Added some macros for asserting when functions are called in an unsafe manner outside the message thread.

extras/Projucer/Source/Licenses/jucer_LicenseController.cpp

@@ -153,7 +153,7 @@ void LicenseController::startWebviewIfNeeded()
 
 void LicenseController::logout()
 {
-    jassert (MessageManager::getInstance()->isThisTheMessageThread());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
    #if ! JUCER_ENABLE_GPL_MODE
     thread.reset();
@@ -169,7 +169,7 @@ void LicenseController::logout()
 
 void LicenseController::chooseNewLicense()
 {
-    jassert (MessageManager::getInstance()->isThisTheMessageThread());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
    #if ! JUCER_ENABLE_GPL_MODE
     thread.reset();

extras/Projucer/Source/Licenses/jucer_LicenseThread.h

@@ -35,7 +35,7 @@ struct NetWorkerThread   : public Thread,
 
     ~NetWorkerThread()
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
         signalThreadShouldExit();
         cancelPendingUpdate();

extras/Projucer/Source/LiveBuildEngine/jucer_ActivityList.h

@@ -105,7 +105,7 @@ private:
 
     static void checkThread()
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
     }
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ActivityList)

extras/Projucer/Source/LiveBuildEngine/jucer_ErrorList.h

@@ -114,7 +114,7 @@ private:
 
     static void checkThread()
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
     }
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ErrorList)

modules/juce_audio_devices/native/juce_mac_CoreMidi.cpp

@@ -222,7 +222,7 @@ namespace CoreMidiHelpers
     {
         // It seems that OSX can be a bit picky about the thread that's first used to
         // search for devices. It's safest to use the message thread for calling this.
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
 
         StringArray s;
         enableSimulatorMidiSession();
@@ -268,7 +268,7 @@ namespace CoreMidiHelpers
         {
             // Since OSX 10.6, the MIDIClientCreate function will only work
             // correctly when called from the message thread!
-            jassert (MessageManager::getInstance()->isThisTheMessageThread());
+            JUCE_ASSERT_MESSAGE_THREAD
 
             enableSimulatorMidiSession();
 

modules/juce_audio_plugin_client/AU/juce_AUv3_Wrapper.mm

@@ -1740,15 +1740,13 @@ public:
     JuceAUViewController (AUViewController<AUAudioUnitFactory>* p)
         : myself (p)
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
-
         PluginHostType::jucePlugInClientCurrentWrapperType = AudioProcessor::wrapperType_AudioUnitv3;
         initialiseJuce_GUI();
     }
 
     ~JuceAUViewController()
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
 
         if (processorHolder != nullptr)
             JuceAudioUnitv3::removeEditor (getAudioProcessor());
@@ -1757,7 +1755,7 @@ public:
     //==============================================================================
     void loadView()
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
 
         if (AudioProcessor* p = createPluginFilterOfType (AudioProcessor::wrapperType_AudioUnitv3))
         {
@@ -1894,7 +1892,7 @@ private:
     //==============================================================================
     AUAudioUnit* createAudioUnitOnMessageThread (const AudioComponentDescription& descr, NSError** error)
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
 
         [myself view];  // this will call [view load] and ensure that the AudioProcessor has been instantiated
 

modules/juce_audio_processors/format/juce_AudioPluginFormat.cpp

@@ -199,7 +199,7 @@ void AudioPluginFormat::createPluginInstanceOnMessageThread (const PluginDescrip
                                                              AudioPluginFormat::InstantiationCompletionCallback* callback)
 {
     jassert (callback != nullptr);
-    jassert (MessageManager::getInstance()->isThisTheMessageThread());
+    JUCE_ASSERT_MESSAGE_THREAD
 
     //==============================================================================
 

modules/juce_audio_processors/format_types/juce_VST3PluginFormat.cpp

@@ -1536,7 +1536,7 @@ struct VST3ComponentHolder
         // On Windows it's highly advisable to create your plugins using the message thread,
         // because many plugins need a chance to create HWNDs that will get their messages
         // delivered by the main message thread, and that's not possible from a background thread.
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
        #endif
 
         factory = ComSmartPtr<IPluginFactory> (module->getPluginFactory());
@@ -1749,7 +1749,7 @@ public:
         // On Windows it's highly advisable to create your plugins using the message thread,
         // because many plugins need a chance to create HWNDs that will get their messages
         // delivered by the main message thread, and that's not possible from a background thread.
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
        #endif
 
         if (! holder->initialise())

modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp

@@ -1210,7 +1210,7 @@ struct VSTPluginInstance     : public AudioPluginInstance,
         // because many plugins need a chance to create HWNDs that will get their
         // messages delivered by the main message thread, and that's not possible from
         // a background thread.
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
        #endif
 
