diff --git a/src/channel.c b/src/channel.c
index ee5b512..33605d4 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -4180,7 +4180,7 @@
  * Return TRUE when there is any channel with a keep_open flag.
  */
     int
-channel_any_keep_open()
+channel_any_keep_open(void)
 {
     channel_T	*channel;
 
diff --git a/src/charset.c b/src/charset.c
index d8feb4e..826a768 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1764,7 +1764,7 @@
  * columns (bytes) at the start of a given line
  */
     int
-getwhitecols_curline()
+getwhitecols_curline(void)
 {
     return getwhitecols(ml_get_curline());
 }
diff --git a/src/clipboard.c b/src/clipboard.c
index b09c678..4ce536a 100644
--- a/src/clipboard.c
+++ b/src/clipboard.c
@@ -257,7 +257,7 @@
  * right text.
  */
     static int
-is_clipboard_needs_update()
+is_clipboard_needs_update(void)
 {
     return clipboard_needs_update;
 }
diff --git a/src/crypt.c b/src/crypt.c
index a2740c9..b4b48c8 100644
--- a/src/crypt.c
+++ b/src/crypt.c
@@ -155,7 +155,7 @@
     // to avoid that a text file is recognized as encrypted.
 };
 
-#ifdef FEAT_SODIUM
+#if defined(FEAT_SODIUM) || defined(PROTO)
 typedef struct {
     size_t	    count;
     unsigned char   key[crypto_box_SEEDBYTES];
@@ -396,7 +396,7 @@
  * Get maximum crypt method specific length of the file header in bytes.
  */
     int
-crypt_get_max_header_len()
+crypt_get_max_header_len(void)
 {
     int i;
     int max = 0;
diff --git a/src/debugger.c b/src/debugger.c
index f627a9a..b158ecd 100644
--- a/src/debugger.c
+++ b/src/debugger.c
@@ -734,7 +734,7 @@
 }
 
     static void
-update_has_expr_breakpoint()
+update_has_expr_breakpoint(void)
 {
     int i;
 
@@ -751,7 +751,7 @@
  * Return TRUE if there is any expression breakpoint.
  */
     int
-debug_has_expr_breakpoint()
+debug_has_expr_breakpoint(void)
 {
     return has_expr_breakpoint;
 }
diff --git a/src/edit.c b/src/edit.c
index 983f1ac..d3fffc5 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -4607,7 +4607,7 @@
 }
 
     static void
-ins_s_left()
+ins_s_left(void)
 {
     int end_change = dont_sync_undo == FALSE; // end undoable change
 #ifdef FEAT_FOLDING
@@ -4676,7 +4676,7 @@
 }
 
     static void
-ins_s_right()
+ins_s_right(void)
 {
     int end_change = dont_sync_undo == FALSE; // end undoable change
 #ifdef FEAT_FOLDING
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index be0e346..2c65bd8 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -1386,7 +1386,7 @@
  * Handle when "did_throw" is set after executing commands.
  */
     void
-handle_did_throw()
+handle_did_throw(void)
 {
     char	*p = NULL;
     msglist_T	*messages = NULL;
diff --git a/src/gui_gtk_x11.c b/src/gui_gtk_x11.c
index b8e08f5..7ef63b8 100644
--- a/src/gui_gtk_x11.c
+++ b/src/gui_gtk_x11.c
@@ -463,7 +463,7 @@
  * This list is empty when there are no outstanding resize requests.
  */
     static void
-clear_resize_hists()
+clear_resize_hists(void)
 {
 # ifdef ENABLE_RESIZE_HISTORY_LOG
     int		    i = 0;
@@ -516,7 +516,7 @@
 
