[Python] Add a boolean parameter "python resolve-operators"

diff --git a/gdb/NEWS b/gdb/NEWS
index 49dc0e6..0e1a94a 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -28,6 +28,14 @@  record btrace bts
 record bts
   Start branch trace recording using Branch Trace Store (BTS) format.
 
+show python resolve-operators
+  Show whether resolving Python operators (in Python scripts) to
+  overloaded C++ operators is enabled/disabled.
+
+set python resolve-operators
+  Enable/disable resolving Python operators (in Python scripts) to
+  overloaded C++ operators.
+
 * New options
 
 set max-completions
diff --git a/gdb/data-directory/Makefile.in b/gdb/data-directory/Makefile.in
index c01b86d..eda541e 100644
--- a/gdb/data-directory/Makefile.in
+++ b/gdb/data-directory/Makefile.in
@@ -74,6 +74,8 @@  PYTHON_FILE_LIST = \
 	gdb/function/__init__.py \
 	gdb/function/caller_is.py \
 	gdb/function/strfns.py \
+	gdb/parameters/__init__.py \
+	gdb/parameters/resolve_operators.py \
 	gdb/printer/__init__.py \
 	gdb/printer/bound_registers.py
 
diff --git a/gdb/python/lib/gdb/__init__.py b/gdb/python/lib/gdb/__init__.py
index 92b06f2..3152b00 100644
--- a/gdb/python/lib/gdb/__init__.py
+++ b/gdb/python/lib/gdb/__init__.py
@@ -82,6 +82,7 @@  PYTHONDIR = os.path.dirname(os.path.dirname(__file__))
 packages = [
     'function',
     'command',
+    'parameters',
     'printer'
 ]
 
diff --git a/gdb/python/lib/gdb/parameters/__init__.py b/gdb/python/lib/gdb/parameters/__init__.py
new file mode 100644
index 0000000..97b8f7e
--- /dev/null
+++ b/gdb/python/lib/gdb/parameters/__init__.py
@@ -0,0 +1,14 @@ 
+# Copyright (C) 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
diff --git a/gdb/python/lib/gdb/parameters/resolve_operators.py b/gdb/python/lib/gdb/parameters/resolve_operators.py
new file mode 100644
index 0000000..7f67458
--- /dev/null
+++ b/gdb/python/lib/gdb/parameters/resolve_operators.py
@@ -0,0 +1,43 @@ 
+# Copyright (C) 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import gdb
+
+
+class ResolveOperators(gdb.Parameter):
+    def __init__(self):
+        self.set_doc = ('Enable/disable resolving Python operators to '
+                        'overloaded C++ operators.\n\n'
+                        'Usage:\n'
+                        '    set python resolve-operators <on|off>\n')
+        self.show_doc = ('Show whether Python operators will be resolved '
+                         'to overloaded C++ operators.\n\n'
+                         'Usage:\n'
+                         '    show python resolve-operators\n')
+        gdb.Parameter.__init__(self, 'python resolve-operators',
+                               gdb.COMMAND_NONE, gdb.PARAM_BOOLEAN)
+        self.value = True
+
+    def get_set_string(self):
+        return ('Resolving Python operators to overloaded C++ operators is ' +
+                'set to "%s".' % ('on' if self.value else 'off'))
+
+    def get_show_string(self, svalue):
+        return ('Resolving Python operators to overloaded C++ operators is ' +
+                '"%s".' % ('on' if self.value else 'off'))
+
+
+ResolveOperators()
diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index 5a13777..015bf8a 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -27,6 +27,7 @@ 
 #include "expression.h"
 #include "cp-abi.h"
 #include "python.h"
+#include "cli/cli-decode.h"
 
 #include "python-internal.h"
 
@@ -920,6 +921,23 @@  enum valpy_opcode
 #define STRIP_REFERENCE(TYPE) \
   ((TYPE_CODE (TYPE) == TYPE_CODE_REF) ? (TYPE_TARGET_TYPE (TYPE)) : (TYPE))
 
+/* */
+
+static int
+resolve_to_overloaded_operators (void)
+{
+  const char *show_cmd = "show python resolve-operators";
+  struct cmd_list_element *alias, *prefix, *cmd;
+  int found = -1;
+  volatile struct gdb_exception except;
+
+  found = lookup_cmd_composition (show_cmd, &alias, &prefix, &cmd);
+  if (!found || !cmd->var || (cmd->var_type != var_boolean))
+    return 0;
+
+  return *((int *) cmd->var);
+}
+
 /* Returns a value object which is the result of applying the operation
    specified by OPCODE to the given arguments.  Returns NULL on error, with
    a python exception set.  */
@@ -1038,7 +1056,8 @@  valpy_binop (enum valpy_opcode opcode, PyObject *self, PyObject *other)
 
       if (!handled)
 	{
-	  if (binop_user_defined_p (op, arg1, arg2))
+	  if (binop_user_defined_p (op, arg1, arg2)
+	      && resolve_to_overloaded_operators ())
 	    res_val = value_x_binop (arg1, arg2, op, OP_NULL, EVAL_NORMAL);
 	  else
 	    res_val = value_binop (arg1, arg2, op);
diff --git a/gdb/testsuite/gdb.python/py-resolve-operators.cc b/gdb/testsuite/gdb.python/py-resolve-operators.cc
new file mode 100644
index 0000000..b4630a7
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-resolve-operators.cc
@@ -0,0 +1,38 @@ 
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see  <http://www.gnu.org/licenses/>.  */
+
+class A
+{
+public:
+  int operator+ (int i);
+
+  int a;
+};
+
+int
+A::operator+ (int i)
+{
+  return a + i;
+}
+
+int
+main (void)
+{
+  A a = { 10 };
+
+  return a + -10;  /*  Break here. */
+}
diff --git a/gdb/testsuite/gdb.python/py-resolve-operators.exp b/gdb/testsuite/gdb.python/py-resolve-operators.exp
new file mode 100644
index 0000000..9d03352
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-resolve-operators.exp
@@ -0,0 +1,50 @@ 
+# Copyright 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the GDB testsuite.  It tests the debug methods
+# feature in the Python extension language.
+
+load_lib gdb-python.exp
+
+if { [skip_cplus_tests] } { continue }
+
+standard_testfile py-resolve-operators.cc
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+# Skip all tests if Python scripting is not enabled.
+if { [skip_python_tests] } { continue }
+
+if ![runto_main] {
+   return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "Break here."]
+gdb_continue_to_breakpoint "Break here" ".*Break here.*"
+
+gdb_test_no_output "python a = gdb.parse_and_eval('a')" "make_a"
+
+gdb_test "show python resolve-operators" ".*on.*" "test_show_with_on"
+gdb_test "python print(a + 113)" "123" "print_a_with_on"
+
+gdb_test "set python resolve-operators off" ".*off.*" "test_set_to_off"
+gdb_test "python print(a + 113)" \
+    ".*gdb\.error: Argument to arithmetic operation not a number or boolean.*" \
+    "print_a_with_off"
+
+gdb_test "set python resolve-operators on" ".*on.*" "test_set_to_on"
+gdb_test "python print(a + 113)" "123" "print_a_with_on_again"