vim-patch:8.1.1542: an OptionSet autocommand does not get enough info

Problem:    An OptionSet autocommand does not get enough info.
Solution:   Add v:option_command, v:option_oldlocal and v:option_oldglobal.
            (Latrice Wilgus, closes vim/vim#4118)
https://github.com/vim/vim/commit/d7c968794710f338d491072171df48f96612cf72

4 files changed, 732 insertions, 146 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index d3d0121632..a09ad7924d 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -134,13 +134,15 @@ typedef struct {
     .vv_flags = flags, \
   }
 
+#define VIMVAR_KEY_LEN 16  // Maximum length of the key of v:variables
+
 // Array to hold the value of v: variables.
 // The value is in a dictitem, so that it can also be used in the v: scope.
 // The reason to use this table anyway is for very quick access to the
 // variables with the VV_ defines.
 static struct vimvar {
   char *vv_name;  ///< Name of the variable, without v:.
-  TV_DICTITEM_STRUCT(17) vv_di;  ///< Value and name for key (max 16 chars).
+  TV_DICTITEM_STRUCT(VIMVAR_KEY_LEN + 1) vv_di;  ///< Value and name for key (max 16 chars).
   char vv_flags;  ///< Flags: #VV_COMPAT, #VV_RO, #VV_RO_SBX.
 } vimvars[] =
 {
@@ -150,100 +152,103 @@ static struct vimvar {
   // VV_SEND_SERVER "servername"
   // VV_REG "register"
   // VV_OP "operator"
-  VV(VV_COUNT,          "count",            VAR_NUMBER, VV_RO),
-  VV(VV_COUNT1,         "count1",           VAR_NUMBER, VV_RO),
-  VV(VV_PREVCOUNT,      "prevcount",        VAR_NUMBER, VV_RO),
-  VV(VV_ERRMSG,         "errmsg",           VAR_STRING, 0),
-  VV(VV_WARNINGMSG,     "warningmsg",       VAR_STRING, 0),
-  VV(VV_STATUSMSG,      "statusmsg",        VAR_STRING, 0),
-  VV(VV_SHELL_ERROR,    "shell_error",      VAR_NUMBER, VV_RO),
-  VV(VV_THIS_SESSION,   "this_session",     VAR_STRING, 0),
-  VV(VV_VERSION,        "version",          VAR_NUMBER, VV_COMPAT+VV_RO),
-  VV(VV_LNUM,           "lnum",             VAR_NUMBER, VV_RO_SBX),
-  VV(VV_TERMRESPONSE,   "termresponse",     VAR_STRING, VV_RO),
-  VV(VV_FNAME,          "fname",            VAR_STRING, VV_RO),
-  VV(VV_LANG,           "lang",             VAR_STRING, VV_RO),
-  VV(VV_LC_TIME,        "lc_time",          VAR_STRING, VV_RO),
-  VV(VV_CTYPE,          "ctype",            VAR_STRING, VV_RO),
-  VV(VV_CC_FROM,        "charconvert_from", VAR_STRING, VV_RO),
-  VV(VV_CC_TO,          "charconvert_to",   VAR_STRING, VV_RO),
-  VV(VV_FNAME_IN,       "fname_in",         VAR_STRING, VV_RO),
-  VV(VV_FNAME_OUT,      "fname_out",        VAR_STRING, VV_RO),
-  VV(VV_FNAME_NEW,      "fname_new",        VAR_STRING, VV_RO),
-  VV(VV_FNAME_DIFF,     "fname_diff",       VAR_STRING, VV_RO),
-  VV(VV_CMDARG,         "cmdarg",           VAR_STRING, VV_RO),
-  VV(VV_FOLDSTART,      "foldstart",        VAR_NUMBER, VV_RO_SBX),
-  VV(VV_FOLDEND,        "foldend",          VAR_NUMBER, VV_RO_SBX),
-  VV(VV_FOLDDASHES,     "folddashes",       VAR_STRING, VV_RO_SBX),
-  VV(VV_FOLDLEVEL,      "foldlevel",        VAR_NUMBER, VV_RO_SBX),
-  VV(VV_PROGNAME,       "progname",         VAR_STRING, VV_RO),
-  VV(VV_SEND_SERVER,    "servername",       VAR_STRING, VV_RO),
-  VV(VV_DYING,          "dying",            VAR_NUMBER, VV_RO),
-  VV(VV_EXCEPTION,      "exception",        VAR_STRING, VV_RO),
-  VV(VV_THROWPOINT,     "throwpoint",       VAR_STRING, VV_RO),
-  VV(VV_REG,            "register",         VAR_STRING, VV_RO),
-  VV(VV_CMDBANG,        "cmdbang",          VAR_NUMBER, VV_RO),
-  VV(VV_INSERTMODE,     "insertmode",       VAR_STRING, VV_RO),
-  VV(VV_VAL,            "val",              VAR_UNKNOWN, VV_RO),
-  VV(VV_KEY,            "key",              VAR_UNKNOWN, VV_RO),
-  VV(VV_PROFILING,      "profiling",        VAR_NUMBER, VV_RO),
-  VV(VV_FCS_REASON,     "fcs_reason",       VAR_STRING, VV_RO),
-  VV(VV_FCS_CHOICE,     "fcs_choice",       VAR_STRING, 0),
-  VV(VV_BEVAL_BUFNR,    "beval_bufnr",      VAR_NUMBER, VV_RO),
-  VV(VV_BEVAL_WINNR,    "beval_winnr",      VAR_NUMBER, VV_RO),
-  VV(VV_BEVAL_WINID,    "beval_winid",      VAR_NUMBER, VV_RO),
-  VV(VV_BEVAL_LNUM,     "beval_lnum",       VAR_NUMBER, VV_RO),
-  VV(VV_BEVAL_COL,      "beval_col",        VAR_NUMBER, VV_RO),
-  VV(VV_BEVAL_TEXT,     "beval_text",       VAR_STRING, VV_RO),
-  VV(VV_SCROLLSTART,    "scrollstart",      VAR_STRING, 0),
-  VV(VV_SWAPNAME,       "swapname",         VAR_STRING, VV_RO),
-  VV(VV_SWAPCHOICE,     "swapchoice",       VAR_STRING, 0),
-  VV(VV_SWAPCOMMAND,    "swapcommand",      VAR_STRING, VV_RO),
-  VV(VV_CHAR,           "char",             VAR_STRING, 0),
