EnableDataBinding PropertyChanged PropertyChangedEventArgs.PropertyName always null

[djwork]

Hi mganss
I am trying to use the PropertyChanged event handler but I seem to be getting null from PropertyChangedEventArgs.PropertyName.

I noticed that "propertyName = null" is being passed to the PropertyChangedEventArgs constructor inside the generated OnPropertyChanged method.

protected virtual void OnPropertyChanged([System.Runtime.CompilerServices.CallerMemberNameAttribute()] string propertyName = null)
{
    PropertyChanged?.Invoke(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName = null));
}

I manually changed "PropertyChangedEventArgs(propertyName = null))" -> "PropertyChangedEventArgs(propertyName))" and the PropertyChangedEventArgs.PropertyName came through correctly.

I think this is a bug in ClassModel.Generate()

var param = new CodeParameterDeclarationExpression(typeof(string), "propertyName = null");
param.CustomAttributes.Add(new(TypeRef<System.Runtime.CompilerServices.CallerMemberNameAttribute>()));
var threadSafeDelegateInvokeExpression = new CodeSnippetExpression($"{propertyChangedEvent.Name}?.Invoke(this, new System.ComponentModel.PropertyChangedEventArgs({param.Name}))");

param's Name property is set to "propertyName = null" via the constructor, which is correct because CallerMemberNameAttribute requires the parameter to have a default value.
But the string passed to the CodeSnippetExpression constructor reuses the param.Name which is what I believe is creating the bug, because the Name property contains the parameter default expression:

So what do think about changing:

var threadSafeDelegateInvokeExpression = new CodeSnippetExpression($"{propertyChangedEvent.Name}?.Invoke(this, new System.ComponentModel.PropertyChangedEventArgs({param.Name}))");

to:

var threadSafeDelegateInvokeExpression = new CodeSnippetExpression($"{propertyChangedEvent.Name}?.Invoke(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName))");

[mganss]

Thanks for catching this one and also providing the fix!

[mganss]

Released in 2.1.1155.