refactor(options): set option value for non-current context directly

Problem: Currently, we use `switch_option_context` to temporarily switch the current option context before setting an option for a different buffer / window. This is not ideal because we already support getting and setting option values for non-current contexts in the underlying implementation.

Solution: Set option value for non-current context by passing the context directly to the lower level functions. Also introduce a new `OptCtx` struct to store option context information, this will scale much better if we add more option scopes and other context information in the future.

11 files changed, 406 insertions, 480 deletions

diff --git a/src/nvim/api/deprecated.c b/src/nvim/api/deprecated.c
index d5eddb74de..47a49436ab 100644
--- a/src/nvim/api/deprecated.c
+++ b/src/nvim/api/deprecated.c
@@ -649,8 +649,8 @@ static Object get_option_from(void *from, OptScope scope, String name, Error *er
   OptVal value = NIL_OPTVAL;
 
   if (option_has_scope(opt_idx, scope)) {
-    value = get_option_value_for(opt_idx, scope == kOptScopeGlobal ? OPT_GLOBAL : OPT_LOCAL,
-                                 scope, from, err);
+    value = get_option_value_from(opt_idx, option_ctx_from(scope, from),
+                                  scope == kOptScopeGlobal ? OPT_GLOBAL : OPT_LOCAL);
     if (ERROR_SET(err)) {
       return (Object)OBJECT_INIT;
     }
@@ -701,7 +701,11 @@ static void set_option_to(uint64_t channel_id, void *to, OptScope scope, String
       : ((scope == kOptScopeGlobal) ? OPT_GLOBAL : OPT_LOCAL);
 
   WITH_SCRIPT_CONTEXT(channel_id, {
-    set_option_value_for(name.data, opt_idx, optval, opt_flags, scope, to, err);
+    const char *errmsg
+      = set_option_value_for(opt_idx, optval, option_ctx_from(scope, to), opt_flags);
+    if (errmsg) {
+      api_set_error(err, kErrorTypeException, "%s", errmsg);
+    }
   });
 }
 
diff --git a/src/nvim/api/options.c b/src/nvim/api/options.c
index 64f8a35d54..2bbbdbbe8c 100644
--- a/src/nvim/api/options.c
+++ b/src/nvim/api/options.c
@@ -157,8 +157,8 @@ Object nvim_get_option_value(String name, Dict(option) *opts, Error *err)
   void *from = NULL;
   char *filetype = NULL;
 
-  if (!validate_option_value_args(opts, name.data, &opt_idx, &opt_flags, &scope, &from,
-                                  &filetype, err)) {
+  if (!validate_option_value_args(opts, name.data, &opt_idx, &opt_flags, &scope, &from, &filetype,
+                                  err)) {
     return (Object)OBJECT_INIT;
   }
 
@@ -182,7 +182,7 @@ Object nvim_get_option_value(String name, Dict(option) *opts, Error *err)
     from = ftbuf;
   }
 
-  OptVal value = get_option_value_for(opt_idx, opt_flags, scope, from, err);
+  OptVal value = get_option_value_from(opt_idx, option_ctx_from(scope, from), opt_flags);
 
   if (ftbuf != NULL) {
     // restore curwin/curbuf and a few other things
@@ -257,7 +257,11 @@ 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, opt_idx, optval, opt_flags, scope, to, err);
+    const char *errmsg
+      = set_option_value_for(opt_idx, optval, option_ctx_from(scope, to), 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 25f44bb4eb..108d1ee98d 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -982,10 +982,10 @@ Buffer nvim_create_buf(Boolean listed, Boolean scratch, Error *err)
     buf_copy_options(buf, BCO_ENTER | BCO_NOHELP);
 
     if (scratch) {
-      set_option_direct_for(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("hide"), OPT_LOCAL, 0,
-                            kOptScopeBuf, buf);
-      set_option_direct_for(kOptBuftype, STATIC_CSTR_AS_OPTVAL("nofile"), OPT_LOCAL, 0,
-                            kOptScopeBuf, buf);
+      set_option_direct_for(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("hide"),
+                            option_ctx_from(kOptScopeBuf, buf), OPT_LOCAL, 0);
+      set_option_direct_for(kOptBuftype, STATIC_CSTR_AS_OPTVAL("nofile"),
+                            option_ctx_from(kOptScopeBuf, buf), 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;
diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index bd98a31a71..ebeb9ba088 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -1391,8 +1391,8 @@ void diff_win_options(win_T *wp, bool addbuf)
     }
     wp->w_p_fdm_save = xstrdup(wp->w_p_fdm);
   }
-  set_option_direct_for(kOptFoldmethod, STATIC_CSTR_AS_OPTVAL("diff"), OPT_LOCAL, 0,
-                        kOptScopeWin, wp);
+  set_option_direct_for(kOptFoldmethod, STATIC_CSTR_AS_OPTVAL("diff"),
+                        option_ctx_from(kOptScopeWin, wp), OPT_LOCAL, 0);
 