         JUCE_VST_LOG ("Initialising VST: " + vstModule->pluginName + " (" + getVersion() + ")");
@@ -3216,7 +3216,7 @@ private:
         {
             // You shouldn't end up hitting this assertion unless the host is trying to do GUI
             // cleanup on a non-GUI thread.. If it does that, bad things could happen in here..
-            jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+            JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
             JUCE_VST_LOG ("Closing VST UI: " + plugin.getName());
             isOpen = false;

modules/juce_audio_utils/gui/juce_AudioThumbnail.cpp

@@ -642,7 +642,7 @@ void AudioThumbnail::saveTo (OutputStream& output) const
 //==============================================================================
 bool AudioThumbnail::setDataSource (LevelDataSource* newSource)
 {
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     numSamplesFinished = 0;
 

modules/juce_blocks_basics/topology/juce_PhysicalTopologySource.cpp

@@ -23,9 +23,6 @@
 namespace juce
 {
 
-#define JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED \
-    jassert (juce::MessageManager::getInstance()->currentThreadHasLockedMessageManager());
-
 #if DUMP_BANDWIDTH_STATS
 namespace
 {

modules/juce_events/broadcasters/juce_ActionBroadcaster.cpp

@@ -52,13 +52,13 @@ private:
 ActionBroadcaster::ActionBroadcaster()
 {
     // are you trying to create this object before or after juce has been intialised??
-    jassert (MessageManager::getInstanceWithoutCreating() != nullptr);
+    JUCE_ASSERT_MESSAGE_MANAGER_EXISTS
 }
 
 ActionBroadcaster::~ActionBroadcaster()
 {
     // all event-based objects must be deleted BEFORE juce is shut down!
-    jassert (MessageManager::getInstanceWithoutCreating() != nullptr);
+    JUCE_ASSERT_MESSAGE_MANAGER_EXISTS
 }
 
 void ActionBroadcaster::addActionListener (ActionListener* const listener)

modules/juce_events/broadcasters/juce_AsyncUpdater.cpp

@@ -63,7 +63,7 @@ void AsyncUpdater::triggerAsyncUpdate()
 {
     // If you're calling this before (or after) the MessageManager is
     // running, then you're not going to get any callbacks!
-    jassert (MessageManager::getInstanceWithoutCreating() != nullptr);
+    JUCE_ASSERT_MESSAGE_MANAGER_EXISTS
 
     if (activeMessage->shouldDeliver.compareAndSetBool (1, 0))
         if (! activeMessage->post())
@@ -79,7 +79,7 @@ void AsyncUpdater::cancelPendingUpdate() noexcept
 void AsyncUpdater::handleUpdateNowIfNeeded()
 {
     // This can only be called by the event thread.
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     if (activeMessage->shouldDeliver.exchange (0) != 0)
         handleAsyncUpdate();

modules/juce_events/broadcasters/juce_ChangeBroadcaster.cpp

@@ -36,7 +36,7 @@ void ChangeBroadcaster::addChangeListener (ChangeListener* const listener)
 {
     // Listeners can only be safely added when the event thread is locked
     // You can  use a MessageManagerLock if you need to call this from another thread.
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     changeListeners.add (listener);
 }
@@ -45,7 +45,7 @@ void ChangeBroadcaster::removeChangeListener (ChangeListener* const listener)
 {
     // Listeners can only be safely removed when the event thread is locked
     // You can  use a MessageManagerLock if you need to call this from another thread.
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     changeListeners.remove (listener);
 }
@@ -54,7 +54,7 @@ void ChangeBroadcaster::removeAllChangeListeners()
 {
     // Listeners can only be safely removed when the event thread is locked
     // You can  use a MessageManagerLock if you need to call this from another thread.
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     changeListeners.clear();
 }
@@ -68,7 +68,7 @@ void ChangeBroadcaster::sendChangeMessage()
 void ChangeBroadcaster::sendSynchronousChangeMessage()
 {
     // This can only be called by the event thread.
-    jassert (MessageManager::getInstance()->isThisTheMessageThread());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     broadcastCallback.cancelPendingUpdate();
     callListeners();

modules/juce_events/messages/juce_MessageListener.cpp

@@ -35,7 +35,7 @@ void Message::messageCallback()
 MessageListener::MessageListener() noexcept
 {
     // Are you trying to create a messagelistener before or after juce has been intialised??
-    jassert (MessageManager::getInstanceWithoutCreating() != nullptr);
+    JUCE_ASSERT_MESSAGE_MANAGER_EXISTS
 }
 
