[RFC v5 05/18] gdb/python: add function () method to gdb.Type object

[Jan Vrany <jan.vrany@labware.com>]

This commit adds a new method to Python type objects that returns
possibly new function type returning that type. Parameter types can be
specified too. This will be useful later to create types for function
symbols created using Python extension code.

Unlike previous version, this commit copies all objfile-owned types
passed to gdb.Type.function to make them arch-owned. This way we do not
have to expose implementation details of type ownership to user.

This commit also prompted creation of type::printable_name in order to
produce nicer error message when user wants use types from different
architectures to create a new function type.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
---
 gdb/NEWS                             |   3 +
 gdb/doc/python.texi                  |  11 +++
 gdb/gdbtypes.c                       |  20 ++++
 gdb/gdbtypes.h                       |   6 ++
 gdb/python/py-type.c                 | 132 +++++++++++++++++++++++++++
 gdb/testsuite/gdb.python/py-type.exp |  36 ++++++++
 6 files changed, 208 insertions(+)

diff --git a/gdb/NEWS b/gdb/NEWS
index 6c8a008d39d..e8e32a5dd5c 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -330,6 +330,9 @@ vFile:stat
   ** Added gdb.Architecture.void_type. Returns a gdb.Type representing "void"
      type for that architecture.
 
+  ** Added gdb.Type.function.  Returns a new gdb.Type representing a function
+     returning that type.  Parameter types can be specified too.
+
 * Debugger Adapter Protocol changes
 
   ** The "scopes" request will now return a scope holding global
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 6fa22851f6a..633526dc875 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -1594,6 +1594,17 @@ Return a new @code{gdb.Type} object which represents a pointer to this
 type.
 @end defun
 
+@defun Type.function (@r{[}param_type@dots{}@r{]}, @r{[}varargs@r{]})
+Return a new @code{gdb.Type} object which represents a type of function
+returning this type.  Returned function type is always marked as prototyped.
+
+@var{param_type@dots{}} positional-only arguments specify parameter types.
+Passing @code{void} type is not allowed.
+
+The optional @var{varargs} keyword-only argument specifies whether to create
+vararg function type.  Defaults to @code{False}.
+@end defun
+
 @defun Type.strip_typedefs ()
 Return a new @code{gdb.Type} that represents the real type,
 after removing all layers of typedefs.
diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index 591a3cc4323..2dc5b7ff417 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -45,6 +45,7 @@
 #include "rust-lang.h"
 #include "ada-lang.h"
 #include "extract-store-integer.h"
+#include "typeprint.h"
 
 /* The value of an invalid conversion badness.  */
 #define INVALID_CONVERSION 100
@@ -5975,6 +5976,25 @@ type::is_array_like ()
   return defn->is_array_like (this);
 }
 
+/* See gdbtypes.h.  */
+
+bool
+type::is_void ()
+{
+  return check_typedef (this)->code () == TYPE_CODE_VOID;
+}
+
+const std::string
+type::printable_name () const
+{
+  string_file thetype;
+
+  current_language->print_type (const_cast<type*>(this), "",
+				&thetype, -1, 0,
+				&type_print_raw_options);
+
+  return thetype.release ();
+}
 \f
 
 static const registry<gdbarch>::key<struct builtin_type> gdbtypes_data;
diff --git a/gdb/gdbtypes.h b/gdb/gdbtypes.h
index ba216c6db54..b736d366fda 100644
--- a/gdb/gdbtypes.h
+++ b/gdb/gdbtypes.h
@@ -1054,6 +1054,9 @@ struct type
     this->main_type->name = name;
   }
 
+  /* Get the name of this type suitable for the user.  */
+  const std::string printable_name () const;
+
   /* Note that if thistype is a TYPEDEF type, you have to call check_typedef.
      But check_typedef does set the TYPE_LENGTH of the TYPEDEF type,
      so you only have to call check_typedef once.  Since value::allocate
@@ -1526,6 +1529,9 @@ struct type
      representations of arrays by the type's language.  */
   bool is_array_like ();
 
