[PATCH 05/10] Return gdbpy_ref<> from value_to_value_object

[Tom Tromey <tromey@adacore.com>]

This changes value_to_value_object to return a gdbpy_ref<>,
using the type system to convey that a new reference is always
returned.
---
 gdb/python/py-finishbreakpoint.c |  4 +--
 gdb/python/py-frame.c            |  8 ++---
 gdb/python/py-function.c         |  2 +-
 gdb/python/py-lazy-string.c      |  4 +--
 gdb/python/py-prettyprint.c      |  4 +--
 gdb/python/py-stopevent.c        |  2 +-
 gdb/python/py-symbol.c           |  4 +--
 gdb/python/py-type.c             |  6 ++--
 gdb/python/py-unwind.c           |  4 +--
 gdb/python/py-value.c            | 70 +++++++++++++++++++---------------------
 gdb/python/py-xmethods.c         | 16 ++++-----
 gdb/python/python-internal.h     |  2 +-
 gdb/python/python.c              |  4 +--
 13 files changed, 64 insertions(+), 66 deletions(-)

diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c
index 43dffd64adc..3370bb02580 100644
--- a/gdb/python/py-finishbreakpoint.c
+++ b/gdb/python/py-finishbreakpoint.c
@@ -122,7 +122,7 @@ bpfinishpy_pre_stop_hook (struct gdbpy_breakpoint_object *bp_obj)
 
       if (ret)
 	{
-	  self_finishbp->return_value = value_to_value_object (ret);
+	  self_finishbp->return_value = value_to_value_object (ret).release ();
 	  if (!self_finishbp->return_value)
 	      gdbpy_print_stack ();
 	}
@@ -264,7 +264,7 @@ bpfinishpy_init (PyObject *self, PyObject *args, PyObject *kwargs)
 		  /* Ignore Python errors at this stage.  */
 		  value *func_value = read_var_value (function, NULL, frame);
 		  self_bpfinish->function_value
-		    = value_to_value_object (func_value);
+		    = value_to_value_object (func_value).release ();
 		  PyErr_Clear ();
 
 		  self_bpfinish->func_symbol
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index d9af3639d29..68c2628c297 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -257,7 +257,7 @@ static PyObject *
 frapy_read_register (PyObject *self, PyObject *args, PyObject *kw)
 {
   PyObject *pyo_reg_id;
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
 
   static const char *keywords[] = { "register", nullptr };
   if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "O", keywords, &pyo_reg_id))
@@ -289,7 +289,7 @@ frapy_read_register (PyObject *self, PyObject *args, PyObject *kw)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Implementation of gdb.Frame.block (self) -> gdb.Block.
@@ -557,7 +557,7 @@ frapy_read_var (PyObject *self, PyObject *args, PyObject *kw)
       return NULL;
     }
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   try
     {
       FRAPY_REQUIRE_VALID (self, frame);
@@ -571,7 +571,7 @@ frapy_read_var (PyObject *self, PyObject *args, PyObject *kw)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Select this frame.  */
diff --git a/gdb/python/py-function.c b/gdb/python/py-function.c
index ee60f08b65c..3bb81527a9c 100644
--- a/gdb/python/py-function.c
+++ b/gdb/python/py-function.c
@@ -45,7 +45,7 @@ convert_values_to_python (int argc, struct value **argv)
 
