;
-      }
-
-      // Disallow changing some options from modelines.
-      if (opt_flags & OPT_MODELINE) {
-        if (flags & (P_SECURE | P_NO_ML)) {
-          errmsg = e_not_allowed_in_modeline;
-          goto skip;
-        }
-        if ((flags & P_MLE) && !p_mle) {
-          errmsg = e_not_allowed_in_modeline_when_modelineexpr_is_off;
-          goto skip;
-        }
-        // In diff mode some options are overruled.  This avoids that
-        // 'foldmethod' becomes "marker" instead of "diff" and that
-        // "wrap" gets set.
-        if (curwin->w_p_diff
-            && opt_idx >= 0              // shut up coverity warning
-            && (options[opt_idx].indir == PV_FDM
-                || options[opt_idx].indir == PV_WRAP)) {
-          goto skip;
-        }
-      }
-
-      // Disallow changing some options in the sandbox
-      if (sandbox != 0 && (flags & P_SECURE)) {
-        errmsg = e_sandbox;
-        goto skip;
-      }
-
-      if (vim_strchr("?=:!&<", (uint8_t)nextchar) != NULL) {
-        arg += len;
-        if (nextchar == '&' && arg[1] == 'v' && arg[2] == 'i') {
-          if (arg[3] == 'm') {  // "opt&vim": set to Vim default
-            arg += 3;
-          } else {  // "opt&vi": set to Vi default
-            arg += 2;
-          }
-        }
-        if (vim_strchr("?!&<", (uint8_t)nextchar) != NULL
-            && arg[1] != NUL && !ascii_iswhite(arg[1])) {
-          errmsg = e_trailing;
-          goto skip;
-        }
-      }
-
-      //
-      // allow '=' and ':' as MS-DOS command.com allows only one
-      // '=' character per "set" command line. grrr. (jw)
-      //
-      if (nextchar == '?'
-          || (prefix == 1
-              && vim_strchr("=:&<", (uint8_t)nextchar) == NULL
-              && !(flags & P_BOOL))) {
-        // print value
-        if (did_show) {
-          msg_putchar('\n');                // cursor below last one
-        } else {
-          gotocmdline(true);                // cursor at status line
-          did_show = true;                  // remember that we did a line
-        }
-        if (opt_idx >= 0) {
-          showoneopt(&options[opt_idx], opt_flags);
-          if (p_verbose > 0) {
-            // Mention where the option was last set.
-            if (varp == (char *)options[opt_idx].var) {
-              option_last_set_msg(options[opt_idx].last_set);
-            } else if ((int)options[opt_idx].indir & PV_WIN) {
-              option_last_set_msg(curwin->w_p_script_ctx[
-                                                         (int)options[opt_idx].indir & PV_MASK]);
-            } else if ((int)options[opt_idx].indir & PV_BUF) {
-              option_last_set_msg(curbuf->b_p_script_ctx[
-                                                         (int)options[opt_idx].indir & PV_MASK]);
-            }
-          }
-        } else {
-          errmsg = e_key_code_not_set;
-          goto skip;
-        }
-        if (nextchar != '?'
-            && nextchar != NUL && !ascii_iswhite(afterchar)) {
-          errmsg = e_trailing;
-        }
-      } else {
-        int value_checked = false;
-        varnumber_T value;
-
-        if (flags & P_BOOL) {                       // boolean
-          if (nextchar == '=' || nextchar == ':') {
-            errmsg = e_invarg;
-            goto skip;
-          }
-
-          // ":set opt!": invert
-          // ":set opt&": reset to default value
-          // ":set opt<": reset to global value
-          if (nextchar == '!') {
-            value = *(int *)(varp) ^ 1;
-          } else if (nextchar == '&') {
-            value = (int)(intptr_t)options[opt_idx].def_val;
-          } else if (nextchar == '<') {
-            // For 'autoread' -1 means to use global value.
-            if ((int *)varp == &curbuf->b_p_ar
-                && opt_flags == OPT_LOCAL) {
-              value = -1;
-            } else {
-              value = *(int *)get_varp_scope(&(options[opt_idx]),
-                                             OPT_GLOBAL);
-            }
-          } else {
-            // ":set invopt": invert
-            // ":set opt" or ":set noopt": set or reset
-            if (nextchar != NUL && !ascii_iswhite(afterchar)) {
-              errmsg = e_trailing;
-              goto skip;
-            }
-            if (prefix == 2) {                  // inv
-              value = *(int *)(varp) ^ 1;
-            } else {
-              value = prefix;
-            }
-          }
-
-          errmsg = set_bool_option(opt_idx, (char_u *)varp, (int)value, opt_flags);
-        } else {  // Numeric or string.
-          if (vim_strchr("=:&<", (uint8_t)nextchar) == NULL
-              || prefix != 1) {
-            errmsg = e_invarg;
-            goto skip;
-          }
-
-          if (flags & P_NUM) {                      // numeric
-            // Different ways to set a number option:
-            // &            set to default value
-            // <            set to global value
-            // <xx>         accept special key codes for 'wildchar'
-            // c            accept any non-digit for 'wildchar'
-            // [-]0-9       set number
-            // other        error
-            arg++;
-            if (nextchar == '&') {
-              value = (long)(intptr_t)options[opt_idx].def_val;
-            } else if (nextchar == '<') {
-              // For 'undolevels' NO_LOCAL_UNDOLEVEL means to
-              // use the global value.
-              if ((long *)varp == &curbuf->b_p_ul && opt_flags == OPT_LOCAL) {
-                value = NO_LOCAL_UNDOLEVEL;
-              } else {
-                value = *(long *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
-              }
-            } else if (((long *)varp == &p_wc
-                        || (long *)varp == &p_wcm)
-                       && (*arg == '<'
-                           || *arg == '^'
-                           || (*arg != NUL && (!arg[1] || ascii_iswhite(arg[1]))
-                               && !ascii_isdigit(*arg)))) {
-              value = string_to_key(arg);
-              if (value == 0 && (long *)varp != &p_wcm) {
-                errmsg = e_invarg;
-                goto skip;
-              }
-            } else if (*arg == '-' || ascii_isdigit(*arg)) {
-              int i;
-              // Allow negative, octal and hex numbers.
-              vim_str2nr(arg, NULL, &i, STR2NR_ALL, &value, NULL, 0, true);
-              if (i == 0 || (arg[i] != NUL && !ascii_iswhite(arg[i]))) {
-                errmsg = e_number_required_after_equal;
-                goto skip;
-              }
-            } else {
-              errmsg = e_number_required_after_equal;
-              goto skip;
-            }
-
-            if (op == OP_ADDING) {
-              value = *(long *)varp + value;
-            }
-            if (op == OP_PREPENDING) {
-              value = *(long *)varp * value;
-            }
-            if (op == OP_REMOVING) {
-              value = *(long *)varp - value;
-            }
-            errmsg = set_num_option(opt_idx, (char_u *)varp, (long)value,
-                                    errbuf, sizeof(errbuf),
-                                    opt_flags);
-          } else if (opt_idx >= 0) {  // String.
-            if (do_set_string(opt_idx, opt_flags, &arg, nextchar,
-                              op, flags, varp, errbuf, sizeof(errbuf),
-                              &value_checked, &errmsg) == FAIL) {
-              if (errmsg != NULL) {
-                goto skip;
-              }
-              break;
-            }
-          } else {
-            // key code option(FIXME(tarruda): Show a warning or something
-            // similar)
-          }
-        }
-
-        if (opt_idx >= 0) {
-          did_set_option(opt_idx, opt_flags, op == OP_NONE, value_checked);
-        }
-      }
-
-skip:
-      // Advance to next argument.
-      // - skip until a blank found, taking care of backslashes
-      // - skip blanks
-      // - skip one "=val" argument (for hidden options ":set gfn =xx")
-      for (int i = 0; i < 2; i++) {
-        while (*arg != NUL && !ascii_iswhite(*arg)) {
-          if (*arg++ == '\\' && *arg != NUL) {
-            arg++;
-          }
-        }
-        arg = skipwhite(arg);
-        if (*arg != '=') {
-          break;
+          return FAIL;
         }
       }
-    }
-
-    if (errmsg != NULL) {
-      xstrlcpy(IObuff, _(errmsg), IOSIZE);
-      int i = (int)strlen(IObuff) + 2;
-      if (i + (arg - startarg) < IOSIZE) {
-        // append the argument with the error
-        STRCAT(IObuff, ": ");
-        assert(arg >= startarg);
-        memmove(IObuff + i, startarg, (size_t)(arg - startarg));
-        IObuff[i + (arg - startarg)] = NUL;
-      }
-      // make sure all characters are printable
-      trans_characters(IObuff, IOSIZE);
-
-      no_wait_return++;         // wait_return() done later
-      emsg(IObuff);             // show error highlighted
-      no_wait_return--;
 
-      return FAIL;
+      arg = skipwhite(arg);
     }
-
-    arg = skipwhite(arg);
   }
 
-theend:
   if (silent_mode && did_show) {
     // After displaying option values in silent mode.
     silent_mode = false;
     info_message = true;        // use os_msg(), not os_errmsg()
     msg_putchar('\n');
-    ui_flush();
     silent_mode = true;
     info_message = false;       // use os_msg(), not os_errmsg()
   }
@@ -1482,29 +1506,6 @@ theend:
   return OK;
 }
 
-/// Call this when an option has been given a new value through a user command.
-/// Sets the P_WAS_SET flag and takes care of the P_INSECURE flag.
-///
-/// @param opt_flags  possibly with OPT_MODELINE
-/// @param new_value  value was replaced completely
-/// @param value_checked  value was checked to be safe, no need to set P_INSECURE
-void did_set_option(int opt_idx, int opt_flags, int new_value, int value_checked)
-{
-  options[opt_idx].flags |= P_WAS_SET;
-
-  // When an option is set in the sandbox, from a modeline or in secure mode
-  // set the P_INSECURE flag.  Otherwise, if a new value is stored reset the
-  // flag.
-  uint32_t *p = insecure_flag(curwin, opt_idx, opt_flags);
-  if (!value_checked && (secure
-                         || sandbox != 0
-                         || (opt_flags & OPT_MODELINE))) {
-    *p = *p | P_INSECURE;
-  } else if (new_value) {
-    *p = *p & ~P_INSECURE;
-  }
-}
-
 /// Convert a key name or string into a key value.
 /// Used for 'wildchar' and 'cedit' options.
 int string_to_key(char *arg)
@@ -1579,6 +1580,9 @@ void set_options_bin(int oldval, int newval, int opt_flags)
       p_et = p_et_nobin;
     }
   }
+
+  // Remember where the dependent option were reset
+  didset_options_sctx(opt_flags, p_bin_dep_opts);
 }
 
 /// Find the parameter represented by the given character (eg ', :, ", or /),
@@ -1642,8 +1646,8 @@ static char *option_expand(int opt_idx, char *val)
   // For 'spellsuggest' expand after "file:".
   expand_env_esc(val, NameBuff, MAXPATHL,
                  (char **)options[opt_idx].var == &p_tags, false,
-                 (char_u **)options[opt_idx].var == (char_u **)&p_sps ? "file:" :
-                 NULL);
+                 (char **)options[opt_idx].var == &p_sps ? "file:"
+                                                         : NULL);
   if (strcmp(NameBuff, val) == 0) {   // they are the same
     return NULL;
   }
@@ -1665,9 +1669,9 @@ static void didset_options(void)
   (void)compile_cap_prog(curwin->w_s);
   (void)did_set_spell_option(true);
   // set cedit_key
-  (void)check_cedit();
+  (void)did_set_cedit(NULL);
   // initialize the table for 'breakat'.
-  fill_breakat_flags();
+  (void)did_set_breakat(NULL);
   didset_window_options(curwin, true);
 }
 
@@ -1678,10 +1682,10 @@ static void didset_options2(void)
   highlight_changed();
 
   // Parse default for 'fillchars'.
-  (void)set_chars_option(curwin, &curwin->w_p_fcs, true);
+  (void)set_fillchars_option(curwin, curwin->w_p_fcs, true);
 
   // Parse default for 'listchars'.
-  (void)set_chars_option(curwin, &curwin->w_p_lcs, true);
+  (void)set_listchars_option(curwin, curwin->w_p_lcs, true);
 
   // Parse default for 'wildmode'.
   check_opt_wim();
@@ -1720,7 +1724,7 @@ int was_set_insecurely(win_T *const wp, char *opt, int opt_flags)
 /// "opt_idx".  For some local options a local flags field is used.
 /// NOTE: Caller must make sure that "wp" is set to the window from which
 /// the option is used.
-static uint32_t *insecure_flag(win_T *const wp, int opt_idx, int opt_flags)
+uint32_t *insecure_flag(win_T *const wp, int opt_idx, int opt_flags)
 {
   if (opt_flags & OPT_LOCAL) {
     assert(wp != NULL);
@@ -1776,7 +1780,7 @@ void check_blending(win_T *wp)
 /// Handle setting `winhighlight' in window "wp"
 bool parse_winhl_opt(win_T *wp)
 {
-  const char *p = (const char *)wp->w_p_winhl;
+  const char *p = wp->w_p_winhl;
 
   if (!*p) {
     if (wp->w_ns_hl_winhl && wp->w_ns_hl == wp->w_ns_hl_winhl) {
@@ -1807,6 +1811,9 @@ bool parse_winhl_opt(win_T *wp)
     char *commap = xstrchrnul(hi, ',');
     size_t len = (size_t)(commap - hi);
     int hl_id = len ? syn_check_group(hi, len) : -1;
+    if (hl_id == 0) {
+      return false;
+    }
     int hl_id_link = nlen ? syn_check_group(p, nlen) : 0;
 
     HlAttrs attrs = HLATTRS_INIT;
@@ -1820,6 +1827,18 @@ bool parse_winhl_opt(win_T *wp)
   return true;
 }
 
+/// Get the script context of global option "name".
+sctx_T *get_option_sctx(const char *const name)
+{
+  int idx = findoption(name);
+
+  if (idx >= 0) {
+    return &options[idx].last_set.script_ctx;
+  }
+  siemsg("no such option: %s", name);
+  return NULL;
+}
+
 /// Set the script_ctx for an option, taking care of setting the buffer- or
 /// window-local value.
 void set_option_sctx_idx(int opt_idx, int opt_flags, sctx_T script_ctx)
@@ -1847,738 +1866,1127 @@ void set_option_sctx_idx(int opt_idx, int opt_flags, sctx_T script_ctx)
       curbuf->b_p_script_ctx[indir & PV_MASK] = last_set;
     } else if (indir & PV_WIN) {
       curwin->w_p_script_ctx[indir & PV_MASK] = last_set;
+      if (both) {
+        // also setting the "all buffers" value
+        curwin->w_allbuf_opt.wo_script_ctx[indir & PV_MASK] = last_set;
+      }
     }
   }
 }
 
 /// Apply the OptionSet autocommand.
-static void apply_optionset_autocmd(int opt_idx, long opt_flags, long oldval, long oldval_g,
-                                    long newval, const char *errmsg)
+static void apply_optionset_autocmd(int opt_idx, int opt_flags, OptVal oldval, OptVal oldval_g,
+                                    OptVal oldval_l, OptVal newval, const char *errmsg)
 {
   // Don't do this while starting up, failure or recursively.
   if (starting || errmsg != NULL || *get_vim_var_str(VV_OPTION_TYPE) != NUL) {
     return;
   }
 
-  char buf_old[12], buf_old_global[12], buf_new[12], buf_type[12];
+  char buf_type[7];
+  typval_T oldval_tv = optval_as_tv(oldval);
+  typval_T oldval_g_tv = optval_as_tv(oldval_g);
+  typval_T oldval_l_tv = optval_as_tv(oldval_l);
+  typval_T newval_tv = optval_as_tv(newval);
 
-  vim_snprintf(buf_old, sizeof(buf_old), "%ld", oldval);
-  vim_snprintf(buf_old_global, sizeof(buf_old_global), "%ld", oldval_g);
-  vim_snprintf(buf_new, sizeof(buf_new), "%ld", newval);
-  vim_snprintf(buf_type, sizeof(buf_type), "%s",
-               (opt_flags & OPT_LOCAL) ? "local" : "global");
-  set_vim_var_string(VV_OPTION_NEW, buf_new, -1);
-  set_vim_var_string(VV_OPTION_OLD, buf_old, -1);
+  vim_snprintf(buf_type, sizeof(buf_type), "%s", (opt_flags & OPT_LOCAL) ? "local" : "global");
+  set_vim_var_tv(VV_OPTION_NEW, &newval_tv);
+  set_vim_var_tv(VV_OPTION_OLD, &oldval_tv);
   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, buf_old, -1);
+    set_vim_var_tv(VV_OPTION_OLDLOCAL, &oldval_tv);
   }
   if (opt_flags & OPT_GLOBAL) {
     set_vim_var_string(VV_OPTION_COMMAND, "setglobal", -1);
-    set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old, -1);
+    set_vim_var_tv(VV_OPTION_OLDGLOBAL, &oldval_tv);
   }
   if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
     set_vim_var_string(VV_OPTION_COMMAND, "set", -1);
-    set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
-    set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old_global, -1);
+    set_vim_var_tv(VV_OPTION_OLDLOCAL, &oldval_l_tv);
+    set_vim_var_tv(VV_OPTION_OLDGLOBAL, &oldval_g_tv);
   }
   if (opt_flags & OPT_MODELINE) {
     set_vim_var_string(VV_OPTION_COMMAND, "modeline", -1);
-    set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
+    set_vim_var_tv(VV_OPTION_OLDLOCAL, &oldval_tv);
   }
   apply_autocmds(EVENT_OPTIONSET, options[opt_idx].fullname, NULL, false, NULL);
   reset_v_option_vars();
 }
 
-/// Set the value of a boolean option, taking care of side effects
-///
-/// @param[in]  opt_idx  Option index in options[] table.
-/// @param[out]  varp  Pointer to the option variable.
-/// @param[in]  value  New value.
-/// @param[in]  opt_flags  OPT_LOCAL and/or OPT_GLOBAL.
-///
-/// @return NULL on success, error message on error.
-static char *set_bool_option(const int opt_idx, char_u *const varp, const int value,
-                             const int opt_flags)
+/// Process the updated 'arabic' option value.
+static const char *did_set_arabic(optset_T *args)
 {
-  int old_value = *(int *)varp;
-  int old_global_value = 0;
-  char *errmsg = NULL;
+  win_T *win = (win_T *)args->os_win;
+  const char *errmsg = NULL;
+
+  if (win->w_p_arab) {
+    // 'arabic' is set, handle various sub-settings.
+    if (!p_tbidi) {
+      // set rightleft mode
+      if (!win->w_p_rl) {
+        win->w_p_rl = true;
+        changed_window_setting();
+      }
 
-  // Disallow changing some options from secure mode
-  if ((secure || sandbox != 0)
-      && (options[opt_idx].flags & P_SECURE)) {
-    return (char *)e_secure;
+      // Enable Arabic shaping (major part of what Arabic requires)
+      if (!p_arshape) {
+        p_arshape = true;
+        redraw_all_later(UPD_NOT_VALID);
+      }
+    }
+
+    // Arabic requires a utf-8 encoding, inform the user if it's not
+    // set.
+    if (strcmp(p_enc, "utf-8") != 0) {
+      static char *w_arabic = N_("W17: Arabic requires UTF-8, do ':set encoding=utf-8'");
+
+      msg_source(HL_ATTR(HLF_W));
+      msg(_(w_arabic), HL_ATTR(HLF_W));
+      set_vim_var_string(VV_WARNINGMSG, _(w_arabic), -1);
+    }
+
+    // set 'delcombine'
+    p_deco = true;
+
+    // Force-set the necessary keymap for arabic.
+    errmsg = set_option_value("keymap", STATIC_CSTR_AS_OPTVAL("arabic"), OPT_LOCAL);
+  } else {
+    // 'arabic' is reset, handle various sub-settings.
+    if (!p_tbidi) {
+      // reset rightleft mode
+      if (win->w_p_rl) {
+        win->w_p_rl = false;
+        changed_window_setting();
+      }
+
+      // 'arabicshape' isn't reset, it is a global option and
+      // another window may still need it "on".
+    }
+
+    // 'delcombine' isn't reset, it is a global option and another
+    // window may still want it "on".
+
+    // Revert to the default keymap
+    curbuf->b_p_iminsert = B_IMODE_NONE;
+    curbuf->b_p_imsearch = B_IMODE_USE_INSERT;
   }
 
-  // Save the global value before changing anything. This is needed as for
-  // a global-only option setting the "local value" in fact sets the global
-  // value (since there is only one value).
-  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
-    old_global_value = *(int *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
+  return errmsg;
+}
+
+/// Process the updated 'autochdir' option value.
+static const char *did_set_autochdir(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // Change directories when the 'acd' option is set now.
+  do_autochdir();
+  return NULL;
+}
+
+/// Process the updated 'binary' option value.
+static const char *did_set_binary(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+
+  // when 'bin' is set also set some other options
+  set_options_bin((int)args->os_oldval.boolean, buf->b_p_bin, args->os_flags);
+  redraw_titles();
+
+  return NULL;
+}
+
+/// Called when the 'breakat' option changes value.
+static const char *did_set_breakat(optset_T *args FUNC_ATTR_UNUSED)
+{
+  for (int i = 0; i < 256; i++) {
+    breakat_flags[i] = false;
   }
 
-  *(int *)varp = value;             // set the new value
-  // Remember where the option was set.
-  set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
+  if (p_breakat != NULL) {
+    for (char *p = p_breakat; *p; p++) {
+      breakat_flags[(uint8_t)(*p)] = true;
+    }
+  }
 
