CodeAnalysis MaybeNull/AllowNull on Collections

[meixger]

Why doesn't the unit test expect MaybeNull and AllowNull on empty collections?
In the end, the property can be set to null at runtime.

XmlSchemaClassGenerator/XmlSchemaClassGenerator.Tests/xsd/nullablereferenceattributes/nullablereference.xsd

Lines 16 to 22 in 44234f6

	<xs:element name="ElementReferenceList">
	<xs:complexType>
	<xs:sequence>
	<xs:element name="text" type="xs:string" minOccurs="0" maxOccurs="unbounded" />
	</xs:sequence>
	</xs:complexType>
	</xs:element>

XmlSchemaClassGenerator/XmlSchemaClassGenerator.Tests/XmlTests.cs

Line 2691 in 44234f6

assertNullable("Test.ElementReferenceList", false);

[XmlIgnoreAttribute()]
private String[] _text;

// generated code is missing analysis attributes
// [AllowNullAttribute()]
// [MaybeNullAttribute()]
[XmlElementAttribute("Text")]
public String[] Text
{
    get
    {
        return _text;
    }
    set
    {
        _text = value;
    }
}

PS: The XmlSerializer is inconsitent when initializing List<> and Array: #538 (comment)

[meixger]

XmlSchemaClassGenerator/XmlSchemaClassGenerator/TypeModel.cs

Lines 603 to 612 in 269889d

	private bool IsNullable => DefaultValue == null && !IsRequired && !IsEnumerable;
	private bool IsValueType => PropertyType is EnumModel || (PropertyType is SimpleModel model && model.ValueType.IsValueType);
	private bool IsNullableValueType => IsNullable && IsValueType;
	// IsNullable excludes enumerables
	// private bool IsNullableReferenceType => IsNullable && (PropertyType is ClassModel || (PropertyType is SimpleModel model && !model.ValueType.IsValueType));
	private bool IsNullableReferenceType => DefaultValue == null && !IsRequired && (PropertyType is ClassModel || (PropertyType is SimpleModel model && !model.ValueType.IsValueType));

[mganss]

I think this may stem from a time prior to collectionSettersMode. Allowing null on collections is only necessary when the setter is not private. If it's private it can never be null.

[mganss]

I'm thinking to change the cited code like this:

private bool IsNullable => DefaultValue == null && !IsRequired;
private bool IsValueType => PropertyType is EnumModel || (PropertyType is SimpleModel model && model.ValueType.IsValueType);
private bool IsNullableValueType => IsNullable && !IsEnumerable && IsValueType;
private bool IsNullableReferenceType => IsNullable && (!IsEnumerable || !IsPrivateSetter) && (PropertyType is ClassModel || (PropertyType is SimpleModel model && !model.ValueType.IsValueType));

[meixger]

Yes, this would work for my use case

master...meixger:XmlSchemaClassGenerator:nullable-reference-collections-exp

[mganss]

OK done in 3a97825