   for (i = 0; i < argc; ++i)
     {
-      gdbpy_ref<> elt (value_to_value_object (argv[i]));
+      gdbpy_ref<> elt = value_to_value_object (argv[i]);
       if (elt == NULL)
 	return NULL;
       PyTuple_SetItem (result.get (), i, elt.release ());
diff --git a/gdb/python/py-lazy-string.c b/gdb/python/py-lazy-string.c
index 58cdea69f56..fe248f6e78f 100644
--- a/gdb/python/py-lazy-string.c
+++ b/gdb/python/py-lazy-string.c
@@ -109,7 +109,7 @@ stpy_convert_to_value (PyObject *self, PyObject *args)
       return NULL;
     }
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   try
     {
       scoped_value_mark free_values;
@@ -149,7 +149,7 @@ stpy_convert_to_value (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 static void
diff --git a/gdb/python/py-prettyprint.c b/gdb/python/py-prettyprint.c
index 6900bf64585..0aa11d29094 100644
--- a/gdb/python/py-prettyprint.c
+++ b/gdb/python/py-prettyprint.c
@@ -591,7 +591,7 @@ gdbpy_apply_val_pretty_printer (const struct extension_language_defn *extlang,
 
   gdbpy_enter enter_py (gdbarch, language);
 
-  gdbpy_ref<> val_obj (value_to_value_object (value));
+  gdbpy_ref<> val_obj = value_to_value_object (value);
   if (val_obj == NULL)
     {
       print_stack_unless_memory_error (stream);
@@ -662,7 +662,7 @@ apply_varobj_pretty_printer (PyObject *printer_obj,
 gdbpy_ref<>
 gdbpy_get_varobj_pretty_printer (struct value *value)
 {
-  gdbpy_ref<> val_obj (value_to_value_object (value));
+  gdbpy_ref<> val_obj = value_to_value_object (value);
   if (val_obj == NULL)
     return NULL;
 
diff --git a/gdb/python/py-stopevent.c b/gdb/python/py-stopevent.c
index 351c0479ee6..cefcfdd0761 100644
--- a/gdb/python/py-stopevent.c
+++ b/gdb/python/py-stopevent.c
@@ -85,7 +85,7 @@ py_print_bpstat (bpstat *bs, enum gdb_signal stop_signal)
      there's no API to add generic Python objects to a py_ui_out.  */
   if (return_value != nullptr)
     {
-      gdbpy_ref<> val (value_to_value_object (return_value));
+      gdbpy_ref<> val = value_to_value_object (return_value);
       if (val == nullptr)
 	return nullptr;
       if (PyDict_SetItemString (dict.get (), "finish-value", val.get ()) < 0)
diff --git a/gdb/python/py-symbol.c b/gdb/python/py-symbol.c
index 492c386b7ee..80c7705aa68 100644
--- a/gdb/python/py-symbol.c
+++ b/gdb/python/py-symbol.c
@@ -282,7 +282,7 @@ sympy_value (PyObject *self, PyObject *args)
       return NULL;
     }
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   try
     {
       if (frame_obj != NULL)
@@ -308,7 +308,7 @@ sympy_value (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Given a symbol, and a symbol_object that has previously been
diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c
index d1ebe852eaa..017937c1c0a 100644
--- a/gdb/python/py-type.c
+++ b/gdb/python/py-type.c
@@ -1045,7 +1045,7 @@ typy_template_argument (PyObject *self, PyObject *args)
       return NULL;
     }
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   try
     {
       scoped_value_mark free_values;
@@ -1057,7 +1057,7 @@ typy_template_argument (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* __repr__ implementation for gdb.Type.  */
@@ -1236,7 +1236,7 @@ typy_optimized_out (PyObject *self, PyObject *args)
   struct type *type = ((type_object *) self)->type;
 
   scoped_value_mark free_values;
-  return value_to_value_object (value::allocate_optimized_out (type));
+  return value_to_value_object (value::allocate_optimized_out (type)).release ();
 }
 
