C++ Compiler Error Traced to Macro Conflict: Developer's 'ErrorMessage' Macro Clashes with XAML Header, Causing Nonsensical Errors

Learning to read C++ compiler errors: Nonsensical errors from a function declaration - The Old New Thing

A customer wanted to add XAML support to their application, so they included (among other things) the header file winrt/Windows.UI.Xaml.h. But the mere act of including that header file produced a horrible series of errors that began with. winrt\impl\Windows.UI.Xaml.0.h(4323,28): warning C4003: not enough arguments for function-like macro invocation 'ErrorMessage' winrt\impl\Windows.UI.Xaml.0.h(4323,28): error C2146: syntax error: missing ')' before identifier 'ErrorMessageString' winrt\impl\Win...