   if (!wp->w_p_diff) {
     wp->w_p_fen_save = wp->w_p_fen;
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 551e8fcb1d..8ee9967465 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -5294,7 +5294,7 @@ static char *findfunc_find_file(char *findarg, size_t findarg_len, int count)
 /// Returns NULL on success and an error message on failure.
 const char *did_set_findfunc(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   int retval;
 
   if (args->os_flags & OPT_LOCAL) {
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 7245b0d6ce..908294872f 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -2398,7 +2398,7 @@ static void copy_global_to_buflocal_cb(Callback *globcb, Callback *bufcb)
 /// lambda expression.
 const char *did_set_completefunc(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   if (option_set_callback_func(buf->b_p_cfu, &cfu_cb) == FAIL) {
     return e_invarg;
   }
@@ -2419,7 +2419,7 @@ void set_buflocal_cfu_callback(buf_T *buf)
 /// lambda expression.
 const char *did_set_omnifunc(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   if (option_set_callback_func(buf->b_p_ofu, &ofu_cb) == FAIL) {
     return e_invarg;
   }
@@ -2440,7 +2440,7 @@ void set_buflocal_ofu_callback(buf_T *buf)
 /// lambda expression.
 const char *did_set_thesaurusfunc(optset_T *args FUNC_ATTR_UNUSED)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   int retval;
 
   if (args->os_flags & OPT_LOCAL) {
diff --git a/src/nvim/option.c b/src/nvim/option.c
index a59e55121f..b8f727cede 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -1322,7 +1322,8 @@ static void do_one_set_option(int opt_flags, char **argp, bool *did_show, char *
     return;
   }
 
-  *errmsg = set_option(opt_idx, newval, opt_flags, 0, false, op == OP_NONE, errbuf, errbuflen);
+  *errmsg = set_option_for(opt_idx, newval, option_ctx(), opt_flags, 0, false,
+                           op == OP_NONE, errbuf, errbuflen);
 }
 
 /// Parse 'arg' for option settings.
@@ -1842,7 +1843,7 @@ void set_option_sctx(OptIndex opt_idx, int opt_flags, sctx_T script_ctx)
 
 /// Apply the OptionSet autocommand.
 static void apply_optionset_autocmd(OptIndex opt_idx, int opt_flags, OptVal oldval, OptVal oldval_g,
-                                    OptVal oldval_l, OptVal newval, const char *errmsg)
+                                    OptVal oldval_l, OptVal newval, OptCtx ctx, const char *errmsg)
 {
   // Don't do this while starting up, failure or recursively.
   if (starting || errmsg != NULL || *get_vim_var_str(VV_OPTION_TYPE) != NUL) {
@@ -1876,14 +1877,18 @@ static void apply_optionset_autocmd(OptIndex opt_idx, int opt_flags, OptVal oldv
     set_vim_var_string(VV_OPTION_COMMAND, "modeline", -1);
     set_vim_var_tv(VV_OPTION_OLDLOCAL, &oldval_tv);
   }
-  apply_autocmds(EVENT_OPTIONSET, options[opt_idx].fullname, NULL, false, NULL);
+
+  WITH_AUCMD_CONTEXT(ctx, {
+    apply_autocmds(EVENT_OPTIONSET, options[opt_idx].fullname, NULL, false, NULL);
+  });
+
   reset_v_option_vars();
 }
 
 /// Process the updated 'arabic' option value.
 static const char *did_set_arabic(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   const char *errmsg = NULL;
 
   if (win->w_p_arab) {
@@ -1952,7 +1957,7 @@ static const char *did_set_autochdir(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the updated 'binary' option value.
 static const char *did_set_binary(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
 
   // when 'bin' is set also set some other options
   set_options_bin((int)args->os_oldval.boolean, buf->b_p_bin, args->os_flags);
@@ -1964,7 +1969,7 @@ static const char *did_set_binary(optset_T *args)
 /// Process the updated 'buflisted' option value.
 static const char *did_set_buflisted(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
 
