private static TypeWithModifiers SubstituteAllTypeParameters(AbstractTypeMap substitution, TypeWithModifiers type)
{
if (substitution != null)
{
TypeWithModifiers previous;
do
{
previous = type;
type = type.SubstituteType(substitution);
} while (type != previous);
}
return type;
}
private static TypeWithModifiers SubstituteAllTypeParameters(AbstractTypeMap substitution, TypeWithModifiers type)
{
if (substitution != null)
{
TypeWithModifiers previous;
do
{
previous = type;
type = type.SubstituteType(substitution);
} while (type != 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(TypeWithModifiers t1, TypeWithModifiers t2, ref MutableTypeMap substitution)
{
if (t1 == t2)
{
return true;
}
else if ((object)t1.Type == null || (object)t2.Type == null)
{
// Can't both be null or they would have been equal
return false;
}
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 (t1 == t2)
{
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.Type.IsTypeParameter() && t2.Type.IsTypeParameter())
{
TypeWithModifiers tmp = t1;
t1 = t2;
t2 = tmp;
}
// If t1 is not a type parameter, then neither is t2
Debug.Assert(t1.Type.IsTypeParameter() || !t2.Type.IsTypeParameter());
switch (t1.Type.Kind)
{
case SymbolKind.ArrayType:
{
if (t2.Type.TypeKind != t1.Type.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return false;
}
ArrayTypeSymbol at1 = (ArrayTypeSymbol)t1.Type;
ArrayTypeSymbol at2 = (ArrayTypeSymbol)t2.Type;
if (!at1.HasSameShapeAs(at2))
{
return false;
}
return CanUnifyHelper(new TypeWithModifiers(at1.ElementType, at1.CustomModifiers), new TypeWithModifiers(at2.ElementType, at2.CustomModifiers), ref substitution);
}
case SymbolKind.PointerType:
{
if (t2.Type.TypeKind != t1.Type.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return false;
}
PointerTypeSymbol pt1 = (PointerTypeSymbol)t1.Type;
PointerTypeSymbol pt2 = (PointerTypeSymbol)t2.Type;
return CanUnifyHelper(new TypeWithModifiers(pt1.PointedAtType, pt1.CustomModifiers), new TypeWithModifiers(pt2.PointedAtType, pt2.CustomModifiers), ref substitution);
}
case SymbolKind.NamedType:
case SymbolKind.ErrorType:
{
if (t2.Type.TypeKind != t1.Type.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return false;
}
NamedTypeSymbol nt1 = (NamedTypeSymbol)t1.Type;
NamedTypeSymbol nt2 = (NamedTypeSymbol)t2.Type;
if (nt1.IsTupleType)
{
if (!nt2.IsTupleType)
{
return false;
}
return CanUnifyHelper(new TypeWithModifiers(nt1.TupleUnderlyingType), new TypeWithModifiers(nt2.TupleUnderlyingType), ref substitution);
}
if (!nt1.IsGenericType)
{
return !nt2.IsGenericType && nt1 == nt2;
}
else if (!nt2.IsGenericType)
{
return false;
}
int arity = nt1.Arity;
if (nt2.Arity != arity || nt2.OriginalDefinition != nt1.OriginalDefinition)
{
return false;
}
var nt1Arguments = nt1.TypeArgumentsNoUseSiteDiagnostics;
var nt2Arguments = nt2.TypeArgumentsNoUseSiteDiagnostics;
var nt1HasModifiers = nt1.HasTypeArgumentsCustomModifiers;
var nt2HasModifiers = nt2.HasTypeArgumentsCustomModifiers;
for (int i = 0; i < arity; i++)
{
if (!CanUnifyHelper(new TypeWithModifiers(nt1Arguments[i], nt1HasModifiers ? nt1.GetTypeArgumentCustomModifiers(i) : default(ImmutableArray<CustomModifier>)),
new TypeWithModifiers(nt2Arguments[i], nt2HasModifiers ? nt2.GetTypeArgumentCustomModifiers(i) : default(ImmutableArray<CustomModifier>)),
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(new TypeWithModifiers(nt1.ContainingType), new TypeWithModifiers(nt2.ContainingType), ref substitution);
}
case SymbolKind.TypeParameter:
{
// These substitutions are not allowed in C#
if (t2.Type.TypeKind == TypeKind.Pointer || t2.Type.SpecialType == SpecialType.System_Void)
{
return false;
}
TypeParameterSymbol tp1 = (TypeParameterSymbol)t1.Type;
// 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.Type, tp1))
{
return false;
}
if (t1.CustomModifiers.IsDefaultOrEmpty)
{
AddSubstitution(ref substitution, tp1, t2);
return true;
}
if (t1.CustomModifiers.SequenceEqual(t2.CustomModifiers))
