private void CheckLiftedUserDefinedConditionalLogicalOperator(BoundUserDefinedConditionalLogicalOperator node)
{
// CS0458: The result of the expression is always 'null' of type '{0}'
if (node.Right.NullableNeverHasValue() || node.Left.NullableNeverHasValue())
{
Error(ErrorCode.WRN_AlwaysNull, node, node.Type);
}
}
private BoundNode VisitBinaryOperatorBase(BoundBinaryOperatorBase binaryOperator)
{
// Use an explicit stack to avoid blowing the managed stack when visiting deeply-recursive
// binary nodes
var stack = ArrayBuilder <BoundBinaryOperatorBase> .GetInstance();
BoundBinaryOperatorBase?currentBinary = binaryOperator;
do
{
stack.Push(currentBinary);
currentBinary = currentBinary.Left as BoundBinaryOperatorBase;
}while (currentBinary is object);
Debug.Assert(stack.Count > 0);
var leftChild = (BoundExpression)Visit(stack.Peek().Left);
do
{
currentBinary = stack.Pop();
bool foundInfo = _updatedNullabilities.TryGetValue(currentBinary, out (NullabilityInfo Info, TypeSymbol? Type)infoAndType);
var right = (BoundExpression)Visit(currentBinary.Right);
var type = foundInfo ? infoAndType.Type : currentBinary.Type;
currentBinary = currentBinary switch
{
BoundBinaryOperator binary => binary.Update(
binary.OperatorKind,
BoundBinaryOperator.UncommonData.CreateIfNeeded(binary.ConstantValue, GetUpdatedSymbol(binary, binary.Method), binary.ConstrainedToType, binary.OriginalUserDefinedOperatorsOpt),
binary.ResultKind,
leftChild,
right,
type !),
// https://github.com/dotnet/roslyn/issues/35031: We'll need to update logical.LogicalOperator
BoundUserDefinedConditionalLogicalOperator logical => logical.Update(logical.OperatorKind, logical.LogicalOperator, logical.TrueOperator, logical.FalseOperator, logical.ConstrainedToTypeOpt, logical.ResultKind, logical.OriginalUserDefinedOperatorsOpt, leftChild, right, type !),
_ => throw ExceptionUtilities.UnexpectedValue(currentBinary.Kind),
};
if (foundInfo)
{
currentBinary.TopLevelNullability = infoAndType.Info;
}
leftChild = currentBinary;
}while (stack.Count > 0);
Debug.Assert(currentBinary != null);
return(currentBinary !);
}
private BoundNode VisitBinaryOperatorBase(BoundBinaryOperatorBase binaryOperator)
{
// Use an explicit stack to avoid blowing the managed stack when visiting deeply-recursive
// binary nodes
var stack = ArrayBuilder <BoundBinaryOperatorBase> .GetInstance();
BoundBinaryOperatorBase?currentBinary = binaryOperator;
do
{
stack.Push(currentBinary);
currentBinary = currentBinary.Left as BoundBinaryOperatorBase;
}while (currentBinary is object);
Debug.Assert(stack.Count > 0);
var leftChild = (BoundExpression)Visit(stack.Peek().Left);
do
{
currentBinary = stack.Pop();
bool foundInfo = _updatedNullabilities.TryGetValue(currentBinary, out (NullabilityInfo Info, TypeSymbol Type)infoAndType);
var right = (BoundExpression)Visit(currentBinary.Right);
var type = foundInfo ? infoAndType.Type : currentBinary.Type;
#pragma warning disable IDE0055 // Fix formatting
// https://github.com/dotnet/roslyn/issues/35031: We'll need to update the symbols for the internal methods/operators used in the binary operators
currentBinary = currentBinary switch
{
BoundBinaryOperator binary => (BoundBinaryOperatorBase)binary.Update(binary.OperatorKind, binary.ConstantValueOpt, binary.MethodOpt, binary.ResultKind, leftChild, right, type),
BoundUserDefinedConditionalLogicalOperator logical => logical.Update(logical.OperatorKind, logical.LogicalOperator, logical.TrueOperator, logical.FalseOperator, logical.ResultKind, leftChild, right, type),
_ => throw ExceptionUtilities.UnexpectedValue(currentBinary.Kind),
};
#pragma warning restore IDE0055 // Fix formatting
if (foundInfo)
{
currentBinary.TopLevelNullability = infoAndType.Info;
}
leftChild = currentBinary;
}while (stack.Count > 0);
Debug.Assert(currentBinary != null);
return(currentBinary);
}
public override BoundNode VisitUserDefinedConditionalLogicalOperator(BoundUserDefinedConditionalLogicalOperator node)
{
// Yes, we could have a lifted, logical, user-defined operator:
//
// struct C {
// public static C operator &(C x, C y) {...}
// public static bool operator true(C? c) { ... }
// public static bool operator false(C? c) { ... }
// }
//
// If we have C? q, r and we say q && r then this gets bound as
// C? tempQ = q ;
// C.false(tempQ) ?
