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, 25 insertions, 25 deletions

diff --git a/gdb/valarith.c b/gdb/valarith.c
index 875f547..3a59ada 100644
--- a/gdb/valarith.c
+++ b/gdb/valarith.c
@@ -281,14 +281,14 @@ unop_user_defined_p (enum exp_opcode op, struct value *arg1)
    situations or combinations thereof.  */
 
 static struct value *
-value_user_defined_cpp_op (struct value **args, int nargs, char *oper,
+value_user_defined_cpp_op (gdb::array_view<value *> args, char *oper,
                            int *static_memfuncp, enum noside noside)
 {
 
   struct symbol *symp = NULL;
   struct value *valp = NULL;
 
-  find_overload_match (args, nargs, oper, BOTH /* could be method */,
+  find_overload_match (args, oper, BOTH /* could be method */,
                        &args[0] /* objp */,
                        NULL /* pass NULL symbol since symbol is unknown */,
                        &valp, &symp, static_memfuncp, 0, noside);
@@ -312,19 +312,19 @@ value_user_defined_cpp_op (struct value **args, int nargs, char *oper,
    function, otherwise return NULL.  */
 
 static struct value *
-value_user_defined_op (struct value **argp, struct value **args, char *name,
-                       int *static_memfuncp, int nargs, enum noside noside)
+value_user_defined_op (struct value **argp, gdb::array_view<value *> args,
+		       char *name, int *static_memfuncp, enum noside noside)
 {
   struct value *result = NULL;
 
   if (current_language->la_language == language_cplus)
     {
-      result = value_user_defined_cpp_op (args, nargs, name, static_memfuncp,
+      result = value_user_defined_cpp_op (args, name, static_memfuncp,
 					  noside);
     }
   else
-    result = value_struct_elt (argp, args, name, static_memfuncp,
-                               "structure");
+    result = value_struct_elt (argp, args.data (), name, static_memfuncp,
+			       "structure");
 
   return result;
 }
@@ -342,7 +342,6 @@ struct value *
 value_x_binop (struct value *arg1, struct value *arg2, enum exp_opcode op,
 	       enum exp_opcode otherop, enum noside noside)
 {
-  struct value **argvec;
   char *ptr;
   char tstr[13];
   int static_memfuncp;
@@ -356,10 +355,11 @@ value_x_binop (struct value *arg1, struct value *arg2, enum exp_opcode op,
   if (TYPE_CODE (check_typedef (value_type (arg1))) != TYPE_CODE_STRUCT)
     error (_("Can't do that binary op on that type"));	/* FIXME be explicit */
 
-  argvec = (struct value **) alloca (sizeof (struct value *) * 4);
+  value *argvec_storage[3];
+  gdb::array_view<value *> argvec = argvec_storage;
+
   argvec[1] = value_addr (arg1);
   argvec[2] = arg2;
-  argvec[3] = 0;
 
   /* Make the right function name up.  */
   strcpy (tstr, "operator__");
@@ -469,15 +469,15 @@ value_x_binop (struct value *arg1, struct value *arg2, enum exp_opcode op,
       error (_("Invalid binary operation specified."));
     }
 
-  argvec[0] = value_user_defined_op (&arg1, argvec + 1, tstr,
-                                     &static_memfuncp, 2, noside);
+  argvec[0] = value_user_defined_op (&arg1, argvec.slice (1), tstr,
+				     &static_memfuncp, noside);
 
   if (argvec[0])
     {
       if (static_memfuncp)
 	{
 	  argvec[1] = argvec[0];
-	  argvec++;
+	  argvec = argvec.slice (1);
 	}
       if (TYPE_CODE (value_type (argvec[0])) == TYPE_CODE_XMETHOD)
 	{
@@ -486,13 +486,13 @@ value_x_binop (struct value *arg1, struct value *arg2, enum exp_opcode op,
 	  if (noside == EVAL_AVOID_SIDE_EFFECTS)
 	    {
 	      struct type *return_type
-		= result_type_of_xmethod (argvec[0], 2, argvec + 1);
+		= result_type_of_xmethod (argvec[0], argvec.slice (1));
 
