fix(terminal): add various missing redraws

Problem: missing redraws when restoring saved cursorline/column, plus missing
statusline and mode redraws when not updating the screen in terminal mode.

Solution: schedule the redraws in a similar manner to other modes and remove
some now unnecessary redrawing logic. Redraw if cursorline-related options
change from entering terminal mode. This fixes test failures in later commits.

WTF: TextChangedT triggers based on must_redraw, which is... fun...? Try to
preserve its behaviour as much as we can for now.

src/nvim/terminal.c

@@ -705,18 +705,19 @@ bool terminal_enter(void)
   } else {
     curwin->w_p_cul = false;
   }
-  if (curwin->w_p_cuc) {
-    redraw_later(curwin, UPD_SOME_VALID);
-  }
   curwin->w_p_cuc = false;
   curwin->w_p_so = 0;
   curwin->w_p_siso = 0;
+  if (curwin->w_p_cuc != save_w_p_cuc) {
+    redraw_later(curwin, UPD_SOME_VALID);
+  } else if (curwin->w_p_cul != save_w_p_cul
+             || (curwin->w_p_cul && curwin->w_p_culopt_flags != save_w_p_culopt_flags)) {
+    redraw_later(curwin, UPD_VALID);
+  }
 
   s->term->pending.cursor = true;  // Update the cursor shape table
   adjust_topline(s->term, buf, 0);  // scroll to end
   showmode();
-  curwin->w_redr_status = true;  // For mode() in statusline. #8323
-  redraw_custom_title_later();
   ui_cursor_shape();
   apply_autocmds(EVENT_TERMENTER, NULL, NULL, false, curbuf);
   may_trigger_modechanged();
@@ -744,6 +745,12 @@ bool terminal_enter(void)
   (void)parse_shape_opt(SHAPE_CURSOR);
 
   if (save_curwin == curwin->handle) {  // Else: window was closed.
+    if (save_w_p_cuc != curwin->w_p_cuc) {
+      redraw_later(curwin, UPD_SOME_VALID);
+    } else if (save_w_p_cul != curwin->w_p_cul
+               || (save_w_p_cul && save_w_p_culopt_flags != curwin->w_p_culopt_flags)) {
+      redraw_later(curwin, UPD_VALID);
+    }
     curwin->w_p_cul = save_w_p_cul;
     if (save_w_p_culopt) {
       free_string_option(curwin->w_p_culopt);
@@ -808,10 +815,18 @@ static int terminal_check(VimState *state)
   assert(s->term == curbuf->terminal);
   terminal_check_cursor();
   validate_cursor(curwin);
+  const bool text_changed = must_redraw != 0;
+  show_cursor_info_later(false);
 
   if (must_redraw) {
     update_screen();
-
+  } else {
+    redraw_statuslines();
+    if (clear_cmdline || redraw_cmdline || redraw_mode) {
+      showmode();  // clear cmdline and show mode
+    }
+  }
+  if (text_changed) {
     // Make sure an invoked autocmd doesn't delete the buffer (and the
     // terminal) under our fingers.
     curbuf->b_locked++;
@@ -827,10 +842,6 @@ static int terminal_check(VimState *state)
 
   may_trigger_win_scrolled_resized();
 
-  if (need_maketitle) {  // Update title in terminal-mode. #7248
-    maketitle();
-  }
-
   setcursor();
   refresh_cursor(s->term, &s->cursor_visible);
   ui_flush();

