private bool bindImplicitConversionFromTypeVar(TypeParameterType tyVarSrc)
{
// 13.1.4
//
// For a type-parameter T that is known to be a reference type (25.7), the following implicit
// reference conversions exist:
//
// * From T to its effective base class C, from T to any base class of C, and from T to any
// interface implemented by C.
// * From T to an interface-type I in T's effective interface set and from T to any base
// interface of I.
// * From T to a type parameter U 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.]
// * From the null type (11.2.7) to T.
//
// 13.1.5
//
// For a type-parameter T that is not known to be a reference type (25.7), the following conversions
// involving T are considered to be boxing conversions at compile-time. At run-time, if T is a value
// type, the conversion is executed as a boxing conversion. At run-time, if T is a reference type,
// the conversion is executed as an implicit reference conversion or identity conversion.
//
// * From T to its effective base class C, from T to any base class of C, and from T to any
// interface implemented by C. [Note: C will be one of the types System.Object, System.ValueType,
// or System.Enum (otherwise T would be known to be a reference type and 13.1.4 would apply
// instead of this clause).]
// * From T to an interface-type I in T's effective interface set and from T to any base
// interface of I.
//
// 13.1.6 Implicit type parameter conversions
//
// This clause details implicit conversions involving type parameters that are not classified as
// implicit reference conversions or implicit boxing conversions.
//
// For a type-parameter T that is not known to be a reference type, there is an implicit conversion
// from T to a type parameter U provided T depends on U. At run-time, if T is a value type and U is
// a reference type, the conversion is executed as a boxing conversion. At run-time, if both T and U
// are value types, then T and U are necessarily the same type and no conversion is performed. At
// run-time, if T is a reference type, then U is necessarily also a reference type and the conversion
// is executed as an implicit reference conversion or identity conversion (25.7).
CType typeTmp = tyVarSrc.GetEffectiveBaseClass();
TypeArray bnds = tyVarSrc.GetBounds();
int itype = -1;
for (; ;)
{
if (binder.canConvert(typeTmp, typeDest, flags | CONVERTTYPE.NOUDC))
{
if (!needsExprDest)
{
return(true);
}
if (typeDest.IsTypeParameterType())
{
// For a type var destination we need to cast to object then to the other type var.
EXPR exprT;
EXPRCLASS exprObj = GetExprFactory().MakeClass(binder.GetReqPDT(PredefinedType.PT_OBJECT));
binder.bindSimpleCast(exprSrc, exprObj, out exprT, EXPRFLAG.EXF_FORCE_BOX);
binder.bindSimpleCast(exprT, exprTypeDest, out exprDest, EXPRFLAG.EXF_FORCE_UNBOX);
}
else
{
binder.bindSimpleCast(exprSrc, exprTypeDest, out exprDest, EXPRFLAG.EXF_FORCE_BOX);
}
return(true);
}
do
{
if (++itype >= bnds.Size)
{
return(false);
}
typeTmp = bnds.Item(itype);
}while (!typeTmp.isInterfaceType() && !typeTmp.IsTypeParameterType());
}
}
private static bool CheckSingleConstraint(CSemanticChecker checker, ErrorHandling errHandling, Symbol symErr, TypeParameterType var, CType arg, TypeArray typeArgsCls, TypeArray typeArgsMeth, CheckConstraintsFlags flags)
{
bool fReportErrors = 0 == (flags & CheckConstraintsFlags.NoErrors);
if (arg.IsOpenTypePlaceholderType())
{
return true;
}
if (arg.IsErrorType())
{
// Error should have been reported previously.
return false;
}
if (checker.CheckBogus(arg))
{
if (fReportErrors)
{
errHandling.ErrorRef(ErrorCode.ERR_BogusType, arg);
}
return false;
}
if (arg.IsPointerType() || arg.isSpecialByRefType())
{
if (fReportErrors)
{
errHandling.Error(ErrorCode.ERR_BadTypeArgument, arg);
}
return false;
}
if (arg.isStaticClass())
{
if (fReportErrors)
{
checker.ReportStaticClassError(null, arg, ErrorCode.ERR_GenericArgIsStaticClass);
}
return false;
}
bool fError = false;
if (var.HasRefConstraint() && !arg.IsRefType())
{
if (fReportErrors)
{
errHandling.ErrorRef(ErrorCode.ERR_RefConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
}
fError = true;
}
TypeArray bnds = checker.GetSymbolLoader().GetTypeManager().SubstTypeArray(var.GetBounds(), typeArgsCls, typeArgsMeth);
int itypeMin = 0;
if (var.HasValConstraint())
{
// If we have a type variable that is constrained to a value type, then we
// want to check if its a nullable type, so that we can report the
// constraint error below. In order to do this however, we need to check
// that either the type arg is not a value type, or it is a nullable type.