 /* Return a gdb.Field object for the field named by the argument.  */
diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index 5465d3d6cf9..872cd00e84f 100644
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -480,7 +480,7 @@ pending_framepy_read_register (PyObject *self, PyObject *args, PyObject *kw)
   if (!gdbpy_parse_register_id (pending_frame->gdbarch, pyo_reg_id, &regnum))
     return nullptr;
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   try
     {
       scoped_value_mark free_values;
@@ -504,7 +504,7 @@ pending_framepy_read_register (PyObject *self, PyObject *args, PyObject *kw)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Implement PendingFrame.is_valid().  Return True if this pending frame
diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index e19be1d2701..c0fcfb882e1 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -243,7 +243,7 @@ gdbpy_preserve_values (const struct extension_language_defn *extlang,
 static PyObject *
 valpy_dereference (PyObject *self, PyObject *args)
 {
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   try
     {
@@ -258,7 +258,7 @@ valpy_dereference (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Given a value of a pointer type or a reference type, return the value
@@ -272,7 +272,7 @@ valpy_dereference (PyObject *self, PyObject *args)
 static PyObject *
 valpy_referenced_value (PyObject *self, PyObject *args)
 {
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   try
     {
@@ -301,7 +301,7 @@ valpy_referenced_value (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Return a value which is a reference to the value.  */
@@ -309,7 +309,7 @@ valpy_referenced_value (PyObject *self, PyObject *args)
 static PyObject *
 valpy_reference_value (PyObject *self, PyObject *args, enum type_code refcode)
 {
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   try
     {
@@ -324,7 +324,7 @@ valpy_reference_value (PyObject *self, PyObject *args, enum type_code refcode)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 static PyObject *
@@ -344,7 +344,7 @@ valpy_rvalue_reference_value (PyObject *self, PyObject *args)
 static PyObject *
 valpy_to_array (PyObject *self, PyObject *args)
 {
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
 
   try
     {
@@ -352,10 +352,7 @@ valpy_to_array (PyObject *self, PyObject *args)
       struct type *type = check_typedef (val->type ());
 
       if (type->code () == TYPE_CODE_ARRAY)
-	{
-	  result = self;
-	  Py_INCREF (result);
-	}
+	result = gdbpy_ref<>::new_reference (self);
       else
 	{
 	  val = value_to_array (val);
@@ -370,7 +367,7 @@ valpy_to_array (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Return a "const" qualified version of the value.  */
@@ -378,7 +375,7 @@ valpy_to_array (PyObject *self, PyObject *args)
 static PyObject *
 valpy_const_value (PyObject *self, PyObject *args)
 {
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   try
     {
@@ -394,7 +391,7 @@ valpy_const_value (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Return "&value".  */
@@ -411,7 +408,7 @@ valpy_get_address (PyObject *self, void *closure)
 	  scoped_value_mark free_values;
 
 	  res_val = value_addr (val_obj->value);
-	  val_obj->address = value_to_value_object (res_val);
+	  val_obj->address = value_to_value_object (res_val).release ();
 	}
       catch (const gdb_exception_forced_quit &except)
 	{
@@ -807,7 +804,7 @@ valpy_format_string (PyObject *self, PyObject *args, PyObject *kw)
 static PyObject *
 valpy_do_cast (PyObject *self, PyObject *args, enum exp_opcode op)
 {
-  PyObject *type_obj, *result = NULL;
+  PyObject *type_obj;
   struct type *type;
 
   if (! PyArg_ParseTuple (args, "O", &type_obj))
@@ -821,6 +818,7 @@ valpy_do_cast (PyObject *self, PyObject *args, enum exp_opcode op)
       return NULL;
     }
 
+  gdbpy_ref<> result;
   try
     {
       struct value *val = ((value_object *) self)->value;
@@ -844,7 +842,7 @@ valpy_do_cast (PyObject *self, PyObject *args, enum exp_opcode op)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Implementation of the "cast" method.  */
@@ -1020,7 +1018,7 @@ valpy_getitem (PyObject *self, PyObject *key)
   gdb::unique_xmalloc_ptr<char> field;
   struct type *base_class_type = NULL, *field_type = NULL;
   long bitpos = -1;
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   if (gdbpy_is_string (key))
     {
@@ -1153,7 +1151,7 @@ valpy_getitem (PyObject *self, PyObject *key)
       return gdbpy_handle_gdb_exception (nullptr, ex);
     }
 
