Fix reflow of empty wrapped cursor line

This bug was caused by trying to grow the terminal while the cursor line
was wrapped but entirely empty. Resizing the terminal now accounts for
the position of the deleted line and moves the cursor up only when the
line deleted was above it.

The deletion of the line was caused by the shell redrawing itself
whenever the cursor is moved.

Fixes #3583.

1 files changed, 15 insertions, 2 deletions

diff --git a/alacritty_terminal/src/grid/resize.rs b/alacritty_terminal/src/grid/resize.rs
index 796c5859..95a8c2fc 100644
--- a/alacritty_terminal/src/grid/resize.rs
+++ b/alacritty_terminal/src/grid/resize.rs
@@ -67,10 +67,12 @@ impl<T: GridCell + Default + PartialEq + Copy> Grid<T> {
             self.scroll_up(&(Line(0)..self.lines), Line(required_scrolling), T::default());
 
             // Clamp cursors to the new viewport size.
-            self.saved_cursor.point.line = min(self.saved_cursor.point.line, target - 1);
             self.cursor.point.line = min(self.cursor.point.line, target - 1);
         }
 
+        // Clamp saved cursor, since only primary cursor is scrolled into viewport.
+        self.saved_cursor.point.line = min(self.saved_cursor.point.line, target - 1);
+
         self.raw.rotate((self.lines - target).0 as isize);
         self.raw.shrink_visible_lines(target);
         self.lines = target;
@@ -135,7 +137,8 @@ impl<T: GridCell + Default + PartialEq + Copy> Grid<T> {
             // Reflow cells to previous row.
             last_row.append(&mut cells);
 
-            if row.is_empty() {
+            let cursor_buffer_line = (self.lines - self.cursor.point.line - 1).0;
+            if row.is_clear() && (i != cursor_buffer_line || row.len() == 0) {
                 if i + reversed.len() < self.lines.0 {
                     // Add new line and move everything up if we can't pull from history.
                     self.saved_cursor.point.line.0 = self.saved_cursor.point.line.saturating_sub(1);
@@ -144,6 +147,16 @@ impl<T: GridCell + Default + PartialEq + Copy> Grid<T> {
                 } else {
                     // Since we removed a line, rotate down the viewport.
                     self.display_offset = self.display_offset.saturating_sub(1);
+
+                    // Rotate cursors down if content below them was pulled from history.
+                    if i < cursor_buffer_line {
+                        self.cursor.point.line += 1;
+                    }
+
+                    let saved_buffer_line = (self.lines - self.saved_cursor.point.line - 1).0;
+                    if i < saved_buffer_line {
+                        self.saved_cursor.point.line += 1;
+                    }
                 }
 
                 // Don't push line into the new buffer.