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

1 files changed, 737 insertions, 1040 deletions

diff --git a/src/nvim/option.c b/src/nvim/option.c
index 5c487a7c62..208112561a 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -30,6 +30,7 @@
 #include "nvim/arglist.h"
 #include "nvim/ascii.h"
 #include "nvim/buffer.h"
+#include "nvim/change.h"
 #include "nvim/charset.h"
 #include "nvim/cursor_shape.h"
 #include "nvim/decoration_provider.h"
@@ -38,7 +39,6 @@
 #include "nvim/edit.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
-#include "nvim/ex_cmds2.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_getln.h"
 #include "nvim/ex_session.h"
@@ -52,6 +52,7 @@
 #include "nvim/indent.h"
 #include "nvim/indent_c.h"
 #include "nvim/keycodes.h"
+#include "nvim/locale.h"
 #include "nvim/macros.h"
 #include "nvim/mapping.h"
 #include "nvim/mbyte.h"
@@ -71,6 +72,7 @@
 #include "nvim/popupmenu.h"
 #include "nvim/regexp.h"
 #include "nvim/screen.h"
+#include "nvim/search.h"
 #include "nvim/spell.h"
 #include "nvim/spellfile.h"
 #include "nvim/spellsuggest.h"
@@ -81,7 +83,7 @@
 #include "nvim/undo.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
-#ifdef WIN32
+#ifdef MSWIN
 # include "nvim/os/pty_conpty_win.h"
 #endif
 #include "nvim/api/extmark.h"
@@ -91,33 +93,18 @@
 #include "nvim/os/input.h"
 #include "nvim/os/lang.h"
 
-/*
- * The options that are local to a window or buffer have "indir" set to one of
- * these values.  Special values:
- * PV_NONE: global option.
- * PV_WIN is added: window-local option
- * PV_BUF is added: buffer-local option
- * PV_BOTH is added: global option which also has a local value.
- */
-#define PV_BOTH 0x1000
-#define PV_WIN  0x2000
-#define PV_BUF  0x4000
-#define PV_MASK 0x0fff
-#define OPT_WIN(x)  (idopt_T)(PV_WIN + (int)(x))
-#define OPT_BUF(x)  (idopt_T)(PV_BUF + (int)(x))
-#define OPT_BOTH(x) (idopt_T)(PV_BOTH + (int)(x))
-
-// WV_ and BV_ values get typecasted to this for the "indir" field
-typedef enum {
-  PV_NONE = 0,
-  PV_MAXVAL = 0xffff,  // to avoid warnings for value out of range
-} idopt_T;
-
-/*
- * Options local to a window have a value local to a buffer and global to all
- * buffers.  Indicate this by setting "var" to VAR_WIN.
- */
-#define VAR_WIN ((char_u *)-1)
+static char e_unknown_option[]
+  = N_("E518: Unknown option");
+static char e_not_allowed_in_modeline[]
+  = N_("E520: Not allowed in a modeline");
+static 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[]
+  = N_("E846: Key code not set");
+static char e_number_required_after_equal[]
+  = N_("E521: Number required after =");
+static char e_preview_window_already_exists[]
+  = N_("E590: A preview window already exists");
 
 static char *p_term = NULL;
 static char *p_ttytype = NULL;
@@ -134,29 +121,14 @@ static int p_et_nopaste;
 static long p_sts_nopaste;
 static long p_tw_nopaste;
 static long p_wm_nopaste;
-static char_u *p_vsts_nopaste;
-
-typedef struct vimoption {
-  char *fullname;        // full option name
-  char *shortname;       // permissible abbreviation
-  uint32_t flags;               // see below
-  char_u *var;             // global option: pointer to variable;
-                           // window-local option: VAR_WIN;
-                           // buffer-local option: global value
-  idopt_T indir;                // global option: PV_NONE;
-                                // local option: indirect option index
-  char_u *def_val;         // default values for variable (neovim!!)
-  LastSet last_set;             // script in which the option was last set
-} vimoption_T;
-
-/*
- * 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()).
- * Exception: "t_" options are at the end.
- * The options with a NULL variable are 'hidden': a set command for them is
- * ignored and they are not printed.
- */
+static char *p_vsts_nopaste;
+
+// 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()).
+// Exception: "t_" options are at the end.
+// The options with a NULL variable are 'hidden': a set command for them is
+// ignored and they are not printed.
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "options.generated.h"
@@ -164,10 +136,24 @@ typedef struct vimoption {
 
