Crash when opening AlertWindow inside PopupMenu

1

On juce 6.1.6, we have noticed a crash when using AlertWindow with JUCE_MODAL_LOOPS_PERMITTED inside a PopupMenu.

The following PIP can be used to reproduce: Simply build and run and click on the button, then the menus.

/*******************************************************************************
 The block below describes the properties of this PIP. A PIP is a short snippet
 of code that can be read by the Projucer and used to generate a JUCE project.

 BEGIN_JUCE_PIP_METADATA

  name:             PopupMenuCrash

  dependencies:     juce_core, juce_data_structures, juce_events, juce_graphics, juce_gui_basics
  exporters:        XCODE_MAC

  defines:          JUCE_MODAL_LOOPS_PERMITTED=1

  type:             Component
  mainClass:        MyComponent

 END_JUCE_PIP_METADATA

*******************************************************************************/

#pragma once

#include <memory>


//==============================================================================

class MenuCallback : public juce::PopupMenu::CustomCallback
{
public:
    MenuCallback() = default;
    
    bool menuItemTriggered() override
    {
        std::unique_ptr<AlertWindow> alert { std::make_unique<AlertWindow>("Alert", "This will crash on the second or third try", MessageBoxIconType::WarningIcon, nullptr) };
        
        alert->addButton("Crash", 0);

        alert->runModalLoop();
        return false;
    }
};

class MyComponent  : public juce::Component
{
public:
    //==============================================================================
    MyComponent()
    {
        button = std::make_unique<TextButton>("Crash");
        button->onClick = [this](){crash();};
        addAndMakeVisible(button.get());
        setSize (600, 400);
    }

    ~MyComponent() override
    {
    }

    //==============================================================================
    void paint (juce::Graphics& g) override
    {
        // (Our component is opaque, so we must completely fill the background with a solid colour)
        g.fillAll (getLookAndFeel().findColour (juce::ResizableWindow::backgroundColourId));

        g.setFont (juce::Font (16.0f));
        g.setColour (juce::Colours::white);
        g.drawText ("Hello World!", getLocalBounds(), juce::Justification::centred, true);
    }
    
    void crash()
    {
        PopupMenu submenu;
        PopupMenu::Item item;
        item.text = "Crash";
        item.itemID = 1;
        item.customCallback = new MenuCallback();
        submenu.addItem(item);
        
        juce::Rectangle<int> pos(button->getBounds());
        
        PopupMenu menu;
        menu.addSubMenu("Crash >", submenu);
                
        menu.showMenuAsync(PopupMenu::Options().withTargetComponent(this).withTargetScreenArea(localAreaToGlobal(pos)).withMinimumWidth(100));
    }

    void resized() override
    {
        button->setBounds(getLocalBounds().withSizeKeepingCentre(100, 25));
        // This is called when the MyComponent is resized.
        // If you add any child components, this is where you should
        // update their positions.
    }


private:
    //==============================================================================
    // Your private member variables go here...
    std::unique_ptr<TextButton> button;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (MyComponent)
};