refactor(options): reduce `findoption()` usage

Problem: Many places in the code use `findoption()` to access an option using its name, even if the option index is available. This is very slow because it requires looping through the options array over and over.

Solution: Use option index instead of name wherever possible. Also introduce an `OptIndex` enum which contains the index for every option as enum constants, this eliminates the need to pass static option names as strings.

37 files changed, 330 insertions, 346 deletions

diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index 0cdce539eb..95ea55f36d 100644
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -332,6 +332,7 @@ set(GENERATED_KEYSETS_DEFS ${GENERATED_DIR}/keysets_defs.generated.h)
 set(GENERATED_EVENTS_ENUM ${GENERATED_INCLUDES_DIR}/auevents_enum.generated.h)
 set(GENERATED_EVENTS_NAMES_MAP ${GENERATED_DIR}/auevents_name_map.generated.h)
 set(GENERATED_OPTIONS ${GENERATED_DIR}/options.generated.h)
+set(GENERATED_OPTIONS_ENUM ${GENERATED_DIR}/options_enum.generated.h)
 set(EX_CMDS_GENERATOR ${GENERATOR_DIR}/gen_ex_cmds.lua)
 set(FUNCS_GENERATOR ${GENERATOR_DIR}/gen_eval.lua)
 set(EVENTS_GENERATOR ${GENERATOR_DIR}/gen_events.lua)
@@ -676,8 +677,8 @@ add_custom_command(OUTPUT ${GENERATED_EVENTS_ENUM} ${GENERATED_EVENTS_NAMES_MAP}
   DEPENDS ${LUA_GEN_DEPS} ${EVENTS_GENERATOR} ${CMAKE_CURRENT_LIST_DIR}/auevents.lua
 )
 
-add_custom_command(OUTPUT ${GENERATED_OPTIONS}
-  COMMAND ${LUA_GEN} ${OPTIONS_GENERATOR} ${GENERATED_OPTIONS}
+add_custom_command(OUTPUT ${GENERATED_OPTIONS} ${GENERATED_OPTIONS_ENUM}
+  COMMAND ${LUA_GEN} ${OPTIONS_GENERATOR} ${GENERATED_OPTIONS} ${GENERATED_OPTIONS_ENUM}
   DEPENDS ${LUA_GEN_DEPS} ${OPTIONS_GENERATOR} ${CMAKE_CURRENT_LIST_DIR}/options.lua
 )
 
diff --git a/src/nvim/api/deprecated.c b/src/nvim/api/deprecated.c
index d6a76617a7..34bf029483 100644
--- a/src/nvim/api/deprecated.c
+++ b/src/nvim/api/deprecated.c
@@ -643,7 +643,7 @@ static Object get_option_from(void *from, OptReqScope req_scope, String name, Er
     return (Object)OBJECT_INIT;
   });
 
-  OptVal value = get_option_value_strict(name.data, req_scope, from, err);
+  OptVal value = get_option_value_strict(findoption(name.data), req_scope, from, err);
   if (ERROR_SET(err)) {
     return (Object)OBJECT_INIT;
   }
@@ -669,8 +669,8 @@ static void set_option_to(uint64_t channel_id, void *to, OptReqScope req_scope,
     return;
   });
 
-  int flags = get_option_attrs(name.data);
-  VALIDATE_S(flags != 0, "option name", name.data, {
+  int opt_idx = findoption(name.data);
+  VALIDATE_S(opt_idx >= 0, "option name", name.data, {
     return;
   });
 
@@ -685,13 +685,14 @@ static void set_option_to(uint64_t channel_id, void *to, OptReqScope req_scope,
     return;
   });
 
+  int attrs = get_option_attrs(opt_idx);
   // For global-win-local options -> setlocal
   // For        win-local options -> setglobal and setlocal (opt_flags == 0)
-  const int opt_flags = (req_scope == kOptReqWin && !(flags & SOPT_GLOBAL))
+  const int opt_flags = (req_scope == kOptReqWin && !(attrs & SOPT_GLOBAL))
                         ? 0
                         : (req_scope == kOptReqGlobal) ? OPT_GLOBAL : OPT_LOCAL;
 
