public bool HasImplicitBoxingConversion(CType pSource, CType pDest)
{
Debug.Assert(pSource != null);
Debug.Assert(pDest != null);
// Certain type parameter conversions are classified as boxing conversions.
if (pSource.IsTypeParameterType() &&
HasImplicitBoxingTypeParameterConversion(pSource.AsTypeParameterType(), pDest))
{
return(true);
}
// The rest of the boxing conversions only operate when going from a value type
// to a reference type.
if (!pSource.IsValType() || !pDest.IsRefType())
{
return(false);
}
// A boxing conversion exists from a nullable type to a reference type
// if and only if a boxing conversion exists from the underlying type.
if (pSource.IsNullableType())
{
return(HasImplicitBoxingConversion(pSource.AsNullableType().GetUnderlyingType(), pDest));
}
// A boxing conversion exists from any non-nullable value type to object,
// to System.ValueType, and to any interface type implemented by the
// non-nullable value type. Furthermore, an enum type can be converted
// to the type System.Enum.
// We set the base class of the structs to System.ValueType, System.Enum, etc,
// so we can just check here.
if (IsBaseClass(pSource, pDest))
{
return(true);
}
if (HasAnyBaseInterfaceConversion(pSource, pDest))
{
return(true);
}
return(false);
}
private bool bindExplicitConversionFromNub()
{
Debug.Assert(_typeSrc != null);
Debug.Assert(_typeDest != null);
// If S and T are value types and there is a builtin conversion from S => T then there is an
// explicit conversion from S? => T that throws on null.
if (_typeDest.IsValType() && _binder.BindExplicitConversion(null, _typeSrc.StripNubs(), _exprTypeDest, _pDestinationTypeForLambdaErrorReporting, _flags | CONVERTTYPE.NOUDC))
{
if (_needsExprDest)
{
Expr valueSrc = _exprSrc;
// This is a holdover from the days when you could have nullable of nullable.
// Can we remove this loop?
while (valueSrc.Type is NullableType)
{
valueSrc = _binder.BindNubValue(valueSrc);
}
Debug.Assert(valueSrc.Type == _typeSrc.StripNubs());
if (!_binder.BindExplicitConversion(valueSrc, valueSrc.Type, _exprTypeDest, _pDestinationTypeForLambdaErrorReporting, _needsExprDest, out _exprDest, _flags | CONVERTTYPE.NOUDC))
{
VSFAIL("BindExplicitConversion failed unexpectedly");
return(false);
}
if (_exprDest is ExprUserDefinedConversion udc)
{
udc.Argument = _exprSrc;
}
}
return(true);
}
if ((_flags & CONVERTTYPE.NOUDC) == 0)
{
return(_binder.bindUserDefinedConversion(_exprSrc, _typeSrc, _typeDest, _needsExprDest, out _exprDest, false));
}
return(false);
}
private bool bindExplicitConversionFromNub()
{
Debug.Assert(typeSrc != null);
Debug.Assert(typeDest != null);
// If S and T are value types and there is a builtin conversion from S => T then there is an
// explicit conversion from S? => T that throws on null.
if (typeDest.IsValType() && binder.BindExplicitConversion(null, typeSrc.StripNubs(), exprTypeDest, m_pDestinationTypeForLambdaErrorReporting, flags | CONVERTTYPE.NOUDC))
{
if (needsExprDest)
{
EXPR valueSrc = exprSrc;
// UNDONE: This is a holdover from the days when you could have nullable of nullable.