-  // May set global value for local option.
-  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
-    *(int *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL) = value;
-  }
-
-  // Ensure that options set to p_force_on cannot be disabled.
-  if ((int *)varp == &p_force_on && p_force_on == false) {
-    p_force_on = true;
-    return e_unsupportedoption;
-    // Ensure that options set to p_force_off cannot be enabled.
-  } else if ((int *)varp == &p_force_off && p_force_off == true) {
-    p_force_off = false;
-    return (char *)e_unsupportedoption;
-  } else if ((int *)varp == &p_lrm) {
-    // 'langremap' -> !'langnoremap'
-    p_lnr = !p_lrm;
-  } else if ((int *)varp == &p_lnr) {
-    // 'langnoremap' -> !'langremap'
-    p_lrm = !p_lnr;
-  } else if ((int *)varp == &curbuf->b_p_udf || (int *)varp == &p_udf) {
-    // 'undofile'
-    // Only take action when the option was set. When reset we do not
-    // delete the undo file, the option may be set again without making
-    // any changes in between.
-    if (curbuf->b_p_udf || p_udf) {
-      char_u hash[UNDO_HASH_SIZE];
-
-      FOR_ALL_BUFFERS(bp) {
-        // When 'undofile' is set globally: for every buffer, otherwise
-        // only for the current buffer: Try to read in the undofile,
-        // if one exists, the buffer wasn't changed and the buffer was
-        // loaded
-        if ((curbuf == bp
-             || (opt_flags & OPT_GLOBAL) || opt_flags == 0)
-            && !bufIsChanged(bp) && bp->b_ml.ml_mfp != NULL) {
-          u_compute_hash(bp, hash);
-          u_read_undo(NULL, hash, bp->b_fname);
-        }
-      }
+  return NULL;
+}
+
+/// Process the updated 'buflisted' option value.
+static const char *did_set_buflisted(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+
+  // when 'buflisted' changes, trigger autocommands
+  if (args->os_oldval.boolean != buf->b_p_bl) {
+    apply_autocmds(buf->b_p_bl ? EVENT_BUFADD : EVENT_BUFDELETE,
+                   NULL, NULL, true, buf);
+  }
+  return NULL;
+}
+
+/// Process the new 'cmdheight' option value.
+static const char *did_set_cmdheight(optset_T *args)
+{
+  OptInt old_value = args->os_oldval.number;
+
+  if (ui_has(kUIMessages)) {
+    p_ch = 0;
+  }
+  if (p_ch > Rows - min_rows() + 1) {
+    p_ch = Rows - min_rows() + 1;
+  }
+
+  // if p_ch changed value, change the command line height
+  // Only compute the new window layout when startup has been
+  // completed. Otherwise the frame sizes may be wrong.
+  if ((p_ch != old_value
+       || tabline_height() + global_stl_height() + topframe->fr_height != Rows - p_ch)
+      && full_screen) {
+    command_height();
+  }
+
+  return NULL;
+}
+
+/// Process the updated 'diff' option value.
+static const char *did_set_diff(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  // May add or remove the buffer from the list of diff buffers.
+  diff_buf_adjust(win);
+  if (foldmethodIsDiff(win)) {
+    foldUpdateAll(win);
+  }
+  return NULL;
+}
+
+/// Process the updated 'endoffile' or 'endofline' or 'fixendofline' or 'bomb'
+/// option value.
+static const char *did_set_eof_eol_fixeol_bomb(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // redraw the window title and tab page text
+  redraw_titles();
+  return NULL;
+}
+
+/// Process the updated 'equalalways' option value.
+static const char *did_set_equalalways(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  if (p_ea && !args->os_oldval.boolean) {
+    win_equal(win, false, 0);
+  }
+
+  return NULL;
+}
+
+/// Process the new 'foldlevel' option value.
+static const char *did_set_foldlevel(optset_T *args FUNC_ATTR_UNUSED)
+{
+  newFoldLevel();
+  return NULL;
+}
+
+/// Process the new 'foldminlines' option value.
+static const char *did_set_foldminlines(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  foldUpdateAll(win);
+  return NULL;
+}
+
+/// Process the new 'foldnestmax' option value.
+static const char *did_set_foldnestmax(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  if (foldmethodIsSyntax(win) || foldmethodIsIndent(win)) {
+    foldUpdateAll(win);
+  }
+  return NULL;
+}
+
+/// Process the new 'helpheight' option value.
+static const char *did_set_helpheight(optset_T *args)
+{
+  // Change window height NOW
+  if (!ONE_WINDOW) {
+    buf_T *buf = (buf_T *)args->os_buf;
+    win_T *win = (win_T *)args->os_win;
+    if (buf->b_help && win->w_height < p_hh) {
+      win_setheight((int)p_hh);
     }
-  } else if ((int *)varp == &curbuf->b_p_ro) {
-    // when 'readonly' is reset globally, also reset readonlymode
-    if (!curbuf->b_p_ro && (opt_flags & OPT_LOCAL) == 0) {
-      readonlymode = false;
-    }
-
-    // when 'readonly' is set may give W10 again
-    if (curbuf->b_p_ro) {
-      curbuf->b_did_warn = false;
-    }
-
-    redraw_titles();
-  } else if ((int *)varp == &curbuf->b_p_ma) {
-    // when 'modifiable' is changed, redraw the window title
-    redraw_titles();
-  } else if ((int *)varp == &curbuf->b_p_eof
-             || (int *)varp == &curbuf->b_p_eol
-             || (int *)varp == &curbuf->b_p_fixeol
-             || (int *)varp == &curbuf->b_p_bomb) {
-    // redraw the window title and tab page text when 'endoffile', 'endofline',
-    // 'fixeol' or 'bomb' is changed
-    redraw_titles();
-  } else if ((int *)varp == &curbuf->b_p_bin) {
-    // when 'bin' is set also set some other options
-    set_options_bin(old_value, curbuf->b_p_bin, opt_flags);
-    redraw_titles();
-  } else if ((int *)varp == &curbuf->b_p_bl && old_value != curbuf->b_p_bl) {
-    // when 'buflisted' changes, trigger autocommands
-    apply_autocmds(curbuf->b_p_bl ? EVENT_BUFADD : EVENT_BUFDELETE,
-                   NULL, NULL, true, curbuf);
-  } else if ((int *)varp == &curbuf->b_p_swf) {
-    // when 'swf' is set, create swapfile, when reset remove swapfile
-    if (curbuf->b_p_swf && p_uc) {
-      ml_open_file(curbuf);                     // create the swap file
-    } else {
-      // no need to reset curbuf->b_may_swap, ml_open_file() will check
-      // buf->b_p_swf
-      mf_close_file(curbuf, true);              // remove the swap file
-    }
-  } else if ((int *)varp == &p_paste) {
-    // when 'paste' is set or reset also change other options
-    paste_option_changed();
-  } else if ((int *)varp == &p_ic && p_hls) {
-    // when 'ignorecase' is set or reset and 'hlsearch' is set, redraw
+  }
+
+  return NULL;
+}
+
+/// Process the updated 'hlsearch' option value.
+static const char *did_set_hlsearch(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // when 'hlsearch' is set or reset: reset no_hlsearch
+  set_no_hlsearch(false);
+  return NULL;
+}
+
+/// Process the updated 'ignorecase' option value.
+static const char *did_set_ignorecase(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // when 'ignorecase' is set or reset and 'hlsearch' is set, redraw
+  if (p_hls) {
     redraw_all_later(UPD_SOME_VALID);
-  } else if ((int *)varp == &p_hls) {
-    // when 'hlsearch' is set or reset: reset no_hlsearch
-    set_no_hlsearch(false);
-  } else if ((int *)varp == &curwin->w_p_scb) {
-    // when 'scrollbind' is set: snapshot the current position to avoid a jump
-    // at the end of normal_cmd()
-    if (curwin->w_p_scb) {
-      do_check_scrollbind(false);
-      curwin->w_scbind_pos = curwin->w_topline;
-    }
-  } else if ((int *)varp == &curwin->w_p_pvw) {
-    // There can be only one window with 'previewwindow' set.
-    if (curwin->w_p_pvw) {
-      FOR_ALL_WINDOWS_IN_TAB(win, curtab) {
-        if (win->w_p_pvw && win != curwin) {
-          curwin->w_p_pvw = false;
-          return e_preview_window_already_exists;
+  }
+  return NULL;
+}
+
+/// Process the new 'iminset' option value.
+static const char *did_set_iminsert(optset_T *args FUNC_ATTR_UNUSED)
+{
+  showmode();
+  // Show/unshow value of 'keymap' in status lines.
+  status_redraw_curbuf();
+
+  return NULL;
+}
+
+/// Process the updated 'langnoremap' option value.
+static const char *did_set_langnoremap(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // 'langnoremap' -> !'langremap'
+  p_lrm = !p_lnr;
+  return NULL;
+}
+
+/// Process the updated 'langremap' option value.
+static const char *did_set_langremap(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // 'langremap' -> !'langnoremap'
+  p_lnr = !p_lrm;
+  return NULL;
+}
+
+/// Process the new 'laststatus' option value.
+static const char *did_set_laststatus(optset_T *args)
+{
+  OptInt old_value = args->os_oldval.number;
+  OptInt value = args->os_newval.number;
+
+  // When switching to global statusline, decrease topframe height
+  // Also clear the cmdline to remove the ruler if there is one
+  if (value == 3 && old_value != 3) {
+    frame_new_height(topframe, topframe->fr_height - STATUS_HEIGHT, false, false);
+    (void)win_comp_pos();
+    clear_cmdline = true;
+  }
+  // When switching from global statusline, increase height of topframe by STATUS_HEIGHT
+  // in order to to re-add the space that was previously taken by the global statusline
+  if (old_value == 3 && value != 3) {
+    frame_new_height(topframe, topframe->fr_height + STATUS_HEIGHT, false, false);
+    (void)win_comp_pos();
+  }
+
+  last_status(false);  // (re)set last window status line.
+  return NULL;
+}
+
+/// Process the updated 'lisp' option value.
+static const char *did_set_lisp(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+  // When 'lisp' option changes include/exclude '-' in keyword characters.
+  (void)buf_init_chartab(buf, false);          // ignore errors
+  return NULL;
+}
+
+/// Process the updated 'modifiable' option value.
+static const char *did_set_modifiable(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // when 'modifiable' is changed, redraw the window title
+  redraw_titles();
+
+  return NULL;
+}
+
+/// Process the updated 'modified' option value.
+static const char *did_set_modified(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+  if (!args->os_newval.boolean) {
+    save_file_ff(buf);  // Buffer is unchanged
+  }
+  redraw_titles();
+  modified_was_set = (int)args->os_newval.boolean;
+  return NULL;
+}
+
+/// Process the updated 'number' or 'relativenumber' option value.
+static const char *did_set_number_relativenumber(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  if (*win->w_p_stc != NUL) {
+    // When 'relativenumber'/'number' is changed and 'statuscolumn' is set, reset width.
+    win->w_nrwidth_line_count = 0;
+  }
+  check_signcolumn(win);
+  return NULL;
+}
+
+/// Process the new 'numberwidth' option value.
+static const char *did_set_numberwidth(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  win->w_nrwidth_line_count = 0;  // trigger a redraw
+
+  return NULL;
+}
+
+/// Process the updated 'paste' option value.
+static const char *did_set_paste(optset_T *args FUNC_ATTR_UNUSED)
+{
+  static int old_p_paste = false;
+  static int save_sm = 0;
+  static int save_sta = 0;
+  static int save_ru = 0;
+  static int save_ri = 0;
+
+  if (p_paste) {
+    // Paste switched from off to on.
+    // Save the current values, so they can be restored later.
+    if (!old_p_paste) {
+      // save options for each buffer
+      FOR_ALL_BUFFERS(buf) {
+        buf->b_p_tw_nopaste = buf->b_p_tw;
+        buf->b_p_wm_nopaste = buf->b_p_wm;
+        buf->b_p_sts_nopaste = buf->b_p_sts;
+        buf->b_p_ai_nopaste = buf->b_p_ai;
+        buf->b_p_et_nopaste = buf->b_p_et;
+        if (buf->b_p_vsts_nopaste) {
+          xfree(buf->b_p_vsts_nopaste);
         }
+        buf->b_p_vsts_nopaste = buf->b_p_vsts && buf->b_p_vsts != empty_string_option
+                                ? xstrdup(buf->b_p_vsts)
+                                : NULL;
+      }
+
+      // save global options
+      save_sm = p_sm;
+      save_sta = p_sta;
+      save_ru = p_ru;
+      save_ri = p_ri;
+      // save global values for local buffer options
+      p_ai_nopaste = p_ai;
+      p_et_nopaste = p_et;
+      p_sts_nopaste = p_sts;
+      p_tw_nopaste = p_tw;
+      p_wm_nopaste = p_wm;
+      if (p_vsts_nopaste) {
+        xfree(p_vsts_nopaste);
       }
+      p_vsts_nopaste = p_vsts && p_vsts != empty_string_option ? xstrdup(p_vsts) : NULL;
     }
-  } else if (varp == (char_u *)&(curbuf->b_p_lisp)) {
-    // When 'lisp' option changes include/exclude '-' in
-    // keyword characters.
-    (void)buf_init_chartab(curbuf, false);          // ignore errors
-  } else if ((int *)varp == &p_title) {
-    // when 'title' changed, may need to change the title; same for 'icon'
-    did_set_title();
-  } else if ((int *)varp == &p_icon) {
-    did_set_title();
-  } else if ((int *)varp == &curbuf->b_changed) {
-    if (!value) {
-      save_file_ff(curbuf);             // Buffer is unchanged
-    }
-    redraw_titles();
-    modified_was_set = value;
 
-#ifdef BACKSLASH_IN_FILENAME
-  } else if ((int *)varp == &p_ssl) {
-    if (p_ssl) {
-      psepc = '/';
-      psepcN = '\\';
-      pseps[0] = '/';
-    } else {
-      psepc = '\\';
-      psepcN = '/';
-      pseps[0] = '\\';
+    // Always set the option values, also when 'paste' is set when it is
+    // already on.
+    // set options for each buffer
+    FOR_ALL_BUFFERS(buf) {
+      buf->b_p_tw = 0;              // textwidth is 0
+      buf->b_p_wm = 0;              // wrapmargin is 0
+      buf->b_p_sts = 0;             // softtabstop is 0
+      buf->b_p_ai = 0;              // no auto-indent
+      buf->b_p_et = 0;              // no expandtab
+      if (buf->b_p_vsts) {
+        free_string_option(buf->b_p_vsts);
+      }
+      buf->b_p_vsts = empty_string_option;
+      XFREE_CLEAR(buf->b_p_vsts_array);
     }
 
-    // need to adjust the file name arguments and buffer names.
-    buflist_slash_adjust();
-    alist_slash_adjust();
-    scriptnames_slash_adjust();
-#endif
-  } else if ((int *)varp == &curwin->w_p_wrap) {
-    // If 'wrap' is set, set w_leftcol to zero.
-    if (curwin->w_p_wrap) {
-      curwin->w_leftcol = 0;
-    }
-  } else if ((int *)varp == &p_ea) {
-    if (p_ea && !old_value) {
-      win_equal(curwin, false, 0);
-    }
-  } else if ((int *)varp == &p_acd) {
-    // Change directories when the 'acd' option is set now.
-    do_autochdir();
-  } else if ((int *)varp == &curwin->w_p_diff) {  // 'diff'
-    // May add or remove the buffer from the list of diff buffers.
-    diff_buf_adjust(curwin);
-    if (foldmethodIsDiff(curwin)) {
-      foldUpdateAll(curwin);
-    }
-  } else if ((int *)varp == &curwin->w_p_spell) {  // 'spell'
-    if (curwin->w_p_spell) {
-      errmsg = did_set_spelllang(curwin);
-    }
-  } else if (((int *)varp == &curwin->w_p_nu || (int *)varp == &curwin->w_p_rnu)
-             && *curwin->w_p_stc != NUL) {  // '(relative)number' + 'statuscolumn'
-    curwin->w_nrwidth_line_count = 0;
-  }
-
-  if ((int *)varp == &curwin->w_p_arab) {
-    if (curwin->w_p_arab) {
-      // 'arabic' is set, handle various sub-settings.
-      if (!p_tbidi) {
-        // set rightleft mode
-        if (!curwin->w_p_rl) {
-          curwin->w_p_rl = true;
-          changed_window_setting();
-        }
+    // set global options
+    p_sm = 0;                       // no showmatch
+    p_sta = 0;                      // no smarttab
+    if (p_ru) {
+      status_redraw_all();          // redraw to remove the ruler
+    }
+    p_ru = 0;                       // no ruler
+    p_ri = 0;                       // no reverse insert
+    // set global values for local buffer options
+    p_tw = 0;
+    p_wm = 0;
+    p_sts = 0;
+    p_ai = 0;
+    p_et = 0;
+    if (p_vsts) {
+      free_string_option(p_vsts);
+    }
+    p_vsts = empty_string_option;
+  } else if (old_p_paste) {
+    // Paste switched from on to off: Restore saved values.
 
-        // Enable Arabic shaping (major part of what Arabic requires)
-        if (!p_arshape) {
-          p_arshape = true;
-          redraw_all_later(UPD_NOT_VALID);
-        }
+    // restore options for each buffer
+    FOR_ALL_BUFFERS(buf) {
+      buf->b_p_tw = buf->b_p_tw_nopaste;
+      buf->b_p_wm = buf->b_p_wm_nopaste;
+      buf->b_p_sts = buf->b_p_sts_nopaste;
+      buf->b_p_ai = buf->b_p_ai_nopaste;
+      buf->b_p_et = buf->b_p_et_nopaste;
+      if (buf->b_p_vsts) {
+        free_string_option(buf->b_p_vsts);
       }
+      buf->b_p_vsts = buf->b_p_vsts_nopaste ? xstrdup(buf->b_p_vsts_nopaste) : empty_string_option;
+      xfree(buf->b_p_vsts_array);
+      if (buf->b_p_vsts && buf->b_p_vsts != empty_string_option) {
+        (void)tabstop_set(buf->b_p_vsts, &buf->b_p_vsts_array);
+      } else {
+        buf->b_p_vsts_array = NULL;
+      }
+    }
 
-      // Arabic requires a utf-8 encoding, inform the user if it's not
-      // set.
-      if (strcmp(p_enc, "utf-8") != 0) {
-        static char *w_arabic = N_("W17: Arabic requires UTF-8, do ':set encoding=utf-8'");
+    // restore global options
+    p_sm = save_sm;
+    p_sta = save_sta;
+    if (p_ru != save_ru) {
+      status_redraw_all();          // redraw to draw the ruler
+    }
+    p_ru = save_ru;
+    p_ri = save_ri;
+    // set global values for local buffer options
+    p_ai = p_ai_nopaste;
+    p_et = p_et_nopaste;
+    p_sts = p_sts_nopaste;
+    p_tw = p_tw_nopaste;
+    p_wm = p_wm_nopaste;
+    if (p_vsts) {
+      free_string_option(p_vsts);
+    }
+    p_vsts = p_vsts_nopaste ? xstrdup(p_vsts_nopaste) : empty_string_option;
+  }
 
-        msg_source(HL_ATTR(HLF_W));
-        msg_attr(_(w_arabic), HL_ATTR(HLF_W));
-        set_vim_var_string(VV_WARNINGMSG, _(w_arabic), -1);
-      }
+  old_p_paste = p_paste;
 
-      // set 'delcombine'
-      p_deco = true;
+  // Remember where the dependent options were reset
+  didset_options_sctx((OPT_LOCAL | OPT_GLOBAL), p_paste_dep_opts);
 
-      // Force-set the necessary keymap for arabic.
-      errmsg = set_option_value("keymap", 0L, "arabic", OPT_LOCAL);
-    } else {
-      // 'arabic' is reset, handle various sub-settings.
-      if (!p_tbidi) {
-        // reset rightleft mode
-        if (curwin->w_p_rl) {
-          curwin->w_p_rl = false;
-          changed_window_setting();
-        }
+  return NULL;
+}
 
-        // 'arabicshape' isn't reset, it is a global option and
-        // another window may still need it "on".
-      }
+/// Process the updated 'previewwindow' option value.
+static const char *did_set_previewwindow(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
 
-      // 'delcombine' isn't reset, it is a global option and another
-      // window may still want it "on".
+  if (!win->w_p_pvw) {
+    return NULL;
+  }
 
-      // Revert to the default keymap
-      curbuf->b_p_iminsert = B_IMODE_NONE;
-      curbuf->b_p_imsearch = B_IMODE_USE_INSERT;
+  // There can be only one window with 'previewwindow' set.
+  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+    if (wp->w_p_pvw && wp != win) {
+      win->w_p_pvw = false;
+      return e_preview_window_already_exists;
     }
   }
 
-  // End of handling side effects for bool options.
+  return NULL;
+}
 
-  // after handling side effects, call autocommand
+/// Process the new 'pumblend' option value.
+static const char *did_set_pumblend(optset_T *args FUNC_ATTR_UNUSED)
+{
+  p_pb = MAX(MIN(p_pb, 100), 0);
+  hl_invalidate_blends();
+  pum_grid.blending = (p_pb > 0);
+  if (pum_drawn()) {
+    pum_redraw();
+  }
 
-  options[opt_idx].flags |= P_WAS_SET;
+  return NULL;
+}
 
-  apply_optionset_autocmd(opt_idx, opt_flags,
-                          (long)(old_value ? true : false),
-                          (long)(old_global_value ? true : false),
-                          (long)(value ? true : false), NULL);
+/// Process the updated 'readonly' option value.
+static const char *did_set_readonly(optset_T *args)
+{
+  // when 'readonly' is reset globally, also reset readonlymode
+  if (!curbuf->b_p_ro && (args->os_flags & OPT_LOCAL) == 0) {
+    readonlymode = false;
+  }
 
-  if (options[opt_idx].flags & P_UI_OPTION) {
-    ui_call_option_set(cstr_as_string(options[opt_idx].fullname),
-                       BOOLEAN_OBJ(*varp));
+  // when 'readonly' is set may give W10 again
+  if (curbuf->b_p_ro) {
+    curbuf->b_did_warn = false;
   }
 
-  comp_col();                       // in case 'ruler' or 'showcmd' changed
-  if (curwin->w_curswant != MAXCOL
-      && (options[opt_idx].flags & (P_CURSWANT | P_RALL)) != 0) {
-    curwin->w_set_curswant = true;
+  redraw_titles();
+
+  return NULL;
+}
+
+/// Process the new 'scrollback' option value.
+static const char *did_set_scrollback(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+  OptInt old_value = args->os_oldval.number;
+  OptInt value = args->os_newval.number;
+
+  if (buf->terminal && value < old_value) {
+    // Force the scrollback to take immediate effect only when decreasing it.
+    on_scrollback_option_changed(buf->terminal);
   }
-  check_redraw(options[opt_idx].flags);
+  return NULL;
+}
 
-  return errmsg;
+/// Process the updated 'scrollbind' option value.
+static const char *did_set_scrollbind(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+
+  // when 'scrollbind' is set: snapshot the current position to avoid a jump
+  // at the end of normal_cmd()
+  if (!win->w_p_scb) {
+    return NULL;
+  }
+  do_check_scrollbind(false);
+  win->w_scbind_pos = win->w_topline;
+  return NULL;
 }
 
-/// Set the value of a number option, taking care of side effects
-///
-/// @param[in]  opt_idx  Option index in options[] table.
-/// @param[out]  varp  Pointer to the option variable.
-/// @param[in]  value  New value.
-/// @param  errbuf  Buffer for error messages.
-/// @param[in]  errbuflen  Length of `errbuf`.
-/// @param[in]  opt_flags  OPT_LOCAL, OPT_GLOBAL or OPT_MODELINE.
-///
-/// @return NULL on success, error message on error.
-static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf, size_t errbuflen,
-                            int opt_flags)
+#ifdef BACKSLASH_IN_FILENAME
+/// Process the updated 'shellslash' option value.
+static const char *did_set_shellslash(optset_T *args FUNC_ATTR_UNUSED)
 {
-  char *errmsg = NULL;
-  long old_value = *(long *)varp;
-  long old_global_value = 0;  // only used when setting a local and global option
-  long old_Rows = Rows;       // remember old Rows
-  long *pp = (long *)varp;
+  if (p_ssl) {
+    psepc = '/';
+    psepcN = '\\';
+    pseps[0] = '/';
+  } else {
+    psepc = '\\';
+    psepcN = '/';
+    pseps[0] = '\\';
+  }
 
-  // Disallow changing some options from secure mode.
-  if ((secure || sandbox != 0)
-      && (options[opt_idx].flags & P_SECURE)) {
-    return e_secure;
+  // need to adjust the file name arguments and buffer names.
+  buflist_slash_adjust();
+  alist_slash_adjust();
+  scriptnames_slash_adjust();
+  return NULL;
+}
+#endif
+
+/// Process the new 'shiftwidth' or the 'tabstop' option value.
+static const char *did_set_shiftwidth_tabstop(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+  win_T *win = (win_T *)args->os_win;
+  OptInt *pp = (OptInt *)args->os_varp;
+
+  if (foldmethodIsIndent(win)) {
+    foldUpdateAll(win);
+  }
+  // When 'shiftwidth' changes, or it's zero and 'tabstop' changes:
+  // parse 'cinoptions'.
+  if (pp == &buf->b_p_sw || buf->b_p_sw == 0) {
+    parse_cino(buf);
   }
 
