dbus: Include some debug messages when failing to connect

When using dbus, there's a number of cases where resolution happens at
runtime. It's useful to see dbus complain when connects don't work,
because otherwise the system doesn't work but we don't know what is
happening.
Added this to debug such an issue, already helped me address other cases
that had gone unnoticed elsewhere, so this is something that benefits
from being in QtDBus.

Change-Id: I5eefb94fcf775182edf1ad0c24e8a6692f84b15f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 7 insertions, 5 deletions

diff --git a/src/dbus/qdbuspendingcall.cpp b/src/dbus/qdbuspendingcall.cpp
index 7674dd10f2..ff5dfc8967 100644
--- a/src/dbus/qdbuspendingcall.cpp
+++ b/src/dbus/qdbuspendingcall.cpp
@@ -123,16 +123,18 @@ bool QDBusPendingCallPrivate::setReplyCallback(QObject *target, const char *memb
         return false;
     }
 
-    methodIdx = QDBusConnectionPrivate::findSlot(target, member + 1, metaTypes);
+    QString errorMsg;
+    methodIdx = QDBusConnectionPrivate::findSlot(target, member + 1, metaTypes, errorMsg);
     if (methodIdx == -1) {
         QByteArray normalizedName = QMetaObject::normalizedSignature(member + 1);
-        methodIdx = QDBusConnectionPrivate::findSlot(target, normalizedName, metaTypes);
+        methodIdx = QDBusConnectionPrivate::findSlot(target, normalizedName, metaTypes, errorMsg);
     }
     if (methodIdx == -1) {
         // would not be able to deliver a reply
-        qWarning("QDBusPendingCall::setReplyCallback: error: cannot deliver a reply to %s::%s (%s)",
-                 target->metaObject()->className(),
-                 member + 1, qPrintable(target->objectName()));
+        qWarning("QDBusPendingCall::setReplyCallback: error: cannot deliver a reply to %s::%s (%s) "
+                 "because %s",
+                 target->metaObject()->className(), member + 1, qPrintable(target->objectName()),
+                 qPrintable(errorMsg));
         return false;
     }