-  VV(VV_MOUSE_WIN,      "mouse_win",        VAR_NUMBER, 0),
-  VV(VV_MOUSE_WINID,    "mouse_winid",      VAR_NUMBER, 0),
-  VV(VV_MOUSE_LNUM,     "mouse_lnum",       VAR_NUMBER, 0),
-  VV(VV_MOUSE_COL,      "mouse_col",        VAR_NUMBER, 0),
-  VV(VV_OP,             "operator",         VAR_STRING, VV_RO),
-  VV(VV_SEARCHFORWARD,  "searchforward",    VAR_NUMBER, 0),
-  VV(VV_HLSEARCH,       "hlsearch",         VAR_NUMBER, 0),
-  VV(VV_OLDFILES,       "oldfiles",         VAR_LIST, 0),
-  VV(VV_WINDOWID,       "windowid",         VAR_NUMBER, VV_RO_SBX),
-  VV(VV_PROGPATH,       "progpath",         VAR_STRING, VV_RO),
-  VV(VV_COMPLETED_ITEM, "completed_item",   VAR_DICT, VV_RO),
-  VV(VV_OPTION_NEW,     "option_new",       VAR_STRING, VV_RO),
-  VV(VV_OPTION_OLD,     "option_old",       VAR_STRING, VV_RO),
-  VV(VV_OPTION_TYPE,    "option_type",      VAR_STRING, VV_RO),
-  VV(VV_ERRORS,         "errors",           VAR_LIST, 0),
-  VV(VV_FALSE,          "false",            VAR_BOOL, VV_RO),
-  VV(VV_TRUE,           "true",             VAR_BOOL, VV_RO),
-  VV(VV_NULL,           "null",             VAR_SPECIAL, VV_RO),
-  VV(VV_NUMBERMAX,      "numbermax",        VAR_NUMBER, VV_RO),
-  VV(VV_NUMBERMIN,      "numbermin",        VAR_NUMBER, VV_RO),
-  VV(VV_NUMBERSIZE,     "numbersize",       VAR_NUMBER, VV_RO),
-  VV(VV_VIM_DID_ENTER,  "vim_did_enter",    VAR_NUMBER, VV_RO),
-  VV(VV_TESTING,        "testing",          VAR_NUMBER, 0),
-  VV(VV_TYPE_NUMBER,    "t_number",         VAR_NUMBER, VV_RO),
-  VV(VV_TYPE_STRING,    "t_string",         VAR_NUMBER, VV_RO),
-  VV(VV_TYPE_FUNC,      "t_func",           VAR_NUMBER, VV_RO),
-  VV(VV_TYPE_LIST,      "t_list",           VAR_NUMBER, VV_RO),
-  VV(VV_TYPE_DICT,      "t_dict",           VAR_NUMBER, VV_RO),
-  VV(VV_TYPE_FLOAT,     "t_float",          VAR_NUMBER, VV_RO),
-  VV(VV_TYPE_BOOL,      "t_bool",           VAR_NUMBER, VV_RO),
-  VV(VV_TYPE_BLOB,      "t_blob",           VAR_NUMBER, VV_RO),
-  VV(VV_EVENT,          "event",            VAR_DICT, VV_RO),
-  VV(VV_ECHOSPACE,      "echospace",        VAR_NUMBER, VV_RO),
-  VV(VV_ARGV,           "argv",             VAR_LIST, VV_RO),
-  VV(VV_COLLATE,        "collate",          VAR_STRING, VV_RO),
-  VV(VV_EXITING,        "exiting",          VAR_NUMBER, VV_RO),
+  VV(VV_COUNT,            "count",            VAR_NUMBER, VV_RO),
+  VV(VV_COUNT1,           "count1",           VAR_NUMBER, VV_RO),
+  VV(VV_PREVCOUNT,        "prevcount",        VAR_NUMBER, VV_RO),
+  VV(VV_ERRMSG,           "errmsg",           VAR_STRING, 0),
+  VV(VV_WARNINGMSG,       "warningmsg",       VAR_STRING, 0),
+  VV(VV_STATUSMSG,        "statusmsg",        VAR_STRING, 0),
+  VV(VV_SHELL_ERROR,      "shell_error",      VAR_NUMBER, VV_RO),
+  VV(VV_THIS_SESSION,     "this_session",     VAR_STRING, 0),
+  VV(VV_VERSION,          "version",          VAR_NUMBER, VV_COMPAT+VV_RO),
+  VV(VV_LNUM,             "lnum",             VAR_NUMBER, VV_RO_SBX),
+  VV(VV_TERMRESPONSE,     "termresponse",     VAR_STRING, VV_RO),
+  VV(VV_FNAME,            "fname",            VAR_STRING, VV_RO),
+  VV(VV_LANG,             "lang",             VAR_STRING, VV_RO),
+  VV(VV_LC_TIME,          "lc_time",          VAR_STRING, VV_RO),
+  VV(VV_CTYPE,            "ctype",            VAR_STRING, VV_RO),
+  VV(VV_CC_FROM,          "charconvert_from", VAR_STRING, VV_RO),
+  VV(VV_CC_TO,            "charconvert_to",   VAR_STRING, VV_RO),
+  VV(VV_FNAME_IN,         "fname_in",         VAR_STRING, VV_RO),
+  VV(VV_FNAME_OUT,        "fname_out",        VAR_STRING, VV_RO),
+  VV(VV_FNAME_NEW,        "fname_new",        VAR_STRING, VV_RO),
+  VV(VV_FNAME_DIFF,       "fname_diff",       VAR_STRING, VV_RO),
+  VV(VV_CMDARG,           "cmdarg",           VAR_STRING, VV_RO),
+  VV(VV_FOLDSTART,        "foldstart",        VAR_NUMBER, VV_RO_SBX),
+  VV(VV_FOLDEND,          "foldend",          VAR_NUMBER, VV_RO_SBX),
+  VV(VV_FOLDDASHES,       "folddashes",       VAR_STRING, VV_RO_SBX),
+  VV(VV_FOLDLEVEL,        "foldlevel",        VAR_NUMBER, VV_RO_SBX),
+  VV(VV_PROGNAME,         "progname",         VAR_STRING, VV_RO),
+  VV(VV_SEND_SERVER,      "servername",       VAR_STRING, VV_RO),
+  VV(VV_DYING,            "dying",            VAR_NUMBER, VV_RO),
+  VV(VV_EXCEPTION,        "exception",        VAR_STRING, VV_RO),
+  VV(VV_THROWPOINT,       "throwpoint",       VAR_STRING, VV_RO),
+  VV(VV_REG,              "register",         VAR_STRING, VV_RO),
+  VV(VV_CMDBANG,          "cmdbang",          VAR_NUMBER, VV_RO),
+  VV(VV_INSERTMODE,       "insertmode",       VAR_STRING, VV_RO),