 # if defined(EXITFREE)
     static void
-free_all_resize_hist()
+free_all_resize_hist(void)
 {
     clear_resize_hists();
     vim_free(latest_resize_hist);
diff --git a/src/gui_xim.c b/src/gui_xim.c
index 0d7b56e..88de7a4 100644
--- a/src/gui_xim.c
+++ b/src/gui_xim.c
@@ -295,7 +295,7 @@
 }
 
     static void
-im_preedit_window_open()
+im_preedit_window_open(void)
 {
     char *preedit_string;
 #if !GTK_CHECK_VERSION(3,16,0)
@@ -417,14 +417,14 @@
 }
 
     static void
-im_preedit_window_close()
+im_preedit_window_close(void)
 {
     if (preedit_window != NULL)
 	gtk_widget_hide(preedit_window);
 }
 
     static void
-im_show_preedit()
+im_show_preedit(void)
 {
     im_preedit_window_open();
 
diff --git a/src/highlight.c b/src/highlight.c
index 79501d2..6716da0 100644
--- a/src/highlight.c
+++ b/src/highlight.c
@@ -469,7 +469,7 @@
  * the user to override the color values. Only loaded once.
  */
     static void
-load_default_colors_lists()
+load_default_colors_lists(void)
 {
     // Lacking a default color list isn't the end of the world but it is likely
     // an inconvenience so users should know when it is missing.
diff --git a/src/if_lua.c b/src/if_lua.c
index 6559550..0af041a 100644
--- a/src/if_lua.c
+++ b/src/if_lua.c
@@ -2736,7 +2736,7 @@
 }
 
     void
-update_package_paths_in_lua()
+update_package_paths_in_lua(void)
 {
     if (!lua_isopen())
 	return;
diff --git a/src/indent.c b/src/indent.c
index 477a44d..be4d563 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -1161,7 +1161,7 @@
  * Return TRUE if the conditions are OK for smart indenting.
  */
     int
-may_do_si()
+may_do_si(void)
 {
     return curbuf->b_p_si
 	&& !curbuf->b_p_cin
diff --git a/src/insexpand.c b/src/insexpand.c
index 779bf5e..1362781 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -2994,7 +2994,7 @@
  * one assigned yet.
  */
     static void
-ins_compl_update_sequence_numbers()
+ins_compl_update_sequence_numbers(void)
 {
     int		number = 0;
     compl_T	*match;
@@ -3457,7 +3457,7 @@
  * Get the next set of command-line completions matching "compl_pattern".
  */
     static void
-get_next_cmdline_completion()
+get_next_cmdline_completion(void)
 {
     char_u	**matches;
     int		num_matches;
diff --git a/src/job.c b/src/job.c
index ddfc8ef..c3ba3b8 100644
--- a/src/job.c
+++ b/src/job.c
@@ -885,7 +885,7 @@
  * Return TRUE when there is any running job that we care about.
  */
     int
-job_any_running()
+job_any_running(void)
 {
     job_T	*job;
 
@@ -1655,7 +1655,7 @@
  * Return TRUE if the cursor is in the editable position of the prompt line.
  */
     int
-prompt_curpos_editable()
+prompt_curpos_editable(void)
 {
     return curwin->w_cursor.lnum == curbuf->b_ml.ml_line_count
 	&& curwin->w_cursor.col >= (int)STRLEN(prompt_text());
diff --git a/src/misc1.c b/src/misc1.c
index c83b7ae..a03c405 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -1313,7 +1313,7 @@
 
 #if defined(MSWIN) || defined(PROTO)
 /*
- * Initilize $VIM and $VIMRUNTIME when 'enc' is updated.
+ * Initialize $VIM and $VIMRUNTIME when 'enc' is updated.
  */
     void
 init_vimdir(void)
@@ -2777,7 +2777,7 @@
  * Fires a ModeChanged autocmd event if appropriate.
  */
     void
-may_trigger_modechanged()
+may_trigger_modechanged(void)
 {
 #ifdef FEAT_EVAL
     dict_T	    *v_event;
diff --git a/src/mouse.c b/src/mouse.c
index 954b213..4e8dd4d 100644
--- a/src/mouse.c
+++ b/src/mouse.c
@@ -2234,7 +2234,7 @@
 static int	held_button = MOUSE_RELEASE;
 
     void
-reset_held_button()
+reset_held_button(void)
 {
     held_button = MOUSE_RELEASE;
 }
diff --git a/src/normal.c b/src/normal.c
index 1ab1599..b3ea5e8 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -976,14 +976,14 @@
 