// tempQ :
// (
// C? tempR = r ;
// tempQ.HasValue & tempR.HasValue ?
// new C?(C.&(tempQ.GetValueOrDefault(), tempR.GetValueOrDefault())) :
// default C?()
// )
//
// Note that the native compiler does not allow q && r. However, the native compiler
// *does* allow q && r if C is defined as:
//
// struct C {
// public static C? operator &(C? x, C? y) {...}
// public static bool operator true(C? c) { ... }
// public static bool operator false(C? c) { ... }
// }
//
// It seems unusual and wrong that an & operator should be allowed to become
// a && operator if there is a "manually lifted" operator in source, but not
// if there is a "synthesized" lifted operator. Roslyn fixes this bug.
//
// Anyway, in this case we must lower this to its non-logical form, and then
// lower the interior of that to its non-lifted form.
// See comments in method IsValidUserDefinedConditionalLogicalOperator for information
// on some subtle aspects of this lowering.
// We generate one of:
//
// x || y --> temp = x; T.true(temp) ? temp : T.|(temp, y);
// x && y --> temp = x; T.false(temp) ? temp : T.&(temp, y);
//
// For the ease of naming locals, we'll assume we're doing an &&.
// TODO: We generate every one of these as "temp = x; T.false(temp) ? temp : T.&(temp, y)" even
// TODO: when x has no side effects. We can optimize away the temporary if there are no side effects.
var syntax = node.Syntax;
var operatorKind = node.OperatorKind;
var type = node.Type;
BoundExpression loweredLeft = VisitExpression(node.Left);
BoundExpression loweredRight = VisitExpression(node.Right);
if (_inExpressionLambda)
{
return node.Update(operatorKind, loweredLeft, loweredRight, node.LogicalOperator, node.TrueOperator, node.FalseOperator, node.ResultKind, type);
}
BoundAssignmentOperator tempAssignment;
var boundTemp = _factory.StoreToTemp(loweredLeft, out tempAssignment);
// T.false(temp)
var falseOperatorCall = BoundCall.Synthesized(syntax, null, operatorKind.Operator() == BinaryOperatorKind.And ? node.FalseOperator : node.TrueOperator, boundTemp);
// T.&(temp, y)
var andOperatorCall = LowerUserDefinedBinaryOperator(syntax, operatorKind & ~BinaryOperatorKind.Logical, boundTemp, loweredRight, type, node.LogicalOperator);
// T.false(temp) ? temp : T.&(temp, y)
BoundExpression conditionalExpression = RewriteConditionalOperator(
syntax: syntax,
rewrittenCondition: falseOperatorCall,
rewrittenConsequence: boundTemp,
rewrittenAlternative: andOperatorCall,
constantValueOpt: null,
rewrittenType: type);
// temp = x; T.false(temp) ? temp : T.&(temp, y)
return new BoundSequence(
syntax: syntax,
locals: ImmutableArray.Create(boundTemp.LocalSymbol),
sideEffects: ImmutableArray.Create<BoundExpression>(tempAssignment),
value: conditionalExpression,
type: type);
}
public override BoundNode?VisitUserDefinedConditionalLogicalOperator(BoundUserDefinedConditionalLogicalOperator node)
{
return(VisitBinaryOperatorBase(node));
}
public override BoundNode VisitUserDefinedConditionalLogicalOperator(BoundUserDefinedConditionalLogicalOperator node)
{
throw ExceptionUtilities.Unreachable;
}
public override BoundNode VisitUserDefinedConditionalLogicalOperator(BoundUserDefinedConditionalLogicalOperator node)
{
CheckLiftedUserDefinedConditionalLogicalOperator(node);
return(base.VisitUserDefinedConditionalLogicalOperator(node));
}
public override BoundNode VisitUserDefinedConditionalLogicalOperator(BoundUserDefinedConditionalLogicalOperator node)
{
CheckLiftedUserDefinedConditionalLogicalOperator(node);
return base.VisitUserDefinedConditionalLogicalOperator(node);
}
private void CheckLiftedUserDefinedConditionalLogicalOperator(BoundUserDefinedConditionalLogicalOperator node)
{
// CS0458: The result of the expression is always 'null' of type '{0}'
if (node.Right.NullableNeverHasValue() || node.Left.NullableNeverHasValue())
{
Error(ErrorCode.WRN_AlwaysNull, node, node.Type);
}
}