-  // Save the global value before changing anything. This is needed as for
-  // a global-only option setting the "local value" in fact sets the global
-  // value (since there is only one value).
-  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
-    old_global_value = *(long *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
+  return NULL;
+}
+
+/// Process the new 'showtabline' option value.
+static const char *did_set_showtabline(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // (re)set tab page line
+  win_new_screen_rows();  // recompute window positions and heights
+  return NULL;
+}
+
+/// Process the updated 'smoothscroll' option value.
+static const char *did_set_smoothscroll(optset_T *args FUNC_ATTR_UNUSED)
+{
+  win_T *win = (win_T *)args->os_win;
+  if (!win->w_p_sms) {
+    win->w_skipcol = 0;
+  }
+
+  return NULL;
+}
+
+/// Process the updated 'spell' option value.
+static const char *did_set_spell(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  if (win->w_p_spell) {
+    return parse_spelllang(win);
+  }
+
+  return NULL;
+}
+
+/// Process the updated 'swapfile' option value.
+static const char *did_set_swapfile(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+  // when 'swf' is set, create swapfile, when reset remove swapfile
+  if (buf->b_p_swf && p_uc) {
+    ml_open_file(buf);                     // create the swap file
+  } else {
+    // no need to reset curbuf->b_may_swap, ml_open_file() will check
+    // buf->b_p_swf
+    mf_close_file(buf, true);              // remove the swap file
+  }
+  return NULL;
+}
+
+/// Process the new 'textwidth' option value.
+static const char *did_set_textwidth(optset_T *args FUNC_ATTR_UNUSED)
+{
+  FOR_ALL_TAB_WINDOWS(tp, wp) {
+    check_colorcolumn(wp);
+  }
+
+  return NULL;
+}
+
+/// Process the updated 'title' or the 'icon' option value.
+static const char *did_set_title_icon(optset_T *args FUNC_ATTR_UNUSED)
+{
+  // when 'title' changed, may need to change the title; same for 'icon'
+  did_set_title();
+  return NULL;
+}
+
+/// Process the new 'titlelen' option value.
+static const char *did_set_titlelen(optset_T *args)
+{
+  OptInt old_value = args->os_oldval.number;
+
+  // if 'titlelen' has changed, redraw the title
+  if (starting != NO_SCREEN && old_value != p_titlelen) {
+    need_maketitle = true;
   }
 
+  return NULL;
+}
+
+/// Process the updated 'undofile' option value.
+static const char *did_set_undofile(optset_T *args)
+{
+  // Only take action when the option was set.
+  if (!curbuf->b_p_udf && !p_udf) {
+    return NULL;
+  }
+
+  // When reset we do not delete the undo file, the option may be set again
+  // without making any changes in between.
+  uint8_t hash[UNDO_HASH_SIZE];
+
+  FOR_ALL_BUFFERS(bp) {
+    // When 'undofile' is set globally: for every buffer, otherwise
+    // only for the current buffer: Try to read in the undofile,
+    // if one exists, the buffer wasn't changed and the buffer was
+    // loaded
+    if ((curbuf == bp
+         || (args->os_flags & OPT_GLOBAL) || args->os_flags == 0)
+        && !bufIsChanged(bp) && bp->b_ml.ml_mfp != NULL) {
+      u_compute_hash(bp, hash);
+      u_read_undo(NULL, hash, bp->b_fname);
+    }
+  }
+
+  return NULL;
+}
+
+/// Process the new global 'undolevels' option value.
+const char *did_set_global_undolevels(OptInt value, OptInt old_value)
+{
+  // sync undo before 'undolevels' changes
+  // use the old value, otherwise u_sync() may not work properly
+  p_ul = old_value;
+  u_sync(true);
+  p_ul = value;
+  return NULL;
+}
+
+/// Process the new buffer local 'undolevels' option value.
+const char *did_set_buflocal_undolevels(buf_T *buf, OptInt value, OptInt old_value)
+{
+  // use the old value, otherwise u_sync() may not work properly
+  buf->b_p_ul = old_value;
+  u_sync(true);
+  buf->b_p_ul = value;
+  return NULL;
+}
+
+/// Process the new 'undolevels' option value.
+static const char *did_set_undolevels(optset_T *args)
+{
+  buf_T *buf = (buf_T *)args->os_buf;
+  OptInt *pp = (OptInt *)args->os_varp;
+
+  if (pp == &p_ul) {                  // global 'undolevels'
+    did_set_global_undolevels(args->os_newval.number, args->os_oldval.number);
+  } else if (pp == &curbuf->b_p_ul) {      // buffer local 'undolevels'
+    did_set_buflocal_undolevels(buf, args->os_newval.number, args->os_oldval.number);
+  }
+
+  return NULL;
+}
+
+/// Process the new 'updatecount' option value.
+static const char *did_set_updatecount(optset_T *args)
+{
+  OptInt old_value = args->os_oldval.number;
+
+  // when 'updatecount' changes from zero to non-zero, open swap files
+  if (p_uc && !old_value) {
+    ml_open_files();
+  }
+
+  return NULL;
+}
+
+/// Process the new 'wildchar' / 'wildcharm' option value.
+static const char *did_set_wildchar(optset_T *args)
+{
+  OptInt c = *(OptInt *)args->os_varp;
+
+  // Don't allow key values that wouldn't work as wildchar.
+  if (c == Ctrl_C || c == '\n' || c == '\r' || c == K_KENTER) {
+    return e_invarg;
+  }
+
+  return NULL;
+}
+
+/// Process the new 'winblend' option value.
+static const char *did_set_winblend(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  OptInt old_value = args->os_oldval.number;
+  OptInt value = args->os_newval.number;
+
+  if (value != old_value) {
+    win->w_p_winbl = MAX(MIN(win->w_p_winbl, 100), 0);
+    win->w_hl_needs_update = true;
+    check_blending(win);
+  }
+
+  return NULL;
+}
+
+/// Process the new 'window' option value.
+static const char *did_set_window(optset_T *args FUNC_ATTR_UNUSED)
+{
+  if (p_window < 1) {
+    p_window = Rows - 1;
+  } else if (p_window >= Rows) {
+    p_window = Rows - 1;
+  }
+  return NULL;
+}
+
+/// Process the new 'winheight' value.
+static const char *did_set_winheight(optset_T *args)
+{
+  // Change window height NOW
+  if (!ONE_WINDOW) {
+    win_T *win = (win_T *)args->os_win;
+    if (win->w_height < p_wh) {
+      win_setheight((int)p_wh);
+    }
+  }
+
+  return NULL;
+}
+
+/// Process the new 'winwidth' option value.
+static const char *did_set_winwidth(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+
+  if (!ONE_WINDOW && win->w_width < p_wiw) {
+    win_setwidth((int)p_wiw);
+  }
+  return NULL;
+}
+
+/// Process the updated 'wrap' option value.
+static const char *did_set_wrap(optset_T *args)
+{
+  win_T *win = (win_T *)args->os_win;
+  // Set w_leftcol or w_skipcol to zero.
+  if (win->w_p_wrap) {
+    win->w_leftcol = 0;
+  } else {
+    win->w_skipcol = 0;
+  }
+
+  return NULL;
+}
+
+// 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_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,lua} 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.*", (int)(p - q), q);
+    source_runtime_vim_lua(fname, DIP_ALL);
+  }
+}
+
+/// Check the bounds of numeric options.
+static const char *check_num_option_bounds(OptInt *pp, OptInt old_value, char *errbuf,
+                                           size_t errbuflen, const char *errmsg)
+{
+  int old_Rows = Rows;  // remember old Rows
+  // Check the (new) bounds for Rows and Columns here.
+  if (p_lines < min_rows() && full_screen) {
+    if (errbuf != NULL) {
+      vim_snprintf(errbuf, errbuflen, _("E593: Need at least %d lines"), min_rows());
+      errmsg = errbuf;
+    }
+    p_lines = min_rows();
+  }
+  if (p_columns < MIN_COLUMNS && full_screen) {
+    if (errbuf != NULL) {
+      vim_snprintf(errbuf, errbuflen, _("E594: Need at least %d columns"), MIN_COLUMNS);
+      errmsg = errbuf;
+    }
+    p_columns = MIN_COLUMNS;
+  }
+
+  // True max size is defined by check_screensize()
+  p_lines = MIN(p_lines, INT_MAX);
+  p_columns = MIN(p_columns, INT_MAX);
+
+  // If the screen (shell) height has been changed, assume it is the
+  // physical screenheight.
+  if (p_lines != Rows || p_columns != Columns) {
+    // Changing the screen size is not allowed while updating the screen.
+    if (updating_screen) {
+      *pp = old_value;
+    } else if (full_screen) {
+      screen_resize((int)p_columns, (int)p_lines);
+    } else {
+      // TODO(bfredl): is this branch ever needed?
+      // Postpone the resizing; check the size and cmdline position for
+      // messages.
+      Rows = (int)p_lines;
+      Columns = (int)p_columns;
+      check_screensize();
+      int new_row = (int)(Rows - MAX(p_ch, 1));
+      if (cmdline_row > new_row && Rows > p_ch) {
+        assert(p_ch >= 0 && new_row <= INT_MAX);
+        cmdline_row = new_row;
+      }
+    }
+    if (p_window >= Rows || !option_was_set("window")) {
+      p_window = Rows - 1;
+    }
+  }
+
+  if ((curwin->w_p_scr <= 0 || (curwin->w_p_scr > curwin->w_height && curwin->w_height > 0))
+      && full_screen) {
+    if (pp == &(curwin->w_p_scr)) {
+      if (curwin->w_p_scr != 0) {
+        errmsg = e_scroll;
+      }
+      win_comp_scroll(curwin);
+    } else if (curwin->w_p_scr <= 0) {
+      // If 'scroll' became invalid because of a side effect silently adjust it.
+      curwin->w_p_scr = 1;
+    } else {  // curwin->w_p_scr > curwin->w_height
+      curwin->w_p_scr = curwin->w_height;
+    }
+  }
+  if ((p_sj < -100 || p_sj >= Rows) && full_screen) {
+    if (Rows != old_Rows) {  // Rows changed, just adjust p_sj
+      p_sj = Rows / 2;
+    } else {
+      errmsg = e_scroll;
+      p_sj = 1;
+    }
+  }
+
+  return errmsg;
+}
+
+/// Options that need some validation.
+static const char *validate_num_option(const OptInt *pp, OptInt *valuep)
+{
+  OptInt value = *valuep;
+
   // Many number options assume their value is in the signed int range.
   if (value < INT_MIN || value > INT_MAX) {
     return e_invarg;
   }
 
-  // Options that need some validation.
   if (pp == &p_wh) {
     if (value < 1) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (p_wmh > value) {
-      errmsg = e_winheight;
+      return e_winheight;
     }
   } else if (pp == &p_hh) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_wmh) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (value > p_wh) {
-      errmsg = e_winheight;
+      return e_winheight;
     }
   } else if (pp == &p_wiw) {
     if (value < 1) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (p_wmw > value) {
-      errmsg = e_winwidth;
+      return e_winwidth;
     }
   } else if (pp == &p_wmw) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (value > p_wiw) {
-      errmsg = e_winwidth;
+      return e_winwidth;
     }
   } else if (pp == &p_mco) {
-    value = MAX_MCO;
+    *valuep = MAX_MCO;
   } else if (pp == &p_titlelen) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_uc) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_ch) {
-    int minval = 0;
-    if (value < minval) {
-      errmsg = e_positive;
+    if (value < 0) {
+      return e_positive;
     } else {
       p_ch_was_zero = value == 0;
     }
   } else if (pp == &p_tm) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_hi) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (value > 10000) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &p_pyx) {
     if (value == 0) {
-      value = 3;
+      *valuep = 3;
     } else if (value != 3) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &p_re) {
     if (value < 0 || value > 2) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &p_report) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_so) {
     if (value < 0 && full_screen) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_siso) {
     if (value < 0 && full_screen) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_cwh) {
     if (value < 1) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_ut) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_ss) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &curwin->w_p_fdl || pp == &curwin->w_allbuf_opt.wo_fdl) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &curwin->w_p_cole || pp == &curwin->w_allbuf_opt.wo_cole) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (value > 3) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &curwin->w_p_nuw || pp == &curwin->w_allbuf_opt.wo_nuw) {
     if (value < 1) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (value > MAX_NUMBERWIDTH) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &curbuf->b_p_iminsert || pp == &p_iminsert) {
     if (value < 0 || value > B_IMODE_LAST) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &curbuf->b_p_imsearch || pp == &p_imsearch) {
     if (value < -1 || value > B_IMODE_LAST) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &curbuf->b_p_channel || pp == &p_channel) {
-    errmsg = e_invarg;
+    return e_invarg;
   } else if (pp == &curbuf->b_p_scbk || pp == &p_scbk) {
     if (value < -1 || value > SB_MAX) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &curbuf->b_p_sw || pp == &p_sw) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &curbuf->b_p_ts || pp == &p_ts) {
     if (value < 1) {
-      errmsg = e_positive;
+      return e_positive;
     } else if (value > TABSTOP_MAX) {
-      errmsg = e_invarg;
+      return e_invarg;
     }
   } else if (pp == &curbuf->b_p_tw || pp == &p_tw) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   } else if (pp == &p_wd) {
     if (value < 0) {
-      errmsg = e_positive;
+      return e_positive;
     }
   }
 
-  // Don't change the value and return early if validation failed.
-  if (errmsg != NULL) {
-    return errmsg;
-  }
-
-  *pp = value;
-  // Remember where the option was set.
-  set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
-
-  // For these options we want to fix some invalid values.
-  if (pp == &p_window) {
-    if (p_window < 1) {
-      p_window = Rows - 1;
-    } else if (p_window >= Rows) {
-      p_window = Rows - 1;
-    }
-  } else if (pp == &p_ch) {
-    if (ui_has(kUIMessages)) {
-      p_ch = 0;
-    }
-    if (p_ch > Rows - min_rows() + 1) {
-      p_ch = Rows - min_rows() + 1;
-    }
-  }
-
-  // Number options that need some action when changed
-  if (pp == &p_wh) {
-    // 'winheight'
-    if (!ONE_WINDOW && curwin->w_height < p_wh) {
-      win_setheight((int)p_wh);
-    }
-  } else if (pp == &p_hh) {
-    // 'helpheight'
-    if (!ONE_WINDOW && curbuf->b_help && curwin->w_height < p_hh) {
-      win_setheight((int)p_hh);
-    }
-  } else if (pp == &p_wmh) {
-    // 'winminheight'
-    win_setminheight();
-  } else if (pp == &p_wiw) {
-    // 'winwidth'
-    if (!ONE_WINDOW && curwin->w_width < p_wiw) {
-      win_setwidth((int)p_wiw);
-    }
-  } else if (pp == &p_wmw) {
-    // 'winminwidth'
-    win_setminwidth();
-  } else if (pp == &p_ls) {
-    // When switching to global statusline, decrease topframe height
-    // Also clear the cmdline to remove the ruler if there is one
-    if (value == 3 && old_value != 3) {
-      frame_new_height(topframe, topframe->fr_height - STATUS_HEIGHT, false, false);
-      (void)win_comp_pos();
-      clear_cmdline = true;
-    }
-    // When switching from global statusline, increase height of topframe by STATUS_HEIGHT
-    // in order to to re-add the space that was previously taken by the global statusline
-    if (old_value == 3 && value != 3) {
-      frame_new_height(topframe, topframe->fr_height + STATUS_HEIGHT, false, false);
-      (void)win_comp_pos();
-    }
-
-    last_status(false);  // (re)set last window status line.
-  } else if (pp == &p_stal) {
-    // (re)set tab page line
-    win_new_screen_rows();   // recompute window positions and heights
-  } else if (pp == &curwin->w_p_fdl) {
-    newFoldLevel();
-  } else if (pp == &curwin->w_p_fml) {
-    foldUpdateAll(curwin);
-  } else if (pp == &curwin->w_p_fdn) {
-    if (foldmethodIsSyntax(curwin) || foldmethodIsIndent(curwin)) {
-      foldUpdateAll(curwin);
-    }
-  } else if (pp == &curbuf->b_p_sw || pp == &curbuf->b_p_ts) {
-    // 'shiftwidth' or 'tabstop'
-    if (foldmethodIsIndent(curwin)) {
-      foldUpdateAll(curwin);
-    }
-    // When 'shiftwidth' changes, or it's zero and 'tabstop' changes:
-    // parse 'cinoptions'.
-    if (pp == &curbuf->b_p_sw || curbuf->b_p_sw == 0) {
-      parse_cino(curbuf);
-    }
-  } else if (pp == &curbuf->b_p_iminsert) {
-    showmode();
-    // Show/unshow value of 'keymap' in status lines.
-    status_redraw_curbuf();
-  } else if (pp == &p_titlelen) {
-    // if 'titlelen' has changed, redraw the title
-    if (starting != NO_SCREEN && old_value != p_titlelen) {
-      need_maketitle = true;
-    }
-  } else if (pp == &p_ch) {
-    // if p_ch changed value, change the command line height
-    // Only compute the new window layout when startup has been
-    // completed. Otherwise the frame sizes may be wrong.
-    if ((p_ch != old_value
-         || tabline_height() + global_stl_height() + topframe->fr_height != Rows - p_ch)
-        && full_screen) {
-      command_height();
-    }
-  } else if (pp == &p_uc) {
-    // when 'updatecount' changes from zero to non-zero, open swap files
-    if (p_uc && !old_value) {
-      ml_open_files();
-    }
-  } else if (pp == &p_pb) {
-    p_pb = MAX(MIN(p_pb, 100), 0);
-    hl_invalidate_blends();
-    pum_grid.blending = (p_pb > 0);
-    if (pum_drawn()) {
-      pum_redraw();
-    }
-  } else if (pp == &p_ul || pp == &curbuf->b_p_ul) {
-    // sync undo before 'undolevels' changes
-    // use the old value, otherwise u_sync() may not work properly
-    *pp = old_value;
-    u_sync(true);
-    *pp = value;
-  } else if (pp == &curbuf->b_p_tw) {
-    FOR_ALL_TAB_WINDOWS(tp, wp) {
-      check_colorcolumn(wp);
-    }
-  } else if (pp == &curbuf->b_p_scbk || pp == &p_scbk) {
-    if (curbuf->terminal && value < old_value) {
-      // Force the scrollback to take immediate effect only when decreasing it.
-      on_scrollback_option_changed(curbuf->terminal);
-    }
-  } else if (pp == &curwin->w_p_nuw) {
-    curwin->w_nrwidth_line_count = 0;
-  } else if (pp == &curwin->w_p_winbl && value != old_value) {
-    // 'winblend'
-    curwin->w_p_winbl = MAX(MIN(curwin->w_p_winbl, 100), 0);
-    curwin->w_hl_needs_update = true;
-    check_blending(curwin);
-  }
-
-  // Check the (new) bounds for Rows and Columns here.
-  if (p_lines < min_rows() && full_screen) {
-    if (errbuf != NULL) {
-      vim_snprintf(errbuf, errbuflen,
-                   _("E593: Need at least %d lines"), min_rows());
-      errmsg = errbuf;
-    }
-    p_lines = min_rows();
-  }
-  if (p_columns < MIN_COLUMNS && full_screen) {
-    if (errbuf != NULL) {
-      vim_snprintf(errbuf, errbuflen,
-                   _("E594: Need at least %d columns"), MIN_COLUMNS);
-      errmsg = errbuf;
-    }
-    p_columns = MIN_COLUMNS;
-  }
-
-  // True max size is defined by check_screensize()
-  p_lines = MIN(p_lines, INT_MAX);
-  p_columns = MIN(p_columns, INT_MAX);
-
-  // If the screen (shell) height has been changed, assume it is the
-  // physical screenheight.
-  if (p_lines != Rows || p_columns != Columns) {
-    // Changing the screen size is not allowed while updating the screen.
-    if (updating_screen) {
-      *pp = old_value;
-    } else if (full_screen) {
-      screen_resize((int)p_columns, (int)p_lines);
-    } else {
-      // TODO(bfredl): is this branch ever needed?
-      // Postpone the resizing; check the size and cmdline position for
-      // messages.
-      Rows = (int)p_lines;
-      Columns = (int)p_columns;
-      check_screensize();
-      int new_row = (int)(Rows - MAX(p_ch, 1));
-      if (cmdline_row > new_row && Rows > p_ch) {
-        assert(p_ch >= 0 && new_row <= INT_MAX);
-        cmdline_row = new_row;
-      }
-    }
-    if (p_window >= Rows || !option_was_set("window")) {
-      p_window = Rows - 1;
-    }
-  }
-
-  if ((curwin->w_p_scr <= 0
-       || (curwin->w_p_scr > curwin->w_height
-           && curwin->w_height > 0))
-      && full_screen) {
-    if (pp == &(curwin->w_p_scr)) {
-      if (curwin->w_p_scr != 0) {
-        errmsg = e_scroll;
-      }
-      win_comp_scroll(curwin);
-    } else if (curwin->w_p_scr <= 0) {
-      // If 'scroll' became invalid because of a side effect silently adjust it.
-      curwin->w_p_scr = 1;
-    } else {  // curwin->w_p_scr > curwin->w_height
-      curwin->w_p_scr = curwin->w_height;
-    }
-  }
-  if ((p_sj < -100 || p_sj >= Rows) && full_screen) {
-    if (Rows != old_Rows) {     // Rows changed, just adjust p_sj
-      p_sj = Rows / 2;
-    } else {
-      errmsg = e_scroll;
-      p_sj = 1;
-    }
-  }
-
-  // May set global value for local option.
-  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
-    *(long *)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL) = *pp;
-  }
-
-  options[opt_idx].flags |= P_WAS_SET;
-
-  apply_optionset_autocmd(opt_idx, opt_flags, old_value, old_global_value,
-                          value, errmsg);
-
-  if (errmsg == NULL && options[opt_idx].flags & P_UI_OPTION) {
-    ui_call_option_set(cstr_as_string(options[opt_idx].fullname),
-                       INTEGER_OBJ(*pp));
-  }
-
-  comp_col();                       // in case 'columns' or 'ls' changed
-  if (curwin->w_curswant != MAXCOL
-      && (options[opt_idx].flags & (P_CURSWANT | P_RALL)) != 0) {
-    curwin->w_set_curswant = true;
-  }
-  check_redraw(options[opt_idx].flags);
-
-  return errmsg;
+  return NULL;
 }
 
 /// Called after an option changed: check if something needs to be redrawn.
@@ -2757,23 +3165,6 @@ bool set_tty_option(const char *name, char *value)
   return false;
 }
 
-void set_tty_background(const char *value)
-{
-  if (option_was_set("bg") || strequal(p_bg, value)) {
-    // background is already set... ignore
-    return;
-  }
-  if (starting) {
-    // Wait until after startup, so OptionSet is triggered.
-    do_cmdline_cmd((value[0] == 'l')
-                   ? "autocmd VimEnter * ++once ++nested set bg=light"
-                   : "autocmd VimEnter * ++once ++nested set bg=dark");
-  } else {
-    set_option_value_give_err("bg", 0L, value, 0);
-    reset_option_was_set("bg");
-  }
-}
-
 /// Find index for an option
 ///
 /// @param[in]  arg  Option name.
@@ -2785,283 +3176,702 @@ int findoption(const char *const arg)
   return findoption_len(arg, strlen(arg));
 }
 