   // when 'buflisted' changes, trigger autocommands
   if (args->os_oldval.boolean != buf->b_p_bl) {
@@ -1998,7 +2003,7 @@ static const char *did_set_cmdheight(optset_T *args)
 /// Process the updated 'diff' option value.
 static const char *did_set_diff(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   // May add or remove the buffer from the list of diff buffers.
   diff_buf_adjust(win);
   if (foldmethodIsDiff(win)) {
@@ -2019,7 +2024,7 @@ static const char *did_set_eof_eol_fixeol_bomb(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the updated 'equalalways' option value.
 static const char *did_set_equalalways(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   if (p_ea && !args->os_oldval.boolean) {
     win_equal(win, false, 0);
   }
@@ -2037,7 +2042,7 @@ static const char *did_set_foldlevel(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the new 'foldminlines' option value.
 static const char *did_set_foldminlines(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   foldUpdateAll(win);
   return NULL;
 }
@@ -2045,7 +2050,7 @@ static const char *did_set_foldminlines(optset_T *args)
 /// Process the new 'foldnestmax' option value.
 static const char *did_set_foldnestmax(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   if (foldmethodIsSyntax(win) || foldmethodIsIndent(win)) {
     foldUpdateAll(win);
   }
@@ -2174,7 +2179,7 @@ static const char *did_set_lines_or_columns(optset_T *args)
 /// Process the updated 'lisp' option value.
 static const char *did_set_lisp(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   // When 'lisp' option changes include/exclude '-' in keyword characters.
   buf_init_chartab(buf, false);          // ignore errors
   return NULL;
@@ -2192,7 +2197,7 @@ static const char *did_set_modifiable(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the updated 'modified' option value.
 static const char *did_set_modified(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   if (!args->os_newval.boolean) {
     save_file_ff(buf);  // Buffer is unchanged
   }
@@ -2204,7 +2209,7 @@ static const char *did_set_modified(optset_T *args)
 /// Process the updated 'number' or 'relativenumber' option value.
 static const char *did_set_number_relativenumber(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   if (*win->w_p_stc != NUL) {
     // When 'relativenumber'/'number' is changed and 'statuscolumn' is set, reset width.
     win->w_nrwidth_line_count = 0;
@@ -2216,7 +2221,7 @@ static const char *did_set_number_relativenumber(optset_T *args)
 /// Process the new 'numberwidth' option value.
 static const char *did_set_numberwidth(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   win->w_nrwidth_line_count = 0;  // trigger a redraw
 
   return NULL;
@@ -2354,7 +2359,7 @@ static const char *did_set_paste(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the updated 'previewwindow' option value.
 static const char *did_set_previewwindow(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
 
   if (!win->w_p_pvw) {
     return NULL;
@@ -2386,7 +2391,7 @@ static const char *did_set_pumblend(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the updated 'readonly' option value.
 static const char *did_set_readonly(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
 
   // when 'readonly' is reset globally, also reset readonlymode
   if (!buf->b_p_ro && (args->os_flags & OPT_LOCAL) == 0) {
@@ -2406,7 +2411,7 @@ static const char *did_set_readonly(optset_T *args)
 /// Process the new 'scrollback' option value.
 static const char *did_set_scrollback(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   OptInt old_value = args->os_oldval.number;
   OptInt value = args->os_newval.number;
 
@@ -2420,7 +2425,7 @@ static const char *did_set_scrollback(optset_T *args)
 /// Process the updated 'scrollbind' option value.
 static const char *did_set_scrollbind(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
 
   // when 'scrollbind' is set: snapshot the current position to avoid a jump
   // at the end of normal_cmd()
@@ -2457,8 +2462,8 @@ static const char *did_set_shellslash(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the new 'shiftwidth' or the 'tabstop' option value.
 static const char *did_set_shiftwidth_tabstop(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
-  win_T *win = (win_T *)args->os_win;
+  buf_T *buf = args->os_ctx.buf;
+  win_T *win = args->os_ctx.win;
   OptInt *pp = (OptInt *)args->os_varp;
 