// UNDONE: Can we remove this loop?
while (valueSrc.type.IsNullableType())
{
valueSrc = binder.BindNubValue(valueSrc);
}
Debug.Assert(valueSrc.type == typeSrc.StripNubs());
if (!binder.BindExplicitConversion(valueSrc, valueSrc.type, exprTypeDest, m_pDestinationTypeForLambdaErrorReporting, needsExprDest, out exprDest, flags | CONVERTTYPE.NOUDC))
{
VSFAIL("BindExplicitConversion failed unexpectedly");
return(false);
}
if (exprDest.kind == ExpressionKind.EK_USERDEFINEDCONVERSION)
{
exprDest.asUSERDEFINEDCONVERSION().Argument = exprSrc;
}
}
return(true);
}
if ((flags & CONVERTTYPE.NOUDC) == 0)
{
return(binder.bindUserDefinedConversion(exprSrc, typeSrc, typeDest, needsExprDest, out exprDest, false));
}
return(false);
}
private bool bindExplicitConversionFromNub()
{
Debug.Assert(_typeSrc != null);
Debug.Assert(_typeDest != null);
// If S and T are value types and there is a builtin conversion from S => T then there is an
// explicit conversion from S? => T that throws on null.
if (_typeDest.IsValType() && _binder.BindExplicitConversion(null, _typeSrc.StripNubs(), _typeDest, _flags | CONVERTTYPE.NOUDC))
{
if (_needsExprDest)
{
Expr valueSrc = _exprSrc;
if (valueSrc.Type is NullableType)
{
valueSrc = _binder.BindNubValue(valueSrc);
}
Debug.Assert(valueSrc.Type == _typeSrc.StripNubs());
if (!_binder.BindExplicitConversion(valueSrc, valueSrc.Type, _typeDest, _needsExprDest, out _exprDest, _flags | CONVERTTYPE.NOUDC))
{
Debug.Fail("BindExplicitConversion failed unexpectedly");
return(false);
}
if (_exprDest is ExprUserDefinedConversion udc)
{
udc.Argument = _exprSrc;
}
}
return(true);
}
if ((_flags & CONVERTTYPE.NOUDC) == 0)
{
return(_binder.bindUserDefinedConversion(_exprSrc, _typeSrc, _typeDest, _needsExprDest, out _exprDest, false));
}
return(false);
}
private bool HasImplicitBoxingConversion(CType pSource, CType pDest)
{
Debug.Assert(pSource != null);
Debug.Assert(pDest != null);
Debug.Assert(!(pSource is TypeParameterType));
// The rest of the boxing conversions only operate when going from a value type
// to a reference type.
if (!pDest.IsRefType())
{
return(false);
}
// A boxing conversion exists from a nullable type to a reference type
// if and only if a boxing conversion exists from the underlying type.
if (pSource is NullableType nubSource)
{
pSource = nubSource.UnderlyingType; // pSource.IsValType() known to be true.
}
else if (!pSource.IsValType())
{
return(false);
}
// A boxing conversion exists from any non-nullable value type to object,
// to System.ValueType, and to any interface type implemented by the
// non-nullable value type. Furthermore, an enum type can be converted
// to the type System.Enum.
// We set the base class of the structs to System.ValueType, System.Enum, etc,
// so we can just check here.
return(IsBaseClass(pSource, pDest) || HasAnyBaseInterfaceConversion(pSource, pDest));
}
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 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;
}
public bool HasImplicitBoxingConversion(CType pSource, CType pDest)
{
Debug.Assert(pSource != null);
Debug.Assert(pDest != null);
// Certain type parameter conversions are classified as boxing conversions.
if (pSource.IsTypeParameterType() &&
HasImplicitBoxingTypeParameterConversion(pSource.AsTypeParameterType(), pDest))
{
return true;
}
// The rest of the boxing conversions only operate when going from a value type
// to a reference type.
if (!pSource.IsValType() || !pDest.IsRefType())
{
return false;
}
// A boxing conversion exists from a nullable type to a reference type
// if and only if a boxing conversion exists from the underlying type.
if (pSource.IsNullableType())
{
return HasImplicitBoxingConversion(pSource.AsNullableType().GetUnderlyingType(), pDest);
}
// A boxing conversion exists from any non-nullable value type to object,
// to System.ValueType, and to any interface type implemented by the
// non-nullable value type. Furthermore, an enum type can be converted
// to the type System.Enum.
// We set the base class of the structs to System.ValueType, System.Enum, etc,
// so we can just check here.
if (IsBaseClass(pSource, pDest))
{
return true;
}
if (HasAnyBaseInterfaceConversion(pSource, pDest))
{
return true;
}
return false;
}