   WITH_SCRIPT_CONTEXT(channel_id, {
-    set_option_value_for(name.data, optval, opt_flags, req_scope, to, err);
+    set_option_value_for(name.data, opt_idx, optval, opt_flags, req_scope, to, err);
   });
 }
diff --git a/src/nvim/api/options.c b/src/nvim/api/options.c
index 53fd8af8b5..0d18c7871c 100644
--- a/src/nvim/api/options.c
+++ b/src/nvim/api/options.c
@@ -23,7 +23,7 @@
 # include "api/options.c.generated.h"
 #endif
 
-static int validate_option_value_args(Dict(option) *opts, char *name, int *scope,
+static int validate_option_value_args(Dict(option) *opts, char *name, int *opt_idx, int *scope,
                                       OptReqScope *req_scope, void **from, char **filetype,
                                       Error *err)
 {
@@ -79,7 +79,8 @@ static int validate_option_value_args(Dict(option) *opts, char *name, int *scope
     return FAIL;
   });
 
-  int flags = get_option_attrs(name);
+  *opt_idx = findoption(name);
+  int flags = get_option_attrs(*opt_idx);
   if (flags == 0) {
     // hidden or unknown option
     api_set_error(err, kErrorTypeValidation, "Unknown option '%s'", name);
@@ -119,10 +120,10 @@ static buf_T *do_ft_buf(char *filetype, aco_save_T *aco, Error *err)
   aucmd_prepbuf(aco, ftbuf);
 
   TRY_WRAP(err, {
-    set_option_value("bufhidden", STATIC_CSTR_AS_OPTVAL("hide"), OPT_LOCAL);
-    set_option_value("buftype", STATIC_CSTR_AS_OPTVAL("nofile"), OPT_LOCAL);
-    set_option_value("swapfile", BOOLEAN_OPTVAL(false), OPT_LOCAL);
-    set_option_value("modeline", BOOLEAN_OPTVAL(false), OPT_LOCAL);  // 'nomodeline'
+    set_option_value(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("hide"), OPT_LOCAL);
+    set_option_value(kOptBuftype, STATIC_CSTR_AS_OPTVAL("nofile"), OPT_LOCAL);
+    set_option_value(kOptSwapfile, BOOLEAN_OPTVAL(false), OPT_LOCAL);
+    set_option_value(kOptModeline, BOOLEAN_OPTVAL(false), OPT_LOCAL);  // 'nomodeline'
 
     ftbuf->b_p_ft = xstrdup(filetype);
     do_filetype_autocmd(ftbuf, false);
@@ -152,12 +153,14 @@ static buf_T *do_ft_buf(char *filetype, aco_save_T *aco, Error *err)
 Object nvim_get_option_value(String name, Dict(option) *opts, Error *err)
   FUNC_API_SINCE(9)
 {
+  int opt_idx = 0;
   int scope = 0;
   OptReqScope req_scope = kOptReqGlobal;
   void *from = NULL;
   char *filetype = NULL;
 
-  if (!validate_option_value_args(opts, name.data, &scope, &req_scope, &from, &filetype, err)) {
+  if (!validate_option_value_args(opts, name.data, &opt_idx, &scope, &req_scope, &from, &filetype,
+                                  err)) {
     return (Object)OBJECT_INIT;
   }
 
@@ -173,7 +176,6 @@ Object nvim_get_option_value(String name, Dict(option) *opts, Error *err)
     from = ftbuf;
   }
 
-  int opt_idx = findoption(name.data);
   OptVal value = get_option_value_for(opt_idx, scope, req_scope, from, err);
   bool hidden = is_option_hidden(opt_idx);
 
@@ -217,10 +219,11 @@ void nvim_set_option_value(uint64_t channel_id, String name, Object value, Dict(
                            Error *err)
   FUNC_API_SINCE(9)
 {
+  int opt_idx = 0;
   int scope = 0;
   OptReqScope req_scope = kOptReqGlobal;
   void *to = NULL;
-  if (!validate_option_value_args(opts, name.data, &scope, &req_scope, &to, NULL, err)) {
+  if (!validate_option_value_args(opts, name.data, &opt_idx, &scope, &req_scope, &to, NULL, err)) {
     return;
   }
 
