/// <summary>
/// Returns true if the members of superType are accessible from subType due to inheritance.
/// </summary>
public static bool IsAccessibleViaInheritance(
this NamedTypeSymbol superType,
NamedTypeSymbol subType,
ref CompoundUseSiteInfo <AssemblySymbol> useSiteInfo
)
{
// NOTE: we don't use strict inheritance. Instead we ignore constructed generic types
// and only consider the unconstructed types. Ecma-334, 4th edition contained the
// following text supporting this (although, for instance members) in 10.5.3 Protected
// access for instance members:
// In the context of generics (25.1.6), the rules for accessing protected and
// protected internal instance members are augmented by the following:
// o Within a generic class G, access to an inherited protected instance member M
// using a primary-expression of the form E.M is permitted if the type of E is a
// class type constructed from G or a class type derived from a class type
// constructed from G.
// This text is missing in the current version of the spec, but we believe this is accidental.
NamedTypeSymbol originalSuperType = superType.OriginalDefinition;
for (
NamedTypeSymbol?current = subType;
(object?)current != null;
current = current.BaseTypeWithDefinitionUseSiteDiagnostics(ref useSiteInfo)
)
{
if (ReferenceEquals(current.OriginalDefinition, originalSuperType))
{
return(true);
}
}
if (originalSuperType.IsInterface)
{
foreach (
NamedTypeSymbol current in subType.AllInterfacesWithDefinitionUseSiteDiagnostics(
ref useSiteInfo
)
)
{
if (ReferenceEquals(current.OriginalDefinition, originalSuperType))
{
return(true);
}
}
}
// The method returns true for superType == subType.
// Two different submission type symbols semantically represent a single type, so we should also return true.
return(superType.TypeKind == TypeKind.Submission &&
subType.TypeKind == TypeKind.Submission);
}
