internal static bool IsNop(ExpressionSyntax candidate, SemanticModel semanticModel, CancellationToken cancellationToken)
{
if (semanticModel.TryGetSymbol(candidate, cancellationToken, out ISymbol symbol) &&
FieldOrProperty.TryCreate(symbol, out var fieldOrProperty) &&
fieldOrProperty.IsStatic &&
IsAssignableFrom(fieldOrProperty.Type, semanticModel.Compilation))
{
if (fieldOrProperty.Type == KnownSymbol.Task ||
symbol == KnownSymbol.RxDisposable.Empty)
{
return(true);
}
using (var walker = ReturnValueWalker.Borrow(candidate, ReturnValueSearch.Recursive, semanticModel, cancellationToken))
{
if (walker.Count > 0)
{
return(walker.TrySingle(out var value) &&
semanticModel.TryGetType(value, cancellationToken, out var type) &&
IsNop(type));
}
}
using (var walker = AssignedValueWalker.Borrow(symbol, semanticModel, cancellationToken))
{
return(walker.TrySingle(out var value) &&
semanticModel.TryGetType(value, cancellationToken, out var type) &&
IsNop(type));
}
}
return(false);
bool IsNop(ITypeSymbol type)
{
return(type.IsSealed &&
type.BaseType == KnownSymbol.Object &&
type.TryFindSingleMethod("Dispose", out var disposeMethod) &&
disposeMethod.Parameters.Length == 0 &&
disposeMethod.TrySingleDeclaration(cancellationToken, out MethodDeclarationSyntax declaration) &&
declaration.Body is BlockSyntax body &&
body.Statements.Count == 0);
}
}
internal static bool IsCachedOrInjected(ExpressionSyntax value, ExpressionSyntax location, SemanticModel semanticModel, CancellationToken cancellationToken)
{
var symbol = semanticModel.GetSymbolSafe(value, cancellationToken);
if (IsInjectedCore(symbol).IsEither(Result.Yes, Result.AssumeYes))
{
return(true);
}
if (symbol is IPropertySymbol property &&
!property.IsAutoProperty())
{
using (var returnValues = ReturnValueWalker.Borrow(value, ReturnValueSearch.TopLevel, semanticModel, cancellationToken))
{
using (var recursive = RecursiveValues.Borrow(returnValues, semanticModel, cancellationToken))
{
return(IsAnyCachedOrInjected(recursive, semanticModel, cancellationToken).IsEither(Result.Yes, Result.AssumeYes));
}
}
}
return(IsAssignedWithInjected(symbol, location, semanticModel, cancellationToken));
}
/// <summary>
/// Check if any path returns a created IDisposable
/// </summary>
internal static Result IsCreation(ExpressionSyntax candidate, SemanticModel semanticModel, CancellationToken cancellationToken)
{
if (!IsPotentiallyAssignableTo(candidate, semanticModel, cancellationToken) ||
candidate is ThisExpressionSyntax ||
candidate is BaseExpressionSyntax)
{
return(Result.No);
}
if (candidate is ObjectCreationExpressionSyntax)
{
return(Result.Yes);
}
using (var pooled = ReturnValueWalker.Create(candidate, Search.Recursive, semanticModel, cancellationToken))
{
if (pooled.Item.Count == 0)
{
var symbol = semanticModel.GetSymbolSafe(candidate, cancellationToken);
if (symbol != null && symbol.DeclaringSyntaxReferences.Length == 0)
{
return(IsCreationCore(candidate, semanticModel, cancellationToken));
}
using (var recursive = RecursiveValues.Create(new[] { candidate }, semanticModel, cancellationToken))
{
return(IsCreationCore(recursive, semanticModel, cancellationToken));
}
}
using (var recursive = RecursiveValues.Create(pooled.Item, semanticModel, cancellationToken))
{
return(IsCreationCore(recursive, semanticModel, cancellationToken));
}
}
}
internal static bool IsDisposing(InvocationExpressionSyntax disposeCall, ISymbol symbol, SemanticModel semanticModel, CancellationToken cancellationToken)
