private static void StructDependsClosure(NamedTypeSymbol type, HashSet <Symbol> partialClosure, NamedTypeSymbol on)
{
Debug.Assert((object)type != null);
if ((object)type.OriginalDefinition == on)
{
// found a possibly expanding cycle, for example
// struct X<T> { public T t; }
// struct W<T> { X<W<W<T>>> x; }
// while not explicitly forbidden by the spec, it should be.
partialClosure.Add(on);
return;
}
if (partialClosure.Add(type))
{
foreach (var member in type.GetMembersUnordered())
{
var field = member as FieldSymbol;
if ((object)field == null || field.Type.TypeKind != TypeKind.Struct || field.IsStatic)
{
continue;
}
StructDependsClosure((NamedTypeSymbol)field.Type.TypeSymbol, partialClosure, on);
}
}
}
/// <summary>
/// Accumulate diagnostics related to the variance safety of an interface.
/// </summary>
internal static void CheckInterfaceVarianceSafety(this NamedTypeSymbol interfaceType, DiagnosticBag diagnostics)
{
Debug.Assert((object)interfaceType != null && interfaceType.IsInterface);
foreach (NamedTypeSymbol baseInterface in interfaceType.InterfacesNoUseSiteDiagnostics())
{
IsVarianceUnsafe(
baseInterface,
requireOutputSafety: true,
requireInputSafety: false,
context: baseInterface,
locationProvider: i => null,
locationArg: baseInterface,
diagnostics: diagnostics);
}
foreach (Symbol member in interfaceType.GetMembersUnordered())
{
switch (member.Kind)
{
case SymbolKind.Method:
if (!member.IsAccessor())
{
CheckMethodVarianceSafety((MethodSymbol)member, diagnostics);
}
break;
case SymbolKind.Property:
CheckPropertyVarianceSafety((PropertySymbol)member, diagnostics);
break;
case SymbolKind.Event:
CheckEventVarianceSafety((EventSymbol)member, diagnostics);
break;
}
}
}
