[lldb] Use the "reverse video" effect when colors are disabled.

lldb/source/Core/Statusline.cpp

@@ -27,6 +27,7 @@
 #define ANSI_CLEAR_LINE ESCAPE "[2K"
 #define ANSI_SET_SCROLL_ROWS ESCAPE "[0;%ur"
 #define ANSI_TO_START_OF_ROW ESCAPE "[%u;0f"
+#define ANSI_REVERSE_VIDEO ESCAPE "[7m"
 #define ANSI_UP_ROWS ESCAPE "[%dA"
 
 using namespace lldb;
@@ -74,6 +75,12 @@ void Statusline::Draw(std::string str) {
   locked_stream << ANSI_SAVE_CURSOR;
   locked_stream.Printf(ANSI_TO_START_OF_ROW,
                        static_cast<unsigned>(m_terminal_height));
+
+  // Use "reverse video" to make sure the statusline has a background. Only do
+  // this when colors are disabled, and rely on the statusline format otherwise.
+  if (!m_debugger.GetUseColor())
+    locked_stream << ANSI_REVERSE_VIDEO;
+
   locked_stream << str;
   locked_stream << ANSI_NORMAL;
   locked_stream << ANSI_RESTORE_CURSOR;

lldb/test/API/functionalities/statusline/TestStatusline.py

@@ -55,3 +55,25 @@ def test(self):
         self.expect(
             "set set show-statusline false", ["\x1b[0;{}r".format(terminal_height)]
         )
+
+    # PExpect uses many timeouts internally and doesn't play well
+    # under ASAN on a loaded machine..
+    @skipIfAsan
+    def test_no_color(self):
+        """Basic test for the statusline with colors disabled."""
+        self.build()
+        self.launch(use_colors=False)
+        self.do_setup()
+
+        # Change the terminal dimensions.
+        terminal_height = 10
+        terminal_width = 60
+        self.child.setwinsize(terminal_height, terminal_width)
+
+        # Enable the statusline and check for the "reverse video" control character.
+        self.expect(
+            "set set show-statusline true",
+            [
+                "\x1b[7m",
+            ],
+        )