     // Reset finish_op, in case it was set
 #ifdef CURSOR_SHAPE
-    c = finish_op;
+    int prev_finish_op = finish_op;
 #endif
     finish_op = FALSE;
     may_trigger_modechanged();
 #ifdef CURSOR_SHAPE
     // Redraw the cursor with another shape, if we were in Operator-pending
     // mode or did a replace command.
-    if (c || ca.cmdchar == 'r')
+    if (prev_finish_op || ca.cmdchar == 'r')
     {
 	ui_cursor_shape();		// may show different cursor shape
 # ifdef FEAT_MOUSESHAPE
@@ -1110,14 +1110,14 @@
  * from do_pending_operator().
  */
     void
-end_visual_mode()
+end_visual_mode(void)
 {
     end_visual_mode_keep_button();
     reset_held_button();
 }
 
     void
-end_visual_mode_keep_button()
+end_visual_mode_keep_button(void)
 {
 #ifdef FEAT_CLIPBOARD
     // If we are using the clipboard, then remember what was selected in case
@@ -3190,7 +3190,7 @@
     else if (cap->oap->op_type != OP_NOP
 	    && (cap->oap->start.lnum > curbuf->b_ml.ml_line_count
 		|| cap->oap->start.col >
-		(colnr_T)STRLEN(ml_get(cap->oap->start.lnum))
+				  (colnr_T)STRLEN(ml_get(cap->oap->start.lnum))
 		|| did_emsg
 	       ))
 	// The start of the operator has become invalid by the Ex command.
diff --git a/src/optionstr.c b/src/optionstr.c
index 71ad1e4..3c9f98a 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -3075,7 +3075,7 @@
  * restore_shm_value() exactly the same number of times.
  */
     void
-save_clear_shm_value()
+save_clear_shm_value(void)
 {
     if (STRLEN(p_shm) >= SHM_LEN)
     {
@@ -3094,7 +3094,7 @@
  * Restore the shortmess Flags set from the save_clear_shm_value() function.
  */
     void
-restore_shm_value()
+restore_shm_value(void)
 {
     if (--set_shm_recursive == 0)
     {
diff --git a/src/popupmenu.c b/src/popupmenu.c
index cbb45a5..a28b3e2 100644
--- a/src/popupmenu.c
+++ b/src/popupmenu.c
@@ -387,7 +387,7 @@
  * This will avoid clearing and redrawing the popup menu, prevent flicker.
  */
     void
-pum_call_update_screen()
+pum_call_update_screen(void)
 {
     call_update_screen = TRUE;
 
diff --git a/src/popupwin.c b/src/popupwin.c
index ff877fd..6e1d925 100644
--- a/src/popupwin.c
+++ b/src/popupwin.c
@@ -3309,7 +3309,7 @@
  * Return FALSE when the job has ended.
  */
     int
-error_if_term_popup_window()
+error_if_term_popup_window(void)
 {
     if (WIN_IS_POPUP(curwin) && curbuf->b_term != NULL
 					   && term_job_running(curbuf->b_term))
@@ -3543,7 +3543,7 @@
  * cursor moved far enough.
  */
     void
-popup_check_cursor_pos()
+popup_check_cursor_pos(void)
 {
     win_T *wp;
 
