[vala/0.34] codegen: Check there is a return error location before using it

[Rico Tzschichholz <ricotz src gnome org>]

commit 41e7279b5970040c70c8e542f4a96646bdc260a0
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Mar 6 14:23:19 2017 +0100

    codegen: Check there is a return error location before using it
    
    Fixes client-side dbus generation on methods that don't throw any error.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=779652

 codegen/valagdbusclientmodule.vala      |   21 +++++++++++++++------
 tests/dbus/enum-string-marshalling.vala |    3 ++-
 2 files changed, 17 insertions(+), 7 deletions(-)
---
diff --git a/codegen/valagdbusclientmodule.vala b/codegen/valagdbusclientmodule.vala
index e1a53fb..40d97e9 100644
--- a/codegen/valagdbusclientmodule.vala
+++ b/codegen/valagdbusclientmodule.vala
@@ -565,6 +565,14 @@ public class Vala.GDBusClientModule : GDBusModule {
                        cfile.add_include ("gio/gunixfdlist.h");
                }
 
+               bool has_error_argument = (m.get_error_types ().size > 0);
+               CCodeExpression error_argument;
+               if (has_error_argument) {
+                       error_argument = new CCodeIdentifier ("error");
+               } else {
+                       error_argument = new CCodeConstant ("NULL");
+               }
+
                if (call_type != CallType.FINISH) {
                        var destination = new CCodeFunctionCall (new CCodeIdentifier 
("g_dbus_proxy_get_name"));
                        destination.add_argument (gdbusproxy);
@@ -671,7 +679,7 @@ public class Vala.GDBusClientModule : GDBusModule {
                                ccall.add_argument (timeout);
                                ccall.add_argument (new CCodeConstant ("NULL"));
                                ccall.add_argument (cancellable);
-                               ccall.add_argument (new CCodeIdentifier ("error"));
+                               ccall.add_argument (error_argument);
                                ccode.add_assignment (new CCodeIdentifier ("_reply_message"), ccall);
                        } else if (call_type == CallType.NO_REPLY) {
                                var set_flags = new CCodeFunctionCall (new CCodeIdentifier 
("g_dbus_message_set_flags"));
@@ -684,7 +692,7 @@ public class Vala.GDBusClientModule : GDBusModule {
                                ccall.add_argument (new CCodeIdentifier ("_message"));
                                ccall.add_argument (new CCodeConstant ("G_DBUS_SEND_MESSAGE_FLAGS_NONE"));
                                ccall.add_argument (new CCodeConstant ("NULL"));
-                               ccall.add_argument (new CCodeIdentifier ("error"));
+                               ccall.add_argument (error_argument);
                                ccode.add_expression (ccall);
                        } else if (call_type == CallType.ASYNC) {
                                ccall = new CCodeFunctionCall (new CCodeIdentifier 
("g_dbus_connection_send_message_with_reply"));
@@ -721,7 +729,7 @@ public class Vala.GDBusClientModule : GDBusModule {
                        inner_res.add_argument (new CCodeCastExpression (new CCodeIdentifier ("_res_"), 
"GSimpleAsyncResult *"));
                        ccall.add_argument (inner_res);
 
-                       ccall.add_argument (new CCodeConstant ("error"));
+                       ccall.add_argument (error_argument);
                        ccode.add_assignment (new CCodeIdentifier ("_reply_message"), ccall);
                }
 
@@ -740,7 +748,7 @@ public class Vala.GDBusClientModule : GDBusModule {
                        // return on remote error
                        var ccall = new CCodeFunctionCall (new CCodeIdentifier ("g_dbus_message_to_gerror"));
                        ccall.add_argument (new CCodeIdentifier ("_reply_message"));
-                       ccall.add_argument (new CCodeIdentifier ("error"));
+                       ccall.add_argument (error_argument);
                        ccode.open_if (ccall);
                        ccode.add_expression (unref_reply);
                        return_default_value (m.return_type);
@@ -787,7 +795,8 @@ public class Vala.GDBusClientModule : GDBusModule {
 
                                                var target = new CCodeIdentifier ("_vala_" + param.name);
                                                bool may_fail;
-                                               receive_dbus_value (param.variable_type, new CCodeIdentifier 
("_reply_message"), new CCodeIdentifier ("_reply_iter"), target, param, new CCodeIdentifier ("error"), out 
may_fail);
+
+                                               receive_dbus_value (param.variable_type, new CCodeIdentifier 
("_reply_message"), new CCodeIdentifier ("_reply_iter"), target, param, error_argument, out may_fail);
 
                                                // TODO check that parameter is not NULL (out parameters are 
optional)
                                                // free value if parameter is NULL
@@ -800,7 +809,7 @@ public class Vala.GDBusClientModule : GDBusModule {
                                                        }
                                                }
 
-                                               if (may_fail) {
+                                               if (may_fail && has_error_argument) {
                                                        ccode.open_if (new CCodeBinaryExpression 
(CCodeBinaryOperator.AND, new CCodeIdentifier ("error"), new CCodeUnaryExpression 
(CCodeUnaryOperator.POINTER_INDIRECTION, new CCodeIdentifier ("error"))));
                                                        ccode.add_expression (unref_reply);
                                                        return_default_value (m.return_type);
diff --git a/tests/dbus/enum-string-marshalling.vala b/tests/dbus/enum-string-marshalling.vala
index 14942a3..2cc7648 100644
--- a/tests/dbus/enum-string-marshalling.vala
+++ b/tests/dbus/enum-string-marshalling.vala
@@ -8,7 +8,8 @@ public interface Test : GLib.Object {
        public abstract async void test1 (FooEnum e) throws DBusError;
        public abstract void test2 (FooEnum e) throws DBusError;
        public abstract void test3 (FooEnum e1, UnixOutputStream output_stream, FooEnum e2) throws DBusError;
-       //FIXME public abstract void test4 (FooEnum e);
+       public abstract void test4 (FooEnum e);
+       public abstract async void test5 (FooEnum e);
 }
 
 void main () {