[PATCH] Use console uiout when executing breakpoint commands

[Simon Marchi <simon.marchi@polymtl.ca>]

As reported here

  https://sourceware.org/ml/gdb/2017-10/msg00020.html

the output of certain commands, like backtrace, doesn't appear anywhere
when it is run as a breakpoint command and when using MI.

The reason is that the current_uiout is set to the mi_ui_out while these
commands run, whereas we want the output as CLI output.  Some commands
like "print" work, because they use printf_filtered (gdb_stdout, ...)
directly, bypassing the current ui_out.

The fix I did is to force setting the cli_uiout as the current_uiout
when calling execute_control_command.  I am not sure if this is the
right way to fix the problem, comments about the approach would be
appreciated.

I enhanced gdb.mi/mi-break.exp to test the backtrace command.

Regtested on the buildbot.

gdb/ChangeLog:

	* cli/cli-script.c (execute_control_command): Rename to ...
	(execute_control_command_1): ... this.
	(execute_control_command): New function.

gdb/testsuite/ChangeLog:

	* gdb.mi/mi-break.exp (test_breakpoint_commands): Test backtrace
	as a breakpoint command.
---
 gdb/cli/cli-script.c              | 23 +++++++++++++++++++----
 gdb/testsuite/gdb.mi/mi-break.exp |  4 ++--
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
index 0a93e8b54f..8fbdc83c5c 100644
--- a/gdb/cli/cli-script.c
+++ b/gdb/cli/cli-script.c
@@ -463,8 +463,10 @@ print_command_trace (const char *cmd)
   printf_filtered ("%s\n", cmd);
 }
 
-enum command_control_type
-execute_control_command (struct command_line *cmd)
+/* Helper for execute_control_command.  */
+
+static enum command_control_type
+execute_control_command_1 (struct command_line *cmd)
 {
   struct command_line *current;
   struct value *val;
@@ -541,7 +543,7 @@ execute_control_command (struct command_line *cmd)
 	      {
 		scoped_restore save_nesting
 		  = make_scoped_restore (&command_nest_depth, command_nest_depth + 1);
-		ret = execute_control_command (current);
+		ret = execute_control_command_1 (current);
 
 		/* If we got an error, or a "break" command, then stop
 		   looping.  */
@@ -600,7 +602,7 @@ execute_control_command (struct command_line *cmd)
 	  {
 	    scoped_restore save_nesting
 	      = make_scoped_restore (&command_nest_depth, command_nest_depth + 1);
-	    ret = execute_control_command (current);
+	    ret = execute_control_command_1 (current);
 
 	    /* If we got an error, get out.  */
 	    if (ret != simple_control)
@@ -644,6 +646,19 @@ execute_control_command (struct command_line *cmd)
   return ret;
 }
 
+enum command_control_type
+execute_control_command (struct command_line *cmd)
+{
+  /* Make sure we use the console interp and uiout.  It's possible
+     that we are executing breakpoint commands while running the MI
+     interpreter.  */
+  interp *console = interp_lookup (current_ui, INTERP_CONSOLE);
+  scoped_restore save_uiout
+    = make_scoped_restore (&current_uiout, interp_ui_out (console));
+
+  return execute_control_command_1 (cmd);
+}
+
 /* Like execute_control_command, but first set
    suppress_next_print_command_trace.  */
 
diff --git a/gdb/testsuite/gdb.mi/mi-break.exp b/gdb/testsuite/gdb.mi/mi-break.exp
index 38670c293b..41a48a1400 100644
--- a/gdb/testsuite/gdb.mi/mi-break.exp
+++ b/gdb/testsuite/gdb.mi/mi-break.exp
@@ -277,7 +277,7 @@ proc test_breakpoint_commands {} {
 	-number 9 -disp keep -func callee2 -file ".*basics.c" \
 	-line $line_callee2_body
 
-    mi_gdb_test "-break-commands 9 \"set \$i=0\" \"while \$i<10\" \"print \$i\" \"set \$i=\$i+1\" \"end\" \"continue\" " \
+    mi_gdb_test "-break-commands 9 \"bt\" \"set \$i=0\" \"while \$i<10\" \"print \$i\" \"set \$i=\$i+1\" \"end\" \"continue\" " \
         "\\^done" \
         "breakpoint commands: set commands"
 
@@ -291,7 +291,7 @@ proc test_breakpoint_commands {} {
     set test "intermediate stop and continue, bp commands"
     gdb_expect {
 	-i $gdb_main_spawn_id
-	-re ".*\\\$1 = 0.*\\\$10 = 9" {
+	-re ".*callee2.*callee1.*main.*\\\$1 = 0.*\\\$10 = 9" {
 	    pass $test
 	}
 	timeout {
-- 
2.14.2