 #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
 
+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;
+}
+
 /// Initialize the options, first part.
 ///
 /// Called only once from main(), just after creating the first buffer.
@@ -182,10 +168,8 @@ void set_init_1(bool clean_arg)
 
   langmap_init();
 
-  /*
-   * Find default value for 'shell' option.
-   * Don't use it if it is empty.
-   */
+  // Find default value for 'shell' option.
+  // Don't use it if it is empty.
   {
     const char *shell = os_getenv("SHELL");
     if (shell != NULL) {
@@ -200,10 +184,8 @@ void set_init_1(bool clean_arg)
     }
   }
 
-  /*
-   * Set the default for 'backupskip' to include environment variables for
-   * temp files.
-   */
+  // Set the default for 'backupskip' to include environment variables for
+  // temp files.
   {
 #ifdef UNIX
     static char *(names[4]) = { "", "TMPDIR", "TEMP", "TMP" };
@@ -285,7 +267,7 @@ void set_init_1(bool clean_arg)
         buf[j] = NUL;
         opt_idx = findoption("cdpath");
         if (opt_idx >= 0) {
-          options[opt_idx].def_val = buf;
+          options[opt_idx].def_val = (char *)buf;
           options[opt_idx].flags |= P_DEF_ALLOCED;
         } else {
           xfree(buf);           // cannot happen
@@ -339,10 +321,8 @@ void set_init_1(bool clean_arg)
     rtp = NULL;  // ownership taken
   }
 
-  /*
-   * Set all the options (except the terminal options) to their default
-   * value.  Also set the global value for local options.
-   */
+  // Set all the options (except the terminal options) to their default
+  // value.  Also set the global value for local options.
   set_options_default(0);
 
   curbuf->b_p_initialized = true;
@@ -365,15 +345,13 @@ void set_init_1(bool clean_arg)
   // didset_options() because it only depends on 'encoding'.
   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.
-   */
+  // 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 (opt_idx = 0; options[opt_idx].fullname; opt_idx++) {
     if (options[opt_idx].flags & P_NO_DEF_EXP) {
       continue;
@@ -383,7 +361,7 @@ void set_init_1(bool clean_arg)
         && options[opt_idx].var != NULL) {
       p = _(*(char **)options[opt_idx].var);
     } else {
-      p = (char *)option_expand(opt_idx, NULL);
+      p = option_expand(opt_idx, NULL);
     }
     if (p != NULL) {
       p = xstrdup(p);
@@ -391,7 +369,7 @@ void set_init_1(bool clean_arg)
       if (options[opt_idx].flags & P_DEF_ALLOCED) {
         xfree(options[opt_idx].def_val);
       }
-      options[opt_idx].def_val = (char_u *)p;
+      options[opt_idx].def_val = p;
       options[opt_idx].flags |= P_DEF_ALLOCED;
     }
   }
@@ -404,7 +382,7 @@ 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("tbidi", 1L, NULL, 0);
+    set_option_value_give_err("tbidi", 1L, NULL, 0);
   }
 
   didset_options2();
@@ -419,12 +397,12 @@ void set_init_1(bool clean_arg)
     // use utf-8 as 'default' if locale encoding can't be detected.
     p = (char_u *)xmemdupz(S_LEN("utf-8"));
   }
-  fenc_default = p;
+  fenc_default = (char *)p;
 