 MessageListener::~MessageListener()

modules/juce_events/messages/juce_MessageManager.cpp

@@ -231,6 +231,22 @@ bool MessageManager::currentThreadHasLockedMessageManager() const noexcept
     return thisThread == messageThreadId || thisThread == threadWithLock.get();
 }
 
+bool MessageManager::existsAndIsLockedByCurrentThread() noexcept
+{
+    if (auto i = getInstanceWithoutCreating())
+        return i->currentThreadHasLockedMessageManager();
+
+    return false;
+}
+
+bool MessageManager::existsAndIsCurrentThread() noexcept
+{
+    if (auto i = getInstanceWithoutCreating())
+        return i->isThisTheMessageThread();
+
+    return false;
+}
+
 //==============================================================================
 //==============================================================================
 /*  The only safe way to lock the message thread while another thread does

modules/juce_events/messages/juce_MessageManager.h

@@ -147,6 +147,16 @@ public:
     */
     bool currentThreadHasLockedMessageManager() const noexcept;
 
+    /** Returns true if there's an instance of the MessageManager, and if the current thread
+        has the lock on it.
+    */
+    static bool existsAndIsLockedByCurrentThread() noexcept;
+
+    /** Returns true if there's an instance of the MessageManager, and if the current thread
+        is running it.
+    */
+    static bool existsAndIsCurrentThread() noexcept;
+
     //==============================================================================
     /** Sends a message to all other JUCE applications that are running.
 
@@ -462,4 +472,28 @@ private:
     JUCE_DECLARE_NON_COPYABLE (MessageManagerLock)
 };
 
+//==============================================================================
+/** This macro is used to catch unsafe use of functions which expect to only be called
+    on the message thread, or when a MessageManagerLock is in place.
+    It will also fail if you try to use the function before the message manager has been
+    created, which could happen if you accidentally invoke it during a static constructor.
+*/
+#define JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED \
+    jassert (juce::MessageManager::existsAndIsLockedByCurrentThread());
+
+/** This macro is used to catch unsafe use of functions which expect to only be called
+    on the message thread.
+    It will also fail if you try to use the function before the message manager has been
+    created, which could happen if you accidentally invoke it during a static constructor.
+*/
+#define JUCE_ASSERT_MESSAGE_THREAD \
+    jassert (juce::MessageManager::existsAndIsCurrentThread());
+
+/** This macro is used to catch unsafe use of functions which expect to not be called
+    outside the lifetime of the MessageManager.
+*/
+#define JUCE_ASSERT_MESSAGE_MANAGER_EXISTS \
+    jassert (juce::MessageManager::getInstanceWithoutCreating() != nullptr);
+
+
 } // namespace juce

modules/juce_events/native/juce_android_Messaging.cpp

@@ -78,7 +78,7 @@ struct AndroidMessageQueue     : private Android::Runnable
 
     ~AndroidMessageQueue()
     {
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
         clearSingletonInstance();
     }
 

modules/juce_events/timers/juce_Timer.cpp

@@ -324,7 +324,7 @@ void Timer::startTimer (int interval) noexcept
 {
     // If you're calling this before (or after) the MessageManager is
     // running, then you're not going to get any timer callbacks!
-    jassert (MessageManager::getInstanceWithoutCreating() != nullptr);
+    JUCE_ASSERT_MESSAGE_MANAGER_EXISTS
 
     const TimerThread::LockType::ScopedLockType sl (TimerThread::lock);
 

modules/juce_gui_basics/commands/juce_ApplicationCommandManager.cpp

@@ -185,7 +185,7 @@ bool ApplicationCommandManager::invoke (const ApplicationCommandTarget::Invocati
 {
     // This call isn't thread-safe for use from a non-UI thread without locking the message
     // manager first..
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     bool ok = false;
     ApplicationCommandInfo commandInfo (0);

modules/juce_gui_basics/components/juce_Component.cpp

@@ -456,7 +456,7 @@ void Component::setName (const String& name)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
 