   if (foldmethodIsIndent(win)) {
@@ -2484,7 +2489,7 @@ static const char *did_set_showtabline(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the updated 'smoothscroll' option value.
 static const char *did_set_smoothscroll(optset_T *args FUNC_ATTR_UNUSED)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   if (!win->w_p_sms) {
     win->w_skipcol = 0;
   }
@@ -2495,7 +2500,7 @@ static const char *did_set_smoothscroll(optset_T *args FUNC_ATTR_UNUSED)
 /// Process the updated 'spell' option value.
 static const char *did_set_spell(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   if (win->w_p_spell) {
     return parse_spelllang(win);
   }
@@ -2506,7 +2511,7 @@ static const char *did_set_spell(optset_T *args)
 /// Process the updated 'swapfile' option value.
 static const char *did_set_swapfile(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   // when 'swf' is set, create swapfile, when reset remove swapfile
   if (buf->b_p_swf && p_uc) {
     ml_open_file(buf);                     // create the swap file
@@ -2551,7 +2556,7 @@ static const char *did_set_titlelen(optset_T *args)
 /// Process the updated 'undofile' option value.
 static const char *did_set_undofile(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
 
   // Only take action when the option was set.
   if (!buf->b_p_udf && !p_udf) {
@@ -2602,7 +2607,7 @@ const char *did_set_buflocal_undolevels(buf_T *buf, OptInt value, OptInt old_val
 /// Process the new 'undolevels' option value.
 static const char *did_set_undolevels(optset_T *args)
 {
-  buf_T *buf = (buf_T *)args->os_buf;
+  buf_T *buf = args->os_ctx.buf;
   OptInt *pp = (OptInt *)args->os_varp;
 
   if (pp == &p_ul) {                  // global 'undolevels'
@@ -2643,7 +2648,7 @@ static const char *did_set_wildchar(optset_T *args)
 /// Process the new 'winblend' option value.
 static const char *did_set_winblend(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   OptInt old_value = args->os_oldval.number;
   OptInt value = args->os_newval.number;
 
@@ -2692,7 +2697,7 @@ static const char *did_set_winwidth(optset_T *args)
 /// Process the updated 'wrap' option value.
 static const char *did_set_wrap(optset_T *args)
 {
-  win_T *win = (win_T *)args->os_win;
+  win_T *win = args->os_ctx.win;
   // Set w_leftcol or w_skipcol to zero.
   if (win->w_p_wrap) {
     win->w_leftcol = 0;
@@ -3143,12 +3148,6 @@ static OptValType option_get_type(const OptIndex opt_idx)
 OptVal optval_from_varp(OptIndex opt_idx, void *varp)
   FUNC_ATTR_NONNULL_ARG(2)
 {
-  // Special case: 'modified' is b_changed, but we also want to consider it set when 'ff' or 'fenc'
-  // changed.
-  if ((int *)varp == &curbuf->b_changed) {
-    return BOOLEAN_OPTVAL(curbufIsChanged());
-  }
-
   if (option_is_multitype(opt_idx)) {
     // Multitype options are stored as OptVal.
     return *(OptVal *)varp;
@@ -3381,21 +3380,37 @@ uint32_t get_option_flags(OptIndex opt_idx)
 /// Gets the value for an option.
 ///
 /// @param  opt_idx    Option index in options[] table.
+/// @param  ctx        Context to get the option value from.
 /// @param  opt_flags  Option flags (can be OPT_LOCAL, OPT_GLOBAL or a combination).
 ///
 /// @return [allocated] Option value. Returns NIL_OPTVAL for invalid option index.
-OptVal get_option_value(OptIndex opt_idx, int opt_flags)
+OptVal get_option_value_from(OptIndex opt_idx, OptCtx ctx, int opt_flags)
 {
   if (opt_idx == kOptInvalid) {  // option not in the options[] table.
     return NIL_OPTVAL;
   }
 
-  vimoption_T *opt = &options[opt_idx];
-  void *varp = get_varp_scope(opt, opt_flags);
+  // Special case: 'modified' is b_changed, but we also want to consider it set when 'ff' or 'fenc'
+  // changed.
+  if (opt_idx == kOptModified) {
+    return BOOLEAN_OPTVAL(bufIsChanged(ctx.buf));
+  }
 
+  void * const varp = get_varp_scope_from(&options[opt_idx], opt_flags, ctx);
   return optval_copy(optval_from_varp(opt_idx, varp));
 }
 