diff --git a/src/proto/filepath.pro b/src/proto/filepath.pro
index 2970e50..fd8de80 100644
--- a/src/proto/filepath.pro
+++ b/src/proto/filepath.pro
@@ -1,11 +1,11 @@
 /* filepath.c */
 int modify_fname(char_u *src, int tilde_file, int *usedlen, char_u **fnamep, char_u **bufp, int *fnamelen);
 void shorten_dir(char_u *str);
+int file_is_readable(char_u *fname);
 void f_chdir(typval_T *argvars, typval_T *rettv);
 void f_delete(typval_T *argvars, typval_T *rettv);
 void f_executable(typval_T *argvars, typval_T *rettv);
 void f_exepath(typval_T *argvars, typval_T *rettv);
-int file_is_readable(char_u *fname);
 void f_filereadable(typval_T *argvars, typval_T *rettv);
 void f_filewritable(typval_T *argvars, typval_T *rettv);
 void f_finddir(typval_T *argvars, typval_T *rettv);
diff --git a/src/proto/gui_motif.pro b/src/proto/gui_motif.pro
index ccbdc0a..400fa86 100644
--- a/src/proto/gui_motif.pro
+++ b/src/proto/gui_motif.pro
@@ -32,8 +32,6 @@
 Window gui_x11_get_wid(void);
 char_u *gui_mch_browse(int saving, char_u *title, char_u *dflt, char_u *ext, char_u *initdir, char_u *filter);
 int gui_mch_dialog(int type, char_u *title, char_u *message, char_u *button_names, int dfltbutton, char_u *textfield, int ex_cmd);
-void gui_mch_enable_footer(int showit);
-void gui_mch_set_footer(char_u *s);
 void gui_mch_show_toolbar(int showit);
 int gui_mch_compute_toolbar_height(void);
 void motif_get_toolbar_colors(Pixel *bgp, Pixel *fgp, Pixel *bsp, Pixel *tsp, Pixel *hsp);
diff --git a/src/quickfix.c b/src/quickfix.c
index 245e20b..63dd541 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -8448,7 +8448,7 @@
 
 # if defined(EXITFREE) || defined(PROTO)
     void
-free_quickfix()
+free_quickfix(void)
 {
     win_T	*win;
     tabpage_T	*tab;
diff --git a/src/register.c b/src/register.c
index 03c26cb..4dc0a68 100644
--- a/src/register.c
+++ b/src/register.c
@@ -977,7 +977,7 @@
  * Shift the delete registers: "9 is cleared, "8 becomes "9, etc.
  */
     void
-shift_delete_registers()
+shift_delete_registers(void)
 {
     int		n;
 
@@ -2328,7 +2328,7 @@
  * Return the index of the register "" points to.
  */
     int
-get_unname_register()
+get_unname_register(void)
 {
     return y_previous == NULL ? -1 : y_previous - &y_regs[0];
 }
diff --git a/src/screen.c b/src/screen.c
index 2e8a6aa..4c3c2b5 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -379,7 +379,7 @@
  * Return the index in ScreenLines[] for the current screen line.
  */
     int
-screen_get_current_line_off()
+screen_get_current_line_off(void)
 {
     return (int)(current_ScreenLine - ScreenLines);
 }
@@ -3962,7 +3962,7 @@
  * or inside a mapping.
  */
     int
-skip_showmode()
+skip_showmode(void)
 {
     // Call char_avail() only when we are going to show something, because it
     // takes a bit of time.  redrawing() may also call char_avail().
diff --git a/src/sound.c b/src/sound.c
index f3d651e..a968ecd 100644
--- a/src/sound.c
+++ b/src/sound.c
@@ -339,7 +339,7 @@
 }
 
