QDnsLookup: remove the #if QT_CONFIG(thread) check

There's no fallback anywhere, so this class simply doesn't work if
threading isn't supported. Writing it is an exercise left for whoever
cares for that configuration.

Change-Id: I3e3bfef633af4130a03afffd175e6f68a3f4673f
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/configure.cmake

@@ -331,7 +331,7 @@ qt_feature("dnslookup" PUBLIC
     SECTION "Networking"
     LABEL "QDnsLookup"
     PURPOSE "Provides API for DNS lookups."
-    CONDITION NOT INTEGRITY
+    CONDITION QT_FEATURE_thread AND NOT INTEGRITY
 )
 qt_feature("gssapi" PUBLIC
     SECTION "Networking"

src/network/kernel/qdnslookup.cpp

@@ -13,9 +13,7 @@
 
 QT_BEGIN_NAMESPACE
 
-#if QT_CONFIG(thread)
 Q_GLOBAL_STATIC(QDnsLookupThreadPool, theDnsLookupThreadPool);
-#endif
 
 static bool qt_qdnsmailexchangerecord_less_than(const QDnsMailExchangeRecord &r1, const QDnsMailExchangeRecord &r2)
 {
@@ -476,9 +474,7 @@ void QDnsLookup::lookup()
     connect(d->runnable, &QDnsLookupRunnable::finished,
             this, [this](const QDnsLookupReply &reply) { d_func()->_q_lookupFinished(reply); },
             Qt::BlockingQueuedConnection);
-#if QT_CONFIG(thread)
-    theDnsLookupThreadPool()->start(d->runnable);
-#endif
+    theDnsLookupThreadPool->start(d->runnable);
 }
 
 /*!
@@ -991,7 +987,6 @@ void QDnsLookupRunnable::run()
     emit finished(reply);
 }
 
-#if QT_CONFIG(thread)
 QDnsLookupThreadPool::QDnsLookupThreadPool()
     : signalsConnected(false)
 {
@@ -1027,7 +1022,7 @@ void QDnsLookupThreadPool::_q_applicationDestroyed()
     waitForDone();
     signalsConnected = false;
 }
-#endif // QT_CONFIG(thread)
+
 QT_END_NAMESPACE
 
 #include "moc_qdnslookup.cpp"

src/network/kernel/qdnslookup_p.h

@@ -117,7 +117,6 @@ private:
     QHostAddress nameserver;
 };
 
-#if QT_CONFIG(thread)
 class QDnsLookupThreadPool : public QThreadPool
 {
     Q_OBJECT
@@ -133,7 +132,6 @@ private:
     QMutex signalsMutex;
     bool signalsConnected;
 };
-#endif // QT_CONFIG(thread)
 
 class QDnsRecordPrivate : public QSharedData
 {