make "set debug target" take effect immediately

Right now, "set debug target" acts a bit strangely.

Most target APIs only notice that it has changed when the target stack
is changed in some way.  This is because many methods implement the
setting using the special debug target.  However, a few spots do
change their behavior immediately -- any place explicitly checking
"targetdebug".

Some of this peculiar behavior is documented.  However, I think that
it just isn't very useful for it to work this way.  So, this patch
changes "set debug target" to take effect immediately in all cases.
This is done by simply calling update_current_target when the setting
is changed.

This required one small change in the test suite.  Here a test was
expecting the current behavior.

Built and regtested on x86-64 Fedora 20.

2014-08-04  Tom Tromey  <tromey@redhat.com>

	* target.c (set_targetdebug): New function.
	(initialize_targets): Pass set_targetdebug when creating "set
	debug target".

2014-08-04  Tom Tromey  <tromey@redhat.com>

	* gdb.texinfo (Debugging Output): Update for change to "set debug
	target".

2014-08-04  Tom Tromey  <tromey@redhat.com>

	* gdb.base/sss-bp-on-user-bp-2.exp: Expect output from "set debug
	target 0".

gdb/ChangeLog

@@ -1,3 +1,9 @@
+2014-08-04  Tom Tromey  <tromey@redhat.com>
+
+	* target.c (set_targetdebug): New function.
+	(initialize_targets): Pass set_targetdebug when creating "set
+	debug target".
+
 2014-08-01  Joel Brobecker  <brobecker@adacore.com>
 
 	* gdbtypes.c (resolve_dynamic_struct): Do not generate an error

gdb/doc/ChangeLog

@@ -1,3 +1,8 @@
+2014-08-04  Tom Tromey  <tromey@redhat.com>
+
+	* gdb.texinfo (Debugging Output): Update for change to "set debug
+	target".
+
 2014-08-01  Masaki Muranaka  <monaka@monami-software.com>
 
 	Pushed by Joel Brobecker  <brobecker@adacore.com>.

gdb/doc/gdb.texinfo

@@ -22996,8 +22996,7 @@ Show the current state of symbol table creation debugging.
 Turns on or off display of @value{GDBN} target debugging info. This info
 includes what is going on at the target level of GDB, as it happens. The
 default is 0.  Set it to 1 to track events, and to 2 to also track the
-value of large memory transfers.  Changes to this flag do not take effect
-until the next time you connect to a target or use the @code{run} command.
+value of large memory transfers.
 @item show debug target
 Displays the current state of displaying @value{GDBN} target debugging
 info.

gdb/target.c

@@ -118,6 +118,8 @@ static struct target_ops debug_target;
 
 static void init_dummy_target (void);
 
+static void update_current_target (void);
+
 /* Pointer to array of target architecture structures; the size of the
    array; the current index into the array; the allocated size of the
    array.  */
@@ -173,6 +175,13 @@ int may_stop = 1;
 /* Non-zero if we want to see trace of target level stuff.  */
 
 static unsigned int targetdebug = 0;
+
+static void
+set_targetdebug  (char *args, int from_tty, struct cmd_list_element *c)
+{
+  update_current_target ();
+}
+
 static void
 show_targetdebug (struct ui_file *file, int from_tty,
 		  struct cmd_list_element *c, const char *value)
@@ -3565,9 +3574,8 @@ initialize_targets (void)
 Set target debugging."), _("\
 Show target debugging."), _("\
 When non-zero, target debugging is enabled.  Higher numbers are more\n\
-verbose.  Changes do not take effect until the next \"run\" or \"target\"\n\
-command."),
-			     NULL,
+verbose."),
+			     set_targetdebug,
 			     show_targetdebug,
 			     &setdebuglist, &showdebuglist);
 

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-08-04  Tom Tromey  <tromey@redhat.com>
+
+	* gdb.base/sss-bp-on-user-bp-2.exp: Expect output from "set debug
+	target 0".
+
 2014-08-04  Tom Tromey  <tromey@redhat.com>
 
 	* gdb.base/sss-bp-on-user-bp-2.exp: Match "to_resume", not

gdb/testsuite/gdb.base/sss-bp-on-user-bp-2.exp

@@ -76,7 +76,7 @@ if { $hardware_step } {
     return
 }
 
-gdb_test_no_output "set debug target 0"
+gdb_test "set debug target 0" "->to_log_command.*\\)"
 
 set line_re "\[^\r\n\]*"