-  return result;
+  return result.release ();
 }
 
 static int
@@ -1173,7 +1171,7 @@ valpy_call (PyObject *self, PyObject *args, PyObject *keywords)
   struct value *function = ((value_object *) self)->value;
   struct value **vargs = NULL;
   struct type *ftype = NULL;
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   try
     {
@@ -1241,7 +1239,7 @@ valpy_call (PyObject *self, PyObject *args, PyObject *keywords)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Called by the Python interpreter to obtain string representation
@@ -1439,10 +1437,10 @@ enum valpy_opcode
    of applying the operation specified by OPCODE to the given
    arguments.  Throws a GDB exception on error.  */
 
-static PyObject *
+static gdbpy_ref<>
 valpy_binop_throw (enum valpy_opcode opcode, PyObject *self, PyObject *other)
 {
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   struct value *arg1, *arg2;
   struct value *res_val = NULL;
@@ -1565,7 +1563,7 @@ valpy_binop_throw (enum valpy_opcode opcode, PyObject *self, PyObject *other)
 static PyObject *
 valpy_binop (enum valpy_opcode opcode, PyObject *self, PyObject *other)
 {
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   try
     {
@@ -1576,7 +1574,7 @@ valpy_binop (enum valpy_opcode opcode, PyObject *self, PyObject *other)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 static PyObject *
@@ -1628,7 +1626,7 @@ valpy_power (PyObject *self, PyObject *other, PyObject *unused)
 static PyObject *
 valpy_negative (PyObject *self)
 {
-  PyObject *result = NULL;
+  gdbpy_ref<> result;
 
   try
     {
@@ -1644,13 +1642,13 @@ valpy_negative (PyObject *self)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 static PyObject *
 valpy_positive (PyObject *self)
 {
-  return value_to_value_object (((value_object *) self)->value);
+  return value_to_value_object (((value_object *) self)->value).release ();
 }
 
 static PyObject *
@@ -1713,7 +1711,7 @@ valpy_nonzero (PyObject *self)
 static PyObject *
 valpy_invert (PyObject *self)
 {
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
 
   try
     {
@@ -1726,7 +1724,7 @@ valpy_invert (PyObject *self)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Implements left shift for value objects.  */
@@ -1972,7 +1970,7 @@ valpy_float (PyObject *self)
 
 /* Returns an object for a value, without releasing it from the
    all_values chain.  */
-PyObject *
+gdbpy_ref<>
 value_to_value_object (struct value *val)
 {
   value_object *val_obj;
@@ -1990,7 +1988,7 @@ value_to_value_object (struct value *val)
       note_value (val_obj);
     }
 
-  return (PyObject *) val_obj;
+  return gdbpy_ref<> (val_obj);
 }
 
 /* Returns a borrowed reference to the struct value corresponding to
@@ -2103,7 +2101,7 @@ gdbpy_history (PyObject *self, PyObject *args)
   if (!PyArg_ParseTuple (args, "i", &i))
     return NULL;
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   try
     {
       scoped_value_mark free_values;
@@ -2115,7 +2113,7 @@ gdbpy_history (PyObject *self, PyObject *args)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Add a gdb.Value into GDB's history, and return (as an integer) the
@@ -2163,7 +2161,7 @@ gdbpy_convenience_variable (PyObject *self, PyObject *args)
   if (!PyArg_ParseTuple (args, "s", &varname))
     return NULL;
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   bool found = false;
   try
     {
@@ -2190,7 +2188,7 @@ gdbpy_convenience_variable (PyObject *self, PyObject *args)
   if (result == nullptr && !found)
     Py_RETURN_NONE;
 
