invoke_xmethod & array_view

This replaces more pointer+length with gdb::array_view.  This time,
around invoke_xmethod, and then propagating the fallout around, which
inevitably leaks to the overload resolution code.

There are several places in the code that want to grab a slice of an
array, by advancing the array pointer, and decreasing the length
pointer.  This patch introduces a pair of new
gdb::array_view::slice(...) methods to make that convenient and clear.
Unit test included.

gdb/ChangeLog:
2018-11-21  Pedro Alves  <palves@redhat.com>

	* common/array-view.h (array_view::splice(size_type, size_t)): New.
	(array_view::splice(size_type)): New.
	* eval.c (eval_call, evaluate_funcall): Adjust to use array_view.
	* extension.c (xmethod_worker::get_arg_types): Adjust to return an
	std::vector.
	(xmethod_worker::get_result_type): Adjust to use gdb::array_view.
	* extension.h: Include "common/array-view.h".
	(xmethod_worker::invoke): Adjust to use gdb::array_view.
	(xmethod_worker::get_arg_types): Adjust to return an std::vector.
	(xmethod_worker::get_result_type): Adjust to use gdb::array_view.
	(xmethod_worker::do_get_arg_types): Adjust to use std::vector.
	(xmethod_worker::do_get_result_type): Adjust to use
	gdb::array_view.
	* gdbtypes.c (rank_function): Adjust to use gdb::array_view.
	* gdbtypes.h: Include "common/array-view.h".
	(rank_function): Adjust to use gdb::array_view.
	* python/py-xmethods.c (python_xmethod_worker::invoke)
	(python_xmethod_worker::do_get_arg_types)
	(python_xmethod_worker::do_get_result_type)
	(python_xmethod_worker::invoke): Adjust to new interfaces.
	* valarith.c (value_user_defined_cpp_op, value_user_defined_op)
	(value_x_binop, value_x_unop): Adjust to use gdb::array_view.
	* valops.c (find_overload_match, find_oload_champ_namespace)
	(find_oload_champ_namespace_loop, find_oload_champ): Adjust to use
	gdb:array_view and the new xmethod_worker interfaces.
	* value.c (result_type_of_xmethod, call_xmethod): Adjust to use
	gdb::array_view.
	* value.h (find_overload_match, result_type_of_xmethod)
	(call_xmethod): Adjust to use gdb::array_view.
	* unittests/array-view-selftests.c: Add slicing tests.

1 files changed, 6 insertions, 7 deletions

diff --git a/gdb/value.c b/gdb/value.c
index 38fc18e..c7b8468 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -2583,24 +2583,23 @@ value_from_xmethod (xmethod_worker_up &&worker)
 /* Return the type of the result of TYPE_CODE_XMETHOD value METHOD.  */
 
 struct type *
-result_type_of_xmethod (struct value *method, int argc, struct value **argv)
+result_type_of_xmethod (struct value *method, gdb::array_view<value *> argv)
 {
   gdb_assert (TYPE_CODE (value_type (method)) == TYPE_CODE_XMETHOD
-	      && method->lval == lval_xcallable && argc > 0);
+	      && method->lval == lval_xcallable && !argv.empty ());
 
-  return method->location.xm_worker->get_result_type
-    (argv[0], argv + 1, argc - 1);
+  return method->location.xm_worker->get_result_type (argv[0], argv.slice (1));
 }
 
 /* Call the xmethod corresponding to the TYPE_CODE_XMETHOD value METHOD.  */
 
 struct value *
-call_xmethod (struct value *method, int argc, struct value **argv)
+call_xmethod (struct value *method, gdb::array_view<value *> argv)
 {
   gdb_assert (TYPE_CODE (value_type (method)) == TYPE_CODE_XMETHOD
-	      && method->lval == lval_xcallable && argc > 0);
+	      && method->lval == lval_xcallable && !argv.empty ());
 
-  return method->location.xm_worker->invoke (argv[0], argv + 1, argc - 1);
+  return method->location.xm_worker->invoke (argv[0], argv.slice (1));
 }
 
 /* Extract a value as a C number (either long or double).