+  VV(VV_VAL,              "val",              VAR_UNKNOWN, VV_RO),
+  VV(VV_KEY,              "key",              VAR_UNKNOWN, VV_RO),
+  VV(VV_PROFILING,        "profiling",        VAR_NUMBER, VV_RO),
+  VV(VV_FCS_REASON,       "fcs_reason",       VAR_STRING, VV_RO),
+  VV(VV_FCS_CHOICE,       "fcs_choice",       VAR_STRING, 0),
+  VV(VV_BEVAL_BUFNR,      "beval_bufnr",      VAR_NUMBER, VV_RO),
+  VV(VV_BEVAL_WINNR,      "beval_winnr",      VAR_NUMBER, VV_RO),
+  VV(VV_BEVAL_WINID,      "beval_winid",      VAR_NUMBER, VV_RO),
+  VV(VV_BEVAL_LNUM,       "beval_lnum",       VAR_NUMBER, VV_RO),
+  VV(VV_BEVAL_COL,        "beval_col",        VAR_NUMBER, VV_RO),
+  VV(VV_BEVAL_TEXT,       "beval_text",       VAR_STRING, VV_RO),
+  VV(VV_SCROLLSTART,      "scrollstart",      VAR_STRING, 0),
+  VV(VV_SWAPNAME,         "swapname",         VAR_STRING, VV_RO),
+  VV(VV_SWAPCHOICE,       "swapchoice",       VAR_STRING, 0),
+  VV(VV_SWAPCOMMAND,      "swapcommand",      VAR_STRING, VV_RO),
+  VV(VV_CHAR,             "char",             VAR_STRING, 0),
+  VV(VV_MOUSE_WIN,        "mouse_win",        VAR_NUMBER, 0),
+  VV(VV_MOUSE_WINID,      "mouse_winid",      VAR_NUMBER, 0),
+  VV(VV_MOUSE_LNUM,       "mouse_lnum",       VAR_NUMBER, 0),
+  VV(VV_MOUSE_COL,        "mouse_col",        VAR_NUMBER, 0),
+  VV(VV_OP,               "operator",         VAR_STRING, VV_RO),
+  VV(VV_SEARCHFORWARD,    "searchforward",    VAR_NUMBER, 0),
+  VV(VV_HLSEARCH,         "hlsearch",         VAR_NUMBER, 0),
+  VV(VV_OLDFILES,         "oldfiles",         VAR_LIST, 0),
+  VV(VV_WINDOWID,         "windowid",         VAR_NUMBER, VV_RO_SBX),
+  VV(VV_PROGPATH,         "progpath",         VAR_STRING, VV_RO),
+  VV(VV_COMPLETED_ITEM,   "completed_item",   VAR_DICT, VV_RO),
+  VV(VV_OPTION_NEW,       "option_new",       VAR_STRING, VV_RO),
+  VV(VV_OPTION_OLD,       "option_old",       VAR_STRING, VV_RO),
+  VV(VV_OPTION_OLDLOCAL,  "option_oldlocal",  VAR_STRING, VV_RO),
+  VV(VV_OPTION_OLDGLOBAL, "option_oldglobal", VAR_STRING, VV_RO),
+  VV(VV_OPTION_COMMAND,   "option_command",   VAR_STRING, VV_RO),
+  VV(VV_OPTION_TYPE,      "option_type",      VAR_STRING, VV_RO),
+  VV(VV_ERRORS,           "errors",           VAR_LIST, 0),
+  VV(VV_FALSE,            "false",            VAR_BOOL, VV_RO),
+  VV(VV_TRUE,             "true",             VAR_BOOL, VV_RO),
+  VV(VV_NULL,             "null",             VAR_SPECIAL, VV_RO),
+  VV(VV_NUMBERMAX,        "numbermax",        VAR_NUMBER, VV_RO),
+  VV(VV_NUMBERMIN,        "numbermin",        VAR_NUMBER, VV_RO),
+  VV(VV_NUMBERSIZE,       "numbersize",       VAR_NUMBER, VV_RO),
+  VV(VV_VIM_DID_ENTER,    "vim_did_enter",    VAR_NUMBER, VV_RO),
+  VV(VV_TESTING,          "testing",          VAR_NUMBER, 0),
+  VV(VV_TYPE_NUMBER,      "t_number",         VAR_NUMBER, VV_RO),
+  VV(VV_TYPE_STRING,      "t_string",         VAR_NUMBER, VV_RO),
+  VV(VV_TYPE_FUNC,        "t_func",           VAR_NUMBER, VV_RO),
+  VV(VV_TYPE_LIST,        "t_list",           VAR_NUMBER, VV_RO),
+  VV(VV_TYPE_DICT,        "t_dict",           VAR_NUMBER, VV_RO),
+  VV(VV_TYPE_FLOAT,       "t_float",          VAR_NUMBER, VV_RO),
+  VV(VV_TYPE_BOOL,        "t_bool",           VAR_NUMBER, VV_RO),
+  VV(VV_TYPE_BLOB,        "t_blob",           VAR_NUMBER, VV_RO),
+  VV(VV_EVENT,            "event",            VAR_DICT, VV_RO),
+  VV(VV_ECHOSPACE,        "echospace",        VAR_NUMBER, VV_RO),
+  VV(VV_ARGV,             "argv",             VAR_LIST, VV_RO),
+  VV(VV_COLLATE,          "collate",          VAR_STRING, VV_RO),
+  VV(VV_EXITING,          "exiting",          VAR_NUMBER, VV_RO),
   // Neovim
-  VV(VV_STDERR,         "stderr",           VAR_NUMBER, VV_RO),
-  VV(VV_MSGPACK_TYPES,  "msgpack_types",    VAR_DICT, VV_RO),
-  VV(VV__NULL_STRING,   "_null_string",     VAR_STRING, VV_RO),
-  VV(VV__NULL_LIST,     "_null_list",       VAR_LIST, VV_RO),
-  VV(VV__NULL_DICT,     "_null_dict",       VAR_DICT, VV_RO),
-  VV(VV__NULL_BLOB,     "_null_blob",       VAR_BLOB, VV_RO),
-  VV(VV_LUA,            "lua",              VAR_PARTIAL, VV_RO),
+  VV(VV_STDERR,           "stderr",           VAR_NUMBER, VV_RO),
+  VV(VV_MSGPACK_TYPES,    "msgpack_types",    VAR_DICT, VV_RO),
+  VV(VV__NULL_STRING,     "_null_string",     VAR_STRING, VV_RO),
+  VV(VV__NULL_LIST,       "_null_list",       VAR_LIST, VV_RO),
+  VV(VV__NULL_DICT,       "_null_dict",       VAR_DICT, VV_RO),
+  VV(VV__NULL_BLOB,       "_null_blob",       VAR_BLOB, VV_RO),
+  VV(VV_LUA,              "lua",              VAR_PARTIAL, VV_RO),
 };
 #undef VV
 