-/// Gets the value for an option.
+/// Free an allocated OptVal.
+void optval_free(OptVal o)
+{
+  switch (o.type) {
+  case kOptValTypeNil:
+  case kOptValTypeBoolean:
+  case kOptValTypeNumber:
+    break;
+  case kOptValTypeString:
+    // Don't free empty string option
+    if (o.data.string.data != empty_string_option) {
+      api_free_string(o.data.string);
+    }
+    break;
+  }
+}
+
+/// Copy an OptVal.
+OptVal optval_copy(OptVal o)
+{
+  switch (o.type) {
+  case kOptValTypeNil:
+  case kOptValTypeBoolean:
+  case kOptValTypeNumber:
+    return o;
+  case kOptValTypeString:
+    return STRING_OPTVAL(copy_string(o.data.string, NULL));
+  }
+  UNREACHABLE;
+}
+
+/// Check if two option values are equal.
+bool optval_equal(OptVal o1, OptVal o2)
+{
+  if (o1.type != o2.type) {
+    return false;
+  }
+
+  switch (o1.type) {
+  case kOptValTypeNil:
+    return true;
+  case kOptValTypeBoolean:
+    return o1.data.boolean == o2.data.boolean;
+  case kOptValTypeNumber:
+    return o1.data.number == o2.data.number;
+  case kOptValTypeString:
+    return o1.data.string.size == o2.data.string.size
+           && strequal(o1.data.string.data, o2.data.string.data);
+  }
+  UNREACHABLE;
+}
+
+/// Match type of OptVal with the type of the target option. Returns true if the types match and
+/// false otherwise.
+static bool optval_match_type(OptVal o, int opt_idx)
+{
+  assert(opt_idx >= 0);
+  uint32_t flags = options[opt_idx].flags;
+
+  switch (o.type) {
+  case kOptValTypeNil:
+    return false;
+  case kOptValTypeBoolean:
+    return flags & P_BOOL;
+  case kOptValTypeNumber:
+    return flags & P_NUM;
+  case kOptValTypeString:
+    return flags & P_STRING;
+  }
+  UNREACHABLE;
+}
+
+/// Create OptVal from var pointer.
 ///
-/// @param stringval  NULL when only checking existence
-/// @param flagsp     set to the option flags (P_xxxx) (if not NULL)
+/// @param       opt_idx  Option index in options[] table.
+/// @param[out]  varp     Pointer to option variable.
+OptVal optval_from_varp(int opt_idx, void *varp)
+{
+  // Special case: 'modified' is b_changed, but we also want to consider it set when 'ff' or 'fenc'
+  // changed.
+  if ((int *)varp == &curbuf->b_changed) {
+    return BOOLEAN_OPTVAL(curbufIsChanged());
+  }
+
+  uint32_t flags = options[opt_idx].flags;
+
+  OptValType type = kOptValTypeNil;
+  if (flags & P_BOOL) {
+    type = kOptValTypeBoolean;
+  } else if (flags & P_NUM) {
+    type = kOptValTypeNumber;
+  } else if (flags & P_STRING) {
+    type = kOptValTypeString;
+  } else {
+    abort();
+  }
+
+  switch (type) {
+  case kOptValTypeNil:
+    return NIL_OPTVAL;
+  case kOptValTypeBoolean:
+    return BOOLEAN_OPTVAL(varp == NULL ? false : TRISTATE_FROM_INT(*(int *)varp));
+  case kOptValTypeNumber:
+    return NUMBER_OPTVAL(varp == NULL ? 0 : *(OptInt *)varp);
+  case kOptValTypeString:
+    return STRING_OPTVAL(varp == NULL ? (String)STRING_INIT : cstr_as_string(*(char **)varp));
+  }
+  UNREACHABLE;
+}
+
+/// Set option var pointer value from Optval.
 ///
-/// @returns:
-///           Number option: gov_number, *numval gets value.
-///           Tottle option: gov_bool,   *numval gets value.
-///           String option: gov_string, *stringval gets allocated string.
-///           Hidden Number option: gov_hidden_number.
-///           Hidden Toggle option: gov_hidden_bool.
-///           Hidden String option: gov_hidden_string.
-///           Unknown option: gov_unknown.
-getoption_T get_option_value(const char *name, long *numval, char **stringval, uint32_t *flagsp,
-                             int scope)
+/// @param       opt_idx      Option index in options[] table.
+/// @param[out]  varp         Pointer to option variable.
+/// @param[in]   value        New option value.
+/// @param       free_oldval  Free old value.
+static void set_option_varp(int opt_idx, void *varp, OptVal value, bool free_oldval)
+  FUNC_ATTR_NONNULL_ARG(2)
 {
-  if (get_tty_option(name, stringval)) {
-    return gov_string;
+  assert(optval_match_type(value, opt_idx));
+
+  if (free_oldval) {
+    optval_free(optval_from_varp(opt_idx, varp));
   }
 
-  int opt_idx = findoption(name);
-  if (opt_idx < 0) {  // option not in the table
-    return gov_unknown;
+  switch (value.type) {
+  case kOptValTypeNil:
+    return;
+  case kOptValTypeBoolean:
+    *(int *)varp = value.data.boolean;
+    return;
+  case kOptValTypeNumber:
+    *(OptInt *)varp = value.data.number;
+    return;
+  case kOptValTypeString:
+    *(char **)varp = value.data.string.data;
+    return;
   }
+  UNREACHABLE;
+}
 
-  char_u *varp = (char_u *)get_varp_scope(&(options[opt_idx]), scope);
+/// Return C-string representation of OptVal. Caller must free the returned C-string.
+static char *optval_to_cstr(OptVal o)
+{
+  switch (o.type) {
+  case kOptValTypeNil:
+    return xstrdup("");
+  case kOptValTypeBoolean:
+    return xstrdup(o.data.boolean ? "true" : "false");
+  case kOptValTypeNumber: {
+    char *buf = xmalloc(NUMBUFLEN);
+    snprintf(buf, NUMBUFLEN, "%" PRId64, o.data.number);
+    return buf;
+  }
+  case kOptValTypeString: {
+    char *buf = xmalloc(o.data.string.size + 3);
+    snprintf(buf, o.data.string.size + 3, "\"%s\"", o.data.string.data);
+    return buf;
+  }
+  }
+  UNREACHABLE;
+}
 
-  if (flagsp != NULL) {
-    // Return the P_xxxx option flags.
-    *flagsp = options[opt_idx].flags;
+/// Convert an OptVal to an API Object.
+Object optval_as_object(OptVal o)
+{
+  switch (o.type) {
+  case kOptValTypeNil:
+    return NIL;
+  case kOptValTypeBoolean:
+    switch (o.data.boolean) {
+    case kFalse:
+    case kTrue:
+      return BOOLEAN_OBJ(o.data.boolean);
+    case kNone:
+      return NIL;
+    }
+    UNREACHABLE;
+  case kOptValTypeNumber:
+    return INTEGER_OBJ(o.data.number);
+  case kOptValTypeString:
+    return STRING_OBJ(o.data.string);
+  }
+  UNREACHABLE;
+}
+
+/// Convert an API Object to an OptVal.
+OptVal object_as_optval(Object o, bool *error)
+{
+  switch (o.type) {
+  case kObjectTypeNil:
+    return NIL_OPTVAL;
+  case kObjectTypeBoolean:
+    return BOOLEAN_OPTVAL(o.data.boolean);
+  case kObjectTypeInteger:
+    return NUMBER_OPTVAL((OptInt)o.data.integer);
+  case kObjectTypeString:
+    return STRING_OPTVAL(o.data.string);
+  default:
+    *error = true;
+    return NIL_OPTVAL;
   }
+  UNREACHABLE;
+}
 
-  if (options[opt_idx].flags & P_STRING) {
-    if (varp == NULL) {  // hidden option
-      return gov_hidden_string;
+/// Unset the local value of an option. The exact semantics of this depend on the option.
+/// TODO(famiu): Remove this once we have a dedicated OptVal type for unset local options.
+///
+/// @param      opt_idx  Option index in options[] table.
+/// @param[in]  varp  Pointer to option variable.
+///
+/// @return [allocated] Option value equal to the unset value for the option.
+static OptVal optval_unset_local(int opt_idx, void *varp)
+{
+  vimoption_T *opt = &options[opt_idx];
+  // For global-local options, use the unset value of the local value.
+  if (opt->indir & PV_BOTH) {
+    // String global-local options always use an empty string for the unset value.
+    if (opt->flags & P_STRING) {
+      return STATIC_CSTR_TO_OPTVAL("");
     }
-    if (stringval != NULL) {
-      if ((char **)varp == &p_pt) {  // 'pastetoggle'
-        *stringval = str2special_save(*(char **)(varp), false, false);
-      } else {
-        *stringval = xstrdup(*(char **)(varp));
-      }
+
+    if ((int *)varp == &curbuf->b_p_ar) {
+      return BOOLEAN_OPTVAL(kNone);
+    } else if ((OptInt *)varp == &curwin->w_p_so || (OptInt *)varp == &curwin->w_p_siso) {
+      return NUMBER_OPTVAL(-1);
+    } else if ((OptInt *)varp == &curbuf->b_p_ul) {
+      return NUMBER_OPTVAL(NO_LOCAL_UNDOLEVEL);
+    } else {
+      // This should never happen.
+      abort();
     }
-    return gov_string;
   }
+  // For options that aren't global-local, just set the local value to the global value.
+  return get_option_value(opt->fullname, NULL, OPT_GLOBAL, NULL);
+}
+
+/// Get an allocated string containing a list of valid types for an option.
+/// For options with a singular type, it returns the name of the type. For options with multiple
+/// possible types, it returns a slash separated list of types. For example, if an option can be a
+/// number, boolean or string, the function returns "Number/Boolean/String"
+static char *option_get_valid_types(int opt_idx)
+{
+  uint32_t flags = options[opt_idx].flags;
+  uint32_t type_count = 0;
 
-  if (varp == NULL) {  // hidden option
-    return (options[opt_idx].flags & P_NUM) ? gov_hidden_number : gov_hidden_bool;
+  StringBuilder str = KV_INITIAL_VALUE;
+  kv_resize(str, 32);
+
+#define OPTION_ADD_TYPE(typename) \
+  do { \
+    if (type_count == 0) { \
+      kv_concat(str, typename); \
+    } else { \
+      kv_printf(str, "/%s", typename); \
+    } \
+    type_count++; \
+  } while (0);
+
+  if (flags & P_NUM) {
+    OPTION_ADD_TYPE("Number");
   }
-  if (options[opt_idx].flags & P_NUM) {
-    *numval = *(long *)varp;
-  } else {
-    // Special case: 'modified' is b_changed, but we also want to consider
-    // it set when 'ff' or 'fenc' changed.
-    if ((int *)varp == &curbuf->b_changed) {
-      *numval = curbufIsChanged();
-    } else {
-      *numval = (long)(*(int *)varp);
-    }
+  if (flags & P_BOOL) {
+    OPTION_ADD_TYPE("Boolean");
   }
-  return (options[opt_idx].flags & P_NUM) ? gov_number : gov_bool;
+  if (flags & P_STRING) {
+    OPTION_ADD_TYPE("String");
+  }
+
+  if (type_count == 0) {
+    abort();
+  }
+
+  // Ensure that the string is NUL-terminated.
+  kv_push(str, NUL);
+  return str.items;
+
+#undef OPTION_ADD_TYPE
 }
 
-// Returns the option attributes and its value. Unlike the above function it
-// will return either global value or local value of the option depending on
-// what was requested, but it will never return global value if it was
-// requested to return local one and vice versa. Neither it will return
-// buffer-local value if it was requested to return window-local one.
-//
-// Pretends that option is absent if it is not present in the requested scope
-// (i.e. has no global, window-local or buffer-local value depending on
-// opt_type).
-//
-// Returned flags:
-//       0 hidden or unknown option, also option that does not have requested
-//         type (see SREQ_* in option_defs.h)
-//  see SOPT_* in option_defs.h for other flags
-//
-// Possible opt_type values: see SREQ_* in option_defs.h
-int get_option_value_strict(char *name, int64_t *numval, char **stringval, int opt_type, void *from)
+/// Gets the value for an option.
+///
+/// @param[in]   name    Option name.
+/// @param[out]  flagsp  Set to the option flags (P_xxxx) (if not NULL).
+/// @param[in]   scope   Option scope (can be OPT_LOCAL, OPT_GLOBAL or a combination).
+/// @param[out]  hidden  Whether option is hidden.
+///
+/// @return [allocated] Option value. Returns NIL_OPTVAL for invalid options.
+OptVal get_option_value(const char *name, uint32_t *flagsp, int scope, bool *hidden)
 {
-  if (get_tty_option(name, stringval)) {
-    return SOPT_STRING | SOPT_GLOBAL;
+  // Make sure that hidden and flagsp are never returned uninitialized
+  if (hidden != NULL) {
+    *hidden = false;
+  }
+  if (flagsp != NULL) {
+    *flagsp = 0;
+  }
+
+  char *str;
+  if (get_tty_option(name, &str)) {
+    return CSTR_AS_OPTVAL(str);
   }
 
-  int rv = 0;
   int opt_idx = findoption(name);
-  if (opt_idx < 0) {
-    return 0;
+  if (opt_idx < 0) {  // option not in the table
+    return NIL_OPTVAL;
   }
 
-  vimoption_T *p = &options[opt_idx];
+  vimoption_T *opt = &options[opt_idx];
+  void *varp = get_varp_scope(opt, scope);
 
-  // Hidden option
-  if (p->var == NULL) {
-    return 0;
+  if (hidden != NULL) {
+    *hidden = varp == NULL;
   }
 
-  if (p->flags & P_BOOL) {
-    rv |= SOPT_BOOL;
-  } else if (p->flags & P_NUM) {
-    rv |= SOPT_NUM;
-  } else if (p->flags & P_STRING) {
-    rv |= SOPT_STRING;
+  if (flagsp != NULL) {
+    // Return the P_xxxx option flags.
+    *flagsp = opt->flags;
   }
 
-  if (p->indir == PV_NONE) {
-    if (opt_type == SREQ_GLOBAL) {
-      rv |= SOPT_GLOBAL;
-    } else {
-      return 0;  // Did not request global-only option
-    }
-  } else {
-    if (p->indir & PV_BOTH) {
-      rv |= SOPT_GLOBAL;
-    }
+  return optval_copy(optval_from_varp(opt_idx, varp));
+}
 
-    if (p->indir & PV_WIN) {
-      if (opt_type == SREQ_BUF) {
-        return 0;  // Requested buffer-local, not window-local option
-      }
-      rv |= SOPT_WIN;
-    } else if (p->indir & PV_BUF) {
-      if (opt_type == SREQ_WIN) {
-        return 0;  // Requested window-local, not buffer-local option
-      }
-      rv |= SOPT_BUF;
+/// Return information for option at 'opt_idx'
+vimoption_T *get_option(int opt_idx)
+{
+  return &options[opt_idx];
+}
+
+/// Check if local value of global-local option is unset for current buffer / window.
+/// Always returns false for options that aren't global-local.
+///
+/// TODO(famiu): Remove this once we have an OptVal type to indicate an unset local value.
+static bool is_option_local_value_unset(vimoption_T *opt, buf_T *buf, win_T *win)
+{
+  // Local value of option that isn't global-local is always considered set.
+  if (!((int)opt->indir & PV_BOTH)) {
+    return false;
+  }
+
+  // Get pointer to local value in varp_local, and a pointer to the currently used value in varp.
+  // If the local value is the one currently being used, that indicates that it's set.
+  // Otherwise it indicates the local value is unset.
+  void *varp = get_varp_from(opt, buf, win);
+  void *varp_local = get_varp_scope_from(opt, OPT_LOCAL, buf, win);
+
+  return varp != varp_local;
+}
+
+/// Handle side-effects of setting an option.
+///
+/// @param       opt_idx         Index in options[] table. Must be >= 0.
+/// @param[in]   varp            Option variable pointer, cannot be NULL.
+/// @param       old_value       Old option value.
+/// @param       new_value       New option value.
+/// @param       opt_flags       Option flags.
+/// @param[out]  value_checked   Value was checked to be safe, no need to set P_INSECURE.
+/// @param       value_replaced  Value was replaced completely.
+/// @param[out]  errbuf          Buffer for error message.
+/// @param       errbuflen       Length of error buffer.
+///
+/// @return  NULL on success, an untranslated error message on error.
+static const char *did_set_option(int opt_idx, void *varp, OptVal old_value, OptVal new_value,
+                                  int opt_flags, bool *value_checked, bool value_replaced,
+                                  char *errbuf, size_t errbuflen)
+{
+  vimoption_T *opt = &options[opt_idx];
+  const char *errmsg = NULL;
+  bool restore_chartab = false;
+  bool free_oldval = (opt->flags & P_ALLOCED);
+  bool value_changed = false;
+
+  optset_T did_set_cb_args = {
+    .os_varp = varp,
+    .os_idx = opt_idx,
+    .os_flags = opt_flags,
+    .os_oldval = old_value.data,
+    .os_newval = new_value.data,
+    .os_value_checked = false,
+    .os_value_changed = false,
+    .os_restore_chartab = false,
+    .os_errbuf = errbuf,
+    .os_errbuflen = errbuflen,
+    .os_buf = curbuf,
+    .os_win = curwin
+  };
+
+  // Disallow changing immutable options.
+  if (opt->immutable && !optval_equal(old_value, new_value)) {
+    errmsg = e_unsupportedoption;
+  }
+  // Disallow changing some options from secure mode.
+  else if ((secure || sandbox != 0) && (opt->flags & P_SECURE)) {
+    errmsg = e_secure;
+  }
+  // Check for a "normal" directory or file name in some string options.
+  else if (new_value.type == kOptValTypeString
+           && check_illegal_path_names(*(char **)varp, opt->flags)) {
+    errmsg = e_invarg;
+  } else if (opt->opt_did_set_cb != NULL) {
+    // Invoke the option specific callback function to validate and apply the new value.
+    errmsg = opt->opt_did_set_cb(&did_set_cb_args);
+    // The 'filetype' and 'syntax' option callback functions may change the os_value_changed field.
+    value_changed = did_set_cb_args.os_value_changed;
+    // The 'keymap', 'filetype' and 'syntax' option callback functions may change the
+    // os_value_checked field.
+    *value_checked = did_set_cb_args.os_value_checked;
+    // The 'isident', 'iskeyword', 'isprint' and 'isfname' options may change the character table.
+    // On failure, this needs to be restored.
+    restore_chartab = did_set_cb_args.os_restore_chartab;
+  }
+
+  // If an error is detected, restore the previous value and don't do any further processing.
+  if (errmsg != NULL) {
+    set_option_varp(opt_idx, varp, old_value, true);
+    // When resetting some values, need to act on it.
+    if (restore_chartab) {
+      (void)buf_init_chartab(curbuf, true);
     }
+
+    // Unset new_value as it is no longer valid.
+    new_value = NIL_OPTVAL;  // NOLINT(clang-analyzer-deadcode.DeadStores)
+    return errmsg;
+  }
+
+  // Re-assign the new value as its value may get freed or modified by the option callback.
+  new_value = optval_from_varp(opt_idx, varp);
+
+  // Remember where the option was set.
+  set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
+  // Free options that are in allocated memory.
+  // Use "free_oldval", because recursiveness may change the flags (esp. init_highlight()).
+  if (free_oldval) {
+    optval_free(old_value);
+  }
+  opt->flags |= P_ALLOCED;
+
+  // Check the bound for num options.
+  if (new_value.type == kOptValTypeNumber) {
+    errmsg = check_num_option_bounds((OptInt *)varp, old_value.data.number, errbuf, errbuflen,
+                                     errmsg);
+    // Re-assign new_value because the new value was modified by the bound check.
+    new_value = optval_from_varp(opt_idx, varp);
+  }
+
+  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0 && (opt->indir & PV_BOTH)) {
+    // Global option with local value set to use global value.
+    // Free the local value and clear it.
+    void *varp_local = get_varp_scope(opt, OPT_LOCAL);
+    OptVal local_unset_value = optval_unset_local(opt_idx, varp_local);
+    set_option_varp(opt_idx, varp_local, local_unset_value, true);
+  } else if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
+    // May set global value for local option.
+    void *varp_global = get_varp_scope(opt, OPT_GLOBAL);
+    set_option_varp(opt_idx, varp_global, optval_copy(new_value), true);
+  }
+
+  // Trigger the autocommand only after setting the flags.
+  if (varp == &curbuf->b_p_syn) {
+    do_syntax_autocmd(curbuf, value_changed);
+  } else if (varp == &curbuf->b_p_ft) {
+    // 'filetype' is set, trigger the FileType autocommand
+    // Skip this when called from a modeline
+    // Force autocmd when the filetype was changed
+    if (!(opt_flags & OPT_MODELINE) || value_changed) {
+      do_filetype_autocmd(curbuf, value_changed);
+    }
+  } else if (varp == &curwin->w_s->b_p_spl) {
+    do_spelllang_source(curwin);
+  }
+
+  // In case 'columns' or 'ls' changed.
+  comp_col();
+
+  if (varp == &p_mouse) {
+    setmouse();  // in case 'mouse' changed
+  } else if ((varp == &p_flp || varp == &(curbuf->b_p_flp)) && curwin->w_briopt_list) {
+    // Changing Formatlistpattern when briopt includes the list setting:
+    // redraw
+    redraw_all_later(UPD_NOT_VALID);
+  } else if (varp == &p_wbr || varp == &(curwin->w_p_wbr)) {
+    // add / remove window bars for 'winbar'
+    set_winbar(true);
   }
 
-  if (stringval == NULL) {
-    return rv;
+  if (curwin->w_curswant != MAXCOL && (opt->flags & (P_CURSWANT | P_RALL)) != 0) {
+    curwin->w_set_curswant = true;
   }
 
-  char_u *varp = NULL;
+  check_redraw(opt->flags);
 
-  if (opt_type == SREQ_GLOBAL) {
-    if (p->var == VAR_WIN) {
-      return 0;
+  if (errmsg == NULL) {
+    uint32_t *p = insecure_flag(curwin, opt_idx, opt_flags);
+    opt->flags |= P_WAS_SET;
+
+    // When an option is set in the sandbox, from a modeline or in secure mode set the P_INSECURE
+    // flag.  Otherwise, if a new value is stored reset the flag.
+    if (!value_checked && (secure || sandbox != 0 || (opt_flags & OPT_MODELINE))) {
+      *p |= P_INSECURE;
+    } else if (value_replaced) {
+      *p &= ~P_INSECURE;
     }
-    varp = p->var;
-  } else {
-    if (opt_type == SREQ_BUF) {
-      // Special case: 'modified' is b_changed, but we also want to
-      // consider it set when 'ff' or 'fenc' changed.
-      if (p->indir == PV_MOD) {
-        *numval = bufIsChanged((buf_T *)from);
-        varp = NULL;
-      } else {
-        buf_T *save_curbuf = curbuf;
-
-        // only getting a pointer, no need to use aucmd_prepbuf()
-        curbuf = (buf_T *)from;
-        curwin->w_buffer = curbuf;
-        varp = (char_u *)get_varp_scope(p, OPT_LOCAL);
-        curbuf = save_curbuf;
-        curwin->w_buffer = curbuf;
-      }
-    } else if (opt_type == SREQ_WIN) {
-      win_T *save_curwin = curwin;
-      curwin = (win_T *)from;
-      curbuf = curwin->w_buffer;
-      varp = (char_u *)get_varp_scope(p, OPT_LOCAL);
-      curwin = save_curwin;
-      curbuf = curwin->w_buffer;
+  }
+
+  return errmsg;
+}
+
+/// Set the value of an option using an OptVal.
+///
+/// @param       opt_idx         Index in options[] table. Must be >= 0.
+/// @param[in]   varp            Option variable pointer, cannot be NULL.
+/// @param       value           New option value. Might get freed.
+/// @param       opt_flags       Option flags.
+/// @param       value_replaced  Value was replaced completely.
+/// @param[out]  errbuf          Buffer for error message.
+/// @param       errbuflen       Length of error buffer.
+///
+/// @return  NULL on success, an untranslated error message on error.
+static const char *set_option(const int opt_idx, void *varp, OptVal value, int opt_flags,
+                              const bool value_replaced, char *errbuf, size_t errbuflen)
+{
+  assert(opt_idx >= 0 && varp != NULL);
+
+  const char *errmsg = NULL;
+  bool value_checked = false;
+
+  vimoption_T *opt = &options[opt_idx];
+
+  static const char *optval_type_names[] = {
+    [kOptValTypeNil] = "Nil",
+    [kOptValTypeBoolean] = "Boolean",
+    [kOptValTypeNumber] = "Number",
+    [kOptValTypeString] = "String"
+  };
+
+  if (value.type == kOptValTypeNil) {
+    // Don't try to unset local value if scope is global.
+    // TODO(famiu): Change this to forbid changing all non-local scopes when the API scope bug is
+    // fixed.
+    if (opt_flags == OPT_GLOBAL) {
+      errmsg = _("Cannot unset global option value");
+    } else {
+      optval_free(value);
+      value = optval_unset_local(opt_idx, varp);
     }
+  } else if (!optval_match_type(value, opt_idx)) {
+    char *rep = optval_to_cstr(value);
+    char *valid_types = option_get_valid_types(opt_idx);
+    snprintf(errbuf, IOSIZE, _("Invalid value for option '%s': expected %s, got %s %s"),
+             opt->fullname, valid_types, optval_type_names[value.type], rep);
+    xfree(rep);
+    xfree(valid_types);
+    errmsg = errbuf;
+  }
 