 #ifdef HAVE_WORKING_LIBINTL
   // GNU gettext 0.10.37 supports this feature: set the codeset used for
   // translated messages independently from the current locale.
-  (void)bind_textdomain_codeset(PROJECT_NAME, (char *)p_enc);
+  (void)bind_textdomain_codeset(PROJECT_NAME, p_enc);
 #endif
 
   // Set the default for 'helplang'.
@@ -440,7 +418,7 @@ static void set_option_default(int opt_idx, int opt_flags)
   char_u *varp;            // pointer to variable for current option
   int both = (opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0;
 
-  varp = get_varp_scope(&(options[opt_idx]), both ? OPT_LOCAL : opt_flags);
+  varp = (char_u *)get_varp_scope(&(options[opt_idx]), both ? OPT_LOCAL : opt_flags);
   uint32_t flags = options[opt_idx].flags;
   if (varp != NULL) {       // skip hidden option, nothing to do for it
     if (flags & P_STRING) {
@@ -448,12 +426,12 @@ static void set_option_default(int opt_idx, int opt_flags)
       // freeing and allocating the value.
       if (options[opt_idx].indir != PV_NONE) {
         set_string_option_direct(NULL, opt_idx,
-                                 (char *)options[opt_idx].def_val, opt_flags, 0);
+                                 options[opt_idx].def_val, opt_flags, 0);
       } else {
         if ((opt_flags & OPT_FREE) && (flags & P_ALLOCED)) {
-          free_string_option(*(char_u **)(varp));
+          free_string_option(*(char **)(varp));
         }
-        *(char_u **)varp = options[opt_idx].def_val;
+        *(char **)varp = options[opt_idx].def_val;
         options[opt_idx].flags &= ~P_ALLOCED;
       }
     } else if (flags & P_NUM) {
@@ -532,9 +510,7 @@ static void set_string_default(const char *name, char *val, bool allocated)
       xfree(options[opt_idx].def_val);
     }
 
-    options[opt_idx].def_val = allocated
-        ? (char_u *)val
-        : (char_u *)xstrdup(val);
+    options[opt_idx].def_val = allocated ? val : xstrdup(val);
     options[opt_idx].flags |= P_DEF_ALLOCED;
   }
 }
@@ -578,7 +554,7 @@ void set_number_default(char *name, long val)
 
   opt_idx = findoption(name);
   if (opt_idx >= 0) {
-    options[opt_idx].def_val = (char_u *)(intptr_t)val;
+    options[opt_idx].def_val = (char *)(intptr_t)val;
   }
 }
 
@@ -590,14 +566,14 @@ 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_u **)options[i].var);
+        free_string_option(*(char **)options[i].var);
       }
       if (options[i].flags & P_DEF_ALLOCED) {
         free_string_option(options[i].def_val);
       }
     } else if (options[i].var != VAR_WIN && (options[i].flags & P_STRING)) {
       // buffer-local option: free global value
-      clear_string_option((char_u **)options[i].var);
+      clear_string_option((char **)options[i].var);
     }
   }
   free_operatorfunc_option();
@@ -620,10 +596,8 @@ void set_init_2(bool headless)
   }
   comp_col();
 
-  /*
-   * 'window' is only for backwards compatibility with Vi.
-   * Default is Rows - 1.
-   */
+  // 'window' is only for backwards compatibility with Vi.
+  // Default is Rows - 1.
   if (!option_was_set("window")) {
     p_window = Rows - 1;
   }
@@ -649,41 +623,41 @@ void set_init_3(void)
     : !(options[idx_sp].flags & P_WAS_SET);
 
   size_t len = 0;
-  char_u *p = (char_u *)invocation_path_tail(p_sh, &len);
-  p = vim_strnsave(p, len);
+  char *p = (char *)invocation_path_tail((char_u *)p_sh, &len);
+  p = xstrnsave(p, len);
 