@@ -344,7 +349,7 @@ void eval_init(void)
 
   for (size_t i = 0; i < ARRAY_SIZE(vimvars); i++) {
     p = &vimvars[i];
-    assert(STRLEN(p->vv_name) <= 16);
+    assert(STRLEN(p->vv_name) <= VIMVAR_KEY_LEN);
     STRCPY(p->vv_di.di_key, p->vv_name);
     if (p->vv_flags & VV_RO) {
       p->vv_di.di_flags = DI_FLAGS_RO | DI_FLAGS_FIX;
@@ -10446,11 +10451,15 @@ void option_last_set_msg(LastSet last_set)
   }
 }
 
-// reset v:option_new, v:option_old and v:option_type
+// reset v:option_new, v:option_old, v:option_oldlocal, v:option_oldglobal,
+// v:option_type, and v:option_command.
 void reset_v_option_vars(void)
 {
-  set_vim_var_string(VV_OPTION_NEW,  NULL, -1);
-  set_vim_var_string(VV_OPTION_OLD,  NULL, -1);
+  set_vim_var_string(VV_OPTION_NEW, NULL, -1);
+  set_vim_var_string(VV_OPTION_OLD, NULL, -1);
+  set_vim_var_string(VV_OPTION_OLDLOCAL, NULL, -1);
+  set_vim_var_string(VV_OPTION_OLDGLOBAL, NULL, -1);
+  set_vim_var_string(VV_OPTION_COMMAND, NULL, -1);
   set_vim_var_string(VV_OPTION_TYPE, NULL, -1);
 }
 
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index d34348a274..986dda2408 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -138,6 +138,9 @@ typedef enum {
   VV_COMPLETED_ITEM,
   VV_OPTION_NEW,
   VV_OPTION_OLD,
+  VV_OPTION_OLDLOCAL,
+  VV_OPTION_OLDGLOBAL,
+  VV_OPTION_COMMAND,
   VV_OPTION_TYPE,
   VV_ERRORS,
   VV_FALSE,
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 45e2032b35..dbe90920cd 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -1301,7 +1301,11 @@ int do_set(char_u *arg, int opt_flags)
             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;
@@ -1319,10 +1323,21 @@ int do_set(char_u *arg, int opt_flags)
             // 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 == 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)) {
+            if (((int)options[opt_idx].indir & PV_BOTH) && (opt_flags & OPT_LOCAL)) {
               origval = *(char_u **)get_varp(&options[opt_idx]);
             } else {
               origval = oldval;
@@ -1388,6 +1403,12 @@ int do_set(char_u *arg, int opt_flags)
                 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;
               }
               /*
@@ -1596,6 +1617,8 @@ int do_set(char_u *arg, int opt_flags)
             // origval may be freed by
             // did_set_string_option(), make a copy.
             saved_origval = (origval != NULL) ? xstrdup((char *)origval) : 0;
+            saved_origval_l = (origval_l != NULL) ? xstrdup((char *)origval_l) : 0;
+            saved_origval_g = (origval_g != NULL) ? xstrdup((char *)origval_g) : 0;
 
             // newval (and varp) may become invalid if the
             // buffer is closed by autocommands.
@@ -1630,8 +1653,8 @@ int do_set(char_u *arg, int opt_flags)
 
             if (errmsg == NULL) {
               if (!starting) {
-                trigger_optionsset_string(opt_idx, opt_flags, saved_origval,
-                                          saved_newval);
+                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),
@@ -1639,6 +1662,8 @@ int do_set(char_u *arg, int opt_flags)
               }
             }
             xfree(saved_origval);
+            xfree(saved_origval_l);
+            xfree(saved_origval_g);
             xfree(saved_newval);
 
             // If error detected, print the error message.
@@ -2233,9 +2258,19 @@ static char *set_string_option(const int opt_idx, const char *const value, const
           ? OPT_GLOBAL : OPT_LOCAL)
           : opt_flags));
   char *const oldval = *varp;
+  char *oldval_l = NULL;
+  char *oldval_g = NULL;
+
+  if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
+    oldval_l = *(char **)get_varp_scope(&(options[opt_idx]), OPT_LOCAL);
+    oldval_g = *(char **)get_varp_scope(&(options[opt_idx]), OPT_GLOBAL);
+  }
+
   *varp = s;
 
   char *const saved_oldval = xstrdup(oldval);
+  char *const saved_oldval_l = (oldval_l != NULL) ? xstrdup((char *)oldval_l) : 0;
+  char *const saved_oldval_g = (oldval_g != NULL) ? xstrdup((char *)oldval_g) : 0;
   char *const saved_newval = xstrdup(s);
 
   int value_checked = false;
@@ -2249,7 +2284,8 @@ static char *set_string_option(const int opt_idx, const char *const value, const
   // call autocommand after handling side effects
   if (r == NULL) {
     if (!starting) {
-      trigger_optionsset_string(opt_idx, opt_flags, saved_oldval, saved_newval);
+      trigger_optionsset_string(opt_idx, opt_flags, saved_oldval, saved_oldval_l, saved_oldval_g,
+                                saved_newval);
     }
     if (options[opt_idx].flags & P_UI_OPTION) {
       ui_call_option_set(cstr_as_string(options[opt_idx].fullname),
@@ -2257,6 +2293,8 @@ static char *set_string_option(const int opt_idx, const char *const value, const
     }
   }
   xfree(saved_oldval);
+  xfree(saved_oldval_l);
+  xfree(saved_oldval_g);
   xfree(saved_newval);
 
   return r;
@@ -3851,6 +3889,7 @@ static char *set_bool_option(const int opt_idx, char_u *const varp, const int va
                              const int opt_flags)
 {
   int old_value = *(int *)varp;
+  int old_global_value = 0;
 
   // Disallow changing some options from secure mode
   if ((secure || sandbox != 0)
@@ -3858,6 +3897,13 @@ static char *set_bool_option(const int opt_idx, char_u *const varp, const int va
     return (char *)e_secure;
   }
 
+  // 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);
+  }
+
   *(int *)varp = value;             // set the new value
   // Remember where the option was set.
   set_option_sctx_idx(opt_idx, opt_flags, current_sctx);
@@ -4134,20 +4180,35 @@ static char *set_bool_option(const int opt_idx, char_u *const varp, const int va
   // Don't do this while starting up or recursively.
   if (!starting && *get_vim_var_str(VV_OPTION_TYPE) == NUL) {
     char buf_old[2];
+    char buf_old_global[2];
     char buf_new[2];
     char buf_type[7];
-    vim_snprintf(buf_old, ARRAY_SIZE(buf_old), "%d",
-                 old_value ? true: false);
-    vim_snprintf(buf_new, ARRAY_SIZE(buf_new), "%d",
-                 value ? true: false);
+    vim_snprintf(buf_old, ARRAY_SIZE(buf_old), "%d", old_value ? true : false);
+    vim_snprintf(buf_old_global, ARRAY_SIZE(buf_old_global), "%d", old_global_value ? true : false);
+    vim_snprintf(buf_new, ARRAY_SIZE(buf_new), "%d", value ? true : false);
     vim_snprintf(buf_type, ARRAY_SIZE(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);
     set_vim_var_string(VV_OPTION_TYPE, buf_type, -1);
-    apply_autocmds(EVENT_OPTIONSET,
-                   (char_u *)options[opt_idx].fullname,
-                   NULL, false, NULL);
+    if (opt_flags & OPT_LOCAL) {
+      set_vim_var_string(VV_OPTION_COMMAND, "setlocal", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
+    }
+    if (opt_flags & OPT_GLOBAL) {
+      set_vim_var_string(VV_OPTION_COMMAND, "setglobal", -1);
+      set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old, -1);
+    }
+    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
+      set_vim_var_string(VV_OPTION_COMMAND, "set", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
+      set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old_global, -1);
+    }
+    if (opt_flags & OPT_MODELINE) {
+      set_vim_var_string(VV_OPTION_COMMAND, "modeline", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
+    }
+    apply_autocmds(EVENT_OPTIONSET, (char_u *)options[opt_idx].fullname, NULL, false, NULL);
     reset_v_option_vars();
   }
 
