/// <summary>
/// Merges nullability.
/// </summary>
public static NullableAnnotation MergeNullableAnnotation(this NullableAnnotation a, NullableAnnotation b, VarianceKind variance)
{
return(variance switch
{
VarianceKind.In => a.Meet(b),
VarianceKind.Out => a.Join(b),
VarianceKind.None => a.EnsureCompatible(b),
_ => throw ExceptionUtilities.UnexpectedValue(variance)
});
public static NullableAnnotation GetNullableAnnotation(ArrayBuilder <TypeSymbolWithAnnotations> types)
{
NullableAnnotation result = NullableAnnotation.NotAnnotated;
foreach (var type in types)
{
Debug.Assert(type.HasType);
Debug.Assert(type.Equals(types[0], TypeCompareKind.AllIgnoreOptions));
// This uses the covariant merging rules.
result = result.Join(type.NullableAnnotation);
}
return(result);
}