-    if (varp == p->var) {
-      return (rv | SOPT_UNSET);
+  if (errmsg != NULL) {
+    goto err;
+  }
+
+  // When using ":set opt=val" for a global option with a local value the local value will be reset,
+  // use the global value here.
+  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0 && ((int)opt->indir & PV_BOTH)) {
+    varp = opt->var;
+  }
+
+  OptVal old_value = optval_from_varp(opt_idx, varp);
+  OptVal old_global_value = NIL_OPTVAL;
+  OptVal old_local_value = NIL_OPTVAL;
+
+  // Save the local and global values before changing anything. This is needed as for a global-only
+  // option setting the "local value" in fact sets the global value (since there is only one value).
+  //
+  // TODO(famiu): This needs to be changed to use the current type of the old value instead of
+  // value.type, when multi-type options are added.
+  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
+    old_global_value = optval_from_varp(opt_idx, get_varp_scope(opt, OPT_GLOBAL));
+    old_local_value = optval_from_varp(opt_idx, get_varp_scope(opt, OPT_LOCAL));
+
+    // If local value of global-local option is unset, use global value as local value.
+    if (is_option_local_value_unset(opt, curbuf, curwin)) {
+      old_local_value = old_global_value;
     }
   }
 
-  if (varp != NULL) {
-    if (p->flags & P_STRING) {
-      *stringval = *(char **)(varp);
-    } else if (p->flags & P_NUM) {
-      *numval = *(long *)varp;
-    } else {
-      *numval = *(int *)varp;
+  // Value that's actually being used.
+  // For local scope of a global-local option, it is equal to the global value.
+  // In every other case, it is the same as old_value.
+  const bool oldval_is_global = ((int)opt->indir & PV_BOTH) && (opt_flags & OPT_LOCAL);
+  OptVal used_old_value = oldval_is_global ? optval_from_varp(opt_idx, get_varp(opt)) : old_value;
+
+  if (value.type == kOptValTypeNumber) {
+    errmsg = validate_num_option((OptInt *)varp, &value.data.number);
+
+    // Don't change the value and return early if validation failed.
+    if (errmsg != NULL) {
+      goto err;
     }
   }
 
-  return rv;
-}
+  set_option_varp(opt_idx, varp, value, false);
 
-// Return information for option at 'opt_idx'
-vimoption_T *get_option(int opt_idx)
-{
-  return &options[opt_idx];
+  OptVal saved_used_value = optval_copy(used_old_value);
+  OptVal saved_old_global_value = optval_copy(old_global_value);
+  OptVal saved_old_local_value = optval_copy(old_local_value);
+  // New value (and varp) may become invalid if the buffer is closed by autocommands.
+  OptVal saved_new_value = optval_copy(value);
+
+  uint32_t *p = insecure_flag(curwin, opt_idx, opt_flags);
+  const int secure_saved = secure;
+
+  // When an option is set in the sandbox, from a modeline or in secure mode, then deal with side
+  // effects in secure mode. Also when the value was set with the P_INSECURE flag and is not
+  // completely replaced.
+  if ((opt_flags & OPT_MODELINE) || sandbox != 0 || (!value_replaced && (*p & P_INSECURE))) {
+    secure = 1;
+  }
+
+  errmsg = did_set_option(opt_idx, varp, old_value, value, opt_flags, &value_checked,
+                          value_replaced, errbuf, errbuflen);
+
+  secure = secure_saved;
+
+  if (errmsg == NULL) {
+    if (!starting) {
+      apply_optionset_autocmd(opt_idx, opt_flags, saved_used_value, saved_old_global_value,
+                              saved_old_local_value, saved_new_value, errmsg);
+    }
+    if (opt->flags & P_UI_OPTION) {
+      // Calculate saved_new_value again as its value might be changed by bound checks.
+      // NOTE: Currently there are no buffer/window local UI options, but if there ever are buffer
+      // or window local UI options added in the future, varp might become invalid if the buffer or
+      // window is closed during an autocommand, and a check would have to be added for it.
+      optval_free(saved_new_value);
+      saved_new_value = optval_copy(optval_from_varp(opt_idx, varp));
+      ui_call_option_set(cstr_as_string(opt->fullname), optval_as_object(saved_new_value));
+    }
+  }
+
+  // Free copied values as they are not needed anymore
+  optval_free(saved_used_value);
+  optval_free(saved_old_local_value);
+  optval_free(saved_old_global_value);
+  optval_free(saved_new_value);
+  return errmsg;
+err:
+  optval_free(value);
+  return errmsg;
 }
 
 /// Set the value of an option
 ///
-/// @param[in]  name  Option name.
-/// @param[in]  number  New value for the number or boolean option.
-/// @param[in]  string  New value for string option.
+/// @param[in]  name       Option name.
+/// @param[in]  value      Option value. If NIL_OPTVAL, the option value is cleared.
 /// @param[in]  opt_flags  Flags: OPT_LOCAL, OPT_GLOBAL, or 0 (both).
-///                        If OPT_CLEAR is set, the value of the option
-///                        is cleared  (the exact semantics of this depend
-///                        on the option).
 ///
-/// @return NULL on success, an untranslated error message on error.
-char *set_option_value(const char *const name, const long number, const char *const string,
-                       const int opt_flags)
+/// @return  NULL on success, an untranslated error message on error.
+const char *set_option_value(const char *const name, const OptVal value, int opt_flags)
   FUNC_ATTR_NONNULL_ARG(1)
 {
+  static char errbuf[IOSIZE];
+
   if (is_tty_option(name)) {
     return NULL;  // Fail silently; many old vimrcs set t_xx options.
   }
 
   int opt_idx = findoption(name);
   if (opt_idx < 0) {
-    semsg(_("E355: Unknown option: %s"), name);
-    return NULL;
+    snprintf(errbuf, IOSIZE, _(e_unknown_option2), name);
+    return errbuf;
   }
 
   uint32_t flags = options[opt_idx].flags;
   // Disallow changing some options in the sandbox
   if (sandbox > 0 && (flags & P_SECURE)) {
-    emsg(_(e_sandbox));
-    return NULL;
-  }
-
-  if (flags & P_STRING) {
-    const char *s = string;
-    if (s == NULL || opt_flags & OPT_CLEAR) {
-      s = "";
-    }
-    return set_string_option(opt_idx, s, opt_flags);
+    return _(e_sandbox);
   }
 
-  char_u *varp = (char_u *)get_varp_scope(&(options[opt_idx]), opt_flags);
+  void *varp = get_varp_scope(&(options[opt_idx]), opt_flags);
   if (varp == NULL) {
     // hidden option is not changed
     return NULL;
   }
 
-  if (number == 0 && string != NULL) {
-    int idx;
+  const char *errmsg = NULL;
 
-    // Either we are given a string or we are setting option
-    // to zero.
-    for (idx = 0; string[idx] == '0'; idx++) {}
-    if (string[idx] != NUL || idx == 0) {
-      // There's another character after zeros or the string
-      // is empty.  In both cases, we are trying to set a
-      // num option using a string.
-      semsg(_("E521: Number required: &%s = '%s'"),
-            name, string);
-      return NULL;  // do nothing as we hit an error
-    }
-  }
-  long numval = number;
-  if (opt_flags & OPT_CLEAR) {
-    if ((int *)varp == &curbuf->b_p_ar) {
-      numval = -1;
-    } else if ((long *)varp == &curbuf->b_p_ul) {
-      numval = NO_LOCAL_UNDOLEVEL;
-    } else if ((long *)varp == &curwin->w_p_so || (long *)varp == &curwin->w_p_siso) {
-      numval = -1;
-    } else {
-      char *s = NULL;
-      (void)get_option_value(name, &numval, &s, NULL, OPT_GLOBAL);
-    }
-  }
-  if (flags & P_NUM) {
-    return set_num_option(opt_idx, varp, numval, NULL, 0, opt_flags);
-  }
-  return set_bool_option(opt_idx, varp, (int)numval, opt_flags);
+  errmsg = set_option(opt_idx, varp, optval_copy(value), opt_flags, true, errbuf, sizeof(errbuf));
+
+  return errmsg;
 }
 
 /// Call set_option_value() and when an error is returned report it.
 ///
 /// @param opt_flags  OPT_LOCAL or 0 (both)
-void set_option_value_give_err(const char *name, long number, const char *string, int opt_flags)
+void set_option_value_give_err(const char *name, OptVal value, int opt_flags)
 {
-  char *errmsg = set_option_value(name, number, string, opt_flags);
+  const char *errmsg = set_option_value(name, value, opt_flags);
 
   if (errmsg != NULL) {
     emsg(_(errmsg));
@@ -3074,14 +3884,6 @@ bool is_option_allocated(const char *name)
   return idx >= 0 && (options[idx].flags & P_ALLOCED);
 }
 
-/// Return true if "name" is a string option.
-/// Returns false if option "name" does not exist.
-bool is_string_option(const char *name)
-{
-  int idx = findoption(name);
-  return idx >= 0 && (options[idx].flags & P_STRING);
-}
-
 // Translate a string like "t_xx", "<t_xx>" or "<S-Tab>" to a key number.
 // When "has_lt" is true there is a '<' before "*arg_arg".
 // Returns 0 when the key is not recognized.
@@ -3111,11 +3913,11 @@ static int find_key_option(const char *arg, bool has_lt)
   return find_key_option_len(arg, strlen(arg), has_lt);
 }
 
-/// if 'all' == 0: show changed options
-/// if 'all' == 1: show all normal options
+/// if 'all' == false: show changed options
+/// if 'all' == true: show all normal options
 ///
 /// @param opt_flags  OPT_LOCAL and/or OPT_GLOBAL
-static void showoptions(int all, int opt_flags)
+static void showoptions(bool all, int opt_flags)
 {
 #define INC 20
 #define GAP 3
@@ -3144,16 +3946,15 @@ static void showoptions(int all, int opt_flags)
         continue;
       }
 
-      char_u *varp = NULL;
+      void *varp = NULL;
       if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) != 0) {
         if (p->indir != PV_NONE) {
-          varp = (char_u *)get_varp_scope(p, opt_flags);
+          varp = get_varp_scope(p, opt_flags);
         }
       } else {
         varp = get_varp(p);
       }
-      if (varp != NULL
-          && (all == 1 || (all == 0 && !optval_default(p, varp)))) {
+      if (varp != NULL && (all || !optval_default(p, varp))) {
         int len;
         if (opt_flags & OPT_ONECOLUMN) {
           len = Columns;
@@ -3204,13 +4005,13 @@ static void showoptions(int all, int opt_flags)
 }
 
 /// Return true if option "p" has its default value.
-static int optval_default(vimoption_T *p, const char_u *varp)
+static int optval_default(vimoption_T *p, const void *varp)
 {
   if (varp == NULL) {
     return true;            // hidden option is always at default
   }
   if (p->flags & P_NUM) {
-    return *(long *)varp == (long)(intptr_t)p->def_val;
+    return *(OptInt *)varp == (OptInt)(intptr_t)p->def_val;
   }
   if (p->flags & P_BOOL) {
     return *(int *)varp == (int)(intptr_t)p->def_val;
@@ -3233,10 +4034,10 @@ void ui_refresh_options(void)
     if (flags & P_BOOL) {
       value = BOOLEAN_OBJ(*(int *)varp);
     } else if (flags & P_NUM) {
-      value = INTEGER_OBJ(*(long *)varp);
+      value = INTEGER_OBJ(*(OptInt *)varp);
     } else if (flags & P_STRING) {
       // cstr_as_string handles NULL string
-      value = STRING_OBJ(cstr_as_string(*(char **)varp));
+      value = CSTR_AS_OBJ(*(char **)varp);
     }
     ui_call_option_set(name, value);
   }
@@ -3256,7 +4057,7 @@ static void showoneopt(vimoption_T *p, int opt_flags)
   silent_mode = false;
   info_message = true;          // use os_msg(), not os_errmsg()
 
-  char_u *varp = (char_u *)get_varp_scope(p, opt_flags);
+  void *varp = get_varp_scope(p, opt_flags);
 
   // for 'modified' we also need to check if 'ff' or 'fenc' changed.
   if ((p->flags & P_BOOL) && ((int *)varp == &curbuf->b_changed
@@ -3272,7 +4073,7 @@ static void showoneopt(vimoption_T *p, int opt_flags)
     msg_putchar('=');
     // put value string in NameBuff
     option_value2string(p, opt_flags);
-    msg_outtrans(NameBuff);
+    msg_outtrans(NameBuff, 0);
   }
 
   silent_mode = save_silent;
@@ -3323,23 +4124,23 @@ int makeset(FILE *fd, int opt_flags, int local_only)
           continue;
         }
 
-        char *varp = get_varp_scope(p, opt_flags);  // currently used value
+        void *varp = get_varp_scope(p, opt_flags);  // currently used value
         // Hidden options are never written.
         if (!varp) {
           continue;
         }
         // Global values are only written when not at the default value.
-        if ((opt_flags & OPT_GLOBAL) && optval_default(p, (char_u *)varp)) {
+        if ((opt_flags & OPT_GLOBAL) && optval_default(p, varp)) {
           continue;
         }
 
         if ((opt_flags & OPT_SKIPRTP)
-            && (p->var == (char_u *)&p_rtp || p->var == (char_u *)&p_pp)) {
+            && (p->var == &p_rtp || p->var == &p_pp)) {
           continue;
         }
 
         int round = 2;
-        char_u *varp_local = NULL;  // fresh value
+        void *varp_local = NULL;  // fresh value
         if (p->indir != PV_NONE) {
           if (p->var == VAR_WIN) {
             // skip window-local option when only doing globals
@@ -3349,11 +4150,11 @@ int makeset(FILE *fd, int opt_flags, int local_only)
             // When fresh value of window-local option is not at the
             // default, need to write it too.
             if (!(opt_flags & OPT_GLOBAL) && !local_only) {
-              char_u *varp_fresh = (char_u *)get_varp_scope(p, OPT_GLOBAL);  // local value
+              void *varp_fresh = get_varp_scope(p, OPT_GLOBAL);  // local value
               if (!optval_default(p, varp_fresh)) {
                 round = 1;
-                varp_local = (char_u *)varp;
-                varp = (char *)varp_fresh;
+                varp_local = varp;
+                varp = varp_fresh;
               }
             }
           }
@@ -3361,7 +4162,7 @@ int makeset(FILE *fd, int opt_flags, int local_only)
 
         // Round 1: fresh value for window-local options.
         // Round 2: other values
-        for (; round <= 2; varp = (char *)varp_local, round++) {
+        for (; round <= 2; varp = varp_local, round++) {
           char *cmd;
           if (round == 1 || (opt_flags & OPT_GLOBAL)) {
             cmd = "set";
@@ -3374,7 +4175,7 @@ int makeset(FILE *fd, int opt_flags, int local_only)
               return FAIL;
             }
           } else if (p->flags & P_NUM) {
-            if (put_setnum(fd, cmd, p->fullname, (long *)varp) == FAIL) {
+            if (put_setnum(fd, cmd, p->fullname, (OptInt *)varp) == FAIL) {
               return FAIL;
             }
           } else {    // P_STRING
@@ -3384,7 +4185,7 @@ int makeset(FILE *fd, int opt_flags, int local_only)
             // already right, avoids reloading the syntax file.
             if (p->indir == PV_SYN || p->indir == PV_FT) {
               if (fprintf(fd, "if &%s != '%s'", p->fullname,
-                          *(char_u **)(varp)) < 0
+                          *(char **)(varp)) < 0
                   || put_eol(fd) < 0) {
                 return FAIL;
               }
@@ -3431,20 +4232,10 @@ static int put_setstring(FILE *fd, char *cmd, char *name, char **valuep, uint64_
   }
 
   char *buf = NULL;
-  char_u *part = NULL;
+  char *part = NULL;
 
   if (*valuep != NULL) {
-    // Output 'pastetoggle' as key names.  For other
-    // options some characters have to be escaped with
-    // CTRL-V or backslash
-    if (valuep == &p_pt) {
-      char_u *s = (char_u *)(*valuep);
-      while (*s != NUL) {
-        if (put_escstr(fd, (char *)str2special((const char **)&s, false, false), 2) == FAIL) {
-          return FAIL;
-        }
-      }
-    } else if ((flags & P_EXPAND) != 0) {
+    if ((flags & P_EXPAND) != 0) {
       size_t size = (size_t)strlen(*valuep) + 1;
 
       // replace home directory in the whole option value into "buf"
@@ -3469,8 +4260,8 @@ static int put_setstring(FILE *fd, char *cmd, char *name, char **valuep, uint64_
           if (fprintf(fd, "%s %s+=", cmd, name) < 0) {
             goto fail;
           }
-          (void)copy_option_part(&p, (char *)part, size, ",");
-          if (put_escstr(fd, (char *)part, 2) == FAIL || put_eol(fd) == FAIL) {
+          (void)copy_option_part(&p, part, size, ",");
+          if (put_escstr(fd, part, 2) == FAIL || put_eol(fd) == FAIL) {
             goto fail;
           }
         }
@@ -3497,15 +4288,15 @@ fail:
   return FAIL;
 }
 
-static int put_setnum(FILE *fd, char *cmd, char *name, long *valuep)
+static int put_setnum(FILE *fd, char *cmd, char *name, OptInt *valuep)
 {
   if (fprintf(fd, "%s %s=", cmd, name) < 0) {
     return FAIL;
   }
-  long wc;
-  if (wc_use_keyname((char_u *)valuep, &wc)) {
+  OptInt wc;
+  if (wc_use_keyname(valuep, &wc)) {
     // print 'wildchar' and 'wildcharm' as a key name
-    if (fputs((char *)get_special_key_name((int)wc, 0), fd) < 0) {
+    if (fputs(get_special_key_name((int)wc, 0), fd) < 0) {
       return FAIL;
     }
   } else if (fprintf(fd, "%" PRId64, (int64_t)(*valuep)) < 0) {
@@ -3529,196 +4320,94 @@ static int put_setbool(FILE *fd, char *cmd, char *name, int value)
   return OK;
 }
 
-// Unset local option value, similar to ":set opt<".
-void unset_global_local_option(char *name, void *from)
-{
-  vimoption_T *p;
-  buf_T *buf = (buf_T *)from;
-
-  int opt_idx = findoption(name);
-  if (opt_idx < 0) {
-    semsg(_("E355: Unknown option: %s"), name);
-    return;
-  }
-  p = &(options[opt_idx]);
-
-  switch ((int)p->indir) {
-  // global option with local value: use local value if it's been set
-  case PV_EP:
-    clear_string_option(&buf->b_p_ep);
-    break;
-  case PV_KP:
-    clear_string_option(&buf->b_p_kp);
-    break;
-  case PV_PATH:
-    clear_string_option(&buf->b_p_path);
-    break;
-  case PV_AR:
-    buf->b_p_ar = -1;
-    break;
-  case PV_BKC:
-    clear_string_option(&buf->b_p_bkc);
-    buf->b_bkc_flags = 0;
-    break;
-  case PV_TAGS:
-    clear_string_option(&buf->b_p_tags);
-    break;
-  case PV_TC:
-    clear_string_option(&buf->b_p_tc);
-    buf->b_tc_flags = 0;
-    break;
-  case PV_SISO:
-    curwin->w_p_siso = -1;
-    break;
-  case PV_SO:
-    curwin->w_p_so = -1;
-    break;
-  case PV_DEF:
-    clear_string_option(&buf->b_p_def);
-    break;
-  case PV_INC:
-    clear_string_option(&buf->b_p_inc);
-    break;
-  case PV_DICT:
-    clear_string_option(&buf->b_p_dict);
-    break;
-  case PV_TSR:
-    clear_string_option(&buf->b_p_tsr);
-    break;
-  case PV_TSRFU:
-    clear_string_option(&buf->b_p_tsrfu);
-    break;
-  case PV_FP:
-    clear_string_option(&buf->b_p_fp);
-    break;
-  case PV_EFM:
-    clear_string_option(&buf->b_p_efm);
-    break;
-  case PV_GP:
-    clear_string_option(&buf->b_p_gp);
-    break;
-  case PV_MP:
-    clear_string_option(&buf->b_p_mp);
-    break;
-  case PV_SBR:
-    clear_string_option(&((win_T *)from)->w_p_sbr);
-    break;
-  case PV_STL:
-    clear_string_option(&((win_T *)from)->w_p_stl);
-    break;
-  case PV_WBR:
-    clear_string_option(&((win_T *)from)->w_p_wbr);
-    break;
-  case PV_UL:
-    buf->b_p_ul = NO_LOCAL_UNDOLEVEL;
-    break;
-  case PV_LW:
-    clear_string_option(&buf->b_p_lw);
-    break;
-  case PV_MENC:
-    clear_string_option(&buf->b_p_menc);
-    break;
-  case PV_LCS:
-    clear_string_option(&((win_T *)from)->w_p_lcs);
-    set_chars_option((win_T *)from, &((win_T *)from)->w_p_lcs, true);
-    redraw_later((win_T *)from, UPD_NOT_VALID);
-    break;
-  case PV_FCS:
-    clear_string_option(&((win_T *)from)->w_p_fcs);
-    set_chars_option((win_T *)from, &((win_T *)from)->w_p_fcs, true);
-    redraw_later((win_T *)from, UPD_NOT_VALID);
-    break;
-  case PV_VE:
-    clear_string_option(&((win_T *)from)->w_p_ve);
-    ((win_T *)from)->w_ve_flags = 0;
-    break;
-  case PV_STC:
-    clear_string_option(&((win_T *)from)->w_p_stc);
-    break;
-  }
-}
-
-char *get_varp_scope_from(vimoption_T *p, int scope, buf_T *buf, win_T *win)
+void *get_varp_scope_from(vimoption_T *p, int scope, buf_T *buf, win_T *win)
 {
   if ((scope & OPT_GLOBAL) && p->indir != PV_NONE) {
     if (p->var == VAR_WIN) {
       return GLOBAL_WO(get_varp_from(p, buf, win));
     }
-    return (char *)p->var;
+    return p->var;
   }
   if ((scope & OPT_LOCAL) && ((int)p->indir & PV_BOTH)) {
     switch ((int)p->indir) {
     case PV_FP:
-      return (char *)&(buf->b_p_fp);
+      return &(buf->b_p_fp);
     case PV_EFM:
-      return (char *)&(buf->b_p_efm);
+      return &(buf->b_p_efm);
     case PV_GP:
-      return (char *)&(buf->b_p_gp);
+      return &(buf->b_p_gp);
     case PV_MP:
-      return (char *)&(buf->b_p_mp);
+      return &(buf->b_p_mp);
     case PV_EP:
-      return (char *)&(buf->b_p_ep);
+      return &(buf->b_p_ep);
     case PV_KP:
-      return (char *)&(buf->b_p_kp);
+      return &(buf->b_p_kp);
     case PV_PATH:
-      return (char *)&(buf->b_p_path);
+      return &(buf->b_p_path);
     case PV_AR:
-      return (char *)&(buf->b_p_ar);
+      return &(buf->b_p_ar);
     case PV_TAGS:
-      return (char *)&(buf->b_p_tags);
+      return &(buf->b_p_tags);
     case PV_TC:
-      return (char *)&(buf->b_p_tc);
+      return &(buf->b_p_tc);
     case PV_SISO:
-      return (char *)&(win->w_p_siso);
+      return &(win->w_p_siso);
     case PV_SO:
-      return (char *)&(win->w_p_so);
+      return &(win->w_p_so);
     case PV_DEF:
-      return (char *)&(buf->b_p_def);
+      return &(buf->b_p_def);
     case PV_INC:
-      return (char *)&(buf->b_p_inc);
+      return &(buf->b_p_inc);
     case PV_DICT:
-      return (char *)&(buf->b_p_dict);
+      return &(buf->b_p_dict);
     case PV_TSR:
-      return (char *)&(buf->b_p_tsr);
+      return &(buf->b_p_tsr);
     case PV_TSRFU:
-      return (char *)&(buf->b_p_tsrfu);
+      return &(buf->b_p_tsrfu);
     case PV_TFU:
-      return (char *)&(buf->b_p_tfu);
+      return &(buf->b_p_tfu);
     case PV_SBR:
-      return (char *)&(win->w_p_sbr);
+      return &(win->w_p_sbr);
     case PV_STL:
-      return (char *)&(win->w_p_stl);
+      return &(win->w_p_stl);
     case PV_WBR:
-      return (char *)&(win->w_p_wbr);
+      return &(win->w_p_wbr);
     case PV_UL:
-      return (char *)&(buf->b_p_ul);
+      return &(buf->b_p_ul);
     case PV_LW:
-      return (char *)&(buf->b_p_lw);
+      return &(buf->b_p_lw);
     case PV_BKC:
-      return (char *)&(buf->b_p_bkc);
+      return &(buf->b_p_bkc);
     case PV_MENC:
-      return (char *)&(buf->b_p_menc);
+      return &(buf->b_p_menc);
     case PV_FCS:
-      return (char *)&(win->w_p_fcs);
+      return &(win->w_p_fcs);
     case PV_LCS:
-      return (char *)&(win->w_p_lcs);
+      return &(win->w_p_lcs);
     case PV_VE:
-      return (char *)&(win->w_p_ve);
+      return &(win->w_p_ve);
     }
     return NULL;     // "cannot happen"
   }
-  return (char *)get_varp_from(p, buf, win);
+  return get_varp_from(p, buf, win);
 }
 
