private AggCastResult bindExplicitConversionBetweenAggregates(AggregateType aggTypeDest)
{
// 13.2.3
//
// The explicit reference conversions are:
//
// * From object to any reference-type.
// * From any class-type S to any class-type T, provided S is a base class of T.
// * From any class-type S to any interface-type T, provided S is not sealed and
// provided S does not implement T.
// * From any interface-type S to any class-type T, provided T is not sealed or provided
// T implements S.
// * From any interface-type S to any interface-type T, provided S is not derived from T.
Debug.Assert(_typeSrc != null);
Debug.Assert(aggTypeDest != null);
if (!(_typeSrc is AggregateType atSrc))
{
return(AggCastResult.Failure);
}
AggregateSymbol aggSrc = atSrc.getAggregate();
AggregateSymbol aggDest = aggTypeDest.getAggregate();
if (GetSymbolLoader().HasBaseConversion(aggTypeDest, atSrc))
{
if (_needsExprDest)
{
if (aggDest.IsValueType() && aggSrc.getThisType().fundType() == FUNDTYPE.FT_REF)
{
_binder.bindSimpleCast(_exprSrc, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_UNBOX);
}
else
{
_binder.bindSimpleCast(_exprSrc, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_REFCHECK | (_exprSrc?.Flags & EXPRFLAG.EXF_CANTBENULL ?? 0));
}
}
return(AggCastResult.Success);
}
if ((aggSrc.IsClass() && !aggSrc.IsSealed() && aggDest.IsInterface()) ||
(aggSrc.IsInterface() && aggDest.IsClass() && !aggDest.IsSealed()) ||
(aggSrc.IsInterface() && aggDest.IsInterface()) ||
CConversions.HasGenericDelegateExplicitReferenceConversion(GetSymbolLoader(), _typeSrc, aggTypeDest))
{
if (_needsExprDest)
{
_binder.bindSimpleCast(_exprSrc, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_REFCHECK | (_exprSrc?.Flags & EXPRFLAG.EXF_CANTBENULL ?? 0));
}
return(AggCastResult.Success);
}
return(AggCastResult.Failure);
}
/***************************************************************************************************
* Determine whether there is an explicit or implicit reference conversion (or identity conversion)
* from typeSrc to typeDst. This is when:
*
* 13.2.3 Explicit reference conversions
*
* The explicit reference conversions are:
* From object to any reference-type.
* From any class-type S to any class-type T, provided S is a base class of T.
* From any class-type S to any interface-type T, provided S is not sealed and provided S does not implement T.
* From any interface-type S to any class-type T, provided T is not sealed or provided T implements S.
* From any interface-type S to any interface-type T, provided S is not derived from T.
* From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
* o S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
* o An explicit reference conversion exists from SE to TE.
* From System.Array and the interfaces it implements, to any array-type.
* From System.Delegate and the interfaces it implements, to any delegate-type.
* From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces, provided there is an explicit reference conversion from S to T.
* From a generic delegate type S to generic delegate type T, provided all of the follow are true:
* o Both types are constructed generic types of the same generic delegate type, D<X1,... Xk>.That is,
* S is D<S1,... Sk> and T is D<T1,... Tk>.
* o S is not compatible with or identical to T.
* o If type parameter Xi is declared to be invariant then Si must be identical to Ti.
* o If type parameter Xi is declared to be covariant ("out") then Si must be convertible
* to Ti via an identify conversion, implicit reference conversion, or explicit reference conversion.
* o If type parameter Xi is declared to be contravariant ("in") then either Si must be identical to Ti,
* or Si and Ti must both be reference types.
* From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T are the same type or there is an implicit or explicit reference conversion from S to T.
*
* For a type-parameter T that is known to be a reference type (25.7), the following explicit reference conversions exist:
* From the effective base class C of T to T and from any base class of C to T.
* From any interface-type to T.
* From T to any interface-type I provided there isn't already an implicit reference conversion from T to I.
* From a type-parameter U to T provided that T depends on U (25.7). [Note: Since T is known to be a reference type, within the scope of T, the run-time type of U will always be a reference type, even if U is not known to be a reference type at compile-time. end note]
*
* Both src and dst are reference types and there is a builtin explicit conversion from
* src to dst.
* Or src is a reference type and dst is a base type of src (in which case the conversion is
* implicit as well).
* Or dst is a reference type and src is a base type of dst.