+/// Gets the value for an option in the current context.
+///
+/// @param  opt_idx  Option index in options[] table.
+/// @param  opt_flags  Option flags (can be OPT_LOCAL, OPT_GLOBAL or a combination).
+///
+/// @return [allocated] Option value. Returns NIL_OPTVAL for invalid option index.
+OptVal get_option_value(OptIndex opt_idx, int opt_flags)
+{
+  return get_option_value_from(opt_idx, option_ctx(), opt_flags);
+}
+
 /// Return information for option at 'opt_idx'
 vimoption_T *get_option(OptIndex opt_idx)
 {
@@ -3464,6 +3479,8 @@ static bool is_option_local_value_unset(OptIndex opt_idx)
 /// @param       opt_idx         Index in options[] table. Must not be kOptInvalid.
 /// @param[in]   varp            Option variable pointer, cannot be NULL.
 /// @param       old_value       Old option value.
+/// @param       new_value       New option value.
+/// @param       ctx             Context in which the option is set.
 /// @param       opt_flags       Option flags (can be OPT_LOCAL, OPT_GLOBAL or a combination).
 /// @param       set_sid         Script ID. Special values:
 ///                                0: Use current script ID.
@@ -3475,8 +3492,9 @@ static bool is_option_local_value_unset(OptIndex opt_idx)
 ///
 /// @return  NULL on success, an untranslated error message on error.
 static const char *did_set_option(OptIndex opt_idx, void *varp, OptVal old_value, OptVal new_value,
-                                  int opt_flags, scid_T set_sid, const bool direct,
-                                  const bool value_replaced, char *errbuf, size_t errbuflen)
+                                  OptCtx ctx, int opt_flags, scid_T set_sid, const bool direct,
+                                  const bool value_replaced, char *errbuf,  // NOLINT(readability-non-const-parameter)
+                                  size_t errbuflen)
 {
   vimoption_T *opt = &options[opt_idx];
   const char *errmsg = NULL;
@@ -3495,8 +3513,7 @@ static const char *did_set_option(OptIndex opt_idx, void *varp, OptVal old_value
     .os_restore_chartab = false,
     .os_errbuf = errbuf,
     .os_errbuflen = errbuflen,
-    .os_buf = curbuf,
-    .os_win = curwin
+    .os_ctx = ctx,
   };
 
   if (direct) {
@@ -3533,7 +3550,7 @@ static const char *did_set_option(OptIndex opt_idx, void *varp, OptVal old_value
     set_option_varp(opt_idx, varp, old_value, true);
     // When resetting some values, need to act on it.
     if (restore_chartab) {
-      buf_init_chartab(curbuf, true);
+      buf_init_chartab(ctx.buf, true);
     }
 
     return errmsg;
@@ -3564,12 +3581,12 @@ static const char *did_set_option(OptIndex opt_idx, void *varp, OptVal old_value
     if (option_is_global_local(opt_idx)) {
       // Global option with local value set to use global value.
       // Free the local value and clear it.
-      void *varp_local = get_varp_scope(opt, OPT_LOCAL);
+      void *varp_local = get_varp_scope_from(opt, OPT_LOCAL, ctx);
       OptVal local_unset_value = get_option_unset_value(opt_idx);
       set_option_varp(opt_idx, varp_local, optval_copy(local_unset_value), true);
     } else {
       // May set global value for local option.
-      void *varp_global = get_varp_scope(opt, OPT_GLOBAL);
+      void *varp_global = get_varp_scope_from(opt, OPT_GLOBAL, ctx);
       set_option_varp(opt_idx, varp_global, optval_copy(new_value), true);
     }
   }
@@ -3580,17 +3597,23 @@ static const char *did_set_option(OptIndex opt_idx, void *varp, OptVal old_value
   }
 
   // Trigger the autocommand only after setting the flags.
-  if (varp == &curbuf->b_p_syn) {
-    do_syntax_autocmd(curbuf, value_changed);
-  } else if (varp == &curbuf->b_p_ft) {
+  if (varp == &ctx.buf->b_p_syn) {
+    WITH_AUCMD_CONTEXT(ctx, {
+      do_syntax_autocmd(ctx.buf, value_changed);
+    });
+  } else if (varp == &ctx.buf->b_p_ft) {
     // 'filetype' is set, trigger the FileType autocommand
     // Skip this when called from a modeline
     // Force autocmd when the filetype was changed
     if (!(opt_flags & OPT_MODELINE) || value_changed) {
-      do_filetype_autocmd(curbuf, value_changed);
+      WITH_AUCMD_CONTEXT(ctx, {
+        do_filetype_autocmd(ctx.buf, value_changed);
+      });
     }
-  } else if (varp == &curwin->w_s->b_p_spl) {
-    do_spelllang_source(curwin);
+  } else if (varp == &ctx.win->w_s->b_p_spl) {
+    WITH_AUCMD_CONTEXT(ctx, {
+      do_spelllang_source(ctx.win);
+    });
   }
 