@@ -231,7 +234,7 @@ void nvim_set_option_value(uint64_t channel_id, String name, Object value, Dict(
   //
   // Then force scope to local since we don't want to change the global option
   if (req_scope == kOptReqWin && scope == 0) {
-    int flags = get_option_attrs(name.data);
+    int flags = get_option_attrs(opt_idx);
     if (flags & SOPT_GLOBAL) {
       scope = OPT_LOCAL;
     }
@@ -249,7 +252,7 @@ void nvim_set_option_value(uint64_t channel_id, String name, Object value, Dict(
   });
 
   WITH_SCRIPT_CONTEXT(channel_id, {
-    set_option_value_for(name.data, optval, scope, req_scope, to, err);
+    set_option_value_for(name.data, opt_idx, optval, scope, req_scope, to, err);
   });
 }
 
@@ -303,10 +306,12 @@ Dictionary nvim_get_all_options_info(Error *err)
 Dictionary nvim_get_option_info2(String name, Dict(option) *opts, Error *err)
   FUNC_API_SINCE(11)
 {
+  int opt_idx = 0;
   int scope = 0;
   OptReqScope req_scope = kOptReqGlobal;
   void *from = NULL;
-  if (!validate_option_value_args(opts, name.data, &scope, &req_scope, &from, NULL, err)) {
+  if (!validate_option_value_args(opts, name.data, &opt_idx, &scope, &req_scope, &from, NULL,
+                                  err)) {
     return (Dictionary)ARRAY_DICT_INIT;
   }
 
@@ -382,19 +387,13 @@ static void restore_option_context(void *const ctx, OptReqScope req_scope)
 
 /// Get attributes for an option.
 ///
-/// @param  name  Option name.
+/// @param  opt_idx  Option index in options[] table.
 ///
 /// @return  Option attributes.
 ///          0 for hidden or unknown option.
 ///          See SOPT_* in option_defs.h for other flags.
-int get_option_attrs(char *name)
+int get_option_attrs(int opt_idx)
 {
-  if (is_tty_option(name)) {
-    return SOPT_GLOBAL;
-  }
-
-  int opt_idx = findoption(name);
-
   if (opt_idx < 0) {
     return 0;
   }
@@ -422,14 +421,12 @@ int get_option_attrs(char *name)
 
 /// Check if option has a value in the requested scope.
 ///
-/// @param  name       Option name.
+/// @param  opt_idx    Option index in options[] table.
 /// @param  req_scope  Requested option scope. See OptReqScope in option.h.
 ///
 /// @return  true if option has a value in the requested scope, false otherwise.
-static bool option_has_scope(char *name, OptReqScope req_scope)
+static bool option_has_scope(int opt_idx, OptReqScope req_scope)
 {
-  int opt_idx = findoption(name);
-
   if (opt_idx < 0) {
     return false;
   }
@@ -458,7 +455,7 @@ static bool option_has_scope(char *name, OptReqScope req_scope)
 
 /// Get the option value in the requested scope.
 ///
-/// @param       name       Option name.
+/// @param       opt_idx    Option index in options[] table.
 /// @param       req_scope  Requested option scope. See OptReqScope in option.h.
 /// @param[in]   from       Pointer to buffer or window for local option value.
 /// @param[out]  err        Error message, if any.
@@ -466,17 +463,11 @@ static bool option_has_scope(char *name, OptReqScope req_scope)
 /// @return  Option value in the requested scope. Returns a Nil option value if option is not found,
 /// hidden or if it isn't present in the requested scope. (i.e. has no global, window-local or
 /// buffer-local value depending on opt_scope).
-OptVal get_option_value_strict(char *name, OptReqScope req_scope, void *from, Error *err)
+OptVal get_option_value_strict(int opt_idx, OptReqScope req_scope, void *from, Error *err)
 {
-  if (!option_has_scope(name, req_scope)) {
+  if (opt_idx < 0 || !option_has_scope(opt_idx, req_scope)) {
     return NIL_OPTVAL;
   }
-  if (is_tty_option(name)) {
-    return get_tty_option(name);
-  }
-
-  int opt_idx = findoption(name);
-  assert(opt_idx != 0);  // option_has_scope() already verifies if option name is valid.
 