*
* The latter two cases can happen with type variables even though the other type variable is not
* a reference type.
***************************************************************************************************/
public static bool FExpRefConv(CType typeSrc, CType typeDst)
{
Debug.Assert(typeSrc != null);
Debug.Assert(typeDst != null);
if (typeSrc.IsReferenceType && typeDst.IsReferenceType)
{
// is there an implicit reference conversion in either direction?
// this handles the bulk of the cases ...
if (SymbolLoader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst) ||
SymbolLoader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc))
{
return(true);
}
// For a type-parameter T that is known to be a reference type (25.7), the following explicit reference conversions exist:
// * From any interface-type to T.
// * From T to any interface-type I provided there isn't already an implicit reference conversion from T to I.
if (typeSrc.IsInterfaceType && typeDst is TypeParameterType || typeSrc is TypeParameterType && typeDst.IsInterfaceType)
{
return(true);
}
// * From any class-type S to any interface-type T, provided S is not sealed
// * From any interface-type S to any class-type T, provided T is not sealed
// * From any interface-type S to any interface-type T, provided S is not derived from T.
if (typeSrc is AggregateType atSrc && typeDst is AggregateType atDst)
{
AggregateSymbol aggSrc = atSrc.OwningAggregate;
AggregateSymbol aggDest = atDst.OwningAggregate;
if ((aggSrc.IsClass() && !aggSrc.IsSealed() && aggDest.IsInterface()) ||
(aggSrc.IsInterface() && aggDest.IsClass() && !aggDest.IsSealed()) ||
(aggSrc.IsInterface() && aggDest.IsInterface()))
{
return(true);
}
}
if (typeSrc is ArrayType arrSrc)
{
// * From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
// o S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
// o An explicit reference conversion exists from SE to TE.
if (typeDst is ArrayType arrDst)
{
return(arrSrc.Rank == arrDst.Rank &&
arrSrc.IsSZArray == arrDst.IsSZArray &&
FExpRefConv(arrSrc.ElementType, arrDst.ElementType));
}
// * From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T>
// and their base interfaces, provided there is an explicit reference conversion from S to T.
if (!arrSrc.IsSZArray || !typeDst.IsInterfaceType)
{
return(false);
}
AggregateType aggDst = (AggregateType)typeDst;
TypeArray typeArgsAll = aggDst.TypeArgsAll;
if (typeArgsAll.Count != 1)
{
return(false);
}
AggregateSymbol aggIList = SymbolLoader.GetPredefAgg(PredefinedType.PT_G_ILIST);
AggregateSymbol aggIReadOnlyList = SymbolLoader.GetPredefAgg(PredefinedType.PT_G_IREADONLYLIST);
if ((aggIList == null ||
!SymbolLoader.IsBaseAggregate(aggIList, aggDst.OwningAggregate)) &&
(aggIReadOnlyList == null ||
!SymbolLoader.IsBaseAggregate(aggIReadOnlyList, aggDst.OwningAggregate)))
{
return(false);
}
return(FExpRefConv(arrSrc.ElementType, typeArgsAll[0]));
}
if (typeDst is ArrayType arrayDest && typeSrc is AggregateType aggtypeSrc)
{
// * From System.Array and the interfaces it implements, to any array-type.
if (SymbolLoader.HasIdentityOrImplicitReferenceConversion(SymbolLoader.GetPredefindType(PredefinedType.PT_ARRAY), typeSrc))
{
return(true);
}
// * From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a
// one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to
// System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T
// are the same type or there is an implicit or explicit reference conversion from S to T.
