[PATCH v2] 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, 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 takes an int instead of a short.
Since this is not available with ncurses versions older than 6.1,
a configure check was added.
This patch was tested with make check-gdb TESTS="gdb.tui/*.exp"
Additionally, I tested this with the python extension from the
bug report.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=34134
---
 gdb/config.in    |  3 +++
 gdb/configure    |  1 +
 gdb/configure.ac |  1 +
 gdb/tui/tui-io.c | 23 +++++++++++------------
 4 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/gdb/config.in b/gdb/config.in
index e357c22e411..fa436f32fbf 100644
--- a/gdb/config.in
+++ b/gdb/config.in
@@ -250,6 +250,9 @@
 /* Define to 1 if you have the `iconvlist' function. */
 #undef HAVE_ICONVLIST
 
+/* Define to 1 if you have the `init_extended_pair' function. */
+#undef HAVE_INIT_EXTENDED_PAIR
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
diff --git a/gdb/configure b/gdb/configure
index 2fc0b583702..6fcba0ba454 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -30235,6 +30235,7 @@ for ac_func in  \
   getrlimit \
   getuid \
   iconvlist \
+  init_extended_pair \
   libiconvlist \
   posix_madvise \
   pread \
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 56ab86d9356..998e2947f03 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1507,6 +1507,7 @@ AC_CHECK_FUNCS([ \
   getrlimit \
   getuid \
   iconvlist \
+  init_extended_pair \
   libiconvlist \
   posix_madvise \
   pread \
diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index 642b88ead0c..943b158be58 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 +295,11 @@ get_color_pair (int fg, int bg)
 	 back to the default if we've used too many.  */
       if (next >= COLOR_PAIRS)
 	return 0;
+#ifdef HAVE_INIT_EXTENDED_PAIR
+      init_extended_pair (next, fg, bg);
+#else
       init_pair (next, fg, bg);
+#endif
       color_pair_map[c] = next;
       return next;
     }
@@ -320,9 +320,8 @@ 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 +341,11 @@ 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;
+#ifdef HAVE_INIT_EXTENDED_PAIR 
+	  wcolor_set (w, 0, &pair);
+#else
+	  wcolor_set (w, pair, nullptr);
+#endif
 	}
     }
 
@@ -907,7 +907,6 @@ 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