Hey Jules,
The following commit broke UTF32 building: https://github.com/julianstorer/JUCE/commit/4317f60173a896c63068d8f9851e9db34c610654
juce_XmlElement.cpp - line 643
XmlElement* XmlElement::createNewChildElement (StringRef childTagName) { XmlElement* const newElement = new XmlElement (childTagName); addChildElement (newElement); return newElement; }
The first line that creates a new XmlElement is the only error:
'juce::XmlElement::XmlElement(const wchar_t *)' : cannot convert argument 1 from 'juce::StringRef' to 'const juce::String &' (..\..\..\juce\modules\juce_core\juce_core.cpp)