     if (componentName != name)
     {
@@ -482,7 +482,7 @@ void Component::setVisible (bool shouldBeVisible)
     {
         // if component methods are being called from threads other than the message
         // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-        ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
+        JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
 
         const WeakReference<Component> safePointer (this);
         flags.visibleFlag = shouldBeVisible;
@@ -562,7 +562,7 @@ void Component::addToDesktop (int styleWanted, void* nativeWindowToAttachTo)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     if (isOpaque())
         styleWanted &= ~ComponentPeer::windowIsSemiTransparent;
@@ -663,7 +663,7 @@ void Component::removeFromDesktop()
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
 
     if (flags.hasHeavyweightPeerFlag)
     {
@@ -839,7 +839,7 @@ void Component::toFront (bool setAsForeground)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
 
     if (flags.hasHeavyweightPeerFlag)
     {
@@ -1030,7 +1030,7 @@ void Component::setBounds (int x, int y, int w, int h)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
 
     if (w < 0) w = 0;
     if (h < 0) h = 0;
@@ -1344,7 +1344,7 @@ void Component::addChildComponent (Component& child, int zOrder)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
 
     jassert (this != &child); // adding a component to itself!?
 
@@ -1422,7 +1422,7 @@ Component* Component::removeChildComponent (int index, bool sendParentEvents, bo
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN
 
     auto* child = childComponentList [index];
 
@@ -1609,7 +1609,7 @@ void Component::enterModalState (bool shouldTakeKeyboardFocus,
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     if (! isCurrentlyModal (false))
     {
@@ -1786,7 +1786,7 @@ void Component::internalRepaintUnchecked (Rectangle<int> area, bool isEntireComp
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     if (flags.visibleFlag)
     {
@@ -2166,10 +2166,12 @@ void Component::addComponentListener (ComponentListener* newListener)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    #if JUCE_DEBUG || JUCE_LOG_ASSERTIONS
+   #if JUCE_DEBUG || JUCE_LOG_ASSERTIONS
     if (getParentComponent() != nullptr)
-        ASSERT_MESSAGE_MANAGER_IS_LOCKED;
-    #endif
+    {
+        JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    }
+   #endif
 
     componentListeners.add (newListener);
 }
@@ -2220,7 +2222,7 @@ void Component::addMouseListener (MouseListener* newListener,
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     // If you register a component as a mouselistener for itself, it'll receive all the events
     // twice - once via the direct callback that all components get anyway, and then again as a listener!
@@ -2236,7 +2238,7 @@ void Component::removeMouseListener (MouseListener* listenerToRemove)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     if (mouseListeners != nullptr)
         mouseListeners->removeListener (listenerToRemove);
@@ -2736,7 +2738,7 @@ void Component::grabKeyboardFocus()
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     grabFocusInternal (focusChangedDirectly, true);
 
@@ -2751,7 +2753,7 @@ void Component::moveKeyboardFocusToSibling (bool moveToNext)
 {
     // if component methods are being called from threads other than the message
     // thread, you'll need to use a MessageManagerLock object to make sure it's thread-safe.
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     if (parentComponent != nullptr)
     {

modules/juce_gui_basics/components/juce_ModalComponentManager.cpp

@@ -254,7 +254,7 @@ bool ModalComponentManager::cancelAllModalComponents()
 int ModalComponentManager::runEventLoopForCurrentComponent()
 {
     // This can only be run from the message thread!
-    jassert (MessageManager::getInstance()->isThisTheMessageThread());
+    JUCE_ASSERT_MESSAGE_THREAD
 
     int returnValue = 0;
 

modules/juce_gui_basics/desktop/juce_Desktop.cpp

@@ -70,7 +70,7 @@ Component* Desktop::getComponent (int index) const noexcept
 
 Component* Desktop::findComponentAt (Point<int> screenPosition) const
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     for (int i = desktopComponents.size(); --i >= 0;)
     {
@@ -105,7 +105,7 @@ LookAndFeel& Desktop::getDefaultLookAndFeel() noexcept
 
 void Desktop::setDefaultLookAndFeel (LookAndFeel* newDefaultLookAndFeel)
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
     currentLookAndFeel = newDefaultLookAndFeel;
 
     for (int i = getNumComponents(); --i >= 0;)
@@ -216,14 +216,14 @@ ListenerList<MouseListener>& Desktop::getMouseListeners()
 