{
AddSubstitution(ref substitution, tp1, new TypeWithModifiers(t2.Type));
return true;
}
if (t1.CustomModifiers.Length < t2.CustomModifiers.Length &&
t1.CustomModifiers.SequenceEqual(t2.CustomModifiers.Take(t1.CustomModifiers.Length)))
{
AddSubstitution(ref substitution, tp1,
new TypeWithModifiers(t2.Type,
ImmutableArray.Create(t2.CustomModifiers, t1.CustomModifiers.Length, t2.CustomModifiers.Length - t1.CustomModifiers.Length)));
return true;
}
if (t2.Type.IsTypeParameter())
{
var tp2 = (TypeParameterSymbol)t2.Type;
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,
new TypeWithModifiers(t1.Type,
ImmutableArray.Create(t1.CustomModifiers, t2.CustomModifiers.Length, t1.CustomModifiers.Length - t2.CustomModifiers.Length)));
return true;
}
}
return false;
}
default:
{
return t1 == t2;
}
}
}
private ArrayTypeSymbol SubstituteArrayType(ArrayTypeSymbol t)
{
var oldElement = new TypeWithModifiers(t.ElementType, t.CustomModifiers);
TypeWithModifiers element = oldElement.SubstituteType(this);
if (element == oldElement)
{
return t;
}
if (t.IsSZArray)
{
ImmutableArray<NamedTypeSymbol> interfaces = t.Interfaces; //.InterfacesNoUseSiteDiagnostics();
Debug.Assert(0 <= interfaces.Length && interfaces.Length <= 2);
if (interfaces.Length == 1)
{
Debug.Assert(interfaces[0] is NamedTypeSymbol); // IList<T>
interfaces = ImmutableArray.Create<NamedTypeSymbol>((NamedTypeSymbol)SubstituteType(interfaces[0]).AsTypeSymbolOnly());
}
else if (interfaces.Length == 2)
{
Debug.Assert(interfaces[0] is NamedTypeSymbol); // IList<T>
interfaces = ImmutableArray.Create<NamedTypeSymbol>((NamedTypeSymbol)SubstituteType(interfaces[0]).AsTypeSymbolOnly(), (NamedTypeSymbol)SubstituteType(interfaces[1]).AsTypeSymbolOnly());
}
else if (interfaces.Length != 0)
{
throw ExceptionUtilities.Unreachable;
}
return ArrayTypeSymbol.CreateSZArray(
element.Type,
t.BaseType, //.BaseTypeNoUseSiteDiagnostics,
interfaces,
element.CustomModifiers);
}
return ArrayTypeSymbol.CreateMDArray(
element.Type,
t.Rank,
t.Sizes,
t.LowerBounds,
t.BaseType, //.BaseTypeNoUseSiteDiagnostics,
element.CustomModifiers);
}
/// <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>
/// <param name="untouchables">
/// Set of type symbols that cannot be replaced by substitution.
/// </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(TypeWithModifiers t1, TypeWithModifiers t2, ref MutableTypeMap substitution, ImmutableHashSet <TypeParameterSymbol> untouchables)
{
if (t1 == t2)
{
return(true);
}
else if ((object)t1.Type == null || (object)t2.Type == null)
{
// Can't both be null or they would have been equal
return(false);
}
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 (t1 == t2)
{
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.Type.IsTypeParameter() && t2.Type.IsTypeParameter())
{
TypeWithModifiers tmp = t1;
t1 = t2;
t2 = tmp;
}
// If t1 is not a type parameter, then neither is t2
Debug.Assert(t1.Type.IsTypeParameter() || !t2.Type.IsTypeParameter());
switch (t1.Type.Kind)
{
case SymbolKind.ArrayType:
{
if (t2.Type.TypeKind != t1.Type.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return(false);
}
ArrayTypeSymbol at1 = (ArrayTypeSymbol)t1.Type;
ArrayTypeSymbol at2 = (ArrayTypeSymbol)t2.Type;
if (!at1.HasSameShapeAs(at2))
{
return(false);
}
return(CanUnifyHelper(new TypeWithModifiers(at1.ElementType, at1.CustomModifiers), new TypeWithModifiers(at2.ElementType, at2.CustomModifiers), ref substitution, untouchables));
}
case SymbolKind.PointerType:
{
if (t2.Type.TypeKind != t1.Type.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return(false);
}
PointerTypeSymbol pt1 = (PointerTypeSymbol)t1.Type;
PointerTypeSymbol pt2 = (PointerTypeSymbol)t2.Type;
return(CanUnifyHelper(new TypeWithModifiers(pt1.PointedAtType, pt1.CustomModifiers), new TypeWithModifiers(pt2.PointedAtType, pt2.CustomModifiers), ref substitution, untouchables));
}
case SymbolKind.NamedType:
case SymbolKind.ErrorType:
{
