patch 8.2.3699: the +title feature adds a lot of #ifdef but little code

Problem:    The +title feature adds a lot of #ifdef but little code.
Solution:   Graduate the +title feature.

runtime/doc/options.txt

@@ -4190,8 +4190,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 						*'icon'* *'noicon'*
 'icon'			boolean	(default off, on when title can be restored)
 			global
-			{not available when compiled without the |+title|
-			feature}
 	When on, the icon text of the window will be set to the value of
 	'iconstring' (if it is not empty), or to the name of the file
 	currently being edited.  Only the last part of the name is used.
@@ -4208,8 +4206,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 						*'iconstring'*
 'iconstring'		string	(default "")
 			global
-			{not available when compiled without the |+title|
-			feature}
 	When this option is not empty, it will be used for the icon text of
 	the window.  This happens only when the 'icon' option is on.
 	Only works if the terminal supports setting window icon text
@@ -8141,8 +8137,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 						*'title'* *'notitle'*
 'title'			boolean	(default off, on when title can be restored)
 			global
-			{not available when compiled without the |+title|
-			feature}
 	When on, the title of the window will be set to the value of
 	'titlestring' (if it is not empty), or to:
 		filename [+=-] (path) - VIM
@@ -8176,8 +8170,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 								*'titlelen'*
 'titlelen'		number	(default 85)
 			global
-			{not available when compiled without the |+title|
-			feature}
 	Gives the percentage of 'columns' to use for the length of the window
 	title.  When the title is longer, only the end of the path name is
 	shown.  A '<' character before the path name is used to indicate this.
@@ -8191,8 +8183,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 						*'titleold'*
 'titleold'		string	(default "Thanks for flying Vim")
 			global
-			{only available when compiled with the |+title|
-			feature}
 	This option will be used for the window title when exiting Vim if the
 	original title cannot be restored.  Only happens if 'title' is on or
 	'titlestring' is not empty.
@@ -8201,8 +8191,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 						*'titlestring'*
 'titlestring'		string	(default "")
 			global
-			{not available when compiled without the |+title|
-			feature}
 	When this option is not empty, it will be used for the title of the
 	window.  This happens only when the 'title' option is on.
 	Only works if the terminal supports setting window titles (currently

runtime/doc/various.txt

@@ -471,7 +471,7 @@ N  *+textobjects*	|text-objects| selection
 N  *+textprop*		|text-properties|
    *+tgetent*		non-Unix only: able to use external termcap
 N  *+timers*		the |timer_start()| function
-N  *+title*		Setting the window 'title' and 'icon'
+N  *+title*		Setting the window 'title' and 'icon'; Always enabled
 N  *+toolbar*		|gui-toolbar|
 T  *+user_commands*	User-defined commands. |user-commands|
 			Always enabled since 8.1.1210.

src/alloc.c

@@ -421,9 +421,7 @@ free_all_mem(void)
 # endif
     }
 
-# ifdef FEAT_TITLE
     free_titles();
-# endif
 # if defined(FEAT_SEARCHPATH)
     free_findfile();
 # endif

src/arglist.c

@@ -770,9 +770,7 @@ ex_argedit(exarg_T *eap)
 
     if (do_arglist(eap->arg, AL_ADD, i, TRUE) == FAIL)
 	return;
-#ifdef FEAT_TITLE
     maketitle();
-#endif
 
     if (curwin->w_arg_idx == 0
 	    && (curbuf->b_ml.ml_flags & ML_EMPTY)
@@ -792,9 +790,7 @@ ex_argadd(exarg_T *eap)
     do_arglist(eap->arg, AL_ADD,
 	       eap->addr_count > 0 ? (int)eap->line2 : curwin->w_arg_idx + 1,
 	       FALSE);
-#ifdef FEAT_TITLE
     maketitle();
-#endif
 }
 
 /*
@@ -853,9 +849,7 @@ ex_argdelete(exarg_T *eap)
     }
     else
 	do_arglist(eap->arg, AL_DEL, 0, FALSE);
-#ifdef FEAT_TITLE
     maketitle();
-#endif
 }
 
 /*

src/autocmd.c

@@ -2253,10 +2253,8 @@ apply_autocmds_group(
 		|| event == EVENT_VIMLEAVE
 		|| event == EVENT_VIMLEAVEPRE))
     {
-#ifdef FEAT_TITLE
 	if (curbuf->b_changed != save_changed)
 	    need_maketitle = TRUE;
-#endif
 	curbuf->b_changed = save_changed;
     }
 

src/buffer.c

@@ -44,9 +44,7 @@ static int	buf_same_ino(buf_T *buf, stat_T *stp);
 #else
 static int	otherfile_buf(buf_T *buf, char_u *ffname);
 #endif
-#ifdef FEAT_TITLE
 static int	value_changed(char_u *str, char_u **last);
-#endif
 static int	append_arg_number(win_T *wp, char_u *buf, int buflen, int add_file);
 static void	free_buffer(buf_T *);
 static void	free_buffer_stuff(buf_T *buf, int free_options);
@@ -1856,9 +1854,7 @@ enter_buffer(buf_T *buf)
 	buflist_getfpos();
 