   vimoption_T *opt = get_option(opt_idx);
   switchwin_T switchwin;
@@ -533,14 +524,16 @@ OptVal get_option_value_for(int opt_idx, int scope, const OptReqScope req_scope,
 
 /// Set option value for buffer / window.
 ///
-/// @param[in]   name        Option name.
+/// @param       name        Option name.
+/// @param       opt_idx     Option index in options[] table.
 /// @param[in]   value       Option value.
 /// @param[in]   opt_flags   Flags: OPT_LOCAL, OPT_GLOBAL, or 0 (both).
 /// @param       req_scope   Requested option scope. See OptReqScope in option.h.
 /// @param[in]   from        Target buffer/window.
 /// @param[out]  err         Error message, if any.
-void set_option_value_for(const char *const name, OptVal value, const int opt_flags,
+void set_option_value_for(const char *name, int opt_idx, OptVal value, const int opt_flags,
                           const OptReqScope req_scope, void *const from, Error *err)
+  FUNC_ATTR_NONNULL_ARG(1)
 {
   switchwin_T switchwin;
   aco_save_T aco;
@@ -552,7 +545,7 @@ void set_option_value_for(const char *const name, OptVal value, const int opt_fl
     return;
   }
 
-  const char *const errmsg = set_option_value(name, value, opt_flags);
+  const char *const errmsg = set_option_value_handle_tty(name, opt_idx, value, opt_flags);
   if (errmsg) {
     api_set_error(err, kErrorTypeException, "%s", errmsg);
   }
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 2c937113e3..a52d7493e3 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -948,8 +948,8 @@ Buffer nvim_create_buf(Boolean listed, Boolean scratch, Error *err)
   buf_copy_options(buf, BCO_ENTER | BCO_NOHELP);
 
