public static SourceParameterSymbol Create(
            Binder context,
            Symbol owner,
            TypeSymbol parameterType,
            ParameterSyntax syntax,
            RefKind refKind,
            SyntaxToken identifier,
            int ordinal,
            bool isParams,
            bool isExtensionMethodThis,
            DiagnosticBag diagnostics)
        {
            var name = identifier.ValueText;
            var locations = ImmutableArray.Create<Location>(new SourceLocation(identifier));

            if (!isParams &&
                !isExtensionMethodThis &&
                (syntax.Default == null) &&
                (syntax.AttributeLists.Count == 0) &&
                !owner.IsPartialMethod())
            {
                return new SourceSimpleParameterSymbol(owner, parameterType, ordinal, refKind, name, locations);
            }

            if (isParams)
            {
                // touch the constructor in order to generate proper use-site diagnostics
                Binder.ReportUseSiteDiagnosticForSynthesizedAttribute(context.Compilation,
                    WellKnownMember.System_ParamArrayAttribute__ctor,
                    diagnostics,
                    identifier.Parent.GetLocation());
            }

            var syntaxRef = syntax.GetReference();
            return new SourceComplexParameterSymbol(
                owner,
                ordinal,
                parameterType,
                refKind,
                ImmutableArray<CustomModifier>.Empty,
                false,
                name,
                locations,
                syntaxRef,
                ConstantValue.Unset,
                isParams,
                isExtensionMethodThis);
        }
        internal SourcePrimaryConstructorParameterSymbolWithBackingField(
            Symbol owner,
            int ordinal,
            TypeSymbol parameterType,
            RefKind refKind,
            string name,
            ImmutableArray<Location> locations,
            ParameterSyntax syntax,
            ConstantValue defaultSyntaxValue,
            bool isParams,
            bool isExtensionMethodThis,
            DiagnosticBag diagnostics
        ) : base(owner, ordinal, parameterType, refKind, ImmutableArray<CustomModifier>.Empty, false, name, locations, syntax.GetReference(), defaultSyntaxValue, isParams, isExtensionMethodThis)
        {
            bool modifierErrors;
            var modifiers = SourceMemberFieldSymbol.MakeModifiers(owner.ContainingType, syntax.Identifier, syntax.Modifiers, diagnostics, out modifierErrors, ignoreParameterModifiers: true);

            backingField = new BackingField(this, modifiers, modifierErrors, diagnostics);
        }