   {
     //
     // Default for p_sp is "| tee", for p_srr is ">".
     // For known shells it is changed here to include stderr.
     //
-    if (FNAMECMP(p, "csh") == 0
-        || FNAMECMP(p, "tcsh") == 0) {
+    if (path_fnamecmp(p, "csh") == 0
+        || path_fnamecmp(p, "tcsh") == 0) {
       if (do_sp) {
-        p_sp = (char_u *)"|& tee";
+        p_sp = "|& tee";
         options[idx_sp].def_val = p_sp;
       }
       if (do_srr) {
-        p_srr = (char_u *)">&";
+        p_srr = ">&";
         options[idx_srr].def_val = p_srr;
       }
-    } else if (FNAMECMP(p, "sh") == 0
-               || FNAMECMP(p, "ksh") == 0
-               || FNAMECMP(p, "mksh") == 0
-               || FNAMECMP(p, "pdksh") == 0
-               || FNAMECMP(p, "zsh") == 0
-               || FNAMECMP(p, "zsh-beta") == 0
-               || FNAMECMP(p, "bash") == 0
-               || FNAMECMP(p, "fish") == 0
-               || FNAMECMP(p, "ash") == 0
-               || FNAMECMP(p, "dash") == 0) {
+    } else if (path_fnamecmp(p, "sh") == 0
+               || path_fnamecmp(p, "ksh") == 0
+               || path_fnamecmp(p, "mksh") == 0
+               || path_fnamecmp(p, "pdksh") == 0
+               || path_fnamecmp(p, "zsh") == 0
+               || path_fnamecmp(p, "zsh-beta") == 0
+               || path_fnamecmp(p, "bash") == 0
+               || path_fnamecmp(p, "fish") == 0
+               || path_fnamecmp(p, "ash") == 0
+               || path_fnamecmp(p, "dash") == 0) {
       // Always use POSIX shell style redirection if we reach this
       if (do_sp) {
-        p_sp = (char_u *)"2>&1| tee";
+        p_sp = "2>&1| tee";
         options[idx_sp].def_val = p_sp;
       }
       if (do_srr) {
-        p_srr = (char_u *)">%s 2>&1";
+        p_srr = ">%s 2>&1";
         options[idx_srr].def_val = p_srr;
       }
     }
@@ -717,7 +691,7 @@ void set_helplang_default(const char *lang)
   int idx = findoption("hlg");
   if (idx >= 0 && !(options[idx].flags & P_WAS_SET)) {
     if (options[idx].flags & P_ALLOCED) {
-      free_string_option(p_hlg);
+      free_string_option((char *)p_hlg);
     }
     p_hlg = (char_u *)xmemdupz(lang, lang_len);
     // zh_CN becomes "cn", zh_TW becomes "tw".
@@ -743,19 +717,17 @@ void set_title_defaults(void)
 {
   int idx1;
 