   if (scratch) {
-    set_string_option_direct_in_buf(buf, "bufhidden", -1, "hide", OPT_LOCAL, 0);
-    set_string_option_direct_in_buf(buf, "buftype", -1, "nofile", OPT_LOCAL, 0);
+    set_string_option_direct_in_buf(buf, kOptBufhidden, "hide", OPT_LOCAL, 0);
+    set_string_option_direct_in_buf(buf, kOptBuftype, "nofile", OPT_LOCAL, 0);
     assert(buf->b_ml.ml_mfp->mf_fd < 0);  // ml_open() should not have opened swapfile already
     buf->b_p_swf = false;
     buf->b_p_ml = false;
@@ -2239,7 +2239,7 @@ Dictionary nvim_eval_statusline(String str, Dict(eval_statusline) *opts, Error *
                                buf,
                                sizeof(buf),
                                str.data,
-                               NULL,
+                               -1,
                                0,
                                fillchar,
                                maxwidth,
diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index 46a08c5706..72b0852d8d 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -704,7 +704,7 @@ char *au_event_disable(char *what)
   } else {
     STRCAT(new_ei, what);
   }
-  set_string_option_direct("ei", -1, new_ei, OPT_FREE, SID_NONE);
+  set_string_option_direct(kOptEventignore, new_ei, OPT_FREE, SID_NONE);
   xfree(new_ei);
   return save_ei;
 }
@@ -712,7 +712,7 @@ char *au_event_disable(char *what)
 void au_event_restore(char *old_ei)
 {
   if (old_ei != NULL) {
-    set_string_option_direct("ei", -1, old_ei, OPT_FREE, SID_NONE);
+    set_string_option_direct(kOptEventignore, old_ei, OPT_FREE, SID_NONE);
     xfree(old_ei);
   }
 }
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index b5fac15af6..0392ff6ebd 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -3281,7 +3281,7 @@ void maketitle(void)
     if (*p_titlestring != NUL) {
       if (stl_syntax & STL_IN_TITLE) {
         build_stl_str_hl(curwin, buf, sizeof(buf), p_titlestring,
-                         "titlestring", 0, 0, maxlen, NULL, NULL, NULL);
+                         kOptTitlestring, 0, 0, maxlen, NULL, NULL, NULL);
         title_str = buf;
       } else {
         title_str = p_titlestring;
@@ -3386,7 +3386,7 @@ void maketitle(void)
     if (*p_iconstring != NUL) {
       if (stl_syntax & STL_IN_ICON) {
         build_stl_str_hl(curwin, icon_str, sizeof(buf), p_iconstring,
-                         "iconstring", 0, 0, 0, NULL, NULL, NULL);
+                         kOptIconstring, 0, 0, 0, NULL, NULL, NULL);
       } else {
         icon_str = p_iconstring;
       }
@@ -4147,9 +4147,9 @@ int buf_open_scratch(handle_T bufnr, char *bufname)
   apply_autocmds(EVENT_BUFFILEPRE, NULL, NULL, false, curbuf);
   (void)setfname(curbuf, bufname, NULL, true);
   apply_autocmds(EVENT_BUFFILEPOST, NULL, NULL, false, curbuf);
-  set_option_value_give_err("bh", STATIC_CSTR_AS_OPTVAL("hide"), OPT_LOCAL);
-  set_option_value_give_err("bt", STATIC_CSTR_AS_OPTVAL("nofile"), OPT_LOCAL);
-  set_option_value_give_err("swf", BOOLEAN_OPTVAL(false), OPT_LOCAL);
+  set_option_value_give_err(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("hide"), OPT_LOCAL);
+  set_option_value_give_err(kOptBuftype, STATIC_CSTR_AS_OPTVAL("nofile"), OPT_LOCAL);
+  set_option_value_give_err(kOptSwapfile, BOOLEAN_OPTVAL(false), OPT_LOCAL);
   RESET_BINDING(curwin);
   return OK;
 }
diff --git a/src/nvim/context.c b/src/nvim/context.c
index 63c0f8c20c..dfb214d065 100644
--- a/src/nvim/context.c
+++ b/src/nvim/context.c
@@ -138,8 +138,8 @@ bool ctx_restore(Context *ctx, const int flags)
     free_ctx = true;
   }
 
-  OptVal op_shada = get_option_value(findoption("shada"), OPT_GLOBAL);
-  set_option_value("shada", STATIC_CSTR_AS_OPTVAL("!,'100,%"), OPT_GLOBAL);
+  OptVal op_shada = get_option_value(kOptShada, OPT_GLOBAL);
+  set_option_value(kOptShada, STATIC_CSTR_AS_OPTVAL("!,'100,%"), OPT_GLOBAL);
 
   if (flags & kCtxRegs) {
     ctx_restore_regs(ctx);
@@ -165,7 +165,7 @@ bool ctx_restore(Context *ctx, const int flags)
     ctx_free(ctx);
   }
 
-  set_option_value("shada", op_shada, OPT_GLOBAL);
+  set_option_value(kOptShada, op_shada, OPT_GLOBAL);
   optval_free(op_shada);
 
   return true;
diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 6578a1121c..483182dc25 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -1389,7 +1389,7 @@ static void set_diff_option(win_T *wp, bool value)
   curwin = wp;
   curbuf = curwin->w_buffer;
   curbuf->b_ro_locked++;
-  set_option_value_give_err("diff", BOOLEAN_OPTVAL(value), OPT_LOCAL);
+  set_option_value_give_err(kOptDiff, BOOLEAN_OPTVAL(value), OPT_LOCAL);
   curbuf->b_ro_locked--;
   curwin = old_curwin;
   curbuf = curwin->w_buffer;
@@ -1430,7 +1430,7 @@ void diff_win_options(win_T *wp, int addbuf)
     }
     wp->w_p_fdm_save = xstrdup(wp->w_p_fdm);
   }
-  set_string_option_direct_in_win(wp, "fdm", -1, "diff", OPT_LOCAL | OPT_FREE, 0);
+  set_string_option_direct_in_win(wp, kOptFoldmethod, "diff", OPT_LOCAL | OPT_FREE, 0);
 