if (!arrayDest.IsSZArray || !typeSrc.IsInterfaceType || aggtypeSrc.TypeArgsAll.Count != 1)
{
return(false);
}
AggregateSymbol aggIList = SymbolLoader.GetPredefAgg(PredefinedType.PT_G_ILIST);
AggregateSymbol aggIReadOnlyList = SymbolLoader.GetPredefAgg(PredefinedType.PT_G_IREADONLYLIST);
if ((aggIList == null ||
!SymbolLoader.IsBaseAggregate(aggIList, aggtypeSrc.OwningAggregate)) &&
(aggIReadOnlyList == null ||
!SymbolLoader.IsBaseAggregate(aggIReadOnlyList, aggtypeSrc.OwningAggregate)))
{
return(false);
}
CType typeArr = arrayDest.ElementType;
CType typeLst = aggtypeSrc.TypeArgsAll[0];
Debug.Assert(!(typeArr is MethodGroupType));
return(typeArr == typeLst || FExpRefConv(typeArr, typeLst));
}
if (HasGenericDelegateExplicitReferenceConversion(typeSrc, typeDst))
{
return(true);
}
}
else if (typeSrc.IsReferenceType)
{
// conversion of T . U, where T : class, U
// .. these constraints implies where U : class
return(SymbolLoader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst));
}
else if (typeDst.IsReferenceType)
{
// conversion of T . U, where U : class, T
// .. these constraints implies where T : class
return(SymbolLoader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc));
}
return(false);
}
/***************************************************************************************************
* Determine whether there is an explicit or implicit reference conversion (or identity conversion)
* from typeSrc to typeDst. This is when:
*
* 13.2.3 Explicit reference conversions
*
* The explicit reference conversions are:
* From object to any reference-type.
* From any class-type S to any class-type T, provided S is a base class of T.
* From any class-type S to any interface-type T, provided S is not sealed and provided S does not implement T.
* From any interface-type S to any class-type T, provided T is not sealed or provided T implements S.
* From any interface-type S to any interface-type T, provided S is not derived from T.
* From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
* o S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
* o An explicit reference conversion exists from SE to TE.
* From System.Array and the interfaces it implements, to any array-type.
* From System.Delegate and the interfaces it implements, to any delegate-type.
* From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces, provided there is an explicit reference conversion from S to T.
* From a generic delegate type S to generic delegate type T, provided all of the follow are true:
* o Both types are constructed generic types of the same generic delegate type, D<X1,... Xk>.That is,
* S is D<S1,... Sk> and T is D<T1,... Tk>.
* o S is not compatible with or identical to T.
* o If type parameter Xi is declared to be invariant then Si must be identical to Ti.
* o If type parameter Xi is declared to be covariant ("out") then Si must be convertible
* to Ti via an identify conversion, implicit reference conversion, or explicit reference conversion.
* o If type parameter Xi is declared to be contravariant ("in") then either Si must be identical to Ti,
* or Si and Ti must both be reference types.
* From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T are the same type or there is an implicit or explicit reference conversion from S to T.
*
* For a type-parameter T that is known to be a reference type (§25.7), the following explicit reference conversions exist:
* From the effective base class C of T to T and from any base class of C to T.
* From any interface-type to T.
* From T to any interface-type I provided there isn’t already an implicit reference conversion from T to I.
* From a type-parameter U to T provided that T depends on U (§25.7). [Note: Since T is known to be a reference type, within the scope of T, the run-time type of U will always be a reference type, even if U is not known to be a reference type at compile-time. end note]
*
* Both src and dst are reference types and there is a builtin explicit conversion from
* src to dst.
* Or src is a reference type and dst is a base type of src (in which case the conversion is
* implicit as well).
* Or dst is a reference type and src is a base type of dst.
*
* The latter two cases can happen with type variables even though the other type variable is not
* a reference type.
***************************************************************************************************/
public static bool FExpRefConv(SymbolLoader loader, CType typeSrc, CType typeDst)
{
Debug.Assert(typeSrc != null);
Debug.Assert(typeDst != null);
if (typeSrc.IsRefType() && typeDst.IsRefType())
{
// is there an implicit reference conversion in either direction?
// this handles the bulk of the cases ...
if (loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst) ||
loader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc))
{
return(true);
}
// For a type-parameter T that is known to be a reference type (§25.7), the following explicit reference conversions exist:
// • From any interface-type to T.
// • From T to any interface-type I provided there isn’t already an implicit reference conversion from T to I.
if (typeSrc.isInterfaceType() && typeDst.IsTypeParameterType())
{
return(true);
}
if (typeSrc.IsTypeParameterType() && typeDst.isInterfaceType())
{
return(true);
}
// * From any class-type S to any interface-type T, provided S is not sealed
// * From any interface-type S to any class-type T, provided T is not sealed
// * From any interface-type S to any interface-type T, provided S is not derived from T.
if (typeSrc.IsAggregateType() && typeDst.IsAggregateType())
{
AggregateSymbol aggSrc = typeSrc.AsAggregateType().getAggregate();
AggregateSymbol aggDest = typeDst.AsAggregateType().getAggregate();
if ((aggSrc.IsClass() && !aggSrc.IsSealed() && aggDest.IsInterface()) ||
(aggSrc.IsInterface() && aggDest.IsClass() && !aggDest.IsSealed()) ||
(aggSrc.IsInterface() && aggDest.IsInterface()))
{
return(true);
}
}
// * From an array-type S with an element type SE to an array-type T with an element type TE, provided all of the following are true:
// o S and T differ only in element type. (In other words, S and T have the same number of dimensions.)
