gdb: Restore selected frame in print_frame_local_vars

PR gdb/23203 reports 'bt full' causing the currently selected frame to
change, this issue is fixed in this commit.

Add a new class scoped_restore_selected_frame that saves and restores
the selected frame.  Make use of this in print_frame_local_vars to
restore the selected frame on exit.

gdb/ChangeLog:

	PR gdb/23203
	* frame.c
	(scoped_restore_selected_frame::scoped_restore_selected_frame):
	Define.
	(scoped_restore_selected_frame::~scoped_restore_selected_frame):
	Define.
	* frame.h (class scoped_restore_selected_frame): New class.
	* stack.c (print_frame_local_vars): Remove catching and rethrowing
	of any exception, use scoped_restore_selected_frame to restore the
	frame instead.

gdb/testsuite/ChangeLog:

	PR gdb/23203
	* gdb.base/bt-selected-frame.c: New file.
	* gdb.base/bt-selected-frame.exp: New file.
	* lib/gdb.exp (get_current_frame_number): New function.

1 files changed, 16 insertions, 0 deletions

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 0f05d04..ee66a38 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -5805,6 +5805,22 @@ proc get_var_address { var } {
     return ""
 }
 
+# Return the frame number for the currently selected frame
+proc get_current_frame_number {{test_name ""}} {
+    global gdb_prompt
+
+    if { $test_name == "" } {
+	set test_name "get current frame number"
+    }
+    set frame_num -1
+    gdb_test_multiple "frame" $test_name {
+	-re "#(\[0-9\]+) .*$gdb_prompt $" {
+	    set frame_num $expect_out(1,string)
+	}
+    }
+    return $frame_num
+}
+
 # Get the current value for remotetimeout and return it.
 proc get_remotetimeout { } {
     global gdb_prompt