[v3 PATCH] Adjust optional's pretty printer for LWG 2900.

[Ville Voutilainen]

Tested on Linux-x64.

2017-03-29  Ville Voutilainen  <ville.voutilai...@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.

diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py 
b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 14025dd..a67b27a 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/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'])