[PATCH v5 08/11] [PR gdb/14441] gdb: python: support rvalue references in the gdb module

[Artemiy Volkov <artemiyv@acm.org>]

This patch adds the ability to inspect rvalue reference types and values using
the gdb python module. This is achieved by creating two wrappers for
valpy_reference_value(), using the ReferenceExplorer class to handle the
objects of rvalue reference types and placing necessary checks for a
TYPE_CODE_RVALUE_REF type code next to the checks for a TYPE_CODE_REF type
code.

gdb/ChangeLog:

2016-06-06  Artemiy Volkov  <artemiyv@acm.org>

    PR gdb/14441
    * python/lib/gdb/command/explore.py: Support exploring values
    of rvalue reference types.
    * python/lib/gdb/types.py: Implement get_basic_type() for
    rvalue reference types.
    * python/py-type.c (pyty_codes) <TYPE_CODE_RVALUE_REF>: New
    constant.
    * python/py-value.c (valpy_getitem): Add an rvalue reference
    check.
    (valpy_reference_value): Add new parameter "refcode".
    (valpy_lvalue_reference_value, valpy_rvalue_reference_value):
    New wrappers for valpy_reference_value().
    * python/py-xmethods.c (gdbpy_get_xmethod_result_type)
    (gdbpy_invoke_xmethod): Likewise.
---
 gdb/python/lib/gdb/command/explore.py |  2 +-
 gdb/python/lib/gdb/types.py           |  4 +++-
 gdb/python/py-type.c                  |  1 +
 gdb/python/py-value.c                 | 26 +++++++++++++++++++++-----
 gdb/python/py-xmethods.c              | 10 ++++++----
 5 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/gdb/python/lib/gdb/command/explore.py b/gdb/python/lib/gdb/command/explore.py
index 6c9f17b..ed25fa6 100644
--- a/gdb/python/lib/gdb/command/explore.py
+++ b/gdb/python/lib/gdb/command/explore.py
@@ -132,6 +132,7 @@ class Explorer(object):
             gdb.TYPE_CODE_UNION : CompoundExplorer,
             gdb.TYPE_CODE_PTR : PointerExplorer,
             gdb.TYPE_CODE_REF : ReferenceExplorer,
+            gdb.TYPE_CODE_RVALUE_REF : ReferenceExplorer,
             gdb.TYPE_CODE_TYPEDEF : TypedefExplorer,
             gdb.TYPE_CODE_ARRAY : ArrayExplorer
         }
@@ -318,7 +319,6 @@ class ReferenceExplorer(object):
         Explorer.explore_type(name, target_type, is_child)
         return False
 
-
 class ArrayExplorer(object):
     """Internal class used to explore arrays."""
 
diff --git a/gdb/python/lib/gdb/types.py b/gdb/python/lib/gdb/types.py
index c22e8a9..59b7df2 100644
--- a/gdb/python/lib/gdb/types.py
+++ b/gdb/python/lib/gdb/types.py
@@ -31,8 +31,10 @@ def get_basic_type(type_):
     """
 
     while (type_.code == gdb.TYPE_CODE_REF or
+           type_.code == gdb.TYPE_CODE_RVALUE_REF or
            type_.code == gdb.TYPE_CODE_TYPEDEF):
-        if type_.code == gdb.TYPE_CODE_REF:
+        if (type_.code == gdb.TYPE_CODE_REF or
+            type_.code == gdb.TYPE_CODE_RVALUE_REF):
             type_ = type_.target()
         else:
             type_ = type_.strip_typedefs()
diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c
index 4ec920e..259bb70 100644
--- a/gdb/python/py-type.c
+++ b/gdb/python/py-type.c
@@ -105,6 +105,7 @@ static struct pyty_code pyty_codes[] =
   ENTRY (TYPE_CODE_METHODPTR),
   ENTRY (TYPE_CODE_MEMBERPTR),
   ENTRY (TYPE_CODE_REF),
+  ENTRY (TYPE_CODE_RVALUE_REF),
   ENTRY (TYPE_CODE_CHAR),
   ENTRY (TYPE_CODE_BOOL),
   ENTRY (TYPE_CODE_COMPLEX),
diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index 73cc6bd..a422796 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -239,7 +239,7 @@ valpy_referenced_value (PyObject *self, PyObject *args)
 /* Return a value which is a reference to the value.  */
 
 static PyObject *
-valpy_reference_value (PyObject *self, PyObject *args)
+valpy_reference_value (PyObject *self, PyObject *args, enum type_code refcode)
 {
   PyObject *result = NULL;
 