     check_arg_idx(curwin);		// check for valid arg_idx
-#ifdef FEAT_TITLE
     maketitle();
-#endif
 	// when autocmds didn't change it
     if (curwin->w_topline == 1 && !curwin->w_topline_was_set)
 	scroll_cursor_halfway(FALSE);	// redisplay at correct position
@@ -3461,9 +3457,7 @@ buf_name_changed(buf_T *buf)
 
     if (curwin->w_buffer == buf)
 	check_arg_idx(curwin);	// check file name for arg list
-#ifdef FEAT_TITLE
     maketitle();		// set window title
-#endif
     status_redraw_all();	// status lines need to be redrawn
     fmarks_check_names(buf);	// check named file marks
     ml_timestamp(buf);		// reset timestamp
@@ -3780,7 +3774,6 @@ col_print(
 	vim_snprintf((char *)buf, buflen, "%d-%d", col, vcol);
 }
 
-#if defined(FEAT_TITLE) || defined(PROTO)
 static char_u *lasttitle = NULL;
 static char_u *lasticon = NULL;
 
@@ -4045,7 +4038,6 @@ free_titles(void)
 }
 # endif
 
-#endif // FEAT_TITLE
 
 #if defined(FEAT_STL_OPT) || defined(FEAT_GUI_TABLINE) || defined(PROTO)
 

src/bufwrite.c

@@ -1630,9 +1630,7 @@ buf_write(
     if (forceit && overwriting && vim_strchr(p_cpo, CPO_KEEPRO) == NULL)
     {
 	buf->b_p_ro = FALSE;
-#ifdef FEAT_TITLE
 	need_maketitle = TRUE;	    // set window title later
-#endif
 	status_redraw_all();	    // redraw status lines later
     }
 

src/change.c

@@ -146,9 +146,7 @@ changed_internal(void)
     ml_setflags(curbuf);
     check_status(curbuf);
     redraw_tabline = TRUE;
-#ifdef FEAT_TITLE
     need_maketitle = TRUE;	    // set window title later
-#endif
 }
 
 #ifdef FEAT_EVAL
@@ -892,9 +890,7 @@ unchanged(buf_T *buf, int ff, int always_inc_changedtick)
 	    save_file_ff(buf);
 	check_status(buf);
 	redraw_tabline = TRUE;
-#ifdef FEAT_TITLE
 	need_maketitle = TRUE;	    // set window title later
-#endif
 	++CHANGEDTICK(buf);
     }
     else if (always_inc_changedtick)

src/drawscreen.c

@@ -610,15 +610,14 @@ showruler(int always)
 	win_redr_ruler(curwin, always, FALSE);
 #endif
 
-#ifdef FEAT_TITLE
     if (need_maketitle
-# ifdef FEAT_STL_OPT
+#ifdef FEAT_STL_OPT
 	    || (p_icon && (stl_syntax & STL_IN_ICON))
 	    || (p_title && (stl_syntax & STL_IN_TITLE))
-# endif
+#endif
        )
 	maketitle();
-#endif
+
     // Redraw the tab pages line if needed.
     if (redraw_tabline)
 	draw_tabline();

src/evalfunc.c

@@ -5787,13 +5787,7 @@ f_has(typval_T *argvars, typval_T *rettv)
 		0
 #endif
 		},
-	{"title",
-#ifdef FEAT_TITLE
-		1
-#else
-		0
-#endif
-		},
+	{"title", 1},
 	{"toolbar",
 #ifdef FEAT_TOOLBAR
 		1

src/ex_cmds.c

@@ -3082,9 +3082,7 @@ do_ecmd(
 	// Even when cursor didn't move we need to recompute topline.
 	changed_line_abv_curs();
 
-#ifdef FEAT_TITLE
 	maketitle();
-#endif
 #if defined(FEAT_PROP_POPUP) && defined(FEAT_QUICKFIX)
 	if (WIN_IS_POPUP(curwin) && curwin->w_p_pvw && retval != FAIL)
 	    popup_set_title(curwin);

src/ex_docmd.c

@@ -6205,14 +6205,10 @@ ex_stop(exarg_T *eap)
 	out_flush();
 	stoptermcap();
 	out_flush();		// needed for SUN to restore xterm buffer
-#ifdef FEAT_TITLE
 	mch_restore_title(SAVE_RESTORE_BOTH);	// restore window titles
-#endif
 	ui_suspend();		// call machine specific function
-#ifdef FEAT_TITLE
 	maketitle();
 	resettitle();		// force updating the title
-#endif
 	starttermcap();
 	scroll_start();		// scroll screen before redrawing
 	redraw_later_clear();
@@ -7047,14 +7043,10 @@ do_exedit(
     {
 	if (eap->do_ecmd_cmd != NULL)
 	    do_cmd_argument(eap->do_ecmd_cmd);
-#ifdef FEAT_TITLE
 	n = curwin->w_arg_idx_invalid;
-#endif
 	check_arg_idx(curwin);
-#ifdef FEAT_TITLE
 	if (n != curwin->w_arg_idx_invalid)
 	    maketitle();
-#endif
     }
 