 /// Get pointer to option variable, depending on local or global scope.
 ///
 /// @param scope  can be OPT_LOCAL, OPT_GLOBAL or a combination.
-char *get_varp_scope(vimoption_T *p, int scope)
+void *get_varp_scope(vimoption_T *p, int scope)
 {
   return get_varp_scope_from(p, scope, curbuf, curwin);
 }
 
-static char_u *get_varp_from(vimoption_T *p, buf_T *buf, win_T *win)
+/// Get pointer to option variable at 'opt_idx', depending on local or global
+/// scope.
+void *get_option_varp_scope_from(int opt_idx, int scope, buf_T *buf, win_T *win)
+{
+  return get_varp_scope_from(&(options[opt_idx]), scope, buf, win);
+}
+
+void *get_varp_from(vimoption_T *p, buf_T *buf, win_T *win)
 {
   // hidden option, always return NULL
   if (p->var == NULL) {
@@ -3731,309 +4420,284 @@ static char_u *get_varp_from(vimoption_T *p, buf_T *buf, win_T *win)
 
   // global option with local value: use local value if it's been set
   case PV_EP:
-    return *buf->b_p_ep != NUL
-           ? (char_u *)&buf->b_p_ep : p->var;
+    return *buf->b_p_ep != NUL ? &buf->b_p_ep : p->var;
   case PV_KP:
-    return *buf->b_p_kp != NUL
-           ? (char_u *)&buf->b_p_kp : p->var;
+    return *buf->b_p_kp != NUL ? &buf->b_p_kp : p->var;
   case PV_PATH:
-    return *buf->b_p_path != NUL
-           ? (char_u *)&(buf->b_p_path) : p->var;
+    return *buf->b_p_path != NUL ? &(buf->b_p_path) : p->var;
   case PV_AR:
-    return buf->b_p_ar >= 0
-           ? (char_u *)&(buf->b_p_ar) : p->var;
+    return buf->b_p_ar >= 0 ? &(buf->b_p_ar) : p->var;
   case PV_TAGS:
-    return *buf->b_p_tags != NUL
-           ? (char_u *)&(buf->b_p_tags) : p->var;
+    return *buf->b_p_tags != NUL ? &(buf->b_p_tags) : p->var;
   case PV_TC:
-    return *buf->b_p_tc != NUL
-           ? (char_u *)&(buf->b_p_tc) : p->var;
+    return *buf->b_p_tc != NUL ? &(buf->b_p_tc) : p->var;
   case PV_SISO:
-    return win->w_p_siso >= 0
-           ? (char_u *)&(win->w_p_siso) : p->var;
+    return win->w_p_siso >= 0 ? &(win->w_p_siso) : p->var;
   case PV_SO:
-    return win->w_p_so >= 0
-           ? (char_u *)&(win->w_p_so) : p->var;
+    return win->w_p_so >= 0 ? &(win->w_p_so) : p->var;
   case PV_BKC:
-    return *buf->b_p_bkc != NUL
-           ? (char_u *)&(buf->b_p_bkc) : p->var;
+    return *buf->b_p_bkc != NUL ? &(buf->b_p_bkc) : p->var;
   case PV_DEF:
-    return *buf->b_p_def != NUL
-           ? (char_u *)&(buf->b_p_def) : p->var;
+    return *buf->b_p_def != NUL ? &(buf->b_p_def) : p->var;
   case PV_INC:
-    return *buf->b_p_inc != NUL
-           ? (char_u *)&(buf->b_p_inc) : p->var;
+    return *buf->b_p_inc != NUL ? &(buf->b_p_inc) : p->var;
   case PV_DICT:
-    return *buf->b_p_dict != NUL
-           ? (char_u *)&(buf->b_p_dict) : p->var;
+    return *buf->b_p_dict != NUL ? &(buf->b_p_dict) : p->var;
   case PV_TSR:
-    return *buf->b_p_tsr != NUL
-           ? (char_u *)&(buf->b_p_tsr) : p->var;
+    return *buf->b_p_tsr != NUL ? &(buf->b_p_tsr) : p->var;
   case PV_TSRFU:
-    return *buf->b_p_tsrfu != NUL
-           ? (char_u *)&(buf->b_p_tsrfu) : p->var;
+    return *buf->b_p_tsrfu != NUL ? &(buf->b_p_tsrfu) : p->var;
   case PV_FP:
-    return *buf->b_p_fp != NUL
-           ? (char_u *)&(buf->b_p_fp) : p->var;
+    return *buf->b_p_fp != NUL ? &(buf->b_p_fp) : p->var;
   case PV_EFM:
-    return *buf->b_p_efm != NUL
-           ? (char_u *)&(buf->b_p_efm) : p->var;
+    return *buf->b_p_efm != NUL ? &(buf->b_p_efm) : p->var;
   case PV_GP:
-    return *buf->b_p_gp != NUL
-           ? (char_u *)&(buf->b_p_gp) : p->var;
+    return *buf->b_p_gp != NUL ? &(buf->b_p_gp) : p->var;
   case PV_MP:
-    return *buf->b_p_mp != NUL
-           ? (char_u *)&(buf->b_p_mp) : p->var;
+    return *buf->b_p_mp != NUL ? &(buf->b_p_mp) : p->var;
   case PV_SBR:
-    return *win->w_p_sbr != NUL
-           ? (char_u *)&(win->w_p_sbr) : p->var;
+    return *win->w_p_sbr != NUL ? &(win->w_p_sbr) : p->var;
   case PV_STL:
-    return *win->w_p_stl != NUL
-           ? (char_u *)&(win->w_p_stl) : p->var;
+    return *win->w_p_stl != NUL ? &(win->w_p_stl) : p->var;
   case PV_WBR:
-    return *win->w_p_wbr != NUL
-           ? (char_u *)&(win->w_p_wbr) : p->var;
+    return *win->w_p_wbr != NUL ? &(win->w_p_wbr) : p->var;
   case PV_UL:
-    return buf->b_p_ul != NO_LOCAL_UNDOLEVEL
-           ? (char_u *)&(buf->b_p_ul) : p->var;
+    return buf->b_p_ul != NO_LOCAL_UNDOLEVEL ? &(buf->b_p_ul) : p->var;
   case PV_LW:
-    return *buf->b_p_lw != NUL
-           ? (char_u *)&(buf->b_p_lw) : p->var;
+    return *buf->b_p_lw != NUL ? &(buf->b_p_lw) : p->var;
   case PV_MENC:
-    return *buf->b_p_menc != NUL
-           ? (char_u *)&(buf->b_p_menc) : p->var;
+    return *buf->b_p_menc != NUL ? &(buf->b_p_menc) : p->var;
   case PV_FCS:
-    return *win->w_p_fcs != NUL
-           ? (char_u *)&(win->w_p_fcs) : p->var;
+    return *win->w_p_fcs != NUL ? &(win->w_p_fcs) : p->var;
   case PV_LCS:
-    return *win->w_p_lcs != NUL
-           ? (char_u *)&(win->w_p_lcs) : p->var;
+    return *win->w_p_lcs != NUL ? &(win->w_p_lcs) : p->var;
   case PV_VE:
-    return *win->w_p_ve != NUL
-           ? (char_u *)&win->w_p_ve : p->var;
+    return *win->w_p_ve != NUL ? &win->w_p_ve : p->var;
 
   case PV_ARAB:
-    return (char_u *)&(win->w_p_arab);
+    return &(win->w_p_arab);
   case PV_LIST:
-    return (char_u *)&(win->w_p_list);
+    return &(win->w_p_list);
   case PV_SPELL:
-    return (char_u *)&(win->w_p_spell);
+    return &(win->w_p_spell);
   case PV_CUC:
-    return (char_u *)&(win->w_p_cuc);
+    return &(win->w_p_cuc);
   case PV_CUL:
-    return (char_u *)&(win->w_p_cul);
+    return &(win->w_p_cul);
   case PV_CULOPT:
-    return (char_u *)&(win->w_p_culopt);
+    return &(win->w_p_culopt);
   case PV_CC:
-    return (char_u *)&(win->w_p_cc);
+    return &(win->w_p_cc);
   case PV_DIFF:
-    return (char_u *)&(win->w_p_diff);
+    return &(win->w_p_diff);
   case PV_FDC:
-    return (char_u *)&(win->w_p_fdc);
+    return &(win->w_p_fdc);
   case PV_FEN:
-    return (char_u *)&(win->w_p_fen);
+    return &(win->w_p_fen);
   case PV_FDI:
-    return (char_u *)&(win->w_p_fdi);
+    return &(win->w_p_fdi);
   case PV_FDL:
-    return (char_u *)&(win->w_p_fdl);
+    return &(win->w_p_fdl);
   case PV_FDM:
-    return (char_u *)&(win->w_p_fdm);
+    return &(win->w_p_fdm);
   case PV_FML:
-    return (char_u *)&(win->w_p_fml);
+    return &(win->w_p_fml);
   case PV_FDN:
-    return (char_u *)&(win->w_p_fdn);
+    return &(win->w_p_fdn);
   case PV_FDE:
-    return (char_u *)&(win->w_p_fde);
+    return &(win->w_p_fde);
   case PV_FDT:
-    return (char_u *)&(win->w_p_fdt);
+    return &(win->w_p_fdt);
   case PV_FMR:
-    return (char_u *)&(win->w_p_fmr);
+    return &(win->w_p_fmr);
   case PV_NU:
-    return (char_u *)&(win->w_p_nu);
+    return &(win->w_p_nu);
   case PV_RNU:
-    return (char_u *)&(win->w_p_rnu);
+    return &(win->w_p_rnu);
   case PV_NUW:
-    return (char_u *)&(win->w_p_nuw);
+    return &(win->w_p_nuw);
   case PV_WFH:
-    return (char_u *)&(win->w_p_wfh);
+    return &(win->w_p_wfh);
   case PV_WFW:
-    return (char_u *)&(win->w_p_wfw);
+    return &(win->w_p_wfw);
   case PV_PVW:
-    return (char_u *)&(win->w_p_pvw);
+    return &(win->w_p_pvw);
   case PV_RL:
-    return (char_u *)&(win->w_p_rl);
+    return &(win->w_p_rl);
   case PV_RLC:
-    return (char_u *)&(win->w_p_rlc);
+    return &(win->w_p_rlc);
   case PV_SCROLL:
-    return (char_u *)&(win->w_p_scr);
+    return &(win->w_p_scr);
+  case PV_SMS:
+    return &(win->w_p_sms);
   case PV_WRAP:
-    return (char_u *)&(win->w_p_wrap);
+    return &(win->w_p_wrap);
   case PV_LBR:
-    return (char_u *)&(win->w_p_lbr);
+    return &(win->w_p_lbr);
   case PV_BRI:
-    return (char_u *)&(win->w_p_bri);
+    return &(win->w_p_bri);
   case PV_BRIOPT:
-    return (char_u *)&(win->w_p_briopt);
+    return &(win->w_p_briopt);
   case PV_SCBIND:
-    return (char_u *)&(win->w_p_scb);
+    return &(win->w_p_scb);
   case PV_CRBIND:
-    return (char_u *)&(win->w_p_crb);
+    return &(win->w_p_crb);
   case PV_COCU:
-    return (char_u *)&(win->w_p_cocu);
+    return &(win->w_p_cocu);
   case PV_COLE:
-    return (char_u *)&(win->w_p_cole);
+    return &(win->w_p_cole);
 
   case PV_AI:
-    return (char_u *)&(buf->b_p_ai);
+    return &(buf->b_p_ai);
   case PV_BIN:
-    return (char_u *)&(buf->b_p_bin);
+    return &(buf->b_p_bin);
   case PV_BOMB:
-    return (char_u *)&(buf->b_p_bomb);
+    return &(buf->b_p_bomb);
   case PV_BH:
-    return (char_u *)&(buf->b_p_bh);
+    return &(buf->b_p_bh);
   case PV_BT:
-    return (char_u *)&(buf->b_p_bt);
+    return &(buf->b_p_bt);
   case PV_BL:
-    return (char_u *)&(buf->b_p_bl);
+    return &(buf->b_p_bl);
   case PV_CHANNEL:
-    return (char_u *)&(buf->b_p_channel);
+    return &(buf->b_p_channel);
   case PV_CI:
-    return (char_u *)&(buf->b_p_ci);
+    return &(buf->b_p_ci);
   case PV_CIN:
-    return (char_u *)&(buf->b_p_cin);
+    return &(buf->b_p_cin);
   case PV_CINK:
-    return (char_u *)&(buf->b_p_cink);
+    return &(buf->b_p_cink);
   case PV_CINO:
-    return (char_u *)&(buf->b_p_cino);
+    return &(buf->b_p_cino);
   case PV_CINSD:
-    return (char_u *)&(buf->b_p_cinsd);
+    return &(buf->b_p_cinsd);
   case PV_CINW:
-    return (char_u *)&(buf->b_p_cinw);
+    return &(buf->b_p_cinw);
   case PV_COM:
-    return (char_u *)&(buf->b_p_com);
+    return &(buf->b_p_com);
   case PV_CMS:
-    return (char_u *)&(buf->b_p_cms);
+    return &(buf->b_p_cms);
   case PV_CPT:
-    return (char_u *)&(buf->b_p_cpt);
+    return &(buf->b_p_cpt);
 #ifdef BACKSLASH_IN_FILENAME
   case PV_CSL:
-    return (char_u *)&(buf->b_p_csl);
+    return &(buf->b_p_csl);
 #endif
   case PV_CFU:
-    return (char_u *)&(buf->b_p_cfu);
+    return &(buf->b_p_cfu);
   case PV_OFU:
-    return (char_u *)&(buf->b_p_ofu);
+    return &(buf->b_p_ofu);
   case PV_EOF:
-    return (char_u *)&(buf->b_p_eof);
+    return &(buf->b_p_eof);
   case PV_EOL:
-    return (char_u *)&(buf->b_p_eol);
+    return &(buf->b_p_eol);
   case PV_FIXEOL:
-    return (char_u *)&(buf->b_p_fixeol);
+    return &(buf->b_p_fixeol);
   case PV_ET:
-    return (char_u *)&(buf->b_p_et);
+    return &(buf->b_p_et);
   case PV_FENC:
-    return (char_u *)&(buf->b_p_fenc);
+    return &(buf->b_p_fenc);
   case PV_FF:
-    return (char_u *)&(buf->b_p_ff);
+    return &(buf->b_p_ff);
   case PV_FT:
-    return (char_u *)&(buf->b_p_ft);
+    return &(buf->b_p_ft);
   case PV_FO:
-    return (char_u *)&(buf->b_p_fo);
+    return &(buf->b_p_fo);
   case PV_FLP:
-    return (char_u *)&(buf->b_p_flp);
+    return &(buf->b_p_flp);
   case PV_IMI:
-    return (char_u *)&(buf->b_p_iminsert);
+    return &(buf->b_p_iminsert);
   case PV_IMS:
-    return (char_u *)&(buf->b_p_imsearch);
+    return &(buf->b_p_imsearch);
   case PV_INF:
-    return (char_u *)&(buf->b_p_inf);
+    return &(buf->b_p_inf);
   case PV_ISK:
-    return (char_u *)&(buf->b_p_isk);
+    return &(buf->b_p_isk);
   case PV_INEX:
-    return (char_u *)&(buf->b_p_inex);
+    return &(buf->b_p_inex);
   case PV_INDE:
-    return (char_u *)&(buf->b_p_inde);
+    return &(buf->b_p_inde);
   case PV_INDK:
-    return (char_u *)&(buf->b_p_indk);
+    return &(buf->b_p_indk);
   case PV_FEX:
-    return (char_u *)&(buf->b_p_fex);
+    return &(buf->b_p_fex);
   case PV_LISP:
-    return (char_u *)&(buf->b_p_lisp);
+    return &(buf->b_p_lisp);
   case PV_LOP:
-    return (char_u *)&(buf->b_p_lop);
+    return &(buf->b_p_lop);
   case PV_ML:
-    return (char_u *)&(buf->b_p_ml);
+    return &(buf->b_p_ml);
   case PV_MPS:
-    return (char_u *)&(buf->b_p_mps);
+    return &(buf->b_p_mps);
   case PV_MA:
-    return (char_u *)&(buf->b_p_ma);
+    return &(buf->b_p_ma);
   case PV_MOD:
-    return (char_u *)&(buf->b_changed);
+    return &(buf->b_changed);
   case PV_NF:
-    return (char_u *)&(buf->b_p_nf);
+    return &(buf->b_p_nf);
   case PV_PI:
-    return (char_u *)&(buf->b_p_pi);
+    return &(buf->b_p_pi);
   case PV_QE:
-    return (char_u *)&(buf->b_p_qe);
+    return &(buf->b_p_qe);
   case PV_RO:
-    return (char_u *)&(buf->b_p_ro);
+    return &(buf->b_p_ro);
   case PV_SCBK:
-    return (char_u *)&(buf->b_p_scbk);
+    return &(buf->b_p_scbk);
   case PV_SI:
-    return (char_u *)&(buf->b_p_si);
+    return &(buf->b_p_si);
   case PV_STS:
-    return (char_u *)&(buf->b_p_sts);
+    return &(buf->b_p_sts);
   case PV_SUA:
-    return (char_u *)&(buf->b_p_sua);
+    return &(buf->b_p_sua);
   case PV_SWF:
-    return (char_u *)&(buf->b_p_swf);
+    return &(buf->b_p_swf);
   case PV_SMC:
-    return (char_u *)&(buf->b_p_smc);
+    return &(buf->b_p_smc);
   case PV_SYN:
-    return (char_u *)&(buf->b_p_syn);
+    return &(buf->b_p_syn);
   case PV_SPC:
-    return (char_u *)&(win->w_s->b_p_spc);
+    return &(win->w_s->b_p_spc);
   case PV_SPF:
-    return (char_u *)&(win->w_s->b_p_spf);
+    return &(win->w_s->b_p_spf);
   case PV_SPL:
-    return (char_u *)&(win->w_s->b_p_spl);
+    return &(win->w_s->b_p_spl);
   case PV_SPO:
-    return (char_u *)&(win->w_s->b_p_spo);
+    return &(win->w_s->b_p_spo);
   case PV_SW:
-    return (char_u *)&(buf->b_p_sw);
+    return &(buf->b_p_sw);
   case PV_TFU:
-    return (char_u *)&(buf->b_p_tfu);
+    return &(buf->b_p_tfu);
   case PV_TS:
-    return (char_u *)&(buf->b_p_ts);
+    return &(buf->b_p_ts);
   case PV_TW:
-    return (char_u *)&(buf->b_p_tw);
+    return &(buf->b_p_tw);
   case PV_UDF:
-    return (char_u *)&(buf->b_p_udf);
+    return &(buf->b_p_udf);
   case PV_WM:
-    return (char_u *)&(buf->b_p_wm);
+    return &(buf->b_p_wm);
   case PV_VSTS:
-    return (char_u *)&(buf->b_p_vsts);
+    return &(buf->b_p_vsts);
   case PV_VTS:
-    return (char_u *)&(buf->b_p_vts);
+    return &(buf->b_p_vts);
   case PV_KMAP:
-    return (char_u *)&(buf->b_p_keymap);
+    return &(buf->b_p_keymap);
   case PV_SCL:
-    return (char_u *)&(win->w_p_scl);
+    return &(win->w_p_scl);
   case PV_WINHL:
-    return (char_u *)&(win->w_p_winhl);
+    return &(win->w_p_winhl);
   case PV_WINBL:
-    return (char_u *)&(win->w_p_winbl);
+    return &(win->w_p_winbl);
   case PV_STC:
-    return (char_u *)&(win->w_p_stc);
+    return &(win->w_p_stc);
   default:
     iemsg(_("E356: get_varp ERROR"));
   }
   // always return a valid pointer to avoid a crash!
-  return (char_u *)&(buf->b_p_wm);
+  return &(buf->b_p_wm);
 }
 
