static bool SatisfiesConstraints(this TypeInfo genericVariable, SigTypeContext typeContextOfConstraintDeclarer, TypeInfo typeArg)
{
GenericParameterAttributes specialConstraints = genericVariable.GenericParameterAttributes & GenericParameterAttributes.SpecialConstraintMask;
if ((specialConstraints & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0)
{
if (!typeArg.IsValueType)
return false;
else
{
// the type argument is a value type, however if it is any kind of Nullable we want to fail
// as the constraint accepts any value type except Nullable types (Nullable itself is a value type)
if (typeArg.IsNullable())
return false;
}
}
if ((specialConstraints & GenericParameterAttributes.ReferenceTypeConstraint) != 0)
{
if (typeArg.IsValueType)
return false;
}
if ((specialConstraints & GenericParameterAttributes.DefaultConstructorConstraint) != 0)
{
if (!typeArg.HasExplicitOrImplicitPublicDefaultConstructor())
return false;
}
// Now check general subtype constraints
foreach (var constraint in genericVariable.GetGenericParameterConstraints())
{
TypeInfo typeConstraint = constraint.GetTypeInfo();
TypeInfo instantiatedTypeConstraint = typeConstraint.Instantiate(typeContextOfConstraintDeclarer);
// System.Object constraint will be always satisfied - even if argList is empty
if (instantiatedTypeConstraint.IsSystemObject())
continue;
// if a concrete type can be cast to the constraint, then this constraint will be satisifed
if (!AreTypesAssignable(typeArg, instantiatedTypeConstraint))
return false;
}
return true;
}