{
if (TryGetDisposed(disposeCall, semanticModel, cancellationToken, out var disposed))
{
if (disposed.Equals(symbol))
{
return(true);
}
if (disposed is IPropertySymbol property &&
property.TrySingleDeclaration(cancellationToken, out var declaration))
{
using (var walker = ReturnValueWalker.Borrow(declaration, ReturnValueSearch.TopLevel, semanticModel, cancellationToken))
{
return(walker.TrySingle(out var returnValue) &&
MemberPath.TrySingle(returnValue, out var expression) &&
semanticModel.TryGetSymbol(expression, cancellationToken, out ISymbol nested) &&
nested.Equals(symbol));
}
}
}
return(false);
}
public bool TryGetValue(SyntaxNode member, out ReturnValueWalker walker)
{
return(this.Map.TryGetValue(member, out walker));
}
public void Add(SyntaxNode member, ReturnValueWalker walker)
{
this.Map.Add(member, walker);
}
private static bool IsReturned(ILocalSymbol symbol, BlockSyntax block, SemanticModel semanticModel, CancellationToken cancellationToken)
{
using (var walker = ReturnValueWalker.Borrow(block, Search.TopLevel, semanticModel, cancellationToken))
{
foreach (var value in walker)
{
var returnedSymbol = semanticModel.GetSymbolSafe(value, cancellationToken);
if (SymbolComparer.Equals(symbol, returnedSymbol))
{
return(true);
}
if (value is ObjectCreationExpressionSyntax objectCreation)
{
if (objectCreation.ArgumentList != null)
{
foreach (var argument in objectCreation.ArgumentList.Arguments)
{
var arg = semanticModel.GetSymbolSafe(argument.Expression, cancellationToken);
if (SymbolComparer.Equals(symbol, arg))
{
return(true);
}
}
}
if (objectCreation.Initializer != null)
{
foreach (var argument in objectCreation.Initializer.Expressions)
{
var arg = semanticModel.GetSymbolSafe(argument, cancellationToken);
if (SymbolComparer.Equals(symbol, arg))
{
return(true);
}
}
}
}
if (value is InvocationExpressionSyntax invocation)
{
if (returnedSymbol == KnownSymbol.RxDisposable.Create &&
invocation.ArgumentList != null &&
invocation.ArgumentList.Arguments.TryGetSingle(out ArgumentSyntax argument) &&
argument.Expression is ParenthesizedLambdaExpressionSyntax lambda)
{
var body = lambda.Body;
using (var pooledInvocations = InvocationWalker.Borrow(body))
{
foreach (var candidate in pooledInvocations.Invocations)
{
if (Disposable.IsDisposing(candidate, symbol, semanticModel, cancellationToken))
{
return(true);
}
}
}
}
}
}
}
return(false);
}
private static Result CheckReturnValues(IParameterSymbol parameter, SyntaxNode memberAccess, SemanticModel semanticModel, CancellationToken cancellationToken, PooledHashSet <SyntaxNode> visited)
{
Result CheckReturnValue(ExpressionSyntax returnValue)
{
if (returnValue is ObjectCreationExpressionSyntax nestedObjectCreation)
{
if (nestedObjectCreation.TryGetMatchingArgument(parameter, out var nestedArgument))
{
return(IsArgumentDisposedByReturnValue(nestedArgument, semanticModel, cancellationToken, visited));
}
return(Result.No);
}
if (returnValue is InvocationExpressionSyntax nestedInvocation)
{
if (nestedInvocation.TryGetMatchingArgument(parameter, out var nestedArgument))
{
return(IsArgumentDisposedByReturnValue(nestedArgument, semanticModel, cancellationToken, visited));
}
return(Result.No);
}
if (returnValue is MemberAccessExpressionSyntax nestedMemberAccess)
{
return(IsArgumentDisposedByInvocationReturnValue(nestedMemberAccess, semanticModel, cancellationToken, visited));