 /// Get pointer to option variable.
-static inline char_u *get_varp(vimoption_T *p)
+static inline void *get_varp(vimoption_T *p)
 {
   return get_varp_from(p, curbuf, curwin);
 }
@@ -4058,8 +4722,8 @@ void win_copy_options(win_T *wp_from, win_T *wp_to)
 
 static char *copy_option_val(const char *val)
 {
-  if (val == empty_option) {
-    return empty_option;  // no need to allocate memory
+  if (val == empty_string_option) {
+    return empty_string_option;  // no need to allocate memory
   }
   return xstrdup(val);
 }
@@ -4079,7 +4743,7 @@ void copy_winopt(winopt_T *from, winopt_T *to)
   to->wo_ve = copy_option_val(from->wo_ve);
   to->wo_ve_flags = from->wo_ve_flags;
   to->wo_nuw = from->wo_nuw;
-  to->wo_rl  = from->wo_rl;
+  to->wo_rl = from->wo_rl;
   to->wo_rlc = copy_option_val(from->wo_rlc);
   to->wo_sbr = copy_option_val(from->wo_sbr);
   to->wo_stl = copy_option_val(from->wo_stl);
@@ -4091,8 +4755,11 @@ void copy_winopt(winopt_T *from, winopt_T *to)
   to->wo_briopt = copy_option_val(from->wo_briopt);
   to->wo_scb = from->wo_scb;
   to->wo_scb_save = from->wo_scb_save;
+  to->wo_sms = from->wo_sms;
   to->wo_crb = from->wo_crb;
   to->wo_crb_save = from->wo_crb_save;
+  to->wo_siso = from->wo_siso;
+  to->wo_so = from->wo_so;
   to->wo_spell = from->wo_spell;
   to->wo_cuc = from->wo_cuc;
   to->wo_cul = from->wo_cul;
@@ -4103,7 +4770,7 @@ void copy_winopt(winopt_T *from, winopt_T *to)
   to->wo_cocu = copy_option_val(from->wo_cocu);
   to->wo_cole = from->wo_cole;
   to->wo_fdc = copy_option_val(from->wo_fdc);
-  to->wo_fdc_save = from->wo_diff_saved ? xstrdup(from->wo_fdc_save) : empty_option;
+  to->wo_fdc_save = from->wo_diff_saved ? xstrdup(from->wo_fdc_save) : empty_string_option;
   to->wo_fen = from->wo_fen;
   to->wo_fen_save = from->wo_fen_save;
   to->wo_fdi = copy_option_val(from->wo_fdi);
@@ -4111,7 +4778,7 @@ void copy_winopt(winopt_T *from, winopt_T *to)
   to->wo_fdl = from->wo_fdl;
   to->wo_fdl_save = from->wo_fdl_save;
   to->wo_fdm = copy_option_val(from->wo_fdm);
-  to->wo_fdm_save = from->wo_diff_saved ? xstrdup(from->wo_fdm_save) : empty_option;
+  to->wo_fdm_save = from->wo_diff_saved ? xstrdup(from->wo_fdm_save) : empty_string_option;
   to->wo_fdn = from->wo_fdn;
   to->wo_fde = copy_option_val(from->wo_fde);
   to->wo_fdt = copy_option_val(from->wo_fdt);
@@ -4133,7 +4800,7 @@ void check_win_options(win_T *win)
   check_winopt(&win->w_allbuf_opt);
 }
 
-/// Check for NULL pointers in a winopt_T and replace them with empty_option.
+/// Check for NULL pointers in a winopt_T and replace them with empty_string_option.
 static void check_winopt(winopt_T *wop)
 {
   check_string_option(&wop->wo_fdc);
@@ -4192,11 +4859,12 @@ void didset_window_options(win_T *wp, bool valid_cursor)
   check_colorcolumn(wp);
   briopt_check(wp);
   fill_culopt_flags(NULL, wp);
-  set_chars_option(wp, &wp->w_p_fcs, true);
-  set_chars_option(wp, &wp->w_p_lcs, true);
+  set_fillchars_option(wp, wp->w_p_fcs, true);
+  set_listchars_option(wp, wp->w_p_lcs, true);
   parse_winhl_opt(wp);  // sets w_hl_needs_update also for w_p_winbl
   check_blending(wp);
   set_winbar_win(wp, false, valid_cursor);
+  check_signcolumn(wp);
   wp->w_grid_alloc.blending = wp->w_p_winbl > 0;
 }
 
@@ -4286,8 +4954,8 @@ void buf_copy_options(buf_T *buf, int flags)
           buf->b_p_ff = xstrdup(p_ff);
           break;
         }
-        buf->b_p_bh = empty_option;
-        buf->b_p_bt = empty_option;
+        buf->b_p_bh = empty_string_option;
+        buf->b_p_bt = empty_string_option;
       } else {
         free_buf_options(buf, false);
       }
@@ -4348,7 +5016,7 @@ void buf_copy_options(buf_T *buf, int flags)
       buf->b_p_sts_nopaste = p_sts_nopaste;
       buf->b_p_vsts = xstrdup(p_vsts);
       COPY_OPT_SCTX(buf, BV_VSTS);
-      if (p_vsts && p_vsts != empty_option) {
+      if (p_vsts && p_vsts != empty_string_option) {
         (void)tabstop_set(p_vsts, &buf->b_p_vsts_array);
       } else {
         buf->b_p_vsts_array = NULL;
@@ -4384,7 +5052,7 @@ void buf_copy_options(buf_T *buf, int flags)
       COPY_OPT_SCTX(buf, BV_LOP);
 
       // Don't copy 'filetype', it must be detected
-      buf->b_p_ft = empty_option;
+      buf->b_p_ft = empty_string_option;
       buf->b_p_pi = p_pi;
       COPY_OPT_SCTX(buf, BV_PI);
       buf->b_p_cinw = xstrdup(p_cinw);
@@ -4392,10 +5060,10 @@ void buf_copy_options(buf_T *buf, int flags)
       buf->b_p_lisp = p_lisp;
       COPY_OPT_SCTX(buf, BV_LISP);
       // Don't copy 'syntax', it must be set
-      buf->b_p_syn = empty_option;
+      buf->b_p_syn = empty_string_option;
       buf->b_p_smc = p_smc;
       COPY_OPT_SCTX(buf, BV_SMC);
-      buf->b_s.b_syn_isk = empty_option;
+      buf->b_s.b_syn_isk = empty_string_option;
       buf->b_s.b_p_spc = xstrdup(p_spc);
       COPY_OPT_SCTX(buf, BV_SPC);
       (void)compile_cap_prog(&buf->b_s);
@@ -4409,7 +5077,7 @@ void buf_copy_options(buf_T *buf, int flags)
       COPY_OPT_SCTX(buf, BV_INDE);
       buf->b_p_indk = xstrdup(p_indk);
       COPY_OPT_SCTX(buf, BV_INDK);
-      buf->b_p_fp = empty_option;
+      buf->b_p_fp = empty_string_option;
       buf->b_p_fex = xstrdup(p_fex);
       COPY_OPT_SCTX(buf, BV_FEX);
       buf->b_p_sua = xstrdup(p_sua);
@@ -4428,30 +5096,30 @@ void buf_copy_options(buf_T *buf, int flags)
       // are not copied, start using the global value
       buf->b_p_ar = -1;
       buf->b_p_ul = NO_LOCAL_UNDOLEVEL;
-      buf->b_p_bkc = empty_option;
+      buf->b_p_bkc = empty_string_option;
       buf->b_bkc_flags = 0;
-      buf->b_p_gp = empty_option;
-      buf->b_p_mp = empty_option;
-      buf->b_p_efm = empty_option;
-      buf->b_p_ep = empty_option;
-      buf->b_p_kp = empty_option;
-      buf->b_p_path = empty_option;
-      buf->b_p_tags = empty_option;
-      buf->b_p_tc = empty_option;
+      buf->b_p_gp = empty_string_option;
+      buf->b_p_mp = empty_string_option;
+      buf->b_p_efm = empty_string_option;
+      buf->b_p_ep = empty_string_option;
+      buf->b_p_kp = empty_string_option;
+      buf->b_p_path = empty_string_option;
+      buf->b_p_tags = empty_string_option;
+      buf->b_p_tc = empty_string_option;
       buf->b_tc_flags = 0;
-      buf->b_p_def = empty_option;
-      buf->b_p_inc = empty_option;
+      buf->b_p_def = empty_string_option;
+      buf->b_p_inc = empty_string_option;
       buf->b_p_inex = xstrdup(p_inex);
       COPY_OPT_SCTX(buf, BV_INEX);
-      buf->b_p_dict = empty_option;
-      buf->b_p_tsr = empty_option;
-      buf->b_p_tsrfu = empty_option;
+      buf->b_p_dict = empty_string_option;
+      buf->b_p_tsr = empty_string_option;
+      buf->b_p_tsrfu = empty_string_option;
       buf->b_p_qe = xstrdup(p_qe);
       COPY_OPT_SCTX(buf, BV_QE);
       buf->b_p_udf = p_udf;
       COPY_OPT_SCTX(buf, BV_UDF);
-      buf->b_p_lw = empty_option;
-      buf->b_p_menc = empty_option;
+      buf->b_p_lw = empty_string_option;
+      buf->b_p_menc = empty_string_option;
 
       // Don't copy the options set by ex_help(), use the saved values,
       // when going from a help buffer to a non-help buffer.
@@ -4459,7 +5127,7 @@ void buf_copy_options(buf_T *buf, int flags)
       // or to a help buffer.
       if (dont_do_help) {
         buf->b_p_isk = save_p_isk;
-        if (p_vts && p_vts != empty_option && !buf->b_p_vts_array) {
+        if (p_vts && p_vts != empty_string_option && !buf->b_p_vts_array) {
           (void)tabstop_set(p_vts, &buf->b_p_vts_array);
         } else {
           buf->b_p_vts_array = NULL;
@@ -4472,7 +5140,7 @@ void buf_copy_options(buf_T *buf, int flags)
         COPY_OPT_SCTX(buf, BV_TS);
         buf->b_p_vts = xstrdup(p_vts);
         COPY_OPT_SCTX(buf, BV_VTS);
-        if (p_vts && p_vts != empty_option && !buf->b_p_vts_array) {
+        if (p_vts && p_vts != empty_string_option && !buf->b_p_vts_array) {
           (void)tabstop_set(p_vts, &buf->b_p_vts_array);
         } else {
           buf->b_p_vts_array = NULL;
@@ -4525,8 +5193,10 @@ void set_imsearch_global(buf_T *buf)
 }
 
 static int expand_option_idx = -1;
-static char_u expand_option_name[5] = { 't', '_', NUL, NUL, NUL };
+static int expand_option_start_col = 0;
+static char expand_option_name[5] = { 't', '_', NUL, NUL, NUL };
 static int expand_option_flags = 0;
+static bool expand_option_append = false;
 
 /// @param opt_flags  OPT_GLOBAL and/or OPT_LOCAL
 void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
@@ -4560,10 +5230,11 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
   }
   if (strncmp(p, "no", 2) == 0) {
     xp->xp_context = EXPAND_BOOL_SETTINGS;
+    xp->xp_prefix = XP_PREFIX_NO;
     p += 2;
-  }
-  if (strncmp(p, "inv", 3) == 0) {
+  } else if (strncmp(p, "inv", 3) == 0) {
     xp->xp_context = EXPAND_BOOL_SETTINGS;
+    xp->xp_prefix = XP_PREFIX_INV;
     p += 3;
   }
   xp->xp_pattern = p;
@@ -4580,15 +5251,15 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
         return;
       }
     }
-    int key = get_special_key_code((char_u *)arg + 1);
+    int key = get_special_key_code(arg + 1);
     if (key == 0) {                 // unknown name
       xp->xp_context = EXPAND_NOTHING;
       return;
     }
     nextchar = *++p;
     is_term_option = true;
-    expand_option_name[2] = (char_u)KEY2TERMCAP0(key);
-    expand_option_name[3] = KEY2TERMCAP1(key);
+    expand_option_name[2] = (char)(uint8_t)KEY2TERMCAP0(key);
+    expand_option_name[3] = (char)(uint8_t)KEY2TERMCAP1(key);
   } else {
     if (p[0] == 't' && p[1] == '_') {
       p += 2;
@@ -4600,8 +5271,8 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
       }
       nextchar = *++p;
       is_term_option = true;
-      expand_option_name[2] = (char_u)p[-2];
-      expand_option_name[3] = (char_u)p[-1];
+      expand_option_name[2] = p[-2];
+      expand_option_name[3] = p[-1];
     } else {
       // Allow * wildcard.
       while (ASCII_ISALNUM(*p) || *p == '_' || *p == '*') {
@@ -4611,7 +5282,7 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
         return;
       }
       nextchar = *p;
-      opt_idx = findoption_len((const char *)arg, (size_t)(p - arg));
+      opt_idx = findoption_len(arg, (size_t)(p - arg));
       if (opt_idx == -1 || options[opt_idx].var == NULL) {
         xp->xp_context = EXPAND_NOTHING;
         return;
@@ -4624,7 +5295,15 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
     }
   }
   // handle "-=" and "+="
+  expand_option_append = false;
+  bool expand_option_subtract = false;
   if ((nextchar == '-' || nextchar == '+' || nextchar == '^') && p[1] == '=') {
+    if (nextchar == '-') {
+      expand_option_subtract = true;
+    }
+    if (nextchar == '+' || nextchar == '^') {
+      expand_option_append = true;
+    }
     p++;
     nextchar = '=';
   }
@@ -4633,25 +5312,53 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
     xp->xp_context = EXPAND_UNSUCCESSFUL;
     return;
   }
-  if (p[1] == NUL) {
+
+  // Below are for handling expanding a specific option's value after the '=' or ':'
+
+  if (is_term_option) {
+    expand_option_idx = -1;
+  } else {
+    expand_option_idx = opt_idx;
+  }
+
+  xp->xp_pattern = p + 1;
+  expand_option_start_col = (int)(p + 1 - xp->xp_line);
+
+  // Certain options currently have special case handling to reuse the
+  // expansion logic with other commands.
+  if (options[opt_idx].var == &p_syn) {
+    xp->xp_context = EXPAND_OWNSYNTAX;
+    return;
+  }
+  if (options[opt_idx].var == &p_ft) {
+    xp->xp_context = EXPAND_FILETYPE;
+    return;
+  }
+
+  // Now pick. If the option has a custom expander, use that. Otherwise, just
+  // fill with the existing option value.
+  if (expand_option_subtract) {
+    xp->xp_context = EXPAND_SETTING_SUBTRACT;
+    return;
+  } else if (expand_option_idx >= 0
+             && options[expand_option_idx].opt_expand_cb != NULL) {
+    xp->xp_context = EXPAND_STRING_SETTING;
+  } else if (*xp->xp_pattern == NUL) {
     xp->xp_context = EXPAND_OLD_SETTING;
-    if (is_term_option) {
-      expand_option_idx = -1;
-    } else {
-      expand_option_idx = opt_idx;
-    }
-    xp->xp_pattern = p + 1;
     return;
+  } else {
+    xp->xp_context = EXPAND_NOTHING;
   }
-  xp->xp_context = EXPAND_NOTHING;
+
   if (is_term_option || (flags & P_NUM)) {
     return;
   }
 
-  xp->xp_pattern = p + 1;
+  // Only string options below
 
+  // Options that have P_EXPAND are considered to all use file/dir expansion.
   if (flags & P_EXPAND) {
-    p = (char *)options[opt_idx].var;
+    p = options[opt_idx].var;
     if (p == (char *)&p_bdir
         || p == (char *)&p_dir
         || p == (char *)&p_path
@@ -4665,8 +5372,6 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
       } else {
         xp->xp_backslash = XP_BS_ONE;
       }
-    } else if (p == (char *)&p_ft) {
-      xp->xp_context = EXPAND_FILETYPE;
     } else {
       xp->xp_context = EXPAND_FILES;
       // for 'tags' need three backslashes for a space
@@ -4676,29 +5381,54 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
         xp->xp_backslash = XP_BS_ONE;
       }
     }
+    if (flags & P_COMMA) {
+      xp->xp_backslash |= XP_BS_COMMA;
+    }
   }
 
-  // For an option that is a list of file names, find the start of the
-  // last file name.
-  for (p = arg + strlen(arg) - 1; p > xp->xp_pattern; p--) {
-    // count number of backslashes before ' ' or ','
-    if (*p == ' ' || *p == ',') {
-      char *s = p;
-      while (s > xp->xp_pattern && *(s - 1) == '\\') {
-        s--;
-      }
-      if ((*p == ' ' && (xp->xp_backslash == XP_BS_THREE && (p - s) < 3))
-          || (*p == ',' && (flags & P_COMMA) && ((p - s) & 1) == 0)) {
-        xp->xp_pattern = p + 1;
-        break;
+  // For an option that is a list of file names, or comma/colon-separated
+  // values, split it by the delimiter and find the start of the current
+  // pattern, while accounting for backslash-escaped space/commas/colons.
+  // Triple-backslashed escaped file names (e.g. 'path') can also be
+  // delimited by space.
+  if ((flags & P_EXPAND) || (flags & P_COMMA) || (flags & P_COLON)) {
+    for (p = arg + strlen(arg) - 1; p > xp->xp_pattern; p--) {
+      // count number of backslashes before ' ' or ','
+      if (*p == ' ' || *p == ',' || (*p == ':' && (flags & P_COLON))) {
+        char *s = p;
+        while (s > xp->xp_pattern && *(s - 1) == '\\') {
+          s--;
+        }
+        if ((*p == ' ' && ((xp->xp_backslash & XP_BS_THREE) && (p - s) < 3))
+#if defined(BACKSLASH_IN_FILENAME)
+            || (*p == ',' && (flags & P_COMMA) && (p - s) < 1)
+#else
+            || (*p == ',' && (flags & P_COMMA) && (p - s) < 2)
+#endif
+            || (*p == ':' && (flags & P_COLON))) {
+          xp->xp_pattern = p + 1;
+          break;
+        }
       }
     }
+  }
 
-    // for 'spellsuggest' start at "file:"
-    if (options[opt_idx].var == (char_u *)&p_sps
-        && strncmp(p, "file:", 5) == 0) {
-      xp->xp_pattern = p + 5;
-      break;
+  // An option that is a list of single-character flags should always start
+  // at the end as we don't complete words.
+  if (flags & P_FLAGLIST) {
+    xp->xp_pattern = arg + strlen(arg);
+  }
+
+  // Some options can either be using file/dir expansions, or custom value
+  // expansion depending on what the user typed. Unfortunately we have to
+  // manually handle it here to make sure we have the correct xp_context set.
+  // for 'spellsuggest' start at "file:"
+  if (options[opt_idx].var == &p_sps) {
+    if (strncmp(xp->xp_pattern, "file:", 5) == 0) {
+      xp->xp_pattern += 5;
+      return;
+    } else if (options[expand_option_idx].opt_expand_cb != NULL) {
+      xp->xp_context = EXPAND_STRING_SETTING;
     }
   }
 }
@@ -4722,7 +5452,7 @@ static bool match_str(char *const str, regmatch_T *const regmatch, char **const
                       const char *const fuzzystr, fuzmatch_str_T *const fuzmatch)
 {
   if (!fuzzy) {
-    if (vim_regexec(regmatch, str, (colnr_T)0)) {
+    if (vim_regexec(regmatch, str, 0)) {
       if (!test_only) {
         matches[idx] = xstrdup(str);
       }
@@ -4757,10 +5487,9 @@ int ExpandSettings(expand_T *xp, regmatch_T *regmatch, char *fuzzystr, int *numM
   // loop == 0: count the number of matching options
   // loop == 1: copy the matching options into allocated memory
   for (int loop = 0; loop <= 1; loop++) {
-    int match;
     regmatch->rm_ic = ic;
     if (xp->xp_context != EXPAND_BOOL_SETTINGS) {
-      for (match = 0; match < (int)ARRAY_SIZE(names);
+      for (int match = 0; match < (int)ARRAY_SIZE(names);
            match++) {
         if (match_str(names[match], regmatch, *matches,
                       count, (loop == 0), fuzzy, fuzzystr, fuzmatch)) {
@@ -4791,7 +5520,7 @@ int ExpandSettings(expand_T *xp, regmatch_T *regmatch, char *fuzzystr, int *numM
           count++;
         }
       } else if (!fuzzy && options[opt_idx].shortname != NULL
-                 && vim_regexec(regmatch, options[opt_idx].shortname, (colnr_T)0)) {
+                 && vim_regexec(regmatch, options[opt_idx].shortname, 0)) {
         // Compare against the abbreviated option name (for regular
         // expression match). Fuzzy matching (previous if) already
         // matches against both the expanded and abbreviated names.
@@ -4824,16 +5553,42 @@ int ExpandSettings(expand_T *xp, regmatch_T *regmatch, char *fuzzystr, int *numM
   return OK;
 }
 
-void ExpandOldSetting(int *num_file, char ***file)
+/// Escape an option value that can be used on the command-line with :set.
+/// Caller needs to free the returned string, unless NULL is returned.
+static char *escape_option_str_cmdline(char *var)
+{
+  // A backslash is required before some characters.  This is the reverse of
+  // what happens in do_set().
+  char *buf = vim_strsave_escaped(var, escape_chars);
+
+#ifdef BACKSLASH_IN_FILENAME
+  // For MS-Windows et al. we don't double backslashes at the start and
+  // before a file name character.
+  // The reverse is found at stropt_copy_value().
+  for (var = buf; *var != NUL; MB_PTR_ADV(var)) {
+    if (var[0] == '\\' && var[1] == '\\'
+        && expand_option_idx >= 0
+        && (options[expand_option_idx].flags & P_EXPAND)
+        && vim_isfilec((uint8_t)var[2])
+        && (var[2] != '\\' || (var == buf && var[4] != '\\'))) {
+      STRMOVE(var, var + 1);
+    }
+  }
+#endif
+  return buf;
+}
+
+/// Expansion handler for :set= when we just want to fill in with the existing value.
+int ExpandOldSetting(int *numMatches, char ***matches)
 {
   char *var = NULL;
 
-  *num_file = 0;
-  *file = xmalloc(sizeof(char_u *));
+  *numMatches = 0;
+  *matches = xmalloc(sizeof(char *));
 
   // For a terminal key code expand_option_idx is < 0.
   if (expand_option_idx < 0) {
-    expand_option_idx = findoption((const char *)expand_option_name);
+    expand_option_idx = findoption(expand_option_name);
   }
 
   if (expand_option_idx >= 0) {
@@ -4844,26 +5599,149 @@ void ExpandOldSetting(int *num_file, char ***file)
     var = "";
   }
 
-  // A backslash is required before some characters.  This is the reverse of
-  // what happens in do_set().
-  char *buf = vim_strsave_escaped(var, escape_chars);
+  char *buf = escape_option_str_cmdline(var);
 