//
// To check whether or not its a nullable type, we need to get the resolved
// bound from the type argument and check against that.
bool bIsValueType = arg.IsValType();
bool bIsNullable = arg.IsNullableType();
if (bIsValueType && arg.IsTypeParameterType())
{
TypeArray pArgBnds = arg.AsTypeParameterType().GetBounds();
if (pArgBnds.size > 0)
{
bIsNullable = pArgBnds.Item(0).IsNullableType();
}
}
if (!bIsValueType || bIsNullable)
{
if (fReportErrors)
{
errHandling.ErrorRef(ErrorCode.ERR_ValConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
}
fError = true;
}
// Since FValCon() is set it is redundant to check System.ValueType as well.
if (bnds.size != 0 && bnds.Item(0).isPredefType(PredefinedType.PT_VALUE))
{
itypeMin = 1;
}
}
for (int j = itypeMin; j < bnds.size; j++)
{
CType typeBnd = bnds.Item(j);
if (!SatisfiesBound(checker, arg, typeBnd))
{
if (fReportErrors)
{
// The bound isn't satisfied because of a constaint type. Explain to the user why not.
// There are 4 main cases, based on the type of the supplied type argument:
// - reference type, or type parameter known to be a reference type
// - nullable type, from which there is a boxing conversion to the constraint type(see below for details)
// - type varaiable
// - value type
// These cases are broken out because: a) The sets of conversions which can be used
// for constraint satisfaction is different based on the type argument supplied,
// and b) Nullable is one funky type, and user's can use all the help they can get
// when using it.
ErrorCode error;
if (arg.IsRefType())
{
// A reference type can only satisfy bounds to types
// to which they have an implicit reference conversion
error = ErrorCode.ERR_GenericConstraintNotSatisfiedRefType;
}
else if (arg.IsNullableType() && checker.GetSymbolLoader().HasBaseConversion(arg.AsNullableType().GetUnderlyingType(), typeBnd)) // This is inlining FBoxingConv
{
// nullable types do not satisfy bounds to every type that they are boxable to
// They only satisfy bounds of object and ValueType
if (typeBnd.isPredefType(PredefinedType.PT_ENUM) || arg.AsNullableType().GetUnderlyingType() == typeBnd)
{
// Nullable types don't satisfy bounds of EnumType, or the underlying type of the enum
// even though the conversion from Nullable to these types is a boxing conversion
// This is a rare case, because these bounds can never be directly stated ...
// These bounds can only occur when one type paramter is constrained to a second type parameter
// and the second type parameter is instantiated with Enum or the underlying type of the first type
// parameter
error = ErrorCode.ERR_GenericConstraintNotSatisfiedNullableEnum;
}
else
{
// Nullable types don't satisfy the bounds of any interface type
// even when there is a boxing conversion from the Nullable type to
// the interface type. This will be a relatively common scenario
// so we cal it out separately from the previous case.
Debug.Assert(typeBnd.isInterfaceType());
error = ErrorCode.ERR_GenericConstraintNotSatisfiedNullableInterface;
}
}
else if (arg.IsTypeParameterType())
{
// Type variables can satisfy bounds through boxing and type variable conversions
Debug.Assert(!arg.IsRefType());
error = ErrorCode.ERR_GenericConstraintNotSatisfiedTyVar;
}
else
{
// Value types can only satisfy bounds through boxing conversions.
// Note that the exceptional case of Nullable types and boxing is handled above.
error = ErrorCode.ERR_GenericConstraintNotSatisfiedValType;
}
errHandling.Error(error, new ErrArgRef(symErr), new ErrArg(typeBnd, ErrArgFlags.Unique), var, new ErrArgRef(arg, ErrArgFlags.Unique));
}
fError = true;
}
}
// Check the newable constraint.
if (!var.HasNewConstraint() || arg.IsValType())
{
return !fError;
}
if (arg.isClassType())
{
AggregateSymbol agg = arg.AsAggregateType().getAggregate();
// Due to late binding nature of IDE created symbols, the AggregateSymbol might not
// have all the information necessary yet, if it is not fully bound.