if (t2.Type.TypeKind != t1.Type.TypeKind || !t2.CustomModifiers.SequenceEqual(t1.CustomModifiers))
{
return(false);
}
NamedTypeSymbol nt1 = (NamedTypeSymbol)t1.Type;
NamedTypeSymbol nt2 = (NamedTypeSymbol)t2.Type;
if (nt1.IsTupleType)
{
if (!nt2.IsTupleType)
{
return(false);
}
return(CanUnifyHelper(new TypeWithModifiers(nt1.TupleUnderlyingType), new TypeWithModifiers(nt2.TupleUnderlyingType), ref substitution, untouchables));
}
if (!nt1.IsGenericType)
{
return(!nt2.IsGenericType && nt1 == nt2);
}
else if (!nt2.IsGenericType)
{
return(false);
}
int arity = nt1.Arity;
if (nt2.Arity != arity || nt2.OriginalDefinition != nt1.OriginalDefinition)
{
return(false);
}
var nt1Arguments = nt1.TypeArgumentsNoUseSiteDiagnostics;
var nt2Arguments = nt2.TypeArgumentsNoUseSiteDiagnostics;
var nt1HasModifiers = nt1.HasTypeArgumentsCustomModifiers;
var nt2HasModifiers = nt2.HasTypeArgumentsCustomModifiers;
for (int i = 0; i < arity; i++)
{
if (!CanUnifyHelper(new TypeWithModifiers(nt1Arguments[i], nt1HasModifiers ? nt1.GetTypeArgumentCustomModifiers(i) : default(ImmutableArray <CustomModifier>)),
new TypeWithModifiers(nt2Arguments[i], nt2HasModifiers ? nt2.GetTypeArgumentCustomModifiers(i) : default(ImmutableArray <CustomModifier>)),
ref substitution,
untouchables))
{
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(new TypeWithModifiers(nt1.ContainingType), new TypeWithModifiers(nt2.ContainingType), ref substitution, untouchables));
}
case SymbolKind.TypeParameter:
{
// These substitutions are not allowed in C#
if (t2.Type.TypeKind == TypeKind.Pointer || t2.Type.SpecialType == SpecialType.System_Void)
{
return(false);
}
TypeParameterSymbol tp1 = (TypeParameterSymbol)t1.Type;
// 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.Type, tp1))
{
return(false);
}
// @MattWindsor91 (Concept-C# 2017)
// Quickfix to make sure that, when there are two TPs
// to be unified, and both are associated, we
//var isAssocFlowingInwards =
// t2.Type.IsTypeParameter()
// && ((TypeParameterSymbol)t2.Type).IsAssociatedType
// && tp1.IsAssociatedType;
if (!untouchables.Contains(tp1)) // && !isAssocFlowingInwards)
{
if (t1.CustomModifiers.IsDefaultOrEmpty)
{
AddSubstitution(ref substitution, tp1, t2);
return(true);
}
if (t1.CustomModifiers.SequenceEqual(t2.CustomModifiers))
{
AddSubstitution(ref substitution, tp1, new TypeWithModifiers(t2.Type));
return(true);
}
if (t1.CustomModifiers.Length < t2.CustomModifiers.Length &&
t1.CustomModifiers.SequenceEqual(t2.CustomModifiers.Take(t1.CustomModifiers.Length)))
{
AddSubstitution(ref substitution, tp1,
new TypeWithModifiers(t2.Type,
ImmutableArray.Create(t2.CustomModifiers, t1.CustomModifiers.Length, t2.CustomModifiers.Length - t1.CustomModifiers.Length)));
return(true);
}
}
if (t2.Type.IsTypeParameter())
{
var tp2 = (TypeParameterSymbol)t2.Type;
if (!untouchables.Contains(tp2))
{
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,
new TypeWithModifiers(t1.Type,
ImmutableArray.Create(t1.CustomModifiers, t2.CustomModifiers.Length, t1.CustomModifiers.Length - t2.CustomModifiers.Length)));
return(true);
}
}
}
return(false);
}
default:
{
return(t1 == t2);
}
}
}
private PointerTypeSymbol SubstitutePointerType(PointerTypeSymbol t)
{
var oldPointedAtType = new TypeWithModifiers(t.PointedAtType, t.CustomModifiers);
TypeWithModifiers pointedAtType = oldPointedAtType.SubstituteType(this);
if (pointedAtType == oldPointedAtType)
{
return t;
}
return new PointerTypeSymbol(pointedAtType.Type, pointedAtType.CustomModifiers);
}
private TypeSymbol SubstituteNonNullableType(NonNullableReferenceTypeSymbol t)
{
var oldUnderlyingType = new TypeWithModifiers(t.UnderlyingType);
TypeWithModifiers underlyingType = oldUnderlyingType.SubstituteType(this);
if (underlyingType == oldUnderlyingType)
{
return t;
}
if (underlyingType.Type.IsValueType)
return underlyingType.Type;
return underlyingType.Type as NonNullableReferenceTypeSymbol ?? NonNullableReferenceTypeSymbol.CreateNonNullableReference(underlyingType.Type);
}