}
return(Result.Unknown);
}
var result = Result.No;
using (var returnWalker = ReturnValueWalker.Borrow(memberAccess, Search.Recursive, semanticModel, cancellationToken))
{
using (visited = PooledHashSet <SyntaxNode> .BorrowOrIncrementUsage(visited))
{
if (!visited.Add(memberAccess))
{
return(Result.Unknown);
}
foreach (var returnValue in returnWalker)
{
switch (CheckReturnValue(returnValue))
{
case Result.Unknown:
return(Result.Unknown);
case Result.Yes:
if (result == Result.No)
{
result = Result.Yes;
}
break;
case Result.AssumeYes:
result = Result.AssumeYes;
break;
case Result.No:
return(Result.No);
case Result.AssumeNo:
return(Result.AssumeNo);
default:
throw new ArgumentOutOfRangeException();
}
}
}
}
return(result);
}
internal static bool IsReturned(ISymbol symbol, SyntaxNode scope, SemanticModel semanticModel, CancellationToken cancellationToken)
{
using (var walker = ReturnValueWalker.Borrow(scope, ReturnValueSearch.TopLevel, semanticModel, cancellationToken))
{
foreach (var value in walker)
{
var candidate = value;
switch (candidate)
{
case CastExpressionSyntax castExpression:
candidate = castExpression.Expression;
break;
case BinaryExpressionSyntax binary when binary.IsKind(SyntaxKind.AsExpression):
candidate = binary.Left;
break;
}
if (candidate is ObjectCreationExpressionSyntax objectCreation)
{
if (objectCreation.ArgumentList != null)
{
foreach (var argument in objectCreation.ArgumentList.Arguments)
{
if (semanticModel.TryGetSymbol(argument.Expression, cancellationToken, out ISymbol argumentSymbol) &&
symbol.Equals(argumentSymbol))
{
return(true);
}
}
}
if (objectCreation.Initializer != null)
{
foreach (var expression in objectCreation.Initializer.Expressions)
{
if (semanticModel.TryGetSymbol(expression, cancellationToken, out ISymbol expressionSymbol) &&
symbol.Equals(expressionSymbol))
{
return(true);
}
}
}
}
if (semanticModel.TryGetSymbol(candidate, cancellationToken, out ISymbol returnedSymbol) &&
symbol.Equals(returnedSymbol))
{
return(true);
}
if (candidate is InvocationExpressionSyntax invocation)
{
if (returnedSymbol == KnownSymbol.RxDisposable.Create &&
invocation.ArgumentList != null &&
invocation.ArgumentList.Arguments.TrySingle(out var argument) &&
argument.Expression is ParenthesizedLambdaExpressionSyntax lambda)
{
var body = lambda.Body;
using (var pooledInvocations = InvocationWalker.Borrow(body))
{
foreach (var disposeCandidate in pooledInvocations.Invocations)
{
if (DisposeCall.IsDisposing(disposeCandidate, symbol, semanticModel, cancellationToken))
{
return(true);
}
}
}
}
}
}
}
return(false);
}
private bool AddRecursiveValues(ExpressionSyntax assignedValue)
{
if (assignedValue == null ||
assignedValue.IsMissing ||
!this.checkedLocations.Add(assignedValue))
{
return(false);
}
if (assignedValue is LiteralExpressionSyntax ||
assignedValue is DefaultExpressionSyntax ||
assignedValue is TypeOfExpressionSyntax ||
assignedValue is ObjectCreationExpressionSyntax ||
assignedValue is ArrayCreationExpressionSyntax ||
assignedValue is ImplicitArrayCreationExpressionSyntax ||
assignedValue is InitializerExpressionSyntax)
{
this.values.Add(assignedValue);
return(true);
}
var argument = assignedValue.Parent as ArgumentSyntax;
if (argument?.RefOrOutKeyword.IsKind(SyntaxKind.OutKeyword) == true)
{
var invocation = assignedValue.FirstAncestor <InvocationExpressionSyntax>();
var invokedMethod = this.semanticModel.GetSymbolSafe(invocation, this.cancellationToken);