+  /* Return true if this type is "void".  Follows typedefs. */
+  bool is_void ();
+
   /* Return the language that this type came from.  */
   enum language language () const
   { return main_type->m_lang; }
diff --git a/gdb/python/py-type.c b/gdb/python/py-type.c
index c546aa7536a..3d6db708f8d 100644
--- a/gdb/python/py-type.c
+++ b/gdb/python/py-type.c
@@ -768,6 +768,135 @@ typy_unqualified (PyObject *self, PyObject *args)
   return type_to_type_object (type);
 }
 
+/* Return a function type. */
+
+static PyObject *
+typy_function (PyObject *self, PyObject *args, PyObject *kw)
+{
+  struct type *return_type = ((type_object *) self)->type;
+
+  /* Process arguments.  We cannot simply use PyArg_ParseTupleAndKeywords
+     because this method take variable number of arguments.  */
+  if (args == nullptr || !PyTuple_Check (args))
+    {
+      PyErr_Format (PyExc_ValueError,
+		    _("Arguments is %s, not a tuple."),
+		    Py_TYPE (args)->tp_name);
+      return nullptr;
+    }
+  int nparam_types = PyTuple_Size (args);
+  if (nparam_types == -1)
+    {
+      /* Can this really happen?  At this point we _know_ that
+	 ARGS is a tuple (or subclass).  */
+      PyErr_Format (PyExc_ValueError,
+		    _("Failed retrieve number of parameters."));
+      return nullptr;
+    }
+  std::vector<struct type *> param_types (nparam_types);
+  for (int i = 0; i < nparam_types; i++)
+    {
+      PyObject *param_type_obj = PySequence_GetItem (args, i);
+
+      if (param_type_obj == nullptr)
+	{
+	  PyErr_Format (PyExc_ValueError,
+			_("Failed to retrieve parameter at index %d."), i);
+	  return nullptr;
+	}
+      else
+	{
+	  param_types[i] = type_object_to_type (param_type_obj);
+	  if (param_types[i] == nullptr)
+	    {
+	      PyErr_Format (PyExc_TypeError,
+			    _("Argument at index %d is %s, not a gdb.Type "
+			      "object."),
+			    i, Py_TYPE (param_type_obj)->tp_name);
+	      return nullptr;
+	    }
+	  if (param_types[i]->is_void ())
+	    {
+		PyErr_Format (PyExc_ValueError,
+			      _("Argument at index %d is a void type but "
+				"void as parameter type is not allowed."),
+				  i);
+		return nullptr;
+	    }
+	}
+    }
+
+  if (kw != nullptr)
+    {
+      if (!PyDict_Check (kw))
+	{
+	  PyErr_Format (PyExc_ValueError,
+			_("Arguments is %s, not a dict."),
+			Py_TYPE (args)->tp_name);
+	  return nullptr;
+	}
+
+      PyObject *key, *value;
+      Py_ssize_t pos = 0;
+      while (PyDict_Next (kw, &pos, &key, &value))
+	{
+	  if (!PyUnicode_Check (key))
+	    {
+	      PyErr_Format (PyExc_ValueError,
+			    _("Keyword argument key is %s, not a string."),
+			    Py_TYPE (key)->tp_name);
+	      return nullptr;
+	    }
+	  if (PyUnicode_CompareWithASCIIString (key, "varargs") != 0)
+	    {
+	      PyErr_Format (PyExc_ValueError,
+			    _("Invalid keyword argument \"%U\"."),
+			    key);
+	      return nullptr;
+	    }
+	  if (!PyBool_Check (value))
+	    {
+	      PyErr_Format (PyExc_ValueError,
+			    _("Value of \"varargs\" argument is \"%s\", "
+			      "not a bool."),
+			    Py_TYPE (value)->tp_name);
+	      return nullptr;
+	    }
+	  if (value == Py_True)
+	    {
+	      param_types.push_back (nullptr);
+	    }
+	}
+    }
+
+  /* Copy all objfile-owned types to arch. This way user does not
+     need to care about mixing types from different objfiles and
+     architectures and we do not need to expose this implementation
+     detail to the user.  */
+
+  copied_types_hash_t copied_types;
+  return_type = copy_type_recursive (return_type, copied_types);
+  for (int i = 0; i < param_types.size (); i++)
+    {
+      if (param_types[i] != nullptr)
+	param_types[i] = copy_type_recursive (param_types[i], copied_types);
+    }
+
+  struct type *function_type = nullptr;
+  try
+    {
+	function_type = lookup_function_type_with_arguments
+	       (return_type, param_types.size (), param_types.data ());
+	function_type->set_is_prototyped (true);
+    }
+  catch (const gdb_exception &except)
+    {
+      return gdbpy_handle_gdb_exception (nullptr, except);
+    }
+
+  return type_to_type_object (function_type);
+}
+
 /* Return the size of the type represented by SELF, in bytes.  */
 static PyObject *
 typy_get_sizeof (PyObject *self, void *closure)
@@ -1630,6 +1759,9 @@ Return the type of a template argument." },
   { "unqualified", typy_unqualified, METH_NOARGS,
     "unqualified () -> Type\n\
 Return a variant of this type without const or volatile attributes." },
+  { "function", (PyCFunction) typy_function, METH_VARARGS | METH_KEYWORDS,
+    "function () -> Type\n\
+Return a function type returning value of this type." },
   { "values", typy_values, METH_NOARGS,
     "values () -> list\n\
 Return a list holding all the fields of this type.\n\
diff --git a/gdb/testsuite/gdb.python/py-type.exp b/gdb/testsuite/gdb.python/py-type.exp
index 0bc4556c653..876ef474a32 100644
--- a/gdb/testsuite/gdb.python/py-type.exp
+++ b/gdb/testsuite/gdb.python/py-type.exp
@@ -378,6 +378,42 @@ if { [build_inferior "${binfile}" "c"] == 0 } {
   gdb_test "python print(gdb.lookup_type('int').optimized_out())" \
       "<optimized out>"
 
