[Lldb-commits] [lldb] [lldb] Fix a bug when disabling the statusline. (PR #169127)

[Jonas Devlieghere via lldb-commits]

https://github.com/JDevlieghere created https://github.com/llvm/llvm-project/pull/169127

Currently, disabling the statusline with `settings set show-statusline false` leaves LLDB in a broken state. The same is true when trying to toggle the setting again.

The issue was that setting the scroll window to 0 is apparently not identical to setting it to the correct number of rows, even though some documentation online incorrectly claims so.

Fixes #166608

>From 0c2ace38aeaed9de6edddec7e9ed568fc1cdf477 Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jonas at devlieghere.com>
Date: Fri, 21 Nov 2025 15:29:43 -0800
Subject: [PATCH] [lldb] Fix a bug when disabling the statusline.

Currently, disabling the statusline with `settings set show-statusline
false` leaves LLDB in a broken state. The same is true when trying to
toggle the setting again.

The issue was that setting the scroll window to 0 is apparently not
identical to setting it to the correct number of rows, even though some
documentation online incorrectly claims so.

Fixes #166608
---
 lldb/source/Core/Statusline.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lldb/source/Core/Statusline.cpp b/lldb/source/Core/Statusline.cpp
index bfbd190fba27c..922aada07e979 100644
--- a/lldb/source/Core/Statusline.cpp
+++ b/lldb/source/Core/Statusline.cpp
@@ -91,7 +91,7 @@ void Statusline::UpdateScrollWindow(ScrollWindowMode mode) {
   if (!stream_sp)
     return;
 
-  const unsigned reduced_scroll_window = m_terminal_height - 1;
+  const unsigned reduced_scroll_rows = m_terminal_height - 1;
   LockedStreamFile locked_stream = stream_sp->Lock();
 
   switch (mode) {
@@ -101,13 +101,14 @@ void Statusline::UpdateScrollWindow(ScrollWindowMode mode) {
     locked_stream.Printf(ANSI_UP_ROWS, 1);
     // Reduce the scroll window.
     locked_stream << ANSI_SAVE_CURSOR;
-    locked_stream.Printf(ANSI_SET_SCROLL_ROWS, reduced_scroll_window);
+    locked_stream.Printf(ANSI_SET_SCROLL_ROWS, reduced_scroll_rows);
     locked_stream << ANSI_RESTORE_CURSOR;
     break;
   case DisableStatusline:
     // Reset the scroll window.
     locked_stream << ANSI_SAVE_CURSOR;
-    locked_stream.Printf(ANSI_SET_SCROLL_ROWS, 0);
+    locked_stream.Printf(ANSI_SET_SCROLL_ROWS,
+                         static_cast<unsigned>(m_terminal_height));
     locked_stream << ANSI_RESTORE_CURSOR;
     // Clear the screen below to hide the old statusline.
     locked_stream << ANSI_CLEAR_BELOW;
@@ -116,7 +117,7 @@ void Statusline::UpdateScrollWindow(ScrollWindowMode mode) {
     // Clear the screen and update the scroll window.
     // FIXME: Find a better solution (#146919).
     locked_stream << ANSI_CLEAR_SCREEN;
-    locked_stream.Printf(ANSI_SET_SCROLL_ROWS, reduced_scroll_window);
+    locked_stream.Printf(ANSI_SET_SCROLL_ROWS, reduced_scroll_rows);
     break;
   }