-  /*
-   * If GUI is (going to be) used, we can always set the window title and
-   * icon name.  Saves a bit of time, because the X11 display server does
-   * not need to be contacted.
-   */
+  // If GUI is (going to be) used, we can always set the window title and
+  // icon name.  Saves a bit of time, because the X11 display server does
+  // not need to be contacted.
   idx1 = findoption("title");
   if (idx1 >= 0 && !(options[idx1].flags & P_WAS_SET)) {
-    options[idx1].def_val = (char_u *)(intptr_t)0;
+    options[idx1].def_val = 0;
     p_title = 0;
   }
   idx1 = findoption("icon");
   if (idx1 >= 0 && !(options[idx1].flags & P_WAS_SET)) {
-    options[idx1].def_val = (char_u *)(intptr_t)0;
+    options[idx1].def_val = 0;
     p_icon = 0;
   }
 }
@@ -775,6 +747,349 @@ 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)
+{
+  char *arg = *argp;
+  set_op_T op = op_arg;
+  char *varp = varp_arg;
+  char *save_arg = NULL;
+  char *s = NULL;
+  char_u *oldval = NULL;  // previous value if *varp
+  char *newval;
+  char_u *origval = NULL;
+  char_u *origval_l = NULL;
+  char_u *origval_g = NULL;
+  char *saved_origval = NULL;
+  char *saved_origval_l = NULL;
+  char *saved_origval_g = NULL;
+  char *saved_newval = NULL;
+  unsigned newlen;
+  int comma;
+  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;
+  }
+
+  // The old value is kept until we are sure that the new value is valid.
+  oldval = *(char_u **)varp;
+
+  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);
+
+    // 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;
+    }
+  }
+
+  // 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_u **)get_varp(&options[opt_idx]);
+  } else {
+    origval = oldval;
+  }
+
+  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;
+      }
+      newval = xstrdup(s);
+    } else {
+      newval = xstrdup(newval);
+    }
+  } else if (nextchar == '<') {  // set to global val
+    newval = xstrdup(*(char **)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL));
+  } else {
+    arg++;  // jump to after the '=' or ':'
+
+    // Set 'keywordprg' to ":help" if an empty
+    // value was passed to :set by the user.
+    if (varp == (char *)&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_u **)varp;
+      }
+      if (origval_l == oldval) {
+        origval_l = *(char_u **)varp;
+      }
+      if (origval_g == oldval) {
+        origval_g = *(char_u **)varp;
+      }
+      oldval = *(char_u **)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
+    newlen = (unsigned)strlen(arg) + 1;
+    if (op != OP_NONE) {
+      newlen += (unsigned)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(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;
+
+    // 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);
+      }
+    }
+
+    // locate newval[] in origval[] when removing it
+    // and when adding to avoid duplicates
+    int len = 0;
+    if (op == OP_REMOVING || (flags & P_NODUP)) {
+      len = (int)STRLEN(newval);
+      s = (char *)find_dup_item(origval, (char_u *)newval, flags);
+
+      // do not add if already there
+      if ((op == OP_ADDING || op == OP_PREPENDING) && s != NULL) {
+        op = OP_NONE;
+        STRCPY(newval, origval);
+      }
+
+      // if no duplicate, move pointer to end of original value
+      if (s == NULL) {
+        s = (char *)origval + (int)STRLEN(origval);
+      }
+    }
+
+    // concatenate the two strings; add a ',' if needed
+    if (op == OP_ADDING || op == OP_PREPENDING) {
+      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);
+      }
+      if (comma) {
+        newval[len] = ',';
+      }
+    }
+
+    // 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 == (char *)origval) {
+            // include comma after string
+            if (s[len] == ',') {
+              len++;
+            }
+          } else {
+            // include comma before string
+            s--;
+            len++;
+          }
+        }
+        STRMOVE(newval + (s - (char *)origval), s + len);
+      }
+    }
+
+    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, *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, *s) != NULL) {
+            STRMOVE(s, s + 1);
+            continue;
+          }
+        }
+        s++;
+      }
+    }
+
+    if (save_arg != NULL) {
+      arg = save_arg;  // arg was temporarily changed, restore it
+    }
+  }
+
+  // Set the new value.
+  *(char_u **)(varp) = (char_u *)newval;
+
+  // origval may be freed by did_set_string_option(), make a copy.
+  saved_origval = (origval != NULL) ? xstrdup((char *)origval) : NULL;
+  saved_origval_l = (origval_l != NULL) ? xstrdup((char *)origval_l) : NULL;
+  saved_origval_g = (origval_g != NULL) ? xstrdup((char *)origval_g) : NULL;
+
+  // newval (and varp) may become invalid if the buffer is closed by
+  // autocommands.
+  saved_newval = (newval != NULL) ? xstrdup(newval) : NULL;
+
+  {
+    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
+        || (op != OP_NONE && (*p & P_INSECURE))) {
+      secure = 1;
+    }
+
+    // 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, (char *)oldval,
+                                    errbuf, errbuflen,
+                                    opt_flags, value_checked);
+
+    secure = secure_saved;
+  }
+
+  if (*errmsg == NULL) {
+    if (!starting) {
+      trigger_optionsset_string(opt_idx, opt_flags, saved_origval, saved_origval_l,
+                                saved_origval_g, saved_newval);
+    }
+    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)));
+    }
+  }
+  xfree(saved_origval);
+  xfree(saved_origval_l);
+  xfree(saved_origval_g);
+  xfree(saved_newval);
+
+  *argp = arg;
+  return *errmsg == NULL ? OK : FAIL;
+}
+
 /// Parse 'arg' for option settings.
 ///
 /// 'arg' may be IObuff, but only when no errors can be present and option
@@ -795,7 +1110,7 @@ int do_set(char *arg, int opt_flags)
   int opt_idx;
   char *errmsg;
   char errbuf[80];
-  char_u *startarg;
+  char *startarg;
   int prefix;           // 1: nothing, 0: "no", 2: "inv" in front of name
   char_u nextchar;                  // next non-white char after option name
   int afterchar;                    // character just after option name
@@ -806,9 +1121,7 @@ int do_set(char *arg, int opt_flags)
   uint32_t flags;                   // flags for current option
   char *varp = NULL;                // pointer to variable for current option
   int did_show = false;             // already showed one value
-  int adding;                       // "opt+=arg"
-  int prepending;                   // "opt^=arg"
-  int removing;                     // "opt-=arg"
+  set_op_T op = 0;
 