// o An explicit reference conversion exists from SE to TE.
if (typeSrc.IsArrayType() && typeDst.IsArrayType())
{
return(typeSrc.AsArrayType().rank == typeDst.AsArrayType().rank&& FExpRefConv(loader, typeSrc.AsArrayType().GetElementType(), typeDst.AsArrayType().GetElementType()));
}
// * From a one-dimensional array-type S[] to System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T>
// and their base interfaces, provided there is an explicit reference conversion from S to T.
if (typeSrc.IsArrayType())
{
if (typeSrc.AsArrayType().rank != 1 ||
!typeDst.isInterfaceType() || typeDst.AsAggregateType().GetTypeArgsAll().Size != 1)
{
return(false);
}
AggregateSymbol aggIList = loader.GetOptPredefAgg(PredefinedType.PT_G_ILIST);
AggregateSymbol aggIReadOnlyList = loader.GetOptPredefAgg(PredefinedType.PT_G_IREADONLYLIST);
if ((aggIList == null ||
!loader.IsBaseAggregate(aggIList, typeDst.AsAggregateType().getAggregate())) &&
(aggIReadOnlyList == null ||
!loader.IsBaseAggregate(aggIReadOnlyList, typeDst.AsAggregateType().getAggregate())))
{
return(false);
}
return(FExpRefConv(loader, typeSrc.AsArrayType().GetElementType(), typeDst.AsAggregateType().GetTypeArgsAll().Item(0)));
}
if (typeDst.IsArrayType() && typeSrc.IsAggregateType())
{
// * From System.Array and the interfaces it implements, to any array-type.
if (loader.HasIdentityOrImplicitReferenceConversion(loader.GetReqPredefType(PredefinedType.PT_ARRAY), typeSrc))
{
return(true);
}
// * From System.Collections.Generic.IList<T>, System.Collections.Generic.IReadOnlyList<T> and their base interfaces to a
// one-dimensional array-type S[], provided there is an implicit or explicit reference conversion from S[] to
// System.Collections.Generic.IList<T> or System.Collections.Generic.IReadOnlyList<T>. This is precisely when either S and T
// are the same type or there is an implicit or explicit reference conversion from S to T.
ArrayType arrayDest = typeDst.AsArrayType();
AggregateType aggtypeSrc = typeSrc.AsAggregateType();
if (arrayDest.rank != 1 || !typeSrc.isInterfaceType() ||
aggtypeSrc.GetTypeArgsAll().Size != 1)
{
return(false);
}
AggregateSymbol aggIList = loader.GetOptPredefAgg(PredefinedType.PT_G_ILIST);
AggregateSymbol aggIReadOnlyList = loader.GetOptPredefAgg(PredefinedType.PT_G_IREADONLYLIST);
if ((aggIList == null ||
!loader.IsBaseAggregate(aggIList, aggtypeSrc.getAggregate())) &&
(aggIReadOnlyList == null ||
!loader.IsBaseAggregate(aggIReadOnlyList, aggtypeSrc.getAggregate())))
{
return(false);
}
CType typeArr = arrayDest.GetElementType();
CType typeLst = aggtypeSrc.GetTypeArgsAll().Item(0);
Debug.Assert(!typeArr.IsNeverSameType());
return(typeArr == typeLst || FExpRefConv(loader, typeArr, typeLst));
}
if (HasGenericDelegateExplicitReferenceConversion(loader, typeSrc, typeDst))
{
return(true);
}
}
else if (typeSrc.IsRefType())
{
// conversion of T . U, where T : class, U
// .. these constraints implies where U : class
return(loader.HasIdentityOrImplicitReferenceConversion(typeSrc, typeDst));
}
else if (typeDst.IsRefType())
{
// conversion of T . U, where U : class, T
// .. these constraints implies where T : class
return(loader.HasIdentityOrImplicitReferenceConversion(typeDst, typeSrc));
}
return(false);
}