// by calling LookupAggMember, it will ensure that we will update all the
// information necessary at least for the given method.
checker.GetSymbolLoader().LookupAggMember(checker.GetNameManager().GetPredefName(PredefinedName.PN_CTOR), agg, symbmask_t.MASK_ALL);
if (agg.HasPubNoArgCtor() && !agg.IsAbstract())
{
return !fError;
}
}
else if (arg.IsTypeParameterType() && arg.AsTypeParameterType().HasNewConstraint())
{
return !fError;
}
if (fReportErrors)
{
errHandling.ErrorRef(ErrorCode.ERR_NewConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
}
return false;
}
private static bool CheckSingleConstraint(CSemanticChecker checker, ErrorHandling errHandling, Symbol symErr, TypeParameterType var, CType arg, TypeArray typeArgsCls, TypeArray typeArgsMeth, CheckConstraintsFlags flags)
{
bool fReportErrors = 0 == (flags & CheckConstraintsFlags.NoErrors);
if (arg is OpenTypePlaceholderType)
{
return(true);
}
if (arg is ErrorType)
{
// Error should have been reported previously.
return(false);
}
if (checker.CheckBogus(arg))
{
if (fReportErrors)
{
errHandling.ErrorRef(ErrorCode.ERR_BogusType, arg);
}
return(false);
}
if (arg is PointerType)
{
if (fReportErrors)
{
errHandling.Error(ErrorCode.ERR_BadTypeArgument, arg);
}
return(false);
}
if (arg.isStaticClass())
{
if (fReportErrors)
{
checker.ReportStaticClassError(null, arg, ErrorCode.ERR_GenericArgIsStaticClass);
}
return(false);
}
bool fError = false;
if (var.HasRefConstraint() && !arg.IsRefType())
{
if (fReportErrors)
{
errHandling.ErrorRef(ErrorCode.ERR_RefConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
}
fError = true;
}
TypeArray bnds = checker.GetSymbolLoader().GetTypeManager().SubstTypeArray(var.GetBounds(), typeArgsCls, typeArgsMeth);
int itypeMin = 0;
if (var.HasValConstraint())
{
// If we have a type variable that is constrained to a value type, then we
// want to check if its a nullable type, so that we can report the
// constraint error below. In order to do this however, we need to check
// that either the type arg is not a value type, or it is a nullable type.
//
// To check whether or not its a nullable type, we need to get the resolved
// bound from the type argument and check against that.
bool bIsValueType = arg.IsValType();
bool bIsNullable = arg is NullableType;
if (bIsValueType && arg is TypeParameterType typeArg)
{
TypeArray pArgBnds = typeArg.GetBounds();
if (pArgBnds.Count > 0)
{
bIsNullable = pArgBnds[0] is NullableType;
}
}
if (!bIsValueType || bIsNullable)
{
if (fReportErrors)
{
errHandling.ErrorRef(ErrorCode.ERR_ValConstraintNotSatisfied, symErr, new ErrArgNoRef(var), arg);
}
fError = true;
}
// Since FValCon() is set it is redundant to check System.ValueType as well.
if (bnds.Count != 0 && bnds[0].isPredefType(PredefinedType.PT_VALUE))
{
itypeMin = 1;
}
}
for (int j = itypeMin; j < bnds.Count; j++)
{
CType typeBnd = bnds[j];
if (!SatisfiesBound(checker, arg, typeBnd))
{
if (fReportErrors)
{
// The bound isn't satisfied because of a constraint type. Explain to the user why not.
// There are 4 main cases, based on the type of the supplied type argument:
// - reference type, or type parameter known to be a reference type
// - nullable type, from which there is a boxing conversion to the constraint type(see below for details)
// - type variable
// - value type
// These cases are broken out because: a) The sets of conversions which can be used
// for constraint satisfaction is different based on the type argument supplied,
// and b) Nullable is one funky type, and user's can use all the help they can get
// when using it.
ErrorCode error;
if (arg.IsRefType())
{
// A reference type can only satisfy bounds to types
// to which they have an implicit reference conversion
error = ErrorCode.ERR_GenericConstraintNotSatisfiedRefType;
}
else if (arg is NullableType nubArg && checker.GetSymbolLoader().HasBaseConversion(nubArg.GetUnderlyingType(), typeBnd)) // This is inlining FBoxingConv
{
// nullable types do not satisfy bounds to every type that they are boxable to
// They only satisfy bounds of object and ValueType
if (typeBnd.isPredefType(PredefinedType.PT_ENUM) || nubArg.GetUnderlyingType() == typeBnd)
{
// Nullable types don't satisfy bounds of EnumType, or the underlying type of the enum
// even though the conversion from Nullable to these types is a boxing conversion
// This is a rare case, because these bounds can never be directly stated ...