   // In case 'ruler' or 'showcmd' or 'columns' or 'ls' changed.
@@ -3598,25 +3621,25 @@ static const char *did_set_option(OptIndex opt_idx, void *varp, OptVal old_value
 
   if (varp == &p_mouse) {
     setmouse();  // in case 'mouse' changed
-  } else if ((varp == &p_flp || varp == &(curbuf->b_p_flp)) && curwin->w_briopt_list) {
+  } else if ((varp == &p_flp || varp == &(ctx.buf->b_p_flp)) && ctx.win->w_briopt_list) {
     // Changing Formatlistpattern when briopt includes the list setting:
     // redraw
     redraw_all_later(UPD_NOT_VALID);
-  } else if (varp == &p_wbr || varp == &(curwin->w_p_wbr)) {
+  } else if (varp == &p_wbr || varp == &(ctx.win->w_p_wbr)) {
     // add / remove window bars for 'winbar'
     set_winbar(true);
   }
 
-  if (curwin->w_curswant != MAXCOL
+  if (ctx.win->w_curswant != MAXCOL
       && (opt->flags & (kOptFlagCurswant | kOptFlagRedrAll)) != 0
       && (opt->flags & kOptFlagHLOnly) == 0) {
-    curwin->w_set_curswant = true;
+    ctx.win->w_set_curswant = true;
   }
 
-  check_redraw(opt->flags);
+  check_redraw_for(ctx.buf, ctx.win, opt->flags);
 
   if (errmsg == NULL) {
-    uint32_t *p = insecure_flag(curwin, opt_idx, opt_flags);
+    uint32_t *p = insecure_flag(ctx.win, opt_idx, opt_flags);
     opt->flags |= kOptFlagWasSet;
 
     // When an option is set in the sandbox, from a modeline or in secure mode set the kOptFlagInsecure
@@ -3676,6 +3699,7 @@ static const char *validate_option_value(const OptIndex opt_idx, OptVal *newval,
 ///
 /// @param       opt_idx         Index in options[] table. Must not be kOptInvalid.
 /// @param       value           New option value. Might get freed.
+/// @param       ctx             Context in which the option is set.
 /// @param       opt_flags       Option flags (can be OPT_LOCAL, OPT_GLOBAL or a combination).
 /// @param       set_sid         Script ID. Special values:
 ///                                0: Use current script ID.
@@ -3686,9 +3710,9 @@ static const char *validate_option_value(const OptIndex opt_idx, OptVal *newval,
 /// @param       errbuflen       Length of error buffer.
 ///
 /// @return  NULL on success, an untranslated error message on error.
-static const char *set_option(const OptIndex opt_idx, OptVal value, int opt_flags, scid_T set_sid,
-                              const bool direct, const bool value_replaced, char *errbuf,
-                              size_t errbuflen)
+static const char *set_option_for(OptIndex opt_idx, OptVal value, OptCtx ctx, int opt_flags,
+                                  scid_T set_sid, const bool direct, const bool value_replaced,
+                                  char *errbuf, size_t errbuflen)
 {
   assert(opt_idx != kOptInvalid);
 
@@ -3713,10 +3737,11 @@ static const char *set_option(const OptIndex opt_idx, OptVal value, int opt_flag
 
   // When using ":set opt=val" for a global option with a local value the local value will be reset,
   // use the global value in that case.
-  void *varp
-    = scope_both && option_is_global_local(opt_idx) ? opt->var : get_varp_scope(opt, opt_flags);
-  void *varp_local = get_varp_scope(opt, OPT_LOCAL);
-  void *varp_global = get_varp_scope(opt, OPT_GLOBAL);
+  void *varp = scope_both && option_is_global_local(opt_idx)
+               ? opt->var
+               : get_varp_scope_from(opt, opt_flags, ctx);
+  void *varp_local = get_varp_scope_from(opt, OPT_LOCAL, ctx);
+  void *varp_global = get_varp_scope_from(opt, OPT_GLOBAL, ctx);
 
   OptVal old_value = optval_from_varp(opt_idx, varp);
   OptVal old_global_value = optval_from_varp(opt_idx, varp_global);
@@ -3729,7 +3754,7 @@ static const char *set_option(const OptIndex opt_idx, OptVal value, int opt_flag
   // unset. In every other case, it is the same as old_value.
   // This value is used instead of old_value when triggering the OptionSet autocommand.
   OptVal used_old_value = (scope_local && is_opt_local_unset)
-                          ? optval_from_varp(opt_idx, get_varp(opt))
+                          ? optval_from_varp(opt_idx, get_varp_from(opt, ctx))
                           : old_value;
 