 void Desktop::addGlobalMouseListener (MouseListener* listener)
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
     mouseListeners.add (listener);
     resetTimer();
 }
 
 void Desktop::removeGlobalMouseListener (MouseListener* listener)
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
     mouseListeners.remove (listener);
     resetTimer();
 }
@@ -323,7 +323,7 @@ bool Desktop::isOrientationEnabled (DisplayOrientation orientation) const noexce
 
 void Desktop::setGlobalScaleFactor (float newScaleFactor) noexcept
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     if (masterScaleFactor != newScaleFactor)
     {

modules/juce_gui_basics/desktop/juce_Displays.cpp

@@ -138,7 +138,7 @@ Point<ValueType> Displays::logicalToPhysical (Point<ValueType> point, const Disp
 
 const Displays::Display& Displays::getMainDisplay() const noexcept
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
     for (auto& d : displays)
         if (d.isMain)
@@ -151,7 +151,7 @@ const Displays::Display& Displays::getMainDisplay() const noexcept
 
 RectangleList<int> Displays::getRectangleList (bool userAreasOnly) const
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
     RectangleList<int> rl;
 
     for (auto& d : displays)
@@ -197,7 +197,7 @@ bool operator!= (const Displays::Display& d1, const Displays::Display& d2) noexc
 // Deprecated method
 const Displays::Display& Displays::getDisplayContaining (Point<int> position) const noexcept
 {
-    ASSERT_MESSAGE_MANAGER_IS_LOCKED
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
     auto* best = &displays.getReference (0);
     auto bestDistance = std::numeric_limits<int>::max();
 

modules/juce_gui_basics/juce_gui_basics.cpp

@@ -139,11 +139,10 @@
 #include <set>
 
 //==============================================================================
-#define ASSERT_MESSAGE_MANAGER_IS_LOCKED \
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
-
-#define ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN \
-    jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager() || getPeer() == nullptr);
+#define JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED_OR_OFFSCREEN \
+    jassert ((MessageManager::getInstanceWithoutCreating() != nullptr \
+               && MessageManager::getInstanceWithoutCreating()->currentThreadHasLockedMessageManager()) \
+              || getPeer() == nullptr);
 
 namespace juce
 {

modules/juce_gui_basics/native/juce_android_Windowing.cpp

@@ -74,7 +74,7 @@ JUCE_JNI_CALLBACK (JUCE_ANDROID_ACTIVITY_CLASSNAME, launchApp, void, (JNIEnv* en
         jassertfalse; // you must supply an application object for an android app!
     }
 
-    jassert (MessageManager::getInstance()->isThisTheMessageThread());
+    JUCE_ASSERT_MESSAGE_THREAD
 }
 
 JUCE_JNI_CALLBACK (JUCE_ANDROID_ACTIVITY_CLASSNAME, suspendApp, void, (JNIEnv* env, jobject))

modules/juce_gui_basics/native/juce_linux_X11_Windowing.cpp

@@ -1051,7 +1051,7 @@ public:
           isAlwaysOnTop (comp.isAlwaysOnTop())
     {
         // it's dangerous to create a window on a thread other than the message thread..
-        jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+        JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
         display = XWindowSystem::getInstance()->displayRef();
 
@@ -1097,7 +1097,7 @@ public:
     ~LinuxComponentPeer()
     {
         // it's dangerous to delete a window on a thread other than the message thread..
-        jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
+        JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
 
        #if JUCE_X11_SUPPORTS_XEMBED
         juce_handleXEmbedEvent (this, nullptr);

modules/juce_gui_basics/native/juce_win32_Windowing.cpp

@@ -1275,7 +1275,7 @@ public:
     void setTitle (const String& title) override
     {
         // Unfortunately some ancient bits of win32 mean you can only perform this operation from the message thread.
-        jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        JUCE_ASSERT_MESSAGE_THREAD
 
         SetWindowText (hwnd, title.toWideCharPointer());
     }

modules/juce_gui_basics/windows/juce_ThreadWithProgressWindow.cpp

@@ -59,7 +59,7 @@ ThreadWithProgressWindow::~ThreadWithProgressWindow()
 
 void ThreadWithProgressWindow::launchThread (int priority)
 {
-    jassert (MessageManager::getInstance()->isThisTheMessageThread());
+    JUCE_ASSERT_MESSAGE_THREAD
 
     startThread (priority);
     startTimer (100);