@@ -4181,7 +4242,8 @@ static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf,
 {
   char *errmsg = NULL;
   long old_value = *(long *)varp;
-  long old_Rows = Rows;                 // remember old Rows
+  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;
 
   // Disallow changing some options from secure mode.
@@ -4190,6 +4252,13 @@ static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf,
     return e_secure;
   }
 
+  // Save the global value before changing anything. This is needed as for
+  // a global-only option setting the "local value" infact 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);
+  }
+
   // Many number options assume their value is in the signed int range.
   if (value < INT_MIN || value > INT_MAX) {
     return e_invarg;
@@ -4534,19 +4603,36 @@ static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf,
   // Don't do this while starting up, failure or recursively.
   if (!starting && errmsg == NULL && *get_vim_var_str(VV_OPTION_TYPE) == NUL) {
     char buf_old[NUMBUFLEN];
+    char buf_old_global[NUMBUFLEN];
     char buf_new[NUMBUFLEN];
     char buf_type[7];
 
     vim_snprintf(buf_old, ARRAY_SIZE(buf_old), "%ld", old_value);
+    vim_snprintf(buf_old_global, ARRAY_SIZE(buf_old_global), "%ld", old_global_value);
     vim_snprintf(buf_new, ARRAY_SIZE(buf_new), "%ld", value);
     vim_snprintf(buf_type, ARRAY_SIZE(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);
     set_vim_var_string(VV_OPTION_TYPE, buf_type, -1);
-    apply_autocmds(EVENT_OPTIONSET,
-                   (char_u *)options[opt_idx].fullname,
-                   NULL, false, NULL);
+    if (opt_flags & OPT_LOCAL) {
+      set_vim_var_string(VV_OPTION_COMMAND, "setlocal", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
+    }
+    if (opt_flags & OPT_GLOBAL) {
+      set_vim_var_string(VV_OPTION_COMMAND, "setglobal", -1);
+      set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old, -1);
+    }
+    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
+      set_vim_var_string(VV_OPTION_COMMAND, "set", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
+      set_vim_var_string(VV_OPTION_OLDGLOBAL, buf_old_global, -1);
+    }
+    if (opt_flags & OPT_MODELINE) {
+      set_vim_var_string(VV_OPTION_COMMAND, "modeline", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, buf_old, -1);
+    }
+    apply_autocmds(EVENT_OPTIONSET, (char_u *)options[opt_idx].fullname, NULL, false, NULL);
     reset_v_option_vars();
   }
 
@@ -4565,7 +4651,15 @@ static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf,
   return (char *)errmsg;
 }
 
-static void trigger_optionsset_string(int opt_idx, int opt_flags, char *oldval, char *newval)
+/// Trigger the OptionSet autocommand.
+/// "opt_idx"   is the index of the option being set.
+/// "opt_flags" can be OPT_LOCAL etc.
+/// "oldval"    the old value
+/// "oldval_l"  the old local value (only non-NULL if global and local value are set)
+/// "oldval_g"  the old global value (only non-NULL if global and local value are set)
+/// "newval"    the new value
+static void trigger_optionsset_string(int opt_idx, int opt_flags, char *oldval, char *oldval_l,
+                                      char *oldval_g, char *newval)
 {
   // Don't do this recursively.
   if (oldval != NULL
@@ -4578,8 +4672,24 @@ static void trigger_optionsset_string(int opt_idx, int opt_flags, char *oldval,
     set_vim_var_string(VV_OPTION_OLD, oldval, -1);
     set_vim_var_string(VV_OPTION_NEW, newval, -1);
     set_vim_var_string(VV_OPTION_TYPE, buf_type, -1);
-    apply_autocmds(EVENT_OPTIONSET,
-                   (char_u *)options[opt_idx].fullname, NULL, false, NULL);
+    if (opt_flags & OPT_LOCAL) {
+      set_vim_var_string(VV_OPTION_COMMAND, "setlocal", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
+    }
+    if (opt_flags & OPT_GLOBAL) {
+      set_vim_var_string(VV_OPTION_COMMAND, "setglobal", -1);
+      set_vim_var_string(VV_OPTION_OLDGLOBAL, oldval, -1);
+    }
+    if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0) {
+      set_vim_var_string(VV_OPTION_COMMAND, "set", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, oldval_l, -1);
+      set_vim_var_string(VV_OPTION_OLDGLOBAL, oldval_g, -1);
+    }
+    if (opt_flags & OPT_MODELINE) {
+      set_vim_var_string(VV_OPTION_COMMAND, "modeline", -1);
+      set_vim_var_string(VV_OPTION_OLDLOCAL, oldval, -1);
+    }
+    apply_autocmds(EVENT_OPTIONSET, (char_u *)options[opt_idx].fullname, NULL, false, NULL);
     reset_v_option_vars();
   }
 }
diff --git a/src/nvim/testdir/test_autocmd.vim b/src/nvim/testdir/test_autocmd.vim
index 0c8b8a45d9..7835556a47 100644
--- a/src/nvim/testdir/test_autocmd.vim
+++ b/src/nvim/testdir/test_autocmd.vim
@@ -580,9 +580,10 @@ func Test_empty_doau()
 endfunc
 
 func s:AutoCommandOptionSet(match)
+  let template = "Option: <%s>, OldVal: <%s>, OldValLocal: <%s>, OldValGlobal: <%s>, NewVal: <%s>, Scope: <%s>, Command: <%s>\n"
   let item     = remove(g:options, 0)
-  let expected = printf("Option: <%s>, Oldval: <%s>, NewVal: <%s>, Scope: <%s>\n", item[0], item[1], item[2], item[3])
-  let actual   = printf("Option: <%s>, Oldval: <%s>, NewVal: <%s>, Scope: <%s>\n", a:match, v:option_old, v:option_new, v:option_type)
+  let expected = printf(template, item[0], item[1], item[2], item[3], item[4], item[5], item[6])
+  let actual   = printf(template, a:match, v:option_old, v:option_oldlocal, v:option_oldglobal, v:option_new, v:option_type, v:option_command)
   let g:opt    = [expected, actual]
   "call assert_equal(expected, actual)
 endfunc
@@ -596,130 +597,593 @@ func Test_OptionSet()
   au OptionSet * :call s:AutoCommandOptionSet(expand("<amatch>"))
 
