patch 9.1.0892: the max value of 'tabheight' is limited by other tabpages

Problem:  the max value of 'tabheight' is limited by other tabpages
Solution: Limit the maximum value of 'cmdheight' to the current tabpage only.
          (Milly)

The Help says that cmdheight is local to the tab page, but says nothing
about the maximum value depending on the state of all tab pages. Users
may wonder why they can't increase cmdheight when there are still rows
available on the current tab page. This PR changes the behavior of
cmdheight so that its maximum value depends only on the state of the
current tab page.

Also, since magic numbers were embedded in various places with the
minimum value of cmdheight being 1, we defined a constant to make it
easier to understand.

closes: #16131

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/option.c

@@ -3417,13 +3417,13 @@ did_set_cmdheight(optset_T *args)
     char *errmsg = NULL;
 
     // if p_ch changed value, change the command line height
-    if (p_ch < 1)
+    if (p_ch < MIN_CMDHEIGHT)
     {
 	errmsg = e_argument_must_be_positive;
-	p_ch = 1;
+	p_ch = MIN_CMDHEIGHT;
     }
-    if (p_ch > Rows - min_rows() + 1)
-	p_ch = Rows - min_rows() + 1;
+    if (p_ch > Rows - min_rows() + MIN_CMDHEIGHT)
+	p_ch = Rows - min_rows() + MIN_CMDHEIGHT;
 
     // Only compute the new window layout when startup has been
     // completed. Otherwise the frame sizes may be wrong.
@@ -4859,15 +4859,15 @@ check_num_option_bounds(
     size_t	errbuflen,
     char	*errmsg)
 {
-    if (Rows < min_rows() && full_screen)
+    if (Rows < min_rows_for_all_tabpages() && full_screen)
     {
 	if (errbuf != NULL)
 	{
 	    vim_snprintf(errbuf, errbuflen,
-		    _(e_need_at_least_nr_lines), min_rows());
+		    _(e_need_at_least_nr_lines), min_rows_for_all_tabpages());
 	    errmsg = errbuf;
 	}
-	Rows = min_rows();
+	Rows = min_rows_for_all_tabpages();
     }
     if (Columns < MIN_COLUMNS && full_screen)
     {

src/proto/window.pro

@@ -89,6 +89,7 @@ void last_status(int morewin);
 int tabline_height(void);
 int last_stl_height(int morewin);
 int min_rows(void);
+int min_rows_for_all_tabpages(void);
 int only_one_window(void);
 void check_lnums(int do_curwin);
 void check_lnums_nested(int do_curwin);

src/term.c

@@ -3564,8 +3564,9 @@ get_bytes_from_buf(char_u *buf, char_u *bytes, int num_bytes)
     void
 check_shellsize(void)
 {
-    if (Rows < min_rows())	// need room for one window and command line
-	Rows = min_rows();
+    // need room for one window and command line
+    if (Rows < min_rows_for_all_tabpages())
+	Rows = min_rows_for_all_tabpages();
     limit_screen_size();
 
     // make sure these values are not invalid

src/testdir/test_options.vim

@@ -2262,13 +2262,46 @@ func Test_opt_default()
 endfunc
 
 " Test for the 'cmdheight' option
-func Test_cmdheight()
+func Test_opt_cmdheight()
   %bw!
   let ht = &lines
   set cmdheight=9999
   call assert_equal(1, winheight(0))
   call assert_equal(ht - 1, &cmdheight)
   set cmdheight&
+
+  " The status line should be taken into account.
+  set laststatus=2
+  set cmdheight=9999
+  call assert_equal(ht - 2, &cmdheight)
+  set cmdheight& laststatus&
+
+  " The tabline should be taken into account only non-GUI.
+  set showtabline=2
+  set cmdheight=9999
+  if has('gui_running')
+    call assert_equal(ht - 1, &cmdheight)
+  else
+    call assert_equal(ht - 2, &cmdheight)
+  endif
+  set cmdheight& showtabline&
+
+  " The 'winminheight' should be taken into account.
+  set winheight=3 winminheight=3
+  split
+  set cmdheight=9999
+  call assert_equal(ht - 8, &cmdheight)
+  %bw!
+  set cmdheight& winminheight& winheight&
+
+  " Only the windows in the current tabpage are taken into account.
+  set winheight=3 winminheight=3 showtabline=0
+  split
+  tabnew
+  set cmdheight=9999
+  call assert_equal(ht - 3, &cmdheight)
+  %bw!
+  set cmdheight& winminheight& winheight& showtabline&
 endfunc
 
 " To specify a control character as an option value, '^' can be used

src/testdir/test_window_cmd.vim

@@ -68,7 +68,7 @@ func Test_cmdheight_not_changed()
 
   tabonly!
   only
-  set winminwidth& cmdheight&
+  set winminheight& cmdheight&
   augroup Maximize
     au!
   augroup END

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    892,
 /**/
     891,
 /**/

src/vim.h

@@ -1625,6 +1625,7 @@ typedef UINT32_TYPEDEF UINT32_T;
  */
 #define MIN_COLUMNS	12	// minimal columns for screen
 #define MIN_LINES	2	// minimal lines for screen
+#define MIN_CMDHEIGHT	1	// minimal height for command line
 #define STATUS_HEIGHT	1	// height of a status line under a window
 #ifdef FEAT_MENU		// height of a status line under a window
 # define WINBAR_HEIGHT(wp)	(wp)->w_winbar_height

src/window.c

@@ -6667,7 +6667,7 @@ win_setminheight(void)
     while (p_wmh > 0)
     {
 	room = Rows - p_ch;
-	needed = min_rows() - 1;  // 1 was added for the cmdline
+	needed = min_rows_for_all_tabpages() - 1;  // 1 was added for the cmdline
 	if (room >= needed)
 	    break;
 	--p_wmh;
@@ -6826,7 +6826,7 @@ win_drag_status_line(win_T *dragwin, int offset)
     row = win_comp_pos();
     screen_fill(row, cmdline_row, 0, (int)Columns, ' ', ' ', 0);
     cmdline_row = row;
-    p_ch = MAX(Rows - cmdline_row, 1);
+    p_ch = MAX(Rows - cmdline_row, MIN_CMDHEIGHT);
     curtab->tp_ch_used = p_ch;
 
     win_fix_scroll(TRUE);
@@ -7496,6 +7496,20 @@ last_stl_height(
  */
     int
 min_rows(void)
+{
+    if (firstwin == NULL)	// not initialized yet
+	return MIN_LINES;
+
+    return frame_minheight(curtab->tp_topframe, NULL) + tabline_height()
+	+ MIN_CMDHEIGHT;
+}
+
+/*
+ * Return the minimal number of rows that is needed on the screen to display
+ * the current number of windows for all tab pages.
+ */
+    int
+min_rows_for_all_tabpages(void)
 {
     int		total;
     tabpage_T	*tp;
@@ -7512,7 +7526,7 @@ min_rows(void)
 	    total = n;
     }
     total += tabline_height();
-    total += 1;		// count the room for the command line
+    total += MIN_CMDHEIGHT;
     return total;
 }