Avoid assertion violations in very small-height windows

* src/xdisp.c (try_cursor_movement, redisplay_window)
(row_containing_pos): Skip tab-line glyph rows in addition to
header-line rows, when working on the top-most glyph row of a
window.  This avoids assertion violations in set_cursor_from_row.
(Bug#38966)

1 files changed, 20 insertions, 8 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 3d286cb22fb..f3a297a7020 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -16244,8 +16244,8 @@ set_cursor_from_row (struct window *w, struct glyph_row *row,
   bool string_from_text_prop = false;
 
   /* Don't even try doing anything if called for a mode-line or
-     header-line row, since the rest of the code isn't prepared to
-     deal with such calamities.  */
+     header-line or tab-line row, since the rest of the code isn't
+     prepared to deal with such calamities.  */
   eassert (!row->mode_line_p);
   if (row->mode_line_p)
     return false;
@@ -17504,6 +17504,9 @@ try_cursor_movement (Lisp_Object window, struct text_pos startp,
       else
         {
           row = MATRIX_ROW (w->current_matrix, w->last_cursor_vpos);
+          /* Skip the tab-line and header-line rows, if any.  */
+          if (row->tab_line_p)
+            ++row;
           if (row->mode_line_p)
             ++row;
           if (!row->enabled_p)
@@ -17576,6 +17579,9 @@ try_cursor_movement (Lisp_Object window, struct text_pos startp,
                   || row->mode_line_p)
                 {
                   row = w->current_matrix->rows;
+                  /* Skip the tab-line and header-line rows, if any.  */
+                  if (row->tab_line_p)
+                    ++row;
                   if (row->mode_line_p)
                     ++row;
                 }
@@ -17640,8 +17646,9 @@ try_cursor_movement (Lisp_Object window, struct text_pos startp,
             ;
           else if (rc != CURSOR_MOVEMENT_SUCCESS
               && MATRIX_ROW_PARTIALLY_VISIBLE_P (w, row)
-              /* Make sure this isn't a header line by any chance, since
-                 then MATRIX_ROW_PARTIALLY_VISIBLE_P might yield true.  */
+              /* Make sure this isn't a header line nor a tab-line by
+                 any chance, since then MATRIX_ROW_PARTIALLY_VISIBLE_P
+                 might yield true.  */
               && !row->mode_line_p
               && !cursor_row_fully_visible_p (w, true, true, true))
             {
@@ -18769,11 +18776,14 @@ redisplay_window (Lisp_Object window, bool just_this_one_p)
             }
         }
       /* Finally, fall back on the first row of the window after the
-         header line (if any).  This is slightly better than not
-         displaying the cursor at all.  */
+         tab-line and header line (if any).  This is slightly better
+         than not displaying the cursor at all.  */
       if (!row)
         {
           row = matrix->rows;
+          /* Skip the tab-line and header-line rows, if any.  */
+          if (row->tab_line_p)
+            ++row;
           if (row->mode_line_p)
             ++row;
         }
@@ -19787,7 +19797,9 @@ row_containing_pos (struct window *w, ptrdiff_t charpos,
   ptrdiff_t mindif = BUF_ZV (XBUFFER (w->contents)) + 1;
   int last_y;
 
-  /* If we happen to start on a header-line, skip that.  */
+  /* If we happen to start on a header-line or a tab-line, skip that.  */
+  if (row->tab_line_p)
+    ++row;
   if (row->mode_line_p)
     ++row;
 
@@ -22380,7 +22392,7 @@ find_row_edges (struct it *it, struct glyph_row *row,
       if (STRINGP (it->object)
           /* this is not the first row */
           && row > it->w->desired_matrix->rows
-          /* previous row is not the header line */
+          /* previous row is not the header line or tab-line */
           && !r1->mode_line_p
           /* previous row also ends in a newline from a string */
           && r1->ends_in_newline_from_string_p)