test/functional/terminal/window_spec.lua

@@ -189,6 +189,149 @@ describe(':terminal window', function()
       ]])
     end)
   end)
+
+  it('redrawn when restoring cursorline/column', function()
+    screen:set_default_attr_ids({
+      [1] = { bold = true },
+      [2] = { foreground = 130 },
+      [3] = { foreground = 130, underline = true },
+      [12] = { underline = true },
+      [19] = { background = 7 },
+    })
+
+    feed([[<C-\><C-N>]])
+    command('setlocal cursorline')
+    screen:expect([[
+      tty ready                                         |
+      {12:^                                                  }|
+                                                        |*5
+    ]])
+    feed('i')
+    screen:expect([[
+      tty ready                                         |
+      ^                                                  |
+                                                        |*4
+      {1:-- TERMINAL --}                                    |
+    ]])
+    feed([[<C-\><C-N>]])
+    screen:expect([[
+      tty ready                                         |
+      {12:^                                                  }|
+                                                        |*5
+    ]])
+
+    command('setlocal number')
+    screen:expect([[
+      {2:  1 }tty ready                                     |
+      {3:  2 }{12:^rows: 6, cols: 46                             }|
+      {2:  3 }                                              |
+      {2:  4 }                                              |
+      {2:  5 }                                              |
+      {2:  6 }                                              |
+                                                        |
+    ]])
+    feed('i')
+    screen:expect([[
+      {2:  1 }tty ready                                     |
+      {2:  2 }rows: 6, cols: 46                             |
+      {3:  3 }^                                              |
+      {2:  4 }                                              |
+      {2:  5 }                                              |
+      {2:  6 }                                              |
+      {1:-- TERMINAL --}                                    |
+    ]])
+    feed([[<C-\><C-N>]])
+    screen:expect([[
+      {2:  1 }tty ready                                     |
+      {2:  2 }rows: 6, cols: 46                             |
+      {3:  3 }{12:^                                              }|
+      {2:  4 }                                              |
+      {2:  5 }                                              |
+      {2:  6 }                                              |
+                                                        |
+    ]])
+
+    command('setlocal nonumber nocursorline cursorcolumn')
+    screen:expect([[
+      {19:t}ty ready                                         |
+      {19:r}ows: 6, cols: 46                                 |
+      ^rows: 6, cols: 50                                 |
+      {19: }                                                 |*3
+                                                        |
+    ]])
+    feed('i')
+    screen:expect([[
+      tty ready                                         |
+      rows: 6, cols: 46                                 |
+      rows: 6, cols: 50                                 |
+      ^                                                  |
+                                                        |*2
+      {1:-- TERMINAL --}                                    |
+    ]])
+    feed([[<C-\><C-N>]])
+    screen:expect([[
+      {19:t}ty ready                                         |
+      {19:r}ows: 6, cols: 46                                 |
+      {19:r}ows: 6, cols: 50                                 |
+      ^                                                  |
+      {19: }                                                 |*2
+                                                        |
+    ]])
+  end)
+
+  it('redraws cursor info in terminal mode', function()
+    skip(is_os('win'), '#31587')
+    command('file AMOGUS | set laststatus=2 ruler')
+    screen:expect([[
+      tty ready                                         |
+      rows: 5, cols: 50                                 |
+      ^                                                  |
+                                                        |*2
+      {120:AMOGUS [-]                      3,0-1          All}|
+      {5:-- TERMINAL --}                                    |
+    ]])
+    feed_data('you are the imposter')
+    screen:expect([[
+      tty ready                                         |
+      rows: 5, cols: 50                                 |
+      you are the imposter^                              |
+                                                        |*2
+      {120:AMOGUS [-]                      3,21           All}|
+      {5:-- TERMINAL --}                                    |
+    ]])
+    feed([[<C-\><C-N>]])
+    screen:expect([[
+      tty ready                                         |
+      rows: 5, cols: 50                                 |
+      you are the imposte^r                              |
+                                                        |*2
+      {120:AMOGUS [-]                      3,20           All}|
+                                                        |
+    ]])
+  end)
+
+  it('redraws stale statuslines and mode when not updating screen', function()
+    command('file foo | set ruler | vsplit')
+    screen:expect([[
+      tty ready                │tty ready               |
+      rows: 5, cols: 25        │rows: 5, cols: 25       |
+      ^                         │                        |
+                               │                        |*2
+      {120:<o [-] 3,0-1          All }{119:< [-] 2,0-1          Top}|
+      {5:-- TERMINAL --}                                    |
+    ]])
+    command("call win_execute(win_getid(winnr('#')), 'call cursor(1, 1)')")
+    screen:expect([[
+      tty ready                │tty ready               |
+      rows: 5, cols: 25        │rows: 5, cols: 25       |
+      ^                         │                        |
+                               │                        |*2
+      {120:<o [-] 3,0-1          All }{119:< [-] 1,1            All}|
+      {5:-- TERMINAL --}                                    |
+    ]])
+    command('echo ""')
+    screen:expect_unchanged()
+  end)
 end)
 
 describe(':terminal with multigrid', function()

test/functional/ui/title_spec.lua

@@ -79,18 +79,27 @@ describe('title', function()
 
   it('is updated in Terminal mode', function()
     api.nvim_set_option_value('title', true, {})
-    api.nvim_set_option_value('titlestring', '(%{mode(1)}) | nvim', {})
+    api.nvim_set_option_value('titlestring', '%t (%{mode(1)}) | nvim', {})
     fn.jobstart({ n.testprg('shell-test'), 'INTERACT' }, { term = true })
+    api.nvim_buf_set_name(0, 'shell-test')
     screen:expect(function()
-      eq('(nt) | nvim', screen.title)
+      eq('shell-test (nt) | nvim', screen.title)
     end)
     feed('i')
     screen:expect(function()
-      eq('(t) | nvim', screen.title)
+      eq('shell-test (t) | nvim', screen.title)
+    end)
+    api.nvim_set_option_value('titlelen', 1, {})
+    screen:expect(function()
+      eq('<t) | nvim', screen.title)
+    end)
+    command('set titlelen&')
+    screen:expect(function()
+      eq('shell-test (t) | nvim', screen.title)
     end)
     feed([[<C-\><C-N>]])
     screen:expect(function()
-      eq('(nt) | nvim', screen.title)
+      eq('shell-test (nt) | nvim', screen.title)
     end)
   end)