   if (!wp->w_p_diff) {
     wp->w_p_fen_save = wp->w_p_fen;
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 2bbc8b58e7..1c30075991 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -681,7 +681,7 @@ int eval_charconvert(const char *const enc_from, const char *const enc_to,
   set_vim_var_string(VV_CC_TO, enc_to, -1);
   set_vim_var_string(VV_FNAME_IN, fname_from, -1);
   set_vim_var_string(VV_FNAME_OUT, fname_to, -1);
-  sctx_T *ctx = get_option_sctx("charconvert");
+  sctx_T *ctx = get_option_sctx(kOptCharconvert);
   if (ctx != NULL) {
     current_sctx = *ctx;
   }
@@ -710,7 +710,7 @@ void eval_diff(const char *const origfile, const char *const newfile, const char
   set_vim_var_string(VV_FNAME_NEW, newfile, -1);
   set_vim_var_string(VV_FNAME_OUT, outfile, -1);
 
-  sctx_T *ctx = get_option_sctx("diffexpr");
+  sctx_T *ctx = get_option_sctx(kOptDiffexpr);
   if (ctx != NULL) {
     current_sctx = *ctx;
   }
@@ -732,7 +732,7 @@ void eval_patch(const char *const origfile, const char *const difffile, const ch
   set_vim_var_string(VV_FNAME_DIFF, difffile, -1);
   set_vim_var_string(VV_FNAME_OUT, outfile, -1);
 
-  sctx_T *ctx = get_option_sctx("patchexpr");
+  sctx_T *ctx = get_option_sctx(kOptPatchexpr);
   if (ctx != NULL) {
     current_sctx = *ctx;
   }
@@ -1134,7 +1134,7 @@ list_T *eval_spell_expr(char *badword, char *expr)
   if (p_verbose == 0) {
     emsg_off++;
   }
-  sctx_T *ctx = get_option_sctx("spellsuggest");
+  sctx_T *ctx = get_option_sctx(kOptSpellsuggest);
   if (ctx != NULL) {
     current_sctx = *ctx;
   }
@@ -1278,7 +1278,7 @@ void *call_func_retlist(const char *func, int argc, typval_T *argv)
 int eval_foldexpr(win_T *wp, int *cp)
 {
   const sctx_T saved_sctx = current_sctx;
-  const bool use_sandbox = was_set_insecurely(wp, "foldexpr", OPT_LOCAL);
+  const bool use_sandbox = was_set_insecurely(wp, kOptFoldexpr, OPT_LOCAL);
 
   char *arg = wp->w_p_fde;
   current_sctx = wp->w_p_script_ctx[WV_FDE].script_ctx;
@@ -1326,7 +1326,7 @@ int eval_foldexpr(win_T *wp, int *cp)
 /// Evaluate 'foldtext', returning an Array or a String (NULL_STRING on failure).
 Object eval_foldtext(win_T *wp)
 {
-  const bool use_sandbox = was_set_insecurely(wp, "foldtext", OPT_LOCAL);
+  const bool use_sandbox = was_set_insecurely(wp, kOptFoldtext, OPT_LOCAL);
   char *arg = wp->w_p_fdt;
   funccal_entry_T funccal_entry;
 
@@ -8715,7 +8715,7 @@ char *do_string_sub(char *str, char *pat, char *sub, typval_T *expr, const char
     // If it's still empty it was changed and restored, need to restore in
     // the complicated way.
     if (*p_cpo == NUL) {
-      set_option_value_give_err("cpo", CSTR_AS_OPTVAL(save_cpo), 0);
+      set_option_value_give_err(kOptCpoptions, CSTR_AS_OPTVAL(save_cpo), 0);
     }
     free_string_option(save_cpo);
   }
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index b4f0be85e5..c35e0b2ada 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -7239,7 +7239,7 @@ int do_searchpair(const char *spat, const char *mpat, const char *epat, int dir,
     // If it's still empty it was changed and restored, need to restore in
     // the complicated way.
     if (*p_cpo == NUL) {
-      set_option_value_give_err("cpo", CSTR_AS_OPTVAL(save_cpo), 0);
+      set_option_value_give_err(kOptCpoptions, CSTR_AS_OPTVAL(save_cpo), 0);
     }
     free_string_option(save_cpo);
   }
diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
index 8864edbf69..9b7a61f969 100644
--- a/src/nvim/eval/vars.c
+++ b/src/nvim/eval/vars.c
@@ -834,7 +834,7 @@ static char *ex_let_option(char *arg, typval_T *const tv, const bool is_const,
     }
   }
 
