2013-12-12 Siva Chandra Reddy <sivachandra@google.com>

PR python/16113
	* NEWS (Python Scripting): Add entry for the new feature and the
	new attribute of gdb.Field objects.
	* python/py-type.c (gdbpy_is_field): New function
	(convert_field): Add 'parent_type' attribute to gdb.Field
	objects.
	* python/py-value.c (valpy_getitem): Allow subscript value to be
	a gdb.Field object.
	(value_has_field): New function
	(get_field_flag): New function
	* python/python-internal.h (gdbpy_is_field): Add declaration.

	testsuite/
	* gdb.python/py-value-cc.cc: Improve test case.
	* gdb.python/py-value-cc.exp: Add new tests to test usage of
	gdb.Field objects as subscripts on gdb.Value objects.

	doc/
	* gdb.texinfo (Values From Inferior): Add a note about using
	gdb.Field objects as subscripts on gdb.Value objects.
	(Types In Python): Add description about the new attribute
	"parent_type" of gdb.Field objects.

gdb/python/python-internal.h

@@ -290,6 +290,7 @@ PyObject *gdbpy_newest_frame (PyObject *self, PyObject *args);
 PyObject *gdbpy_selected_frame (PyObject *self, PyObject *args);
 PyObject *gdbpy_block_for_pc (PyObject *self, PyObject *args);
 PyObject *gdbpy_lookup_type (PyObject *self, PyObject *args, PyObject *kw);
+int gdbpy_is_field (PyObject *obj);
 PyObject *gdbpy_create_lazy_string_object (CORE_ADDR address, long length,
 					   const char *encoding,
 					   struct type *type);