private static bool ReturnTypesMatch(MethodSymbol candidateMethod, TypeMap candidateMethodTypeMap, ref ParamInfo <TypeSymbol> targetReturnParam)
{
Debug.Assert(candidateMethodTypeMap != null);
if (candidateMethod.ReturnsByRef != targetReturnParam.IsByRef)
{
return(false);
}
TypeSymbolWithAnnotations candidateMethodType = candidateMethod.ReturnType;
TypeSymbol targetReturnType = targetReturnParam.Type;
// CONSIDER: Do we want to add special handling for error types? Right now, we expect they'll just fail to match.
var substituted = candidateMethodType.SubstituteType(candidateMethodTypeMap);
if (!TypeSymbol.Equals(substituted.TypeSymbol, targetReturnType, TypeCompareKind.ConsiderEverything2))
{
return(false);
}
if (!CustomModifiersMatch(substituted.CustomModifiers, targetReturnParam.CustomModifiers) ||
!CustomModifiersMatch(candidateMethodTypeMap.SubstituteCustomModifiers(candidateMethod.RefCustomModifiers), targetReturnParam.RefCustomModifiers))
{
return(false);
}
return(true);
}
private static TypeSymbolWithAnnotations SubstituteAllTypeParameters(AbstractTypeMap substitution, TypeSymbolWithAnnotations type)
{
if (substitution != null)
{
TypeSymbolWithAnnotations previous;
do
{
previous = type;
type = type.SubstituteType(substitution);
} while (!type.IsSameAs(previous));
}
return(type);
}
/// <summary>
/// Determine whether there is any substitution of type parameters that will
/// make two types identical.
/// </summary>
/// <param name="t1">LHS</param>
/// <param name="t2">RHS</param>
/// <param name="substitution">
/// Substitutions performed so far (or null for none).
/// Keys are type parameters, values are types (possibly type parameters).
/// Will be updated with new substitutions by the callee.
/// Should be ignored when false is returned.
/// </param>
/// <returns>True if there exists a type map such that Map(LHS) == Map(RHS).</returns>
/// <remarks>
/// Derived from Dev10's BSYMMGR::UnifyTypes.
/// Two types will not unify if they have different custom modifiers.
/// </remarks>
private static bool CanUnifyHelper(TypeSymbolWithAnnotations t1, TypeSymbolWithAnnotations t2, ref MutableTypeMap substitution)
{
if (t1.IsNull || t2.IsNull)
{
return(t1.IsSameAs(t2));
}
if (TypeSymbol.Equals(t1.TypeSymbol, t2.TypeSymbol, TypeCompareKind.ConsiderEverything2) && t1.CustomModifiers.SequenceEqual(t2.CustomModifiers))
{
return(true);
}
if (substitution != null)
{
t1 = t1.SubstituteType(substitution);
t2 = t2.SubstituteType(substitution);
}
// If one of the types is a type parameter, then the substitution could make them equal.
if (TypeSymbol.Equals(t1.TypeSymbol, t2.TypeSymbol, TypeCompareKind.ConsiderEverything2) && t1.CustomModifiers.SequenceEqual(t2.CustomModifiers))
{
return(true);
}
// We can avoid a lot of redundant checks if we ensure that we only have to check
// for type parameters on the LHS
if (!t1.TypeSymbol.IsTypeParameter() && t2.TypeSymbol.IsTypeParameter())
{
TypeSymbolWithAnnotations tmp = t1;
t1 = t2;
t2 = tmp;
}
// If t1 is not a type parameter, then neither is t2
Debug.Assert(t1.TypeSymbol.IsTypeParameter() || !t2.TypeSymbol.IsTypeParameter());
switch (t1.Kind)
{
case SymbolKind.ArrayType:
{
if (t2.TypeKind != t1.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return(false);
}
ArrayTypeSymbol at1 = (ArrayTypeSymbol)t1.TypeSymbol;
ArrayTypeSymbol at2 = (ArrayTypeSymbol)t2.TypeSymbol;
return(CanUnifyHelper(at1.ElementType, at2.ElementType, ref substitution));
}
case SymbolKind.PointerType:
{
if (t2.TypeKind != t1.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return(false);
}
PointerTypeSymbol pt1 = (PointerTypeSymbol)t1.TypeSymbol;
