Adjust optional's pretty printer for LWG 2900.

* python/libstdcxx/v6/printers.py (StdExpOptionalPrinter.__init__):
Look at the nested payload in case of non-experimental optional.

From-SVN: r246566

libstdc++-v3/ChangeLog

 2017-03-29  Ville Voutilainen  <ville.voutilainen@gmail.com>
 
+	Adjust optional's pretty printer for LWG 2900.
+	* python/libstdcxx/v6/printers.py (StdExpOptionalPrinter.__init__):
+	Look at the nested payload in case of non-experimental optional.
+
+2017-03-29  Ville Voutilainen  <ville.voutilainen@gmail.com>
+
 	Implement LWG 2900, The copy and move constructors
 	of optional are not constexpr.
 	* include/std/optional (_Optional_payload): New.

libstdc++-v3/python/libstdcxx/v6/printers.py

@@ -1023,6 +1023,8 @@ class StdExpOptionalPrinter(SingleObjContainerPrinter):
         valtype = self._recognize (val.type.template_argument(0))
         self.typename = re.sub('^std::(experimental::|)(fundamentals_v\d::|)(.*)', r'std::\1\3<%s>' % valtype, typename, 1)
         self.typename = strip_versioned_namespace(self.typename)
+        if not self.typename.startswith('std::experimental'):
+            val = val['_M_payload']
         self.val = val
         contained_value = val['_M_payload'] if self.val['_M_engaged'] else None
         visualizer = gdb.default_visualizer (val['_M_payload'])