   if (*arg == NUL) {
     showoptions(0, opt_flags);
@@ -818,14 +1131,12 @@ int do_set(char *arg, int opt_flags)
 
   while (*arg != NUL) {         // loop to process all options
     errmsg = NULL;
-    startarg = (char_u *)arg;             // remember for error message
+    startarg = arg;             // remember for error message
 
     if (STRNCMP(arg, "all", 3) == 0 && !isalpha(arg[3])
         && !(opt_flags & OPT_MODELINE)) {
-      /*
-       * ":set all"  show all options.
-       * ":set all&" set all options to their default value.
-       */
+      // ":set all"  show all options.
+      // ":set all&" set all options to their default value.
       arg += 3;
       if (*arg == '&') {
         arg++;
@@ -834,7 +1145,7 @@ int do_set(char *arg, int opt_flags)
         didset_options();
         didset_options2();
         ui_refresh_options();
-        redraw_all_later(CLEAR);
+        redraw_all_later(UPD_CLEAR);
       } else {
         showoptions(1, opt_flags);
         did_show = true;
@@ -897,25 +1208,23 @@ int do_set(char *arg, int opt_flags)
         len++;
       }
 
-      adding = false;
-      prepending = false;
-      removing = false;
+      op = OP_NONE;
       if (arg[len] != NUL && arg[len + 1] == '=') {
         if (arg[len] == '+') {
-          adding = true;                        // "+="
+          op = OP_ADDING;                       // "+="
           len++;
         } else if (arg[len] == '^') {
-          prepending = true;                    // "^="
+          op = OP_PREPENDING;                   // "^="
           len++;
         } else if (arg[len] == '-') {
-          removing = true;                      // "-="
+          op = OP_REMOVING;                     // "-="
           len++;
         }
       }
       nextchar = (uint8_t)arg[len];
 
       if (opt_idx == -1 && key == 0) {          // found a mismatch: skip
-        errmsg = N_("E518: Unknown option");
+        errmsg = e_unknown_option;
         goto skip;
       }
 
@@ -926,13 +1235,13 @@ int do_set(char *arg, int opt_flags)
           if (vim_strchr("=:!&<", nextchar) == NULL
               && (!(options[opt_idx].flags & P_BOOL)
                   || nextchar == '?')) {
-            errmsg = _(e_unsupportedoption);
+            errmsg = e_unsupportedoption;
           }
           goto skip;
         }
 