   " 1: Setting number option"
-  let g:options = [['number', 0, 1, 'global']]
+  let g:options = [['number', 0, 0, 0, 1, 'global', 'set']]
   set nu
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 2: Setting local number option"
-  let g:options = [['number', 1, 0, 'local']]
+  let g:options = [['number', 1, 1, '', 0, 'local', 'setlocal']]
   setlocal nonu
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 3: Setting global number option"
-  let g:options = [['number', 1, 0, 'global']]
+  let g:options = [['number', 1, '', 1, 0, 'global', 'setglobal']]
   setglobal nonu
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 4: Setting local autoindent option"
-  let g:options = [['autoindent', 0, 1, 'local']]
+  let g:options = [['autoindent', 0, 0, '', 1, 'local', 'setlocal']]
   setlocal ai
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 5: Setting global autoindent option"
-  let g:options = [['autoindent', 0, 1, 'global']]
+  let g:options = [['autoindent', 0, '', 0, 1, 'global', 'setglobal']]
   setglobal ai
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 6: Setting global autoindent option"
-  let g:options = [['autoindent', 1, 0, 'global']]
+  let g:options = [['autoindent', 1, 1, 1, 0, 'global', 'set']]
+  set ai!
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 6a: Setting global autoindent option"
+  let g:options = [['autoindent', 1, 1, 0, 0, 'global', 'set']]
+  noa setlocal ai
+  noa setglobal noai
   set ai!
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " Should not print anything, use :noa
   " 7: don't trigger OptionSet"
-  let g:options = [['invalid', 1, 1, 'invalid']]
+  let g:options = [['invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid']]
   noa set nonu
-  call assert_equal([['invalid', 1, 1, 'invalid']], g:options)
+  call assert_equal([['invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid']], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 8: Setting several global list and number option"
-  let g:options = [['list', 0, 1, 'global'], ['number', 0, 1, 'global']]
+  let g:options = [['list', 0, 0, 0, 1, 'global', 'set'], ['number', 0, 0, 0, 1, 'global', 'set']]
   set list nu
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 9: don't trigger OptionSet"
-  let g:options = [['invalid', 1, 1, 'invalid'], ['invalid', 1, 1, 'invalid']]
+  let g:options = [['invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid'], ['invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid']]
   noa set nolist nonu
-  call assert_equal([['invalid', 1, 1, 'invalid'], ['invalid', 1, 1, 'invalid']], g:options)
+  call assert_equal([['invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid'], ['invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid', 'invalid']], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 10: Setting global acd"
-  let g:options = [['autochdir', 0, 1, 'local']]
+  let g:options = [['autochdir', 0, 0, '', 1, 'local', 'setlocal']]
   setlocal acd
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 11: Setting global autoread (also sets local value)"
-  let g:options = [['autoread', 0, 1, 'global']]
+  let g:options = [['autoread', 0, 0, 0, 1, 'global', 'set']]
   set ar
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 12: Setting local autoread"
-  let g:options = [['autoread', 1, 1, 'local']]
+  let g:options = [['autoread', 1, 1, '', 1, 'local', 'setlocal']]
   setlocal ar
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 13: Setting global autoread"
-  let g:options = [['autoread', 1, 0, 'global']]
+  let g:options = [['autoread', 1, '', 1, 0, 'global', 'setglobal']]
   setglobal invar
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 14: Setting option backspace through :let"
-  let g:options = [['backspace', '', 'eol,indent,start', 'global']]
+  let g:options = [['backspace', '', '', '', 'eol,indent,start', 'global', 'set']]
   let &bs = "eol,indent,start"
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 15: Setting option backspace through setbufvar()"
-  let g:options = [['backup', 0, 1, 'local']]
+  let g:options = [['backup', 0, 0, '', 1, 'local', 'setlocal']]
   " try twice, first time, shouldn't trigger because option name is invalid,
   " second time, it should trigger
-  call assert_fails("call setbufvar(1, '&l:bk', 1)", "E355")
+  let bnum = bufnr('%')
+  call assert_fails("call setbufvar(bnum, '&l:bk', 1)", 'E355:')
   " should trigger, use correct option name
-  call setbufvar(1, '&backup', 1)
+  call setbufvar(bnum, '&backup', 1)
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 16: Setting number option using setwinvar"
-  let g:options = [['number', 0, 1, 'local']]
+  let g:options = [['number', 0, 0, '', 1, 'local', 'setlocal']]
   call setwinvar(0, '&number', 1)
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
   " 17: Setting key option, shouldn't trigger"
-  let g:options = [['key', 'invalid', 'invalid1', 'invalid']]
+  let g:options = [['key', 'invalid', 'invalid1', 'invalid2', 'invalid3', 'invalid4', 'invalid5']]
   setlocal key=blah
   setlocal key=
-  call assert_equal([['key', 'invalid', 'invalid1', 'invalid']], g:options)
+  call assert_equal([['key', 'invalid', 'invalid1', 'invalid2', 'invalid3', 'invalid4', 'invalid5']], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
-  " 18: Setting string option"
+
+  " 18a: Setting string global option"
+  let oldval = &backupext
+  let g:options = [['backupext', oldval, oldval, oldval, 'foo', 'global', 'set']]
+  set backupext=foo
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 18b: Resetting string global option"
+  let g:options = [['backupext', 'foo', 'foo', 'foo', oldval, 'global', 'set']]
+  set backupext&
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 18c: Setting global string global option"
+  let g:options = [['backupext', oldval, '', oldval, 'bar', 'global', 'setglobal']]
+  setglobal backupext=bar
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 18d: Setting local string global option"
+  " As this is a global option this sets the global value even though
+  " :setlocal is used!
+  noa set backupext& " Reset global and local value (without triggering autocmd)
+  let g:options = [['backupext', oldval, oldval, '', 'baz', 'local', 'setlocal']]
+  setlocal backupext=baz
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 18e: Setting again string global option"
+  noa setglobal backupext=ext_global " Reset global and local value (without triggering autocmd)
+  noa setlocal backupext=ext_local " Sets the global(!) value!
+  let g:options = [['backupext', 'ext_local', 'ext_local', 'ext_local', 'fuu', 'global', 'set']]
+  set backupext=fuu
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 19a: Setting string local-global (to buffer) option"
   let oldval = &tags
-  let g:options = [['tags', oldval, 'tagpath', 'global']]
+  let g:options = [['tags', oldval, oldval, oldval, 'tagpath', 'global', 'set']]
   set tags=tagpath
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
-  " 1l: Resetting string option"
-  let g:options = [['tags', 'tagpath', oldval, 'global']]
+  " 19b: Resetting string local-global (to buffer) option"
+  let g:options = [['tags', 'tagpath', 'tagpath', 'tagpath', oldval, 'global', 'set']]
   set tags&
   call assert_equal([], g:options)
   call assert_equal(g:opt[0], g:opt[1])
 