     /*
@@ -8178,10 +8170,8 @@ ex_redraw(exarg_T *eap)
     validate_cursor();
     update_topline();
     update_screen(eap->forceit ? CLEAR : VIsual_active ? INVERTED : 0);
-#ifdef FEAT_TITLE
     if (need_maketitle)
 	maketitle();
-#endif
 #if defined(MSWIN) && (!defined(FEAT_GUI_MSWIN) || defined(VIMDLL))
 # ifdef VIMDLL
     if (!gui.in_use)

src/feature.h

@@ -109,6 +109,7 @@
  * +insert_expand	CTRL-N/CTRL-P/CTRL-X in insert mode.
  * +modify_fname	modifiers for file name.  E.g., "%:p:h".
  * +comments		'comments' option.
+ * +title		'title' and 'icon' options
  *
  * Obsolete:
  * +tag_old_static	Old style static tags: "file:tag  file  ..".
@@ -360,24 +361,21 @@
 #endif
 
 /*
- * +title		'title' and 'icon' options
  * +statusline		'statusline', 'rulerformat' and special format of
  *			'titlestring' and 'iconstring' options.
- * +byte_offset		'%o' in 'statusline' and builtin functions line2byte()
- *			and byte2line().
- *			Note: Required for Macintosh.
  */
-#if defined(FEAT_NORMAL)
-# define FEAT_TITLE
-#endif
-
 #ifdef FEAT_NORMAL
 # define FEAT_STL_OPT
 # ifndef FEAT_CMDL_INFO
 #  define FEAT_CMDL_INFO	// 'ruler' is required for 'statusline'
 # endif
 #endif
 
+/*
+ * +byte_offset		'%o' in 'statusline' and builtin functions line2byte()
+ *			and byte2line().
+ *			Note: Required for Macintosh.
+ */
 #ifdef FEAT_NORMAL
 # define FEAT_BYTEOFF
 #endif

src/globals.h

@@ -252,9 +252,7 @@ EXTERN int	no_wait_return INIT(= 0);   // don't wait for return for now
 EXTERN int	need_wait_return INIT(= 0); // need to wait for return later
 EXTERN int	did_wait_return INIT(= FALSE);	// wait_return() was used and
 						// nothing written since then
-#ifdef FEAT_TITLE
 EXTERN int	need_maketitle INIT(= TRUE); // call maketitle() soon
-#endif
 
 EXTERN int	quit_more INIT(= FALSE);    // 'q' hit at "--more--" msg
 #if defined(UNIX) || defined(VMS) || defined(MACOS_X)
@@ -1037,17 +1035,26 @@ EXTERN vimconv_T output_conv;			// type of output conversion
  */
 // length of char in bytes, including following composing chars
 EXTERN int (*mb_ptr2len)(char_u *p) INIT(= latin_ptr2len);
+
 // idem, with limit on string length
 EXTERN int (*mb_ptr2len_len)(char_u *p, int size) INIT(= latin_ptr2len_len);
+
 // byte length of char
 EXTERN int (*mb_char2len)(int c) INIT(= latin_char2len);
-// convert char to bytes, return the length
+
+// Convert char "c" to bytes in "buf", return the length.  "buf" must have room
+// for at least 6 bytes.
 EXTERN int (*mb_char2bytes)(int c, char_u *buf) INIT(= latin_char2bytes);
+
 EXTERN int (*mb_ptr2cells)(char_u *p) INIT(= latin_ptr2cells);
 EXTERN int (*mb_ptr2cells_len)(char_u *p, int size) INIT(= latin_ptr2cells_len);
 EXTERN int (*mb_char2cells)(int c) INIT(= latin_char2cells);
 EXTERN int (*mb_off2cells)(unsigned off, unsigned max_off) INIT(= latin_off2cells);
 EXTERN int (*mb_ptr2char)(char_u *p) INIT(= latin_ptr2char);
+
+// Byte offset from "p" to the start of a character, including any composing
+// characters. "base" must be the start of the string, which must be NUL
+// terminated.
 EXTERN int (*mb_head_off)(char_u *base, char_u *p) INIT(= latin_head_off);
 
 # if defined(USE_ICONV) && defined(DYNAMIC_ICONV)
@@ -1402,7 +1409,7 @@ EXTERN struct subs_expr_S	*substitute_instr INIT(= NULL);
 // table to store parsed 'wildmode'
 EXTERN char_u	wim_flags[4];
 
-#if defined(FEAT_TITLE) && defined(FEAT_STL_OPT)
+#if defined(FEAT_STL_OPT)
 // whether titlestring and iconstring contains statusline syntax
 # define STL_IN_ICON	1
 # define STL_IN_TITLE	2