[Lldb-commits] [lldb] [lldb] Recompute the statusline on resize without clearing the screen (PR #202691)

[Pavel Labath via lldb-commits]

================
@@ -114,13 +126,44 @@ void Statusline::UpdateScrollWindow(ScrollWindowMode mode) {
       // Clear the screen below to hide the old statusline.
       locked_stream << ANSI_CLEAR_BELOW;
       break;
-    case ResizeStatusline:
-      // Clear the screen and update the scroll window.
-      // FIXME: Find a better solution (#146919).
-      locked_stream << ANSI_CLEAR_SCREEN;
+    case ResizeStatusline: {
+      // The old statusline is still on screen after a resize: a width shrink
+      // reflows that full-width line into ceil(prev_width / width) rows at the
+      // bottom, and growing taller strands it at its old row. Clear from the
+      // topmost row it can occupy to the bottom (preserving the scrollback
+      // above), then re-establish the scroll region. DECSTBM homes the cursor,
+      // so save and restore it.
+      const unsigned height = static_cast<unsigned>(m_terminal_height);
+      unsigned reflow = 1;
+      if (prev_width > m_terminal_width && m_terminal_width > 0)
+        reflow = (prev_width + m_terminal_width - 1) / m_terminal_width;
----------------
labath wrote:

```suggestion
        reflow = llvm::divideCeil(prev_width, m_terminal_width);
```

https://github.com/llvm/llvm-project/pull/202691