[PATCH] gdb/tui: Fix unexpected reuse of color pairs

[jakob.schaeffeler@tum.de]

From: Jakob Schäffeler <jakob.schaeffeler@tum.de>

TUI translates ANSI styling sequences to curses color pairs.
Currently in this process uses COLOR_PAIR which only returns values from 0 to 255 which results in unexpected reuse of color pairs.
This patch avoids calling COLOR_PAIR(pair) to be able to render more than 256 color pairs. For this the wattron call is replaced with wcolor_set.
This also results in last_color_pair no longer being needed since we set the color directly with wcolor_set and do not need wattron/off pairs any longer.
This results in SHRT_MAX different color pairs to be available. To get all 65535 color pairs init_pair is replaced with init_extended_pair, which returns an int instead of short.
This patch was tested with make check-gdb TESTS="gdb.tui/*.exp"

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=34134
---
 gdb/tui/tui-io.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index 642b88ead0c..5e239179b5e 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -265,10 +265,6 @@ get_color (const ui_file_style::color &color, int *result)
   return true;
 }
 
-/* The most recently emitted color pair.  */
-
-static int last_color_pair = -1;
-
 /* The most recently applied style.  */
 
 static ui_file_style last_style;
@@ -299,7 +295,7 @@ get_color_pair (int fg, int bg)
 	 back to the default if we've used too many.  */
       if (next >= COLOR_PAIRS)
 	return 0;
-      init_pair (next, fg, bg);
+      init_extended_pair (next, fg, bg);
       color_pair_map[c] = next;
       return next;
     }
@@ -320,9 +316,7 @@ tui_apply_style (WINDOW *w, ui_file_style style)
 #endif
   wattroff (w, A_UNDERLINE);
   wattroff (w, A_REVERSE);
-  if (last_color_pair != -1)
-    wattroff (w, COLOR_PAIR (last_color_pair));
-  wattron (w, COLOR_PAIR (0));
+  wcolor_set (w, 0, nullptr);
 
   const ui_file_style::color &fg = style.get_foreground ();
   const ui_file_style::color &bg = style.get_background ();
@@ -342,10 +336,7 @@ tui_apply_style (WINDOW *w, ui_file_style style)
 	    bgi = (ncurses_norm_attr >> 4) & 15;
 #endif
 	  int pair = get_color_pair (fgi, bgi);
-	  if (last_color_pair != -1)
-	    wattroff (w, COLOR_PAIR (last_color_pair));
-	  wattron (w, COLOR_PAIR (pair));
-	  last_color_pair = pair;
+	  wcolor_set (w, 0, &pair);
 	}
     }
 
@@ -907,7 +898,6 @@ tui_setup_io (int mode)
       savetty ();
 
       /* Clean up color information.  */
-      last_color_pair = -1;
       last_style = ui_file_style ();
       color_map.clear ();
       color_pair_map.clear ();
-- 
2.54.0