-  const char *err = set_option_value(arg, newval, scope);
+  const char *err = set_option_value_handle_tty(arg, opt_idx, newval, scope);
   arg_end = p;
   if (err != NULL) {
     emsg(_(err));
@@ -1945,15 +1945,18 @@ static void set_option_from_tv(const char *varname, typval_T *varp)
     semsg(_(e_unknown_option2), varname);
     return;
   }
-  uint32_t opt_p_flags = get_option(opt_idx)->flags;
 
   bool error = false;
+  uint32_t opt_p_flags = get_option_flags(opt_idx);
   OptVal value = tv_to_optval(varp, varname, opt_p_flags, &error);
 
   if (!error) {
-    set_option_value_give_err(varname, value, OPT_LOCAL);
-  }
+    const char *errmsg = set_option_value_handle_tty(varname, opt_idx, value, OPT_LOCAL);
 
+    if (errmsg) {
+      emsg(errmsg);
+    }
+  }
   optval_free(value);
 }
 
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 68c316fde0..786612070e 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -4265,7 +4265,7 @@ skip:
   // Show 'inccommand' preview if there are matched lines.
   if (cmdpreview_ns > 0 && !aborting()) {
     if (got_quit || profile_passed_limit(timeout)) {  // Too slow, disable.
-      set_string_option_direct("icm", -1, "", OPT_FREE, SID_NONE);
+      set_string_option_direct(kOptInccommand, "", OPT_FREE, SID_NONE);
     } else if (*p_icm != NUL && pat != NULL) {
       if (pre_hl_id == 0) {
         pre_hl_id = syn_check_group(S_LEN("Substitute"));
@@ -4544,8 +4544,8 @@ bool prepare_tagpreview(bool undo_sync)
   curwin->w_p_wfh = true;
   RESET_BINDING(curwin);                // don't take over 'scrollbind' and 'cursorbind'
   curwin->w_p_diff = false;             // no 'diff'
-  set_string_option_direct("fdc", -1,     // no 'foldcolumn'
-                           "0", OPT_FREE, SID_NONE);
+
+  set_string_option_direct(kOptFoldcolumn, "0", OPT_FREE, SID_NONE);  // no 'foldcolumn'
   return true;
 }
 
@@ -4564,7 +4564,7 @@ static int show_sub(exarg_T *eap, pos_T old_cusr, PreviewLines *preview_lines, i
   buf_T *cmdpreview_buf = NULL;
 
   // disable file info message
-  set_string_option_direct("shm", -1, "F", OPT_FREE, SID_NONE);
+  set_string_option_direct(kOptShortmess, "F", OPT_FREE, SID_NONE);
 
   // Update the topline to ensure that main window is on the correct line
   update_topline(curwin);
@@ -4665,7 +4665,7 @@ static int show_sub(exarg_T *eap, pos_T old_cusr, PreviewLines *preview_lines, i
 
   xfree(str);
 
-  set_string_option_direct("shm", -1, save_shm_p, OPT_FREE, SID_NONE);
+  set_string_option_direct(kOptShortmess, save_shm_p, OPT_FREE, SID_NONE);
   xfree(save_shm_p);
 
   return preview ? 2 : 1;
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 90b816bb6f..ff80ee9e54 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -2653,7 +2653,7 @@ static void apply_cmdmod(cmdmod_T *cmod)
     // Set 'eventignore' to "all".
     // First save the existing option value for restoring it later.
     cmod->cmod_save_ei = xstrdup(p_ei);
-    set_string_option_direct("ei", -1, "all", OPT_FREE, SID_NONE);
+    set_string_option_direct(kOptEventignore, "all", OPT_FREE, SID_NONE);
   }
 }
 