// These bounds can only occur when one type paramter is constrained to a second type parameter
// and the second type parameter is instantiated with Enum or the underlying type of the first type
// parameter
error = ErrorCode.ERR_GenericConstraintNotSatisfiedNullableEnum;
}
else
{
// Nullable types don't satisfy the bounds of any interface type
// even when there is a boxing conversion from the Nullable type to
// the interface type. This will be a relatively common scenario
// so we cal it out separately from the previous case.
Debug.Assert(typeBnd.isInterfaceType());
error = ErrorCode.ERR_GenericConstraintNotSatisfiedNullableInterface;
}
}
else if (arg is TypeParameterType)
{
// Type variables can satisfy bounds through boxing and type variable conversions
Debug.Assert(!arg.IsRefType());
error = ErrorCode.ERR_GenericConstraintNotSatisfiedTyVar;
}
else
{
// Value types can only satisfy bounds through boxing conversions.
// Note that the exceptional case of Nullable types and boxing is handled above.
error = ErrorCode.ERR_GenericConstraintNotSatisfiedValType;
}
errHandling.Error(error, new ErrArgRef(symErr), new ErrArg(typeBnd, ErrArgFlags.Unique), var, new ErrArgRef(arg, ErrArgFlags.Unique));
}
fError = true;
}
}
private bool bindImplicitConversionFromTypeVar(TypeParameterType tyVarSrc)
{
// 13.1.4
//
// For a type-parameter T that is known to be a reference type (25.7), the following implicit
// reference conversions exist:
//
// * From T to its effective base class C, from T to any base class of C, and from T to any
// interface implemented by C.
// * From T to an interface-type I in T's effective interface set and from T to any base
// interface of I.
// * From T to a type parameter U 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.]
// * From the null type (11.2.7) to T.
//
// 13.1.5
//
// For a type-parameter T that is not known to be a reference type (25.7), the following conversions
// involving T are considered to be boxing conversions at compile-time. At run-time, if T is a value
// type, the conversion is executed as a boxing conversion. At run-time, if T is a reference type,
// the conversion is executed as an implicit reference conversion or identity conversion.
//
// * From T to its effective base class C, from T to any base class of C, and from T to any
// interface implemented by C. [Note: C will be one of the types System.Object, System.ValueType,
// or System.Enum (otherwise T would be known to be a reference type and 13.1.4 would apply
// instead of this clause).]
// * From T to an interface-type I in T's effective interface set and from T to any base
// interface of I.
//
// 13.1.6 Implicit type parameter conversions
//
// This clause details implicit conversions involving type parameters that are not classified as
// implicit reference conversions or implicit boxing conversions.
//
// For a type-parameter T that is not known to be a reference type, there is an implicit conversion
// from T to a type parameter U provided T depends on U. At run-time, if T is a value type and U is
// a reference type, the conversion is executed as a boxing conversion. At run-time, if both T and U
// are value types, then T and U are necessarily the same type and no conversion is performed. At
// run-time, if T is a reference type, then U is necessarily also a reference type and the conversion
// is executed as an implicit reference conversion or identity conversion (25.7).
CType typeTmp = tyVarSrc.GetEffectiveBaseClass();
TypeArray bnds = tyVarSrc.GetBounds();
int itype = -1;
for (; ;)
{
if (_binder.canConvert(typeTmp, _typeDest, _flags | CONVERTTYPE.NOUDC))
{
if (!_needsExprDest)
{
return true;
}
if (_typeDest.IsTypeParameterType())
{
// For a type var destination we need to cast to object then to the other type var.
EXPR exprT;
EXPRCLASS exprObj = GetExprFactory().MakeClass(_binder.GetReqPDT(PredefinedType.PT_OBJECT));
_binder.bindSimpleCast(_exprSrc, exprObj, out exprT, EXPRFLAG.EXF_FORCE_BOX);
_binder.bindSimpleCast(exprT, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_FORCE_UNBOX);
}
else
{
_binder.bindSimpleCast(_exprSrc, _exprTypeDest, out _exprDest, EXPRFLAG.EXF_FORCE_BOX);
}
return true;
}
do
{
if (++itype >= bnds.Size)
{
return false;
}
typeTmp = bnds.Item(itype);
}
while (!typeTmp.isInterfaceType() && !typeTmp.IsTypeParameterType());
}
}