Style variable names

This adds style support for variable names.  For the time being, this
is only done in backtraces, not in ptype or print; those places do not
use ui-out and so would need ad hoc changes.

This also adds styling to the names printed for local variables in
"backtrace full".  This code does not use ui-out, so the styling is
done using the low-level API.

gdb/ChangeLog
2018-12-28  Tom Tromey  <tom@tromey.com>

	* ui-out.h (enum class ui_out_style_kind) <VARIABLE>: New global.
	* stack.c (print_frame_arg): Style name.
	* printcmd.c (print_variable_and_value): Style variable name.
	* cli/cli-style.h (variable_name_style): Declare.
	* cli/cli-style.c (variable_name_style): New global.
	(_initialize_cli_style): Update.
	* cli-out.c (cli_ui_out::do_field_string): Update.

gdb/testsuite/ChangeLog
2018-12-28  Tom Tromey  <tom@tromey.com>

	* gdb.base/style.exp: Add test for variable names.

9 files changed, 42 insertions, 4 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index cb126ff..6a6a535 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,15 @@
 2018-12-28  Tom Tromey  <tom@tromey.com>
 
+	* ui-out.h (enum class ui_out_style_kind) <VARIABLE>: New global.
+	* stack.c (print_frame_arg): Style name.
+	* printcmd.c (print_variable_and_value): Style variable name.
+	* cli/cli-style.h (variable_name_style): Declare.
+	* cli/cli-style.c (variable_name_style): New global.
+	(_initialize_cli_style): Update.
+	* cli-out.c (cli_ui_out::do_field_string): Update.
+
+2018-12-28  Tom Tromey  <tom@tromey.com>
+
 	* utils.h (reset_terminal_style): Declare.
 	* utils.c (can_emit_style_escape): New function.
 	(set_output_style): Use it.
diff --git a/gdb/cli-out.c b/gdb/cli-out.c
index 4b5fc17..e1005e1 100644
--- a/gdb/cli-out.c
+++ b/gdb/cli-out.c
@@ -173,6 +173,9 @@ cli_ui_out::do_field_string (int fldno, int width, ui_align align,
 	case ui_out_style_kind::FUNCTION:
 	  fstyle = function_name_style.style ();
 	  break;
+	case ui_out_style_kind::VARIABLE:
+	  fstyle = variable_name_style.style ();
+	  break;
 	default:
 	  gdb_assert_not_reached ("missing case");
 	}
diff --git a/gdb/cli/cli-style.c b/gdb/cli/cli-style.c
index 9f16824..929f18f 100644
--- a/gdb/cli/cli-style.c
+++ b/gdb/cli/cli-style.c
@@ -62,6 +62,10 @@ cli_style_option function_name_style (ui_file_style::YELLOW);
 
 /* See cli-style.h.  */
 
+cli_style_option variable_name_style (ui_file_style::CYAN);
+
+/* See cli-style.h.  */
+
 cli_style_option::cli_style_option (ui_file_style::basic_color fg)
   : m_foreground (cli_colors[fg - ui_file_style::NONE]),
     m_background (cli_colors[0]),
@@ -254,4 +258,11 @@ Configure function name colors and display intensity"),
 					    "style function",
 					    &style_set_list,
 					    &style_show_list);
+  variable_name_style.add_setshow_commands ("variable", no_class,
+					    "style variable",
+					    _("\
+Variable name display styling\n\
+Configure variable name colors and display intensity"),
+					    &style_set_list,
+					    &style_show_list);
 }
diff --git a/gdb/cli/cli-style.h b/gdb/cli/cli-style.h
index 7d5370c..80ba7bf 100644
--- a/gdb/cli/cli-style.h
+++ b/gdb/cli/cli-style.h
@@ -83,6 +83,9 @@ extern cli_style_option file_name_style;
 /* The function name style.  */
 extern cli_style_option function_name_style;
 
+/* The variable name style.  */
+extern cli_style_option variable_name_style;
+
 /* True if styling is enabled.  */
 extern int cli_styling;
 
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index 79c3d2d..dd16264 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -46,6 +46,7 @@
 #include "arch-utils.h"
 #include "cli/cli-utils.h"
 #include "cli/cli-script.h"
+#include "cli/cli-style.h"
 #include "format.h"
 #include "source.h"
 #include "common/byte-vector.h"
@@ -2156,7 +2157,10 @@ print_variable_and_value (const char *name, struct symbol *var,
   if (!name)
     name = SYMBOL_PRINT_NAME (var);
 
-  fprintf_filtered (stream, "%s%s = ", n_spaces (2 * indent), name);
+  fputs_filtered (n_spaces (2 * indent), stream);
+  fputs_styled (name, variable_name_style.style (), stream);
+  fputs_filtered (" = ", stream);
+
   TRY
     {
       struct value *val;
diff --git a/gdb/stack.c b/gdb/stack.c
index b32bf8f..103b8c9 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -256,7 +256,7 @@ print_frame_arg (const struct frame_arg *arg)
   if (arg->entry_kind == print_entry_values_only
       || arg->entry_kind == print_entry_values_compact)
     stb.puts ("@entry");
-  uiout->field_stream ("name", stb);
+  uiout->field_stream ("name", stb, ui_out_style_kind::VARIABLE);
   annotate_arg_name_end ();
   uiout->text ("=");
 
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 6b3ca5a..d27272d 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2018-12-28  Tom Tromey  <tom@tromey.com>
 
+	* gdb.base/style.exp: Add test for variable names.
+
+2018-12-28  Tom Tromey  <tom@tromey.com>
+
 	* gdb.base/style.exp: New file.
 	* gdb.base/style.c: New file.
 
diff --git a/gdb/testsuite/gdb.base/style.exp b/gdb/testsuite/gdb.base/style.exp
index 20b7b8c..df66e99 100644
--- a/gdb/testsuite/gdb.base/style.exp
+++ b/gdb/testsuite/gdb.base/style.exp
@@ -34,8 +34,9 @@ save_vars { env(TERM) } {
 
     set main_expr "\033\\\[33mmain\033\\\[m"
     set file_expr "\033\\\[32m.*style\\.c\033\\\[m:\[0-9\]"
+    set arg_expr "\033\\\[36marg.\033\\\[m"
 
     gdb_test "frame" \
-	"$main_expr.*$file_expr.*"
+	"$main_expr.*$arg_expr.*$arg_expr.*$file_expr.*"
     gdb_test "info breakpoints" "$main_expr at $file_expr.*"
 }
diff --git a/gdb/ui-out.h b/gdb/ui-out.h
index 8604105..93be9a9 100644
--- a/gdb/ui-out.h
+++ b/gdb/ui-out.h
@@ -75,7 +75,9 @@ enum class ui_out_style_kind
   /* File name.  */
   FILE,
   /* Function name.  */
-  FUNCTION
+  FUNCTION,
+  /* Variable name.  */
+  VARIABLE
 };
 
 class ui_out