@@ -249,7 +249,7 @@ valpy_reference_value (PyObject *self, PyObject *args)
       struct cleanup *cleanup = make_cleanup_value_free_to_mark (value_mark ());
 
       self_val = ((value_object *) self)->value;
-      result = value_to_value_object (value_ref (self_val, TYPE_CODE_REF));
+      result = value_to_value_object (value_ref (self_val, refcode));
 
       do_cleanups (cleanup);
     }
@@ -262,6 +262,18 @@ valpy_reference_value (PyObject *self, PyObject *args)
   return result;
 }
 
+static PyObject *
+valpy_lvalue_reference_value (PyObject *self, PyObject *args)
+{
+  return valpy_reference_value (self, args, TYPE_CODE_REF);
+}
+
+static PyObject *
+valpy_rvalue_reference_value (PyObject *self, PyObject *args)
+{
+  return valpy_reference_value (self, args, TYPE_CODE_RVALUE_REF);
+}
+
 /* Return a "const" qualified version of the value.  */
 
 static PyObject *
@@ -598,8 +610,7 @@ value_has_field (struct value *v, PyObject *field)
     {
       val_type = value_type (v);
       val_type = check_typedef (val_type);
-      if (TYPE_CODE (val_type) == TYPE_CODE_REF
-	  || TYPE_CODE (val_type) == TYPE_CODE_PTR)
+      if (TYPE_IS_REFERENCE (val_type) || TYPE_CODE (val_type) == TYPE_CODE_PTR)
       val_type = check_typedef (TYPE_TARGET_TYPE (val_type));
 
       type_code = TYPE_CODE (val_type);
@@ -768,6 +779,9 @@ valpy_getitem (PyObject *self, PyObject *key)
 	  else if (TYPE_CODE (val_type) == TYPE_CODE_REF)
 	    res_val = value_cast (lookup_lvalue_reference_type (base_class_type),
 	                          tmp);
+	  else if (TYPE_CODE (val_type) == TYPE_CODE_RVALUE_REF)
+	    res_val = value_cast (lookup_rvalue_reference_type (base_class_type),
+	                          tmp);
 	  else
 	    res_val = value_cast (base_class_type, tmp);
 	}
@@ -1776,8 +1790,10 @@ reinterpret_cast operator."
   { "dereference", valpy_dereference, METH_NOARGS, "Dereferences the value." },
   { "referenced_value", valpy_referenced_value, METH_NOARGS,
     "Return the value referenced by a TYPE_CODE_REF or TYPE_CODE_PTR value." },
-  { "reference_value", valpy_reference_value, METH_NOARGS,
+  { "reference_value", valpy_lvalue_reference_value, METH_NOARGS,
     "Return a value of type TYPE_CODE_REF referencing this value." },
+  { "rvalue_reference_value", valpy_rvalue_reference_value, METH_NOARGS,
+    "Return a value of type TYPE_CODE_RVALUE_REF referencing this value." },
   { "const_value", valpy_const_value, METH_NOARGS,
     "Return a 'const' qualied version of the same value." },
   { "lazy_string", (PyCFunction) valpy_lazy_string,
diff --git a/gdb/python/py-xmethods.c b/gdb/python/py-xmethods.c
index d70cdd1..debc3a8 100644
--- a/gdb/python/py-xmethods.c
+++ b/gdb/python/py-xmethods.c
@@ -548,9 +548,10 @@ gdbpy_get_xmethod_result_type (const struct extension_language_defn *extlang,
       if (!types_equal (obj_type, this_ptr))
 	obj = value_cast (this_ptr, obj);
     }
-  else if (TYPE_CODE (obj_type) == TYPE_CODE_REF)
+  else if (TYPE_IS_REFERENCE (obj_type))
     {
-      struct type *this_ref = lookup_lvalue_reference_type (this_type);
+      struct type *this_ref
+        = lookup_reference_type (this_type, TYPE_CODE (obj_type));
 
       if (!types_equal (obj_type, this_ref))
 	obj = value_cast (this_ref, obj);
@@ -634,9 +635,10 @@ gdbpy_invoke_xmethod (const struct extension_language_defn *extlang,
       if (!types_equal (obj_type, this_ptr))
 	obj = value_cast (this_ptr, obj);
     }
-  else if (TYPE_CODE (obj_type) == TYPE_CODE_REF)
+  else if (TYPE_IS_REFERENCE (obj_type))
     {
-      struct type *this_ref = lookup_lvalue_reference_type (this_type);
+      struct type *this_ref
+        = lookup_reference_type (this_type, TYPE_CODE (obj_type));
 
       if (!types_equal (obj_type, this_ref))
 	obj = value_cast (this_ref, obj);
-- 
2.8.3