AttributeWriter and Positional Arguments

[DorianGreen]

I have an issue with attributes with positional arguments.
some attributes like https://github.com/SteveDunn/Vogen/blob/main/src/Vogen.SharedTypes/VogenDefaultsAttribute.cs do not contain named arguments.

when using the attribute and providing just one argument as a positional one like

[assembly: VogenDefaults(staticAbstractsGeneration: StaticAbstractsGeneration.ValueObjectsDeriveFromTheInterface)]

The AttributeWriter only detects the explicit named arguments and ignores the other argument's default values.
The generated attribute looks like this:

new global::Vogen.VogenDefaultsAttribute(global::Vogen.StaticAbstractsGeneration.ValueObjectsDeriveFromTheInterface)

This results in compilation errors as it omits the positional name so the arguments are out of order

Copilot suggests the following to fetch the default values when arguments are not explicitly provided:

var constructorArguments = attributeData.ConstructorArguments.Select((arg, index) =>
        {
            var parameter = attributeData.AttributeConstructor.Parameters[index];
            if (arg.IsNull && parameter.HasExplicitDefaultValue)
            {
                return TypedConstantParser.GetTypedConstantValue(context.SemanticModel, parameter.ExplicitDefaultValue, arg.Type);
            }
            return TypedConstantParser.GetTypedConstantValue(context.SemanticModel, attributeSyntax.DescendantNodes().OfType<AttributeArgumentSyntax>().ElementAt(index).Expression, arg.Type);
        });

[thomhurst]

Thanks for the report @DorianGreen! I'm not available the next few days, but I'll try and get a fix out for you next week 😄