[PATCH] gdb/cli: if redirecting output, also redirect top-level interpreter's ui-out

[Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>]

When executing commands from Python, the API provides an option to
capture the command output in a string and return this to the user.
See the `gdb.execute` function at

  https://sourceware.org/gdb/onlinedocs/gdb/Basic-Python.html#Basic-Python

When the `to_string` argument is True, the output of the executed
command is supposed to be captured and returned to the caller.  For
this, GDB temporarily redirects the ui-outs to a string file.

However, output does not get captured if the executed command prints
its output through the top-level interpreter's ui-out.  E.g., in the
following we still see the output being printed.

  (gdb) python gdb.execute("inferior 1", from_tty=False, to_string=True)
  [Switching to inferior 1 [<null>] (<noexec>)]
  (gdb)

To fix, also redirect the top-level interpreter's ui-out.

gdb/ChangeLog:
2020-10-06  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* cli/cli-script.c (execute_control_commands_to_string): Redirect
	top level interpreter's ui-out before running the command.
---
 gdb/cli/cli-script.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
index f8ac610d4d6..21a4065a5f2 100644
--- a/gdb/cli/cli-script.c
+++ b/gdb/cli/cli-script.c
@@ -425,6 +425,10 @@ execute_control_commands_to_string (struct command_line *commands,
     current_uiout->redirect (&str_file);
     ui_out_redirect_pop redirect_popper (current_uiout);
 
+    ui_out *uiout = top_level_interpreter ()->interp_ui_out ();
+    uiout->redirect (&str_file);
+    ui_out_redirect_pop redirect_popper2 (uiout);
+
     scoped_restore save_stdout
       = make_scoped_restore (&gdb_stdout, &str_file);
     scoped_restore save_stderr
-- 
2.17.1