 	      if (return_type == NULL)
 		error (_("Xmethod is missing return type."));
 	      return value_zero (return_type, VALUE_LVAL (arg1));
 	    }
-	  return call_xmethod (argvec[0], 2, argvec + 1);
+	  return call_xmethod (argvec[0], argvec.slice (1));
 	}
       if (noside == EVAL_AVOID_SIDE_EFFECTS)
 	{
@@ -503,7 +503,7 @@ value_x_binop (struct value *arg1, struct value *arg2, enum exp_opcode op,
 	  return value_zero (return_type, VALUE_LVAL (arg1));
 	}
       return call_function_by_hand (argvec[0], NULL,
-				    {argvec + 1, 2u - static_memfuncp});
+				    argvec.slice (1, 2 - static_memfuncp));
     }
   throw_error (NOT_FOUND_ERROR,
                _("member function %s not found"), tstr);
@@ -519,7 +519,6 @@ struct value *
 value_x_unop (struct value *arg1, enum exp_opcode op, enum noside noside)
 {
   struct gdbarch *gdbarch = get_type_arch (value_type (arg1));
-  struct value **argvec;
   char *ptr;
   char tstr[13], mangle_tstr[13];
   int static_memfuncp, nargs;
@@ -532,7 +531,9 @@ value_x_unop (struct value *arg1, enum exp_opcode op, enum noside noside)
   if (TYPE_CODE (check_typedef (value_type (arg1))) != TYPE_CODE_STRUCT)
     error (_("Can't do that unary op on that type"));	/* FIXME be explicit */
 
-  argvec = (struct value **) alloca (sizeof (struct value *) * 4);
+  value *argvec_storage[3];
+  gdb::array_view<value *> argvec = argvec_storage;
+
   argvec[1] = value_addr (arg1);
   argvec[2] = 0;
 
@@ -584,16 +585,15 @@ value_x_unop (struct value *arg1, enum exp_opcode op, enum noside noside)
       error (_("Invalid unary operation specified."));
     }
 
-  argvec[0] = value_user_defined_op (&arg1, argvec + 1, tstr,
-                                     &static_memfuncp, nargs, noside);
+  argvec[0] = value_user_defined_op (&arg1, argvec.slice (1, nargs), tstr,
+				     &static_memfuncp, noside);
 
   if (argvec[0])
     {
       if (static_memfuncp)
 	{
 	  argvec[1] = argvec[0];
-	  nargs --;
-	  argvec++;
+	  argvec = argvec.slice (1);
 	}
       if (TYPE_CODE (value_type (argvec[0])) == TYPE_CODE_XMETHOD)
 	{
@@ -602,13 +602,13 @@ value_x_unop (struct value *arg1, enum exp_opcode op, enum noside noside)
 	  if (noside == EVAL_AVOID_SIDE_EFFECTS)
 	    {
 	      struct type *return_type
-		= result_type_of_xmethod (argvec[0], 1, argvec + 1);
+		= result_type_of_xmethod (argvec[0], argvec[1]);
 
 	      if (return_type == NULL)
 		error (_("Xmethod is missing return type."));
 	      return value_zero (return_type, VALUE_LVAL (arg1));
 	    }
-	  return call_xmethod (argvec[0], 1, argvec + 1);
+	  return call_xmethod (argvec[0], argvec[1]);
 	}
       if (noside == EVAL_AVOID_SIDE_EFFECTS)
 	{
@@ -619,7 +619,7 @@ value_x_unop (struct value *arg1, enum exp_opcode op, enum noside noside)
 	  return value_zero (return_type, VALUE_LVAL (arg1));
 	}
       return call_function_by_hand (argvec[0], NULL,
-				    gdb::make_array_view (argvec + 1, nargs));
+				    argvec.slice (1, nargs));
     }
   throw_error (NOT_FOUND_ERROR,
                _("member function %s not found"), tstr);