   // Save the old values and the new value in case they get changed.
@@ -3739,7 +3764,7 @@ static const char *set_option(const OptIndex opt_idx, OptVal value, int opt_flag
   // New value (and varp) may become invalid if the buffer is closed by autocommands.
   OptVal saved_new_value = optval_copy(value);
 
-  uint32_t *p = insecure_flag(curwin, opt_idx, opt_flags);
+  uint32_t *p = insecure_flag(ctx.win, 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
@@ -3752,7 +3777,7 @@ static const char *set_option(const OptIndex opt_idx, OptVal value, int opt_flag
   // Set option through its variable pointer.
   set_option_varp(opt_idx, varp, value, false);
   // Process any side effects.
-  errmsg = did_set_option(opt_idx, varp, old_value, value, opt_flags, set_sid, direct,
+  errmsg = did_set_option(opt_idx, varp, old_value, value, ctx, opt_flags, set_sid, direct,
                           value_replaced, errbuf, errbuflen);
 
   secure = secure_saved;
@@ -3760,7 +3785,7 @@ static const char *set_option(const OptIndex opt_idx, OptVal value, int opt_flag
   if (errmsg == NULL && !direct) {
     if (!starting) {
       apply_optionset_autocmd(opt_idx, opt_flags, saved_used_value, saved_old_global_value,
-                              saved_old_local_value, saved_new_value, errmsg);
+                              saved_old_local_value, saved_new_value, ctx, errmsg);
     }
     if (opt->flags & kOptFlagUIOption) {
       ui_call_option_set(cstr_as_string(opt->fullname), optval_as_object(saved_new_value));
@@ -3780,11 +3805,13 @@ static const char *set_option(const OptIndex opt_idx, OptVal value, int opt_flag
 ///
 /// @param  opt_idx    Option index in options[] table.
 /// @param  value      Option value.
+/// @param  ctx        Context in which the option is set.
 /// @param  opt_flags  Option flags (can be OPT_LOCAL, OPT_GLOBAL or a combination).
 /// @param  set_sid    Script ID. Special values:
 ///                      0: Use current script ID.
 ///                      SID_NONE: Don't set script ID.
-void set_option_direct(OptIndex opt_idx, OptVal value, int opt_flags, scid_T set_sid)
+void set_option_direct_for(OptIndex opt_idx, OptVal value, OptCtx ctx, int opt_flags,
+                           scid_T set_sid)
 {
   static char errbuf[IOSIZE];
 
@@ -3792,57 +3819,35 @@ void set_option_direct(OptIndex opt_idx, OptVal value, int opt_flags, scid_T set
     return;
   }
 
-  const char *errmsg = set_option(opt_idx, optval_copy(value), opt_flags, set_sid, true, true,
-                                  errbuf, sizeof(errbuf));
+  const char *errmsg = set_option_for(opt_idx, optval_copy(value), ctx, opt_flags, set_sid, true,
+                                      true, errbuf, sizeof(errbuf));
   assert(errmsg == NULL);
   (void)errmsg;  // ignore unused warning
 }
 
-/// Set option value directly for buffer / window, without processing any side effects.
+/// Set option value for current context directly, without processing any side effects.
 ///
-/// @param      opt_idx    Option index in options[] table.
-/// @param      value      Option value.
-/// @param      opt_flags  Option flags (can be OPT_LOCAL, OPT_GLOBAL or a combination).
-/// @param      set_sid    Script ID. Special values:
-///                          0: Use current script ID.
-///                          SID_NONE: Don't set script ID.
-/// @param      scope      Option scope. See OptScope in option.h.
-/// @param[in]  from       Target buffer/window.
-void set_option_direct_for(OptIndex opt_idx, OptVal value, int opt_flags, scid_T set_sid,
-                           OptScope scope, void *const from)
-{
-  buf_T *save_curbuf = curbuf;
-  win_T *save_curwin = curwin;
-
-  // Don't use switch_option_context(), as that calls aucmd_prepbuf(), which may have unintended
-  // side-effects when setting an option directly. Just change the values of curbuf and curwin if
-  // needed, no need to properly switch the window / buffer.
-  switch (scope) {
-  case kOptScopeGlobal:
-    break;
-  case kOptScopeWin:
-    curwin = (win_T *)from;
-    curbuf = curwin->w_buffer;
-    break;
-  case kOptScopeBuf:
-    curbuf = (buf_T *)from;
-    break;
-  }
-
-  set_option_direct(opt_idx, value, opt_flags, set_sid);
-
-  curwin = save_curwin;
-  curbuf = save_curbuf;
+/// @param  opt_idx    Option index in options[] table.
+/// @param  value      Option value.
+/// @param  ctx        Context in which the option is set.
+/// @param  opt_flags  Option flags (can be OPT_LOCAL, OPT_GLOBAL or a combination).
+/// @param  set_sid    Script ID. Special values:
+///                      0: Use current script ID.
+///                      SID_NONE: Don't set script ID.
+void set_option_direct(OptIndex opt_idx, OptVal value, int opt_flags, scid_T set_sid)
+{
+  set_option_direct_for(opt_idx, value, option_ctx(), opt_flags, set_sid);
 }
 