         flags = options[opt_idx].flags;
-        varp = (char *)get_varp_scope(&(options[opt_idx]), opt_flags);
+        varp = get_varp_scope(&(options[opt_idx]), opt_flags);
       } else {
         flags = P_STRING;
       }
@@ -953,11 +1262,11 @@ int do_set(char *arg, int opt_flags)
       // Disallow changing some options from modelines.
       if (opt_flags & OPT_MODELINE) {
         if (flags & (P_SECURE | P_NO_ML)) {
-          errmsg = N_("E520: Not allowed in a modeline");
+          errmsg = e_not_allowed_in_modeline;
           goto skip;
         }
         if ((flags & P_MLE) && !p_mle) {
-          errmsg = N_("E992: Not allowed in a modeline when 'modelineexpr' is off");
+          errmsg = e_not_allowed_in_modeline_when_modelineexpr_is_off;
           goto skip;
         }
         // In diff mode some options are overruled.  This avoids that
@@ -1001,9 +1310,7 @@ int do_set(char *arg, int opt_flags)
           || (prefix == 1
               && vim_strchr("=:&<", nextchar) == NULL
               && !(flags & P_BOOL))) {
-        /*
-         * print value
-         */
+        // print value
         if (did_show) {
           msg_putchar('\n');                // cursor below last one
         } else {
@@ -1025,7 +1332,7 @@ int do_set(char *arg, int opt_flags)
             }
           }
         } else {
-          errmsg = N_("E846: Key code not set");
+          errmsg = e_key_code_not_set;
           goto skip;
         }
         if (nextchar != '?'
@@ -1033,7 +1340,6 @@ int do_set(char *arg, int opt_flags)
           errmsg = e_trailing;
         }
       } else {
-        int value_is_replaced = !prepending && !adding && !removing;
         int value_checked = false;
 
         if (flags & P_BOOL) {                       // boolean
@@ -1042,11 +1348,9 @@ int do_set(char *arg, int opt_flags)
             goto skip;
           }
 
-          /*
-           * ":set opt!": invert
-           * ":set opt&": reset to default value
-           * ":set opt<": reset to global value
-           */
+          // ":set opt!": invert
+          // ":set opt&": reset to default value
+          // ":set opt<": reset to global value
           if (nextchar == '!') {
             value = *(int *)(varp) ^ 1;
           } else if (nextchar == '&') {
@@ -1061,10 +1365,8 @@ int do_set(char *arg, int opt_flags)
                                              OPT_GLOBAL);
             }
           } else {
-            /*
-             * ":set invopt": invert
-             * ":set opt" or ":set noopt": set or reset
-             */
+            // ":set invopt": invert
+            // ":set opt" or ":set noopt": set or reset
             if (nextchar != NUL && !ascii_iswhite(afterchar)) {
               errmsg = e_trailing;
               goto skip;
@@ -1116,383 +1418,36 @@ int do_set(char *arg, int opt_flags)
               }
             } else if (*arg == '-' || ascii_isdigit(*arg)) {
               // Allow negative, octal and hex numbers.
-              vim_str2nr((char_u *)arg, NULL, &i, STR2NR_ALL, &value, NULL, 0, true);
+              vim_str2nr(arg, NULL, &i, STR2NR_ALL, &value, NULL, 0, true);
               if (i == 0 || (arg[i] != NUL && !ascii_iswhite(arg[i]))) {
-                errmsg = N_("E521: Number required after =");
+                errmsg = e_number_required_after_equal;
                 goto skip;
               }
             } else {
-              errmsg = N_("E521: Number required after =");
+              errmsg = e_number_required_after_equal;
               goto skip;
             }
 
-            if (adding) {
+            if (op == OP_ADDING) {
               value = *(long *)varp + value;
             }
-            if (prepending) {
+            if (op == OP_PREPENDING) {
               value = *(long *)varp * value;
             }
-            if (removing) {
+            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.
-            char_u *save_arg = NULL;
-            char_u *s = NULL;
-            char_u *oldval = NULL;         // previous value if *varp
-            char_u *newval;
-            char_u *origval = NULL;
-            char_u *origval_l = NULL;
-            char_u *origval_g = NULL;
-            char *saved_origval = NULL;
-            char *saved_origval_l = NULL;
-            char *saved_origval_g = NULL;
-            char *saved_newval = NULL;
-            unsigned newlen;
-            int comma;
-
-            // When using ":set opt=val" for a global option
-            // with a local value the local value will be
-