/// <summary>
/// Resolve the constraints - but only resolve things into Expression's, not
/// into actual types.
/// </summary>
public bool Resolve (MemberCore ec, TypeParameter tp, Report Report)
{
if (resolved)
return true;
if (ec == null)
return false;
iface_constraints = new ArrayList (2); // TODO: Too expensive allocation
type_param_constraints = new ArrayList ();
foreach (object obj in constraints) {
if (HasConstructorConstraint) {
Report.Error (401, loc,
"The new() constraint must be the last constraint specified");
return false;
}
if (obj is SpecialConstraint) {
SpecialConstraint sc = (SpecialConstraint) obj;
if (sc == SpecialConstraint.Constructor) {
if (!HasValueTypeConstraint) {
attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
continue;
}
Report.Error (451, loc, "The `new()' constraint " +
"cannot be used with the `struct' constraint");
return false;
}
if ((num_constraints > 0) || HasReferenceTypeConstraint || HasValueTypeConstraint) {
Report.Error (449, loc, "The `class' or `struct' " +
"constraint must be the first constraint specified");
return false;
}
if (sc == SpecialConstraint.ReferenceType)
attrs |= GenericParameterAttributes.ReferenceTypeConstraint;
else
attrs |= GenericParameterAttributes.NotNullableValueTypeConstraint;
continue;
}
int errors = Report.Errors;
FullNamedExpression fn = ((Expression) obj).ResolveAsTypeStep (ec, false);
if (fn == null) {
if (errors != Report.Errors)
return false;
NamespaceEntry.Error_NamespaceNotFound (loc, ((Expression)obj).GetSignatureForError (), Report);
return false;
}
TypeExpr expr;
GenericTypeExpr cexpr = fn as GenericTypeExpr;
if (cexpr != null) {
expr = cexpr.ResolveAsBaseTerminal (ec, false);
} else
expr = ((Expression) obj).ResolveAsTypeTerminal (ec, false);
if ((expr == null) || (expr.Type == null))
return false;
if (!ec.IsAccessibleAs (fn.Type)) {
Report.SymbolRelatedToPreviousError (fn.Type);
Report.Error (703, loc,
"Inconsistent accessibility: constraint type `{0}' is less accessible than `{1}'",
fn.GetSignatureForError (), ec.GetSignatureForError ());
return false;
}
if (TypeManager.IsGenericParameter (expr.Type))
type_param_constraints.Add (expr);
else if (expr.IsInterface)
iface_constraints.Add (expr);
else if (class_constraint != null || iface_constraints.Count != 0) {
Report.Error (406, loc,
"The class type constraint `{0}' must be listed before any other constraints. Consider moving type constraint to the beginning of the constraint list",
expr.GetSignatureForError ());
return false;
} else if (HasReferenceTypeConstraint || HasValueTypeConstraint) {
Report.Error (450, loc, "`{0}': cannot specify both " +
"a constraint class and the `class' " +
"or `struct' constraint", expr.GetSignatureForError ());
return false;
} else
class_constraint = expr;
//
// Checks whether each generic method parameter constraint type
// is valid with respect to T
//
if (tp != null && tp.Type.DeclaringMethod != null) {
TypeManager.CheckTypeVariance (expr.Type, Variance.Contravariant, ec as MemberCore);
}
num_constraints++;
}
ArrayList list = new ArrayList ();
foreach (TypeExpr iface_constraint in iface_constraints) {
foreach (Type type in list) {
if (!type.Equals (iface_constraint.Type))
continue;
Report.Error (405, loc,
"Duplicate constraint `{0}' for type " +
"parameter `{1}'.", iface_constraint.GetSignatureForError (),
name);
return false;
}
list.Add (iface_constraint.Type);
}
foreach (TypeExpr expr in type_param_constraints) {
foreach (Type type in list) {
if (!type.Equals (expr.Type))
continue;
Report.Error (405, loc,
"Duplicate constraint `{0}' for type " +
"parameter `{1}'.", expr.GetSignatureForError (), name);
return false;
}
list.Add (expr.Type);
}
iface_constraint_types = new Type [list.Count];
list.CopyTo (iface_constraint_types, 0);
if (class_constraint != null) {
class_constraint_type = class_constraint.Type;
if (class_constraint_type == null)
return false;
if (class_constraint_type.IsSealed) {
if (class_constraint_type.IsAbstract)
{
Report.Error (717, loc, "`{0}' is not a valid constraint. Static classes cannot be used as constraints",
TypeManager.CSharpName (class_constraint_type));
}
else
{
Report.Error (701, loc, "`{0}' is not a valid constraint. A constraint must be an interface, " +
"a non-sealed class or a type parameter", TypeManager.CSharpName(class_constraint_type));
}
return false;
}
if ((class_constraint_type == TypeManager.array_type) ||
(class_constraint_type == TypeManager.delegate_type) ||
(class_constraint_type == TypeManager.enum_type) ||
(class_constraint_type == TypeManager.value_type) ||
(class_constraint_type == TypeManager.object_type) ||
class_constraint_type == TypeManager.multicast_delegate_type) {
Report.Error (702, loc,
"A constraint cannot be special class `{0}'",
TypeManager.CSharpName (class_constraint_type));
return false;
}
if (TypeManager.IsDynamicType (class_constraint_type)) {
Report.Error (1967, loc, "A constraint cannot be the dynamic type");
return false;
}
}
if (class_constraint_type != null)
effective_base_type = class_constraint_type;
else if (HasValueTypeConstraint)
effective_base_type = TypeManager.value_type;
else
effective_base_type = TypeManager.object_type;
if ((attrs & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0)
attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
resolved = true;
return true;
}