     static HWND
-sound_window()
+sound_window(void)
 {
     if (g_hWndSound == NULL)
     {
diff --git a/src/term.c b/src/term.c
index c90efe5..18500a3 100644
--- a/src/term.c
+++ b/src/term.c
@@ -2081,7 +2081,7 @@
 #endif
     {
 	// Use the 'keyprotocol' option to adjust the t_TE and t_TI
-	// termcap entries if there is an entry maching "term".
+	// termcap entries if there is an entry matching "term".
 	keyprot_T kpc = match_keyprotocol(term);
 	if (kpc == KEYPROTOCOL_KITTY)
 	    apply_builtin_tcap(term, builtin_kitty, TRUE);
@@ -2092,7 +2092,7 @@
 	// There is no good way to detect that the terminal supports RGB
 	// colors.  Since these termcap entries are non-standard anyway and
 	// only used when the user sets 'termguicolors' we might as well add
-	// them.  But not when one of them was alredy set.
+	// them.  But not when one of them was already set.
 	if (term_strings_not_set(KS_8F)
 		&& term_strings_not_set(KS_8B)
 		&& term_strings_not_set(KS_8U))
@@ -2341,7 +2341,7 @@
  * Avoids that valgrind reports possibly lost memory.
  */
     void
-free_cur_term()
+free_cur_term(void)
 {
 # ifdef HAVE_DEL_CURTERM
     if (cur_term)
@@ -2997,7 +2997,7 @@
  * Return TRUE if we can request the terminal for a response.
  */
     static int
-can_get_termresponse()
+can_get_termresponse(void)
 {
     return cur_tmode == TMODE_RAW
 	    && termcap_active
@@ -3021,7 +3021,7 @@
  * Return TRUE if any of the requests are in STATUS_SENT.
  */
     static int
-termrequest_any_pending()
+termrequest_any_pending(void)
 {
     int	    i;
     time_t  now = time(NULL);
@@ -4367,7 +4367,7 @@
 # endif
 
     int
-blink_state_is_inverted()
+blink_state_is_inverted(void)
 {
 #ifdef FEAT_TERMRESPONSE
     return rbm_status.tr_progress == STATUS_GOT
diff --git a/src/terminal.c b/src/terminal.c
index 3aaedf6..997f83a 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -392,7 +392,7 @@
  * Flush messages on channels.
  */
     static void
-term_flush_messages()
+term_flush_messages(void)
 {
     mch_check_messages();
     parse_queued_messages();
@@ -1104,7 +1104,7 @@
 }
 
     void
-free_unused_terminals()
+free_unused_terminals(void)
 {
     while (terminals_to_free != NULL)
     {
@@ -2157,7 +2157,7 @@
  * Restores updating the terminal window.
  */
     void
-term_enter_job_mode()
+term_enter_job_mode(void)
 {
     term_T	*term = curbuf->b_term;
 
@@ -2224,7 +2224,7 @@
  * closed and ++close was used.  This may even happen before we get here.
  */
     static int
-term_vgetc()
+term_vgetc(void)
 {
     int c;
     int save_State = State;
@@ -2451,7 +2451,7 @@
  * terminal should be displayed.
  */
     int
-terminal_is_active()
+terminal_is_active(void)
 {
     return in_terminal_loop != NULL;
 }
@@ -2609,7 +2609,7 @@
  * we may want to change state.
  */
     void
-term_win_entered()
+term_win_entered(void)
 {
     term_T *term = curbuf->b_term;
 
@@ -3702,7 +3702,7 @@
  * channel was closed.
  */
     void
-term_check_channel_closed_recently()
+term_check_channel_closed_recently(void)
 {
     term_T *term;
     term_T *next_term;
@@ -4203,7 +4203,7 @@
  * or when any highlight is changed.
  */
     void
-term_update_wincolor_all()
+term_update_wincolor_all(void)
 {
     win_T	 *wp = NULL;
     int		 did_curwin = FALSE;
@@ -4300,7 +4300,7 @@
  * "ansi_colors" argument in term_start()) shall be applied.
  */
     static int
-term_use_palette()
+term_use_palette(void)
 {
     if (0
 #ifdef FEAT_GUI
@@ -4866,7 +4866,7 @@
  * Called when option 'termguicolors' is changed.
  */
     void
-term_update_palette_all()
+term_update_palette_all(void)
 {
     term_T *term;
 