PointerTypeSymbol pt2 = (PointerTypeSymbol)t2.TypeSymbol;
return(CanUnifyHelper(pt1.PointedAtType, pt2.PointedAtType, ref substitution));
}
case SymbolKind.NamedType:
case SymbolKind.ErrorType:
{
if (t2.TypeKind != t1.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return(false);
}
NamedTypeSymbol nt1 = (NamedTypeSymbol)t1.TypeSymbol;
NamedTypeSymbol nt2 = (NamedTypeSymbol)t2.TypeSymbol;
if (nt1.IsTupleType)
{
if (!nt2.IsTupleType)
{
return(false);
}
return(CanUnifyHelper(nt1.TupleUnderlyingType, nt2.TupleUnderlyingType, ref substitution));
}
if (!nt1.IsGenericType)
{
return(!nt2.IsGenericType && TypeSymbol.Equals(nt1, nt2, TypeCompareKind.ConsiderEverything2));
}
else if (!nt2.IsGenericType)
{
return(false);
}
int arity = nt1.Arity;
if (nt2.Arity != arity || !TypeSymbol.Equals(nt2.OriginalDefinition, nt1.OriginalDefinition, TypeCompareKind.ConsiderEverything2))
{
return(false);
}
var nt1Arguments = nt1.TypeArgumentsNoUseSiteDiagnostics;
var nt2Arguments = nt2.TypeArgumentsNoUseSiteDiagnostics;
for (int i = 0; i < arity; i++)
{
if (!CanUnifyHelper(nt1Arguments[i],
nt2Arguments[i],
ref substitution))
{
return(false);
}
}
// Note: Dev10 folds this into the loop since GetTypeArgsAll includes type args for containing types
// TODO: Calling CanUnifyHelper for the containing type is an overkill, we simply need to go through type arguments for all containers.
return((object)nt1.ContainingType == null || CanUnifyHelper(nt1.ContainingType, nt2.ContainingType, ref substitution));
}
case SymbolKind.TypeParameter:
{
// These substitutions are not allowed in C#
if (t2.TypeKind == TypeKind.Pointer || t2.SpecialType == SpecialType.System_Void)
{
return(false);
}
TypeParameterSymbol tp1 = (TypeParameterSymbol)t1.TypeSymbol;
// Perform the "occurs check" - i.e. ensure that t2 doesn't contain t1 to avoid recursive types
// Note: t2 can't be the same type param - we would have caught that with ReferenceEquals above
if (Contains(t2.TypeSymbol, tp1))
{
return(false);
}
if (t1.CustomModifiers.IsDefaultOrEmpty)
{
AddSubstitution(ref substitution, tp1, t2);
return(true);
}
if (t1.CustomModifiers.SequenceEqual(t2.CustomModifiers))
{
AddSubstitution(ref substitution, tp1, TypeSymbolWithAnnotations.Create(t2.TypeSymbol));
return(true);
}
if (t1.CustomModifiers.Length < t2.CustomModifiers.Length &&
t1.CustomModifiers.SequenceEqual(t2.CustomModifiers.Take(t1.CustomModifiers.Length)))
{
AddSubstitution(ref substitution, tp1,
TypeSymbolWithAnnotations.Create(t2.TypeSymbol,
customModifiers: ImmutableArray.Create(t2.CustomModifiers, t1.CustomModifiers.Length, t2.CustomModifiers.Length - t1.CustomModifiers.Length)));
return(true);
}
if (t2.TypeSymbol.IsTypeParameter())
{
var tp2 = (TypeParameterSymbol)t2.TypeSymbol;
if (t2.CustomModifiers.IsDefaultOrEmpty)
{
AddSubstitution(ref substitution, tp2, t1);
return(true);
}
if (t2.CustomModifiers.Length < t1.CustomModifiers.Length &&
t2.CustomModifiers.SequenceEqual(t1.CustomModifiers.Take(t2.CustomModifiers.Length)))
{
AddSubstitution(ref substitution, tp2,
TypeSymbolWithAnnotations.Create(t1.TypeSymbol,
customModifiers: ImmutableArray.Create(t1.CustomModifiers, t2.CustomModifiers.Length, t1.CustomModifiers.Length - t2.CustomModifiers.Length)));
return(true);
}
}
return(false);
}
default:
{
return(false);
}
}
}
private static TypeSymbolWithAnnotations SubstituteType(TypeMap typeMap, TypeSymbolWithAnnotations typeSymbol)
{
return(typeMap == null ? typeSymbol : typeSymbol.SubstituteType(typeMap));
}
internal TypeSymbolWithAnnotations SubstituteType(TypeSymbolWithAnnotations previous)
{
return(previous.SubstituteType(this));
}