+  gdb_test_no_output "python int_t = gdb.lookup_type('int')"
+  gdb_test_no_output "python uu_t = gdb.parse_and_eval ('uu').type"
+
+  gdb_test "python print(repr(int_t.function()))" \
+      "<gdb.Type code=TYPE_CODE_FUNC name=int \\(void\\)>"
+
+  gdb_test "python print(repr(int_t.function(int_t, int_t, int_t)))" \
+      "<gdb.Type code=TYPE_CODE_FUNC name=int \\(int, int, int\\)>"
+
+  gdb_test "python print(repr(int_t.function(int_t, varargs=True)))" \
+      "<gdb.Type code=TYPE_CODE_FUNC name=int \\(int, ...\\)>"
+
+  gdb_test "python print(repr(int_t.function(varargs=True)))" \
+      "<gdb.Type code=TYPE_CODE_FUNC name=int \\(void\\)>"
+
+  gdb_test "python print(repr(int_t.function(varargs=False)))" \
+      "<gdb.Type code=TYPE_CODE_FUNC name=int \\(void\\)>"
+
+  gdb_test "python print(repr(int_t.function(123)))" \
+      "TypeError.*:.*"
+
+  gdb_test "python print(repr(int_t.function(gdb.lookup_type('void'))))" \
+      "ValueError.*:.*"
+
+  gdb_test "python print(repr(int_t.function(int_t, gdb.lookup_type('void'))))" \
+      "ValueError.*:.*"
+
+  gdb_test "python print(repr(int_t.function(int_t, varargs=\[1,2,3\])))" \
+      "ValueError.*:.*"
+
+  gdb_test "python print(repr(int_t.function(int_t, kw=False)))" \
+      "ValueError.*:.*"
+
+  gdb_test "python print(repr(int_t.function(gdb.lookup_type('void'), varargs=True)))" \
+      "ValueError.*:.*"
+
   set sint [get_sizeof int 0]
   gdb_test "python print(gdb.parse_and_eval('aligncheck').type.alignof)" \
       $sint
-- 
2.47.2