gdb: pass/return setting setter/getter scalar values by value

The getter and setter in struct setting always receive and return values
by const reference.  This is not necessary for scalar values (like bool
and int), but more importantly it makes it a bit annoying to write a
getter, you have to use a scratch static variable or something similar
that you can refer to:

  const bool &
  my_getter ()
  {
    static bool value;
    value = function_returning_bool ();
    return value;
  }

Change the getter and setter function signatures to receive and return
value by value instead of by reference, when the underlying data type is
scalar.  This means that string-based settings will still use
references, but all others will be by value.  The getter above would
then be re-written as:

  bool
  my_getter ()
  {
    return function_returning_bool ();
  }

This is useful for a patch later in this series that defines a boolean
setting with a getter and a setter.

Change-Id: Ieca3a2419fcdb75a6f75948b2c920b548a0af0fd

1 files changed, 5 insertions, 1 deletions

diff --git a/gdb/remote.c b/gdb/remote.c
index 0fb4275..abf63de 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -1873,6 +1873,9 @@ struct packet_config
        have an associated command always have this set to auto.  */
     enum auto_boolean detect;
 
+    /* The "show remote foo-packet" command created for this packet.  */
+    cmd_list_element *show_cmd;
+
     /* Does the target support this packet?  */
     enum packet_support support;
   };
@@ -1936,6 +1939,7 @@ add_packet_config_cmd (struct packet_config *config, const char *name,
 				    NULL,
 				    show_remote_protocol_packet_cmd,
 				    &remote_set_cmdlist, &remote_show_cmdlist);
+  config->show_cmd = cmds.show;
 
   /* The command code copies the documentation strings.  */
   xfree (set_doc);
@@ -2245,7 +2249,7 @@ show_remote_protocol_packet_cmd (struct ui_file *file, int from_tty,
        packet < &remote_protocol_packets[PACKET_MAX];
        packet++)
     {
-      if (&packet->detect == &c->var->get<enum auto_boolean> ())
+      if (c == packet->show_cmd)
 	{
 	  show_packet_config_cmd (packet);
 	  return;