+  " 19c: Setting global string local-global (to buffer) option "
+  let g:options = [['tags', oldval, '', oldval, 'tagpath1', 'global', 'setglobal']]
+  setglobal tags=tagpath1
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 19d: Setting local string local-global (to buffer) option"
+  let g:options = [['tags', 'tagpath1', 'tagpath1', '', 'tagpath2', 'local', 'setlocal']]
+  setlocal tags=tagpath2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 19e: Setting again string local-global (to buffer) option"
+  " Note: v:option_old is the old global value for local-global string options
+  " but the old local value for all other kinds of options.
+  noa setglobal tags=tag_global " Reset global and local value (without triggering autocmd)
+  noa setlocal tags=tag_local
+  let g:options = [['tags', 'tag_global', 'tag_local', 'tag_global', 'tagpath', 'global', 'set']]
+  set tags=tagpath
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 19f: Setting string local-global (to buffer) option to an empty string"
+  " Note: v:option_old is the old global value for local-global string options
+  " but the old local value for all other kinds of options.
+  noa set tags=tag_global " Reset global and local value (without triggering autocmd)
+  noa setlocal tags= " empty string
+  let g:options = [['tags', 'tag_global', '', 'tag_global', 'tagpath', 'global', 'set']]
+  set tags=tagpath
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 20a: Setting string local (to buffer) option"
+  let oldval = &spelllang
+  let g:options = [['spelllang', oldval, oldval, oldval, 'elvish,klingon', 'global', 'set']]
+  set spelllang=elvish,klingon
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 20b: Resetting string local (to buffer) option"
+  let g:options = [['spelllang', 'elvish,klingon', 'elvish,klingon', 'elvish,klingon', oldval, 'global', 'set']]
+  set spelllang&
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 20c: Setting global string local (to buffer) option"
+  let g:options = [['spelllang', oldval, '', oldval, 'elvish', 'global', 'setglobal']]
+  setglobal spelllang=elvish
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 20d: Setting local string local (to buffer) option"
+  noa set spelllang& " Reset global and local value (without triggering autocmd)
+  let g:options = [['spelllang', oldval, oldval, '', 'klingon', 'local', 'setlocal']]
+  setlocal spelllang=klingon
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 20e: Setting again string local (to buffer) option"
+  " Note: v:option_old is the old global value for local-global string options
+  " but the old local value for all other kinds of options.
+  noa setglobal spelllang=spellglobal " Reset global and local value (without triggering autocmd)
+  noa setlocal spelllang=spelllocal
+  let g:options = [['spelllang', 'spelllocal', 'spelllocal', 'spellglobal', 'foo', 'global', 'set']]
+  set spelllang=foo
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 21a: Setting string local-global (to window) option"
+  let oldval = &statusline
+  let g:options = [['statusline', oldval, oldval, oldval, 'foo', 'global', 'set']]
+  set statusline=foo
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 21b: Resetting string local-global (to window) option"
+  " Note: v:option_old is the old global value for local-global string options
+  " but the old local value for all other kinds of options.
+  let g:options = [['statusline', 'foo', 'foo', 'foo', oldval, 'global', 'set']]
+  set statusline&
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 21c: Setting global string local-global (to window) option"
+  let g:options = [['statusline', oldval, '', oldval, 'bar', 'global', 'setglobal']]
+  setglobal statusline=bar
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 21d: Setting local string local-global (to window) option"
+  noa set statusline& " Reset global and local value (without triggering autocmd)
+  let g:options = [['statusline', oldval, oldval, '', 'baz', 'local', 'setlocal']]
+  setlocal statusline=baz
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 21e: Setting again string local-global (to window) option"
+  " Note: v:option_old is the old global value for local-global string options
+  " but the old local value for all other kinds of options.
+  noa setglobal statusline=bar " Reset global and local value (without triggering autocmd)
+  noa setlocal statusline=baz
+  let g:options = [['statusline', 'bar', 'baz', 'bar', 'foo', 'global', 'set']]
+  set statusline=foo
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 22a: Setting string local (to window) option"
+  let oldval = &foldignore
+  let g:options = [['foldignore', oldval, oldval, oldval, 'fo', 'global', 'set']]
+  set foldignore=fo
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 22b: Resetting string local (to window) option"
+  let g:options = [['foldignore', 'fo', 'fo', 'fo', oldval, 'global', 'set']]
+  set foldignore&
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 22c: Setting global string local (to window) option"
+  let g:options = [['foldignore', oldval, '', oldval, 'bar', 'global', 'setglobal']]
+  setglobal foldignore=bar
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 22d: Setting local string local (to window) option"
+  noa set foldignore& " Reset global and local value (without triggering autocmd)
+  let g:options = [['foldignore', oldval, oldval, '', 'baz', 'local', 'setlocal']]
+  setlocal foldignore=baz
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 22e: Setting again string local (to window) option"
+  noa setglobal foldignore=glob " Reset global and local value (without triggering autocmd)
+  noa setlocal foldignore=loc
+  let g:options = [['foldignore', 'loc', 'loc', 'glob', 'fo', 'global', 'set']]
+  set foldignore=fo
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 23a: Setting global number local option"
+  noa setglobal cmdheight=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal cmdheight=1 " Sets the global(!) value!
+  let g:options = [['cmdheight', '1', '', '1', '2', 'global', 'setglobal']]
+  setglobal cmdheight=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 23b: Setting local number global option"
+  noa setglobal cmdheight=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal cmdheight=1 " Sets the global(!) value!
+  let g:options = [['cmdheight', '1', '1', '', '2', 'local', 'setlocal']]
+  setlocal cmdheight=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 23c: Setting again number global option"
+  noa setglobal cmdheight=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal cmdheight=1 " Sets the global(!) value!
+  let g:options = [['cmdheight', '1', '1', '1', '2', 'global', 'set']]
+  set cmdheight=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 23d: Setting again number global option"
+  noa set cmdheight=8 " Reset global and local value (without triggering autocmd)
+  let g:options = [['cmdheight', '8', '8', '8', '2', 'global', 'set']]
+  set cmdheight=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 24a: Setting global number global-local (to buffer) option"
+  noa setglobal undolevels=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal undolevels=1
+  let g:options = [['undolevels', '8', '', '8', '2', 'global', 'setglobal']]
+  setglobal undolevels=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 24b: Setting local number global-local (to buffer) option"
+  noa setglobal undolevels=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal undolevels=1
+  let g:options = [['undolevels', '1', '1', '', '2', 'local', 'setlocal']]
+  setlocal undolevels=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 24c: Setting again number global-local (to buffer) option"
+  noa setglobal undolevels=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal undolevels=1
+  let g:options = [['undolevels', '1', '1', '8', '2', 'global', 'set']]
+  set undolevels=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 24d: Setting again global number global-local (to buffer) option"
+  noa set undolevels=8 " Reset global and local value (without triggering autocmd)
+  let g:options = [['undolevels', '8', '8', '8', '2', 'global', 'set']]
+  set undolevels=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 25a: Setting global number local (to buffer) option"