-#ifdef BACKSLASH_IN_FILENAME
-  // For MS-Windows et al. we don't double backslashes at the start and
-  // before a file name character.
-  for (var = buf; *var != NUL; MB_PTR_ADV(var)) {
-    if (var[0] == '\\' && var[1] == '\\'
-        && expand_option_idx >= 0
-        && (options[expand_option_idx].flags & P_EXPAND)
-        && vim_isfilec((uint8_t)var[2])
-        && (var[2] != '\\' || (var == buf && var[4] != '\\'))) {
-      STRMOVE(var, var + 1);
+  (*matches)[0] = buf;
+  *numMatches = 1;
+  return OK;
+}
+
+/// Expansion handler for :set=/:set+= when the option has a custom expansion handler.
+int ExpandStringSetting(expand_T *xp, regmatch_T *regmatch, int *numMatches, char ***matches)
+{
+  if (expand_option_idx < 0
+      || options[expand_option_idx].opt_expand_cb == NULL) {
+    // Not supposed to reach this. This function is only for options with
+    // custom expansion callbacks.
+    return FAIL;
+  }
+
+  optexpand_T args = {
+    .oe_varp = get_varp_scope(&options[expand_option_idx], expand_option_flags),
+    .oe_append = expand_option_append,
+    .oe_regmatch = regmatch,
+    .oe_xp = xp,
+    .oe_set_arg = xp->xp_line + expand_option_start_col,
+  };
+  args.oe_include_orig_val = !expand_option_append && (*args.oe_set_arg == NUL);
+
+  // Retrieve the existing value, but escape it as a reverse of setting it.
+  // We technically only need to do this when oe_append or
+  // oe_include_orig_val is true.
+  option_value2string(&options[expand_option_idx], expand_option_flags);
+  char *var = NameBuff;
+  char *buf = escape_option_str_cmdline(var);
+  args.oe_opt_value = buf;
+
+  int num_ret = options[expand_option_idx].opt_expand_cb(&args, numMatches, matches);
+
+  xfree(buf);
+  return num_ret;
+}
+
+/// Expansion handler for :set-=
+int ExpandSettingSubtract(expand_T *xp, regmatch_T *regmatch, int *numMatches, char ***matches)
+{
+  if (expand_option_idx < 0) {
+    // term option
+    return ExpandOldSetting(numMatches, matches);
+  }
+
+  char *option_val = *(char **)get_option_varp_scope_from(expand_option_idx,
+                                                          expand_option_flags,
+                                                          curbuf, curwin);
+
+  uint32_t option_flags = options[expand_option_idx].flags;
+
+  if (option_flags & P_NUM) {
+    return ExpandOldSetting(numMatches, matches);
+  } else if (option_flags & P_COMMA) {
+    // Split the option by comma, then present each option to the user if
+    // it matches the pattern.
+    // This condition needs to go first, because 'whichwrap' has both
+    // P_COMMA and P_FLAGLIST.
+
+    if (*option_val == NUL) {
+      return FAIL;
     }
+
+    // Make a copy as we need to inject null characters destructively.
+    char *option_copy = xstrdup(option_val);
+    char *next_val = option_copy;
+
+    garray_T ga;
+    ga_init(&ga, sizeof(char *), 10);
+
+    do {
+      char *item = next_val;
+      char *comma = vim_strchr(next_val, ',');
+      while (comma != NULL && comma != next_val && *(comma - 1) == '\\') {
+        // "\," is interpreted as a literal comma rather than option
+        // separator when reading options in copy_option_part(). Skip
+        // it.
+        comma = vim_strchr(comma + 1, ',');
+      }
+      if (comma != NULL) {
+        *comma = NUL;  // null-terminate this value, required by later functions
+        next_val = comma + 1;
+      } else {
+        next_val = NULL;
+      }
+
+      if (*item == NUL) {
+        // empty value, don't add to list
+        continue;
+      }
+
+      if (!vim_regexec(regmatch, item, 0)) {
+        continue;
+      }
+
+      char *buf = escape_option_str_cmdline(item);
+      GA_APPEND(char *, &ga, buf);
+    } while (next_val != NULL);
+
+    xfree(option_copy);
+
+    *matches = ga.ga_data;
+    *numMatches = ga.ga_len;
+    return OK;
+  } else if (option_flags & P_FLAGLIST) {
+    // Only present the flags that are set on the option as the other flags
+    // are not meaningful to do set-= on.
+
+    if (*xp->xp_pattern != NUL) {
+      // Don't suggest anything if cmdline is non-empty. Vim's set-=
+      // behavior requires consecutive strings and it's usually
+      // unintuitive to users if they try to subtract multiple flags at
+      // once.
+      return FAIL;
+    }
+
+    size_t num_flags = strlen(option_val);
+    if (num_flags == 0) {
+      return FAIL;
+    }
+
+    *matches = xmalloc(sizeof(char *) * (num_flags + 1));
+
+    int count = 0;
+
+    (*matches)[count++] = xstrdup(option_val);
+
+    if (num_flags > 1) {
+      // If more than one flags, split the flags up and expose each
+      // character as individual choice.
+      for (char *flag = option_val; *flag != NUL; flag++) {
+        (*matches)[count++] = xmemdupz(flag, 1);
+      }
+    }
+
+    *numMatches = count;
+    return OK;
   }
-#endif
 
-  *file[0] = buf;
-  *num_file = 1;
+  return ExpandOldSetting(numMatches, matches);
 }
 
 /// Get the value for the numeric or string option///opp in a nice format into
@@ -4872,30 +5750,27 @@ void ExpandOldSetting(int *num_file, char ***file)
 /// @param opt_flags  OPT_GLOBAL and/or OPT_LOCAL
 static void option_value2string(vimoption_T *opp, int scope)
 {
-  char *varp = get_varp_scope(opp, scope);
+  void *varp = get_varp_scope(opp, scope);
 
   if (opp->flags & P_NUM) {
-    long wc = 0;
+    OptInt wc = 0;
 
-    if (wc_use_keyname((char_u *)varp, &wc)) {
-      xstrlcpy(NameBuff, (char *)get_special_key_name((int)wc, 0), sizeof(NameBuff));
+    if (wc_use_keyname(varp, &wc)) {
+      xstrlcpy(NameBuff, get_special_key_name((int)wc, 0), sizeof(NameBuff));
     } else if (wc != 0) {
       xstrlcpy(NameBuff, transchar((int)wc), sizeof(NameBuff));
     } else {
       snprintf(NameBuff,
                sizeof(NameBuff),
                "%" PRId64,
-               (int64_t)(*(long *)varp));
+               (int64_t)(*(OptInt *)varp));
     }
   } else {  // P_STRING
     varp = *(char **)(varp);
     if (varp == NULL) {  // Just in case.
       NameBuff[0] = NUL;
     } else if (opp->flags & P_EXPAND) {
-      home_replace(NULL, varp, (char *)NameBuff, MAXPATHL, false);
-      // Translate 'pastetoggle' into special key names.
-    } else if ((char **)opp->var == &p_pt) {
-      str2specialbuf((const char *)p_pt, NameBuff, MAXPATHL);
+      home_replace(NULL, varp, NameBuff, MAXPATHL, false);
     } else {
       xstrlcpy(NameBuff, varp, MAXPATHL);
     }
@@ -4905,10 +5780,10 @@ static void option_value2string(vimoption_T *opp, int scope)
 /// Return true if "varp" points to 'wildchar' or 'wildcharm' and it can be
 /// printed as a keyname.
 /// "*wcp" is set to the value of the option if it's 'wildchar' or 'wildcharm'.
-static int wc_use_keyname(const char_u *varp, long *wcp)
+static int wc_use_keyname(const void *varp, OptInt *wcp)
 {
-  if (((long *)varp == &p_wc) || ((long *)varp == &p_wcm)) {
-    *wcp = *(long *)varp;
+  if (((OptInt *)varp == &p_wc) || ((OptInt *)varp == &p_wcm)) {
+    *wcp = *(OptInt *)varp;
     if (IS_SPECIAL(*wcp) || find_special_key_in_table((int)(*wcp)) >= 0) {
       return true;
     }
@@ -4926,133 +5801,6 @@ bool shortmess(int x)
                   && vim_strchr(SHM_ALL_ABBREVIATIONS, x) != NULL)));
 }
 
-/// paste_option_changed() - Called after p_paste was set or reset.
-static void paste_option_changed(void)
-{
-  static int old_p_paste = false;
-  static int save_sm = 0;
-  static int save_sta = 0;
-  static int save_ru = 0;
-  static int save_ri = 0;
-  static int save_hkmap = 0;
-
-  if (p_paste) {
-    // Paste switched from off to on.
-    // Save the current values, so they can be restored later.
-    if (!old_p_paste) {
-      // save options for each buffer
-      FOR_ALL_BUFFERS(buf) {
-        buf->b_p_tw_nopaste = buf->b_p_tw;
-        buf->b_p_wm_nopaste = buf->b_p_wm;
-        buf->b_p_sts_nopaste = buf->b_p_sts;
-        buf->b_p_ai_nopaste = buf->b_p_ai;
-        buf->b_p_et_nopaste = buf->b_p_et;
-        if (buf->b_p_vsts_nopaste) {
-          xfree(buf->b_p_vsts_nopaste);
-        }
-        buf->b_p_vsts_nopaste = buf->b_p_vsts && buf->b_p_vsts != empty_option
-                                    ? xstrdup(buf->b_p_vsts)
-                                    : NULL;
-      }
-
-      // save global options
-      save_sm = p_sm;
-      save_sta = p_sta;
-      save_ru = p_ru;
-      save_ri = p_ri;
-      save_hkmap = p_hkmap;
-      // save global values for local buffer options
-      p_ai_nopaste = p_ai;
-      p_et_nopaste = p_et;
-      p_sts_nopaste = p_sts;
-      p_tw_nopaste = p_tw;
-      p_wm_nopaste = p_wm;
-      if (p_vsts_nopaste) {
-        xfree(p_vsts_nopaste);
-      }
-      p_vsts_nopaste = p_vsts && p_vsts != empty_option ? xstrdup(p_vsts) : NULL;
-    }
-
-    // Always set the option values, also when 'paste' is set when it is
-    // already on.
-    // set options for each buffer
-    FOR_ALL_BUFFERS(buf) {
-      buf->b_p_tw = 0;              // textwidth is 0
-      buf->b_p_wm = 0;              // wrapmargin is 0
-      buf->b_p_sts = 0;             // softtabstop is 0
-      buf->b_p_ai = 0;              // no auto-indent
-      buf->b_p_et = 0;              // no expandtab
-      if (buf->b_p_vsts) {
-        free_string_option(buf->b_p_vsts);
-      }
-      buf->b_p_vsts = empty_option;
-      XFREE_CLEAR(buf->b_p_vsts_array);
-    }
-
-    // set global options
-    p_sm = 0;                       // no showmatch
-    p_sta = 0;                      // no smarttab
-    if (p_ru) {
-      status_redraw_all();          // redraw to remove the ruler
-    }
-    p_ru = 0;                       // no ruler
-    p_ri = 0;                       // no reverse insert
-    p_hkmap = 0;                    // no Hebrew keyboard
-    // set global values for local buffer options
-    p_tw = 0;
-    p_wm = 0;
-    p_sts = 0;
-    p_ai = 0;
-    if (p_vsts) {
-      free_string_option(p_vsts);
-    }
-    p_vsts = empty_option;
-  } else if (old_p_paste) {
-    // Paste switched from on to off: Restore saved values.
-
-    // restore options for each buffer
-    FOR_ALL_BUFFERS(buf) {
-      buf->b_p_tw = buf->b_p_tw_nopaste;
-      buf->b_p_wm = buf->b_p_wm_nopaste;
-      buf->b_p_sts = buf->b_p_sts_nopaste;
-      buf->b_p_ai = buf->b_p_ai_nopaste;
-      buf->b_p_et = buf->b_p_et_nopaste;
-      if (buf->b_p_vsts) {
-        free_string_option(buf->b_p_vsts);
-      }
-      buf->b_p_vsts = buf->b_p_vsts_nopaste ? xstrdup(buf->b_p_vsts_nopaste) : empty_option;
-      xfree(buf->b_p_vsts_array);
-      if (buf->b_p_vsts && buf->b_p_vsts != empty_option) {
-        (void)tabstop_set(buf->b_p_vsts, &buf->b_p_vsts_array);
-      } else {
-        buf->b_p_vsts_array = NULL;
-      }
-    }
-
-    // restore global options
-    p_sm = save_sm;
-    p_sta = save_sta;
-    if (p_ru != save_ru) {
-      status_redraw_all();          // redraw to draw the ruler
-    }
-    p_ru = save_ru;
-    p_ri = save_ri;
-    p_hkmap = save_hkmap;
-    // set global values for local buffer options
-    p_ai = p_ai_nopaste;
-    p_et = p_et_nopaste;
-    p_sts = p_sts_nopaste;
-    p_tw = p_tw_nopaste;
-    p_wm = p_wm_nopaste;
-    if (p_vsts) {
-      free_string_option(p_vsts);
-    }
-    p_vsts = p_vsts_nopaste ? xstrdup(p_vsts_nopaste) : empty_option;
-  }
-
-  old_p_paste = p_paste;
-}
-
 /// vimrc_found() - Called when a vimrc or "VIMINIT" has been found.
 ///
 /// Set the values for options that didn't get set yet to the defaults.
@@ -5105,25 +5853,11 @@ void reset_option_was_set(const char *name)
   options[idx].flags &= ~P_WAS_SET;
 }
 
-/// fill_breakat_flags() -- called when 'breakat' changes value.
-void fill_breakat_flags(void)
-{
-  for (int i = 0; i < 256; i++) {
-    breakat_flags[i] = false;
-  }
-
-  if (p_breakat != NULL) {
-    for (char_u *p = (char_u *)p_breakat; *p; p++) {
-      breakat_flags[*p] = true;
-    }
-  }
-}
-
 /// fill_culopt_flags() -- called when 'culopt' changes value
 int fill_culopt_flags(char *val, win_T *wp)
 {
   char *p;
-  char_u culopt_flags_new = 0;
+  uint8_t culopt_flags_new = 0;
 
   if (val == NULL) {
     p = wp->w_p_culopt;
@@ -5131,6 +5865,7 @@ int fill_culopt_flags(char *val, win_T *wp)
     p = val;
   }
   while (*p != NUL) {
+    // Note: Keep this in sync with p_culopt_values.
     if (strncmp(p, "line", 4) == 0) {
       p += 4;
       culopt_flags_new |= CULOPT_LINE;
@@ -5191,7 +5926,7 @@ int option_set_callback_func(char *optval, Callback *optcb)
       || (strncmp(optval, "function(", 9) == 0)
       || (strncmp(optval, "funcref(", 8) == 0)) {
     // Lambda expression or a funcref
-    tv = eval_expr(optval);
+    tv = eval_expr(optval, NULL);
     if (tv == NULL) {
       return FAIL;
     }
@@ -5214,6 +5949,20 @@ int option_set_callback_func(char *optval, Callback *optcb)
   return OK;
 }
 
+static void didset_options_sctx(int opt_flags, char **buf)
+{
+  for (int i = 0;; i++) {
+    if (buf[i] == NULL) {
+      break;
+    }
+
+    int idx = findoption(buf[i]);
+    if (idx >= 0) {
+      set_option_sctx_idx(idx, opt_flags, current_sctx);
+    }
+  }
+}
+
 /// Check if backspacing over something is allowed.
 /// @param  what  BS_INDENT, BS_EOL, BS_START, or BS_NOSTOP
 bool can_bs(int what)
@@ -5221,23 +5970,20 @@ bool can_bs(int what)
   if (what == BS_START && bt_prompt(curbuf)) {
     return false;
   }
-  switch (*p_bs) {
-  case '3':
-    return true;
-  case '2':
+
+  // support for number values was removed but we keep '2' since it is used in
+  // legacy tests
+  if (*p_bs == '2') {
     return what != BS_NOSTOP;
-  case '1':
-    return what != BS_START;
-  case '0':
-    return false;
   }
+
   return vim_strchr(p_bs, what) != NULL;
 }
 
 /// Get the local or global value of 'backupcopy'.
 ///
 /// @param buf The buffer.
-unsigned int get_bkc_value(buf_T *buf)
+unsigned get_bkc_value(buf_T *buf)
 {
   return buf->b_bkc_flags ? buf->b_bkc_flags : bkc_flags;
 }
@@ -5254,7 +6000,7 @@ char *get_flp_value(buf_T *buf)
 }
 
 /// Get the local or global value of the 'virtualedit' flags.
-unsigned int get_ve_flags(void)
+unsigned get_ve_flags(void)
 {
   return (curwin->w_ve_flags ? curwin->w_ve_flags : ve_flags) & ~(VE_NONE | VE_NONEU);
 }
@@ -5270,7 +6016,7 @@ char *get_showbreak_value(win_T *const win)
     return p_sbr;
   }
   if (strcmp(win->w_p_sbr, "NONE") == 0) {
-    return empty_option;
+    return empty_string_option;
   }
   return win->w_p_sbr;
 }
@@ -5428,53 +6174,12 @@ bool fish_like_shell(void)
 /// buffer signs and on user configuration.
 int win_signcol_count(win_T *wp)
 {
-  return win_signcol_configured(wp, NULL);
-}
-
-/// Return the number of requested sign columns, based on user / configuration.
-int win_signcol_configured(win_T *wp, int *is_fixed)
-{
-  const char *scl = (const char *)wp->w_p_scl;
-
-  if (is_fixed) {
-    *is_fixed = 1;
-  }
-
-  // Note: It checks "no" or "number" in 'signcolumn' option
-  if (*scl == 'n'
-      && (*(scl + 1) == 'o' || (*(scl + 1) == 'u'
-                                && (wp->w_p_nu || wp->w_p_rnu)))) {
+  if (wp->w_minscwidth <= SCL_NO) {
     return 0;
   }
 
-  // yes or yes
-  if (!strncmp(scl, "yes:", 4)) {
-    // Fixed amount of columns
-    return scl[4] - '0';
-  }
-  if (*scl == 'y') {
-    return 1;
-  }
-
-  if (is_fixed) {
-    // auto or auto:<NUM>
-    *is_fixed = 0;
-  }
-
-  int minimum = 0, maximum = 1;
-
-  if (!strncmp(scl, "auto:", 5)) {
-    // Variable depending on a configuration
-    maximum = scl[5] - '0';
-    // auto:<NUM>-<NUM>
-    if (strlen(scl) == 8 && *(scl + 6) == '-') {
-      minimum = maximum;
-      maximum = scl[7] - '0';
-    }
-  }
-
-  int needed_signcols = buf_signcols(wp->w_buffer, maximum);
-  int ret = MAX(minimum, MIN(maximum, needed_signcols));
+  int needed_signcols = buf_signcols(wp->w_buffer, wp->w_maxscwidth);
+  int ret = MAX(wp->w_minscwidth, MIN(wp->w_maxscwidth, needed_signcols));
   assert(ret <= SIGN_SHOW_MAX);
   return ret;
 }
@@ -5490,7 +6195,7 @@ dict_T *get_winbuf_options(const int bufopt)
 
     if ((bufopt && (opt->indir & PV_BUF))
         || (!bufopt && (opt->indir & PV_WIN))) {
-      char_u *varp = get_varp(opt);
+      void *varp = get_varp(opt);
 
       if (varp != NULL) {
         if (opt->flags & P_STRING) {
@@ -5498,7 +6203,7 @@ dict_T *get_winbuf_options(const int bufopt)
                           *(const char **)varp);
         } else if (opt->flags & P_NUM) {
           tv_dict_add_nr(d, opt->fullname, strlen(opt->fullname),
-                         *(long *)varp);
+                         *(OptInt *)varp);
         } else {
           tv_dict_add_nr(d, opt->fullname, strlen(opt->fullname), *(int *)varp);
         }
@@ -5511,43 +6216,43 @@ dict_T *get_winbuf_options(const int bufopt)
 
 /// Return the effective 'scrolloff' value for the current window, using the
 /// global value when appropriate.
-long get_scrolloff_value(win_T *wp)
+int get_scrolloff_value(win_T *wp)
 {
   // Disallow scrolloff in terminal-mode. #11915
   if (State & MODE_TERMINAL) {
     return 0;
   }
-  return wp->w_p_so < 0 ? p_so : wp->w_p_so;
+  return (int)(wp->w_p_so < 0 ? p_so : wp->w_p_so);
 }
 
 /// Return the effective 'sidescrolloff' value for the current window, using the
 /// global value when appropriate.
-long get_sidescrolloff_value(win_T *wp)
+int get_sidescrolloff_value(win_T *wp)
 {
-  return wp->w_p_siso < 0 ? p_siso : wp->w_p_siso;
+  return (int)(wp->w_p_siso < 0 ? p_siso : wp->w_p_siso);
 }
 
-Dictionary get_vimoption(String name, Error *err)
+Dictionary get_vimoption(String name, int scope, buf_T *buf, win_T *win, Error *err)
 {
-  int opt_idx = findoption_len((const char *)name.data, name.size);
-  if (opt_idx < 0) {
-    api_set_error(err, kErrorTypeValidation, "no such option: '%s'", name.data);
+  int opt_idx = findoption_len(name.data, name.size);
+  VALIDATE_S(opt_idx >= 0, "option (not found)", name.data, {
     return (Dictionary)ARRAY_DICT_INIT;
-  }
-  return vimoption2dict(&options[opt_idx]);
+  });
+
+  return vimoption2dict(&options[opt_idx], scope, buf, win);
 }
 
 Dictionary get_all_vimoptions(void)
 {
   Dictionary retval = ARRAY_DICT_INIT;
   for (size_t i = 0; options[i].fullname != NULL; i++) {
-    Dictionary opt_dict = vimoption2dict(&options[i]);
+    Dictionary opt_dict = vimoption2dict(&options[i], OPT_GLOBAL, curbuf, curwin);
     PUT(retval, options[i].fullname, DICTIONARY_OBJ(opt_dict));
   }
   return retval;
 }
 
-static Dictionary vimoption2dict(vimoption_T *opt)
+static Dictionary vimoption2dict(vimoption_T *opt, int req_scope, buf_T *buf, win_T *win)
 {
   Dictionary dict = ARRAY_DICT_INIT;
 
@@ -5566,35 +6271,51 @@ static Dictionary vimoption2dict(vimoption_T *opt)
   PUT(dict, "scope", CSTR_TO_OBJ(scope));
 
   // welcome to the jungle
-  PUT(dict, "global_local", BOOL(opt->indir & PV_BOTH));
-  PUT(dict, "commalist", BOOL(opt->flags & P_COMMA));
-  PUT(dict, "flaglist", BOOL(opt->flags & P_FLAGLIST));
+  PUT(dict, "global_local", BOOLEAN_OBJ(opt->indir & PV_BOTH));
+  PUT(dict, "commalist", BOOLEAN_OBJ(opt->flags & P_COMMA));
+  PUT(dict, "flaglist", BOOLEAN_OBJ(opt->flags & P_FLAGLIST));
 
-  PUT(dict, "was_set", BOOL(opt->flags & P_WAS_SET));
+  PUT(dict, "was_set", BOOLEAN_OBJ(opt->flags & P_WAS_SET));
+
+  LastSet last_set = { .channel_id = 0 };
+  if (req_scope == OPT_GLOBAL) {
+    last_set = opt->last_set;
+  } else {
+    // Scope is either OPT_LOCAL or a fallback mode was requested.
+    if (opt->indir & PV_BUF) {
+      last_set = buf->b_p_script_ctx[opt->indir & PV_MASK];
+    }
+    if (opt->indir & PV_WIN) {
+      last_set = win->w_p_script_ctx[opt->indir & PV_MASK];
+    }
+    if (req_scope != OPT_LOCAL && last_set.script_ctx.sc_sid == 0) {
+      last_set = opt->last_set;
+    }
+  }
 
-  PUT(dict, "last_set_sid", INTEGER_OBJ(opt->last_set.script_ctx.sc_sid));
-  PUT(dict, "last_set_linenr", INTEGER_OBJ(opt->last_set.script_ctx.sc_lnum));
-  PUT(dict, "last_set_chan", INTEGER_OBJ((int64_t)opt->last_set.channel_id));
+  PUT(dict, "last_set_sid", INTEGER_OBJ(last_set.script_ctx.sc_sid));
+  PUT(dict, "last_set_linenr", INTEGER_OBJ(last_set.script_ctx.sc_lnum));
+  PUT(dict, "last_set_chan", INTEGER_OBJ((int64_t)last_set.channel_id));
 
   const char *type;
   Object def;
   // TODO(bfredl): do you even nocp?
-  char_u *def_val = (char_u *)opt->def_val;
+  char *def_val = opt->def_val;
   if (opt->flags & P_STRING) {
     type = "string";
-    def = CSTR_TO_OBJ(def_val ? (char *)def_val : "");
+    def = CSTR_TO_OBJ(def_val ? def_val : "");
   } else if (opt->flags & P_NUM) {
     type = "number";
     def = INTEGER_OBJ((Integer)(intptr_t)def_val);
   } else if (opt->flags & P_BOOL) {
     type = "boolean";
-    def = BOOL((intptr_t)def_val);
+    def = BOOLEAN_OBJ((intptr_t)def_val);
   } else {
     type = ""; def = NIL;
   }
   PUT(dict, "type", CSTR_TO_OBJ(type));
   PUT(dict, "default", def);
-  PUT(dict, "allows_duplicates", BOOL(!(opt->flags & P_NODUP)));
+  PUT(dict, "allows_duplicates", BOOLEAN_OBJ(!(opt->flags & P_NODUP)));
 
   return dict;
 }