-  return result;
+  return result.release ();
 }
 
 /* Set the value of a convenience variable.  */
diff --git a/gdb/python/py-xmethods.c b/gdb/python/py-xmethods.c
index de6c9d0b07d..64f9807cfee 100644
--- a/gdb/python/py-xmethods.c
+++ b/gdb/python/py-xmethods.c
@@ -444,7 +444,7 @@ python_xmethod_worker::do_get_result_type (value *obj,
       if (!types_equal (obj_type, this_type))
 	obj = value_cast (this_type, obj);
     }
-  gdbpy_ref<> py_value_obj (value_to_value_object (obj));
+  gdbpy_ref<> py_value_obj = value_to_value_object (obj);
   if (py_value_obj == NULL)
     {
       gdbpy_print_stack ();
@@ -464,14 +464,14 @@ python_xmethod_worker::do_get_result_type (value *obj,
 
   for (i = 0; i < args.size (); i++)
     {
-      PyObject *py_value_arg = value_to_value_object (args[i]);
+      gdbpy_ref<> py_value_arg = value_to_value_object (args[i]);
 
-      if (py_value_arg == NULL)
+      if (py_value_arg == nullptr)
 	{
 	  gdbpy_print_stack ();
 	  return EXT_LANG_RC_ERROR;
 	}
-      PyTuple_SET_ITEM (py_arg_tuple.get (), i + 1, py_value_arg);
+      PyTuple_SET_ITEM (py_arg_tuple.get (), i + 1, py_value_arg.release ());
     }
 
   gdbpy_ref<> py_result_type
@@ -529,7 +529,7 @@ python_xmethod_worker::invoke (struct value *obj,
       if (!types_equal (obj_type, this_type))
 	obj = value_cast (this_type, obj);
     }
-  gdbpy_ref<> py_value_obj (value_to_value_object (obj));
+  gdbpy_ref<> py_value_obj = value_to_value_object (obj);
   if (py_value_obj == NULL)
     {
       gdbpy_print_stack ();
@@ -549,15 +549,15 @@ python_xmethod_worker::invoke (struct value *obj,
 
   for (i = 0; i < args.size (); i++)
     {
-      PyObject *py_value_arg = value_to_value_object (args[i]);
+      gdbpy_ref<> py_value_arg = value_to_value_object (args[i]);
 
-      if (py_value_arg == NULL)
+      if (py_value_arg == nullptr)
 	{
 	  gdbpy_print_stack ();
 	  error (_("Error while executing Python code."));
 	}
 
-      PyTuple_SET_ITEM (py_arg_tuple.get (), i + 1, py_value_arg);
+      PyTuple_SET_ITEM (py_arg_tuple.get (), i + 1, py_value_arg.release ());
     }
 
   gdbpy_ref<> py_result (PyObject_CallObject (m_py_worker,
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index de4226868dc..c7e812d6893 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -500,7 +500,7 @@ gdbpy_ref<> symtab_to_symtab_object (struct symtab *symtab);
 gdbpy_ref<> symbol_to_symbol_object (struct symbol *sym);
 gdbpy_ref<> block_to_block_object (const struct block *block,
 				   struct objfile *objfile);
-PyObject *value_to_value_object (struct value *v);
+gdbpy_ref<> value_to_value_object (struct value *v);
 PyObject *type_to_type_object (struct type *);
 PyObject *frame_info_to_frame_object (const frame_info_ptr &frame);
 PyObject *symtab_to_linetable_object (PyObject *symtab);
diff --git a/gdb/python/python.c b/gdb/python/python.c
index d2a77890072..aec2c7559a8 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1073,7 +1073,7 @@ gdbpy_parse_and_eval (PyObject *self, PyObject *args, PyObject *kw)
 	flags |= PARSER_LEAVE_BLOCK_ALONE;
     }
 
-  PyObject *result = nullptr;
+  gdbpy_ref<> result;
   try
     {
       scoped_value_mark free_values;
@@ -1094,7 +1094,7 @@ gdbpy_parse_and_eval (PyObject *self, PyObject *args, PyObject *kw)
       return gdbpy_handle_gdb_exception (nullptr, except);
     }
 
-  return result;
+  return result.release ();
 }
 
 /* Implementation of gdb.invalidate_cached_frames.  */

-- 
2.53.0