+  noa setglobal wrapmargin=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal wrapmargin=1
+  let g:options = [['wrapmargin', '8', '', '8', '2', 'global', 'setglobal']]
+  setglobal wrapmargin=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 25b: Setting local number local (to buffer) option"
+  noa setglobal wrapmargin=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal wrapmargin=1
+  let g:options = [['wrapmargin', '1', '1', '', '2', 'local', 'setlocal']]
+  setlocal wrapmargin=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 25c: Setting again number local (to buffer) option"
+  noa setglobal wrapmargin=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal wrapmargin=1
+  let g:options = [['wrapmargin', '1', '1', '8', '2', 'global', 'set']]
+  set wrapmargin=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 25d: Setting again global number local (to buffer) option"
+  noa set wrapmargin=8 " Reset global and local value (without triggering autocmd)
+  let g:options = [['wrapmargin', '8', '8', '8', '2', 'global', 'set']]
+  set wrapmargin=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 26: Setting number global-local (to window) option.
+  " Such option does currently not exist.
+
+
+  " 27a: Setting global number local (to window) option"
+  noa setglobal foldcolumn=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal foldcolumn=1
+  let g:options = [['foldcolumn', '8', '', '8', '2', 'global', 'setglobal']]
+  setglobal foldcolumn=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 27b: Setting local number local (to window) option"
+  noa setglobal foldcolumn=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal foldcolumn=1
+  let g:options = [['foldcolumn', '1', '1', '', '2', 'local', 'setlocal']]
+  setlocal foldcolumn=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 27c: Setting again number local (to window) option"
+  noa setglobal foldcolumn=8 " Reset global and local value (without triggering autocmd)
+  noa setlocal foldcolumn=1
+  let g:options = [['foldcolumn', '1', '1', '8', '2', 'global', 'set']]
+  set foldcolumn=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 27d: Ssettin again global number local (to window) option"
+  noa set foldcolumn=8 " Reset global and local value (without triggering autocmd)
+  let g:options = [['foldcolumn', '8', '8', '8', '2', 'global', 'set']]
+  set foldcolumn=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 28a: Setting global boolean global option"
+  noa setglobal nowrapscan " Reset global and local value (without triggering autocmd)
+  noa setlocal wrapscan " Sets the global(!) value!
+  let g:options = [['wrapscan', '1', '', '1', '0', 'global', 'setglobal']]
+  setglobal nowrapscan
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 28b: Setting local boolean global option"
+  noa setglobal nowrapscan " Reset global and local value (without triggering autocmd)
+  noa setlocal wrapscan " Sets the global(!) value!
+  let g:options = [['wrapscan', '1', '1', '', '0', 'local', 'setlocal']]
+  setlocal nowrapscan
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 28c: Setting again boolean global option"
+  noa setglobal nowrapscan " Reset global and local value (without triggering autocmd)
+  noa setlocal wrapscan " Sets the global(!) value!
+  let g:options = [['wrapscan', '1', '1', '1', '0', 'global', 'set']]
+  set nowrapscan
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 28d: Setting again global boolean global option"
+  noa set nowrapscan " Reset global and local value (without triggering autocmd)
+  let g:options = [['wrapscan', '0', '0', '0', '1', 'global', 'set']]
+  set wrapscan
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 29a: Setting global boolean global-local (to buffer) option"
+  noa setglobal noautoread " Reset global and local value (without triggering autocmd)
+  noa setlocal autoread
+  let g:options = [['autoread', '0', '', '0', '1', 'global', 'setglobal']]
+  setglobal autoread
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 29b: Setting local boolean global-local (to buffer) option"
+  noa setglobal noautoread " Reset global and local value (without triggering autocmd)
+  noa setlocal autoread
+  let g:options = [['autoread', '1', '1', '', '0', 'local', 'setlocal']]
+  setlocal noautoread
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 29c: Setting again boolean global-local (to buffer) option"
+  noa setglobal noautoread " Reset global and local value (without triggering autocmd)
+  noa setlocal autoread
+  let g:options = [['autoread', '1', '1', '0', '1', 'global', 'set']]
+  set autoread
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 29d: Setting again global boolean global-local (to buffer) option"
+  noa set noautoread " Reset global and local value (without triggering autocmd)
+  let g:options = [['autoread', '0', '0', '0', '1', 'global', 'set']]
+  set autoread
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 30a: Setting global boolean local (to buffer) option"
+  noa setglobal nocindent " Reset global and local value (without triggering autocmd)
+  noa setlocal cindent
+  let g:options = [['cindent', '0', '', '0', '1', 'global', 'setglobal']]
+  setglobal cindent
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 30b: Setting local boolean local (to buffer) option"
+  noa setglobal nocindent " Reset global and local value (without triggering autocmd)
+  noa setlocal cindent
+  let g:options = [['cindent', '1', '1', '', '0', 'local', 'setlocal']]
+  setlocal nocindent
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 30c: Setting again boolean local (to buffer) option"
+  noa setglobal nocindent " Reset global and local value (without triggering autocmd)
+  noa setlocal cindent
+  let g:options = [['cindent', '1', '1', '0', '1', 'global', 'set']]
+  set cindent
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 30d: Setting again global boolean local (to buffer) option"
+  noa set nocindent " Reset global and local value (without triggering autocmd)
+  let g:options = [['cindent', '0', '0', '0', '1', 'global', 'set']]
+  set cindent
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 31: Setting boolean global-local (to window) option
+  " Currently no such option exists.
+
+
+  " 32a: Setting global boolean local (to window) option"
+  noa setglobal nocursorcolumn " Reset global and local value (without triggering autocmd)
+  noa setlocal cursorcolumn
+  let g:options = [['cursorcolumn', '0', '', '0', '1', 'global', 'setglobal']]
+  setglobal cursorcolumn
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 32b: Setting local boolean local (to window) option"
+  noa setglobal nocursorcolumn " Reset global and local value (without triggering autocmd)
+  noa setlocal cursorcolumn
+  let g:options = [['cursorcolumn', '1', '1', '', '0', 'local', 'setlocal']]
+  setlocal nocursorcolumn
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 32c: Setting again boolean local (to window) option"
+  noa setglobal nocursorcolumn " Reset global and local value (without triggering autocmd)
+  noa setlocal cursorcolumn
+  let g:options = [['cursorcolumn', '1', '1', '0', '1', 'global', 'set']]
+  set cursorcolumn
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+  " 32d: Setting again global boolean local (to window) option"
+  noa set nocursorcolumn " Reset global and local value (without triggering autocmd)
+  let g:options = [['cursorcolumn', '0', '0', '0', '1', 'global', 'set']]
+  set cursorcolumn
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
+  " 33: Test autocommands when an option value is converted internally.
+  noa set backspace=1 " Reset global and local value (without triggering autocmd)
+  let g:options = [['backspace', 'indent,eol', 'indent,eol', 'indent,eol', '2', 'global', 'set']]
+  set backspace=2
+  call assert_equal([], g:options)
+  call assert_equal(g:opt[0], g:opt[1])
+
+
   " Cleanup
   au! OptionSet
   " set tags&
-  for opt in ['nu', 'ai', 'acd', 'ar', 'bs', 'backup', 'cul', 'cp', 'tags']
+  for opt in ['nu', 'ai', 'acd', 'ar', 'bs', 'backup', 'cul', 'cp', 'backupext', 'tags', 'spelllang', 'statusline', 'foldignore', 'cmdheight', 'undolevels', 'wrapmargin', 'foldcolumn', 'wrapscan', 'autoread', 'cindent', 'cursorcolumn']
     exe printf(":set %s&vim", opt)
   endfor
   call test_override('starting', 0)