@@ -2673,7 +2673,7 @@ void undo_cmdmod(cmdmod_T *cmod)
 
   if (cmod->cmod_save_ei != NULL) {
     // Restore 'eventignore' to the value before ":noautocmd".
-    set_string_option_direct("ei", -1, cmod->cmod_save_ei, OPT_FREE, SID_NONE);
+    set_string_option_direct(kOptEventignore, cmod->cmod_save_ei, OPT_FREE, SID_NONE);
     free_string_option(cmod->cmod_save_ei);
     cmod->cmod_save_ei = NULL;
   }
@@ -7306,7 +7306,7 @@ static void ex_setfiletype(exarg_T *eap)
     arg += 9;
   }
 
-  set_option_value_give_err("filetype", CSTR_AS_OPTVAL(arg), OPT_LOCAL);
+  set_option_value_give_err(kOptFiletype, CSTR_AS_OPTVAL(arg), OPT_LOCAL);
   if (arg != eap->arg) {
     did_filetype = false;
   }
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 14d230331a..afaf0a6e2b 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -905,7 +905,7 @@ static uint8_t *command_line_enter(int firstc, int count, int indent, bool clear
     need_wait_return = false;
   }
 
-  set_string_option_direct("icm", -1, s->save_p_icm, OPT_FREE, SID_NONE);
+  set_string_option_direct(kOptInccommand, s->save_p_icm, OPT_FREE, SID_NONE);
   State = s->save_State;
   if (cmdpreview != save_cmdpreview) {
     cmdpreview = save_cmdpreview;  // restore preview state
@@ -4326,7 +4326,7 @@ static int open_cmdwin(void)
     return Ctrl_C;
   }
   // Command-line buffer has bufhidden=wipe, unlike a true "scratch" buffer.
-  set_option_value_give_err("bh", STATIC_CSTR_AS_OPTVAL("wipe"), OPT_LOCAL);
+  set_option_value_give_err(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("wipe"), OPT_LOCAL);
   curbuf->b_p_ma = true;
   curwin->w_p_fen = false;
   curwin->w_p_rl = cmdmsg_rl;
@@ -4344,7 +4344,7 @@ static int open_cmdwin(void)
       add_map("<Tab>", "<C-X><C-V>", MODE_INSERT, true);
       add_map("<Tab>", "a<C-X><C-V>", MODE_NORMAL, true);
     }
-    set_option_value_give_err("ft", STATIC_CSTR_AS_OPTVAL("vim"), OPT_LOCAL);
+    set_option_value_give_err(kOptFiletype, STATIC_CSTR_AS_OPTVAL("vim"), OPT_LOCAL);
   }
   curbuf->b_ro_locked--;
 
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 4fe5b1cd44..0e2959835b 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -1617,7 +1617,7 @@ failed:
     save_file_ff(curbuf);
     // If editing a new file: set 'fenc' for the current buffer.
     // Also for ":read ++edit file".
-    set_string_option_direct("fenc", -1, fenc, OPT_FREE | OPT_LOCAL, 0);
+    set_string_option_direct(kOptFileencoding, fenc, OPT_FREE | OPT_LOCAL, 0);
   }
   if (fenc_alloced) {
     xfree(fenc);
@@ -1965,7 +1965,7 @@ void set_forced_fenc(exarg_T *eap)
   }
 
   char *fenc = enc_canonize(eap->cmd + eap->force_enc);
-  set_string_option_direct("fenc", -1, fenc, OPT_FREE|OPT_LOCAL, 0);
+  set_string_option_direct(kOptFileencoding, fenc, OPT_FREE|OPT_LOCAL, 0);
   xfree(fenc);
 }
 
diff --git a/src/nvim/generators/gen_options.lua b/src/nvim/generators/gen_options.lua
index 3a355634f3..2b17add7ba 100644
--- a/src/nvim/generators/gen_options.lua
+++ b/src/nvim/generators/gen_options.lua
@@ -1,4 +1,5 @@
 local options_file = arg[1]
+local options_enum_file = arg[2]
 
 local opt_fd = assert(io.open(options_file, 'w'))<