 /// Set the value of an option.
 ///
 /// @param      opt_idx    Index in options[] table. Must not be kOptInvalid.
 /// @param[in]  value      Option value. If NIL_OPTVAL, the option value is cleared.
+/// @param      ctx        Context to set option for.
 /// @param[in]  opt_flags  Flags: OPT_LOCAL, OPT_GLOBAL, or 0 (both).
 ///
 /// @return  NULL on success, an untranslated error message on error.
-const char *set_option_value(const OptIndex opt_idx, const OptVal value, int opt_flags)
+const char *set_option_value_for(OptIndex opt_idx, OptVal value, OptCtx ctx, int opt_flags)
 {
   assert(opt_idx != kOptInvalid);
 
@@ -3854,7 +3859,21 @@ const char *set_option_value(const OptIndex opt_idx, const OptVal value, int opt
     return _(e_sandbox);
   }
 
-  return set_option(opt_idx, optval_copy(value), opt_flags, 0, false, true, errbuf, sizeof(errbuf));
+  return set_option_for(opt_idx, optval_copy(value), ctx, opt_flags, 0, false, true, errbuf,
+                        sizeof(errbuf));
+}
+
+/// Set the value of an option for current context.
+///
+/// @param      opt_idx    Index in options[] table. Must not be kOptInvalid.
+/// @param[in]  value      Option value. If NIL_OPTVAL, the option value is cleared.
+/// @param      ctx        Context to set option for.
+/// @param[in]  opt_flags  Flags: OPT_LOCAL, OPT_GLOBAL, or 0 (both).
+///
+/// @return  NULL on success, an untranslated error message on error.
+const char *set_option_value(OptIndex opt_idx, OptVal value, int opt_flags)
+{
+  return set_option_value_for(opt_idx, value, option_ctx(), opt_flags);
 }
 
 /// Unset the local value of a global-local option.
@@ -3910,135 +3929,6 @@ void set_option_value_give_err(const OptIndex opt_idx, OptVal value, int opt_fla
   }
 }
 
-/// Switch current context to get/set option value for window/buffer.
-///
-/// @param[out]  ctx        Current context. switchwin_T for window and aco_save_T for buffer.
-/// @param       scope      Option scope. See OptScope in option.h.
-/// @param[in]   from       Target buffer/window.
-/// @param[out]  err        Error message, if any.
-///
-/// @return  true if context was switched, false otherwise.
-static bool switch_option_context(void *const ctx, OptScope scope, void *const from, Error *err)
-{
-  switch (scope) {
-  case kOptScopeGlobal:
-    return false;
-  case kOptScopeWin: {
-    win_T *const win = (win_T *)from;
-    switchwin_T *const switchwin = (switchwin_T *)ctx;
-
-    if (win == curwin) {
-      return false;
-    }
-
-    if (switch_win_noblock(switchwin, win, win_find_tabpage(win), true)
-        == FAIL) {
-      restore_win_noblock(switchwin, true);
-
-      if (ERROR_SET(err)) {
-        return false;
-      }
-      api_set_error(err, kErrorTypeException, "Problem while switching windows");
-      return false;
-    }
-    return true;
-  }
-  case kOptScopeBuf: {
-    buf_T *const buf = (buf_T *)from;
-    aco_save_T *const aco = (aco_save_T *)ctx;
-
-    if (buf == curbuf) {
-      return false;
-    }
-    aucmd_prepbuf(aco, buf);
-    return true;
-  }
-  }
-  UNREACHABLE;
-}
-
-/// Restore context after getting/setting option for window/buffer. See switch_option_context() for
-/// params.
-static void restore_option_context(void *const ctx, OptScope scope)
-{
-  switch (scope) {
-  case kOptScopeGlobal:
-    break;