@@ -5816,7 +5816,7 @@
  * Return FAIL when this is not possible.
  */
     int
-term_swap_diff()
+term_swap_diff(void)
 {
     term_T	*term = curbuf->b_term;
     linenr_T	line_count;
diff --git a/src/time.c b/src/time.c
index 692cef3..c82a79a 100644
--- a/src/time.c
+++ b/src/time.c
@@ -802,7 +802,7 @@
 
 # if defined(EXITFREE) || defined(PROTO)
     void
-timer_free_all()
+timer_free_all(void)
 {
     while (first_timer != NULL)
     {
diff --git a/src/userfunc.c b/src/userfunc.c
index c3b2a25..2575e7d 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -36,7 +36,7 @@
 static void handle_defer_one(funccall_T *funccal);
 
     void
-func_init()
+func_init(void)
 {
     hash_init(&func_hashtab);
 }
@@ -2709,7 +2709,7 @@
  * current_funccal.
  */
     void
-remove_funccal()
+remove_funccal(void)
 {
     funccall_T *fc = current_funccal;
 
@@ -6662,7 +6662,7 @@
  * Return NULL if there is no current funccal.
  */
     hashtab_T *
-get_funccal_local_ht()
+get_funccal_local_ht(void)
 {
     if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0)
 	return NULL;
@@ -6674,7 +6674,7 @@
  * Return NULL if there is no current funccal.
  */
     dictitem_T *
-get_funccal_local_var()
+get_funccal_local_var(void)
 {
     if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0)
 	return NULL;
@@ -6686,7 +6686,7 @@
  * Return NULL if there is no current funccal.
  */
     hashtab_T *
-get_funccal_args_ht()
+get_funccal_args_ht(void)
 {
     if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0)
 	return NULL;
@@ -6698,7 +6698,7 @@
  * Return NULL if there is no current funccal.
  */
     dictitem_T *
-get_funccal_args_var()
+get_funccal_args_var(void)
 {
     if (current_funccal == NULL || current_funccal->fc_l_vars.dv_refcount == 0)
 	return NULL;
diff --git a/src/version.c b/src/version.c
index d1dd656..fd8e887 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1336,
+/**/
     1335,
 /**/
     1334,
diff --git a/src/vim.h b/src/vim.h
index db38da2..d1ec26c 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2287,6 +2287,9 @@
 /*
  * Type for the callback function that is invoked after an option value is
  * changed to validate and apply the new value.
+ *
+ * Returns NULL if the option value is valid is successfully applied.
+ * Otherwise returns an error message.
  */
 typedef char *(*opt_did_set_cb_T)(optset_T *args);
 
diff --git a/src/vim9compile.c b/src/vim9compile.c
index e2e5b76..d45dd63 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -291,7 +291,7 @@
  * Return TRUE if the script context is Vim9 script.
  */
     int
-script_is_vim9()
+script_is_vim9(void)
 {
     return SCRIPT_ITEM(current_sctx.sc_sid)->sn_version == SCRIPT_VERSION_VIM9;
 }
diff --git a/src/window.c b/src/window.c
index e903332..bfdf825 100644
--- a/src/window.c
+++ b/src/window.c
@@ -824,7 +824,7 @@
  * Otherwise return OK.
  */
     static int
-check_split_disallowed()
+check_split_disallowed(void)
 {
     if (split_disallowed > 0)
     {
@@ -6014,7 +6014,7 @@
  * Make the current window show at least one line and one column.
  */
     void
-win_ensure_size()
+win_ensure_size(void)
 {
     if (curwin->w_height == 0)
 	win_setheight(1);
@@ -7357,7 +7357,7 @@
  * check_lnums() must have been called first!
  */
     void
-reset_lnums()
+reset_lnums(void)
 {
     win_T	*wp;
     tabpage_T	*tp;