if (invokedMethod == null ||
invokedMethod.DeclaringSyntaxReferences.Length == 0)
{
this.values.Add(invocation);
return(true);
}
var before = this.values.Count;
foreach (var reference in invokedMethod.DeclaringSyntaxReferences)
{
var methodDeclaration = reference.GetSyntax(this.cancellationToken) as MethodDeclarationSyntax;
if (methodDeclaration.TryGetMatchingParameter(argument, out ParameterSyntax parameter))
{
using (var pooled = AssignedValueWalker.Create(this.semanticModel.GetDeclaredSymbolSafe(parameter, this.cancellationToken), this.semanticModel, this.cancellationToken))
{
pooled.Item.HandleInvoke(invokedMethod, invocation.ArgumentList);
return(this.AddManyRecursively(pooled.Item));
}
}
}
return(before != this.values.Count);
}
if (assignedValue is BinaryExpressionSyntax binaryExpression)
{
switch (binaryExpression.Kind())
{
case SyntaxKind.CoalesceExpression:
var left = this.AddRecursiveValues(binaryExpression.Left);
var right = this.AddRecursiveValues(binaryExpression.Right);
return(left || right);
case SyntaxKind.AsExpression:
return(this.AddRecursiveValues(binaryExpression.Left));
default:
return(false);
}
}
if (assignedValue is CastExpressionSyntax cast)
{
return(this.AddRecursiveValues(cast.Expression));
}
if (assignedValue is ConditionalExpressionSyntax conditional)
{
var whenTrue = this.AddRecursiveValues(conditional.WhenTrue);
var whenFalse = this.AddRecursiveValues(conditional.WhenFalse);
return(whenTrue || whenFalse);
}
if (assignedValue is AwaitExpressionSyntax @await)
{
using (var pooled = ReturnValueWalker.Create(@await, Search.Recursive, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(pooled.Item));
}
}
if (assignedValue is ElementAccessExpressionSyntax)
{
this.values.Add(assignedValue);
return(true);
}
var symbol = this.semanticModel.GetSymbolSafe(assignedValue, this.cancellationToken);
if (symbol == null)
{
return(false);
}
if (symbol is IFieldSymbol)
{
this.values.Add(assignedValue);
return(true);
}
if (symbol is IParameterSymbol)
{
this.values.Add(assignedValue);
using (var pooled = AssignedValueWalker.Create(assignedValue, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(pooled.Item));
}
}
if (symbol is ILocalSymbol)
{
using (var pooled = AssignedValueWalker.Create(assignedValue, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(pooled.Item));
}
}
if (symbol is IPropertySymbol property)
{
if (property.DeclaringSyntaxReferences.Length == 0)
{
this.values.Add(assignedValue);
return(true);
}
using (var returnValues = ReturnValueWalker.Create(assignedValue, Search.Recursive, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(returnValues.Item));
}
}
if (symbol is IMethodSymbol method)
{
if (method.DeclaringSyntaxReferences.Length == 0)
{
this.values.Add(assignedValue);
return(true);
}
using (var pooled = ReturnValueWalker.Create(assignedValue, Search.Recursive, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(pooled.Item));
}
}
return(false);
}
private static bool MustBeHandled(
ExpressionSyntax node,
SemanticModel semanticModel,
CancellationToken cancellationToken)
{
if (node.Parent is AnonymousFunctionExpressionSyntax ||
node.Parent is UsingStatementSyntax ||
node.Parent is EqualsValueClauseSyntax ||
node.Parent is ReturnStatementSyntax ||
node.Parent is ArrowExpressionClauseSyntax)
{
return(false);
}
if (Disposable.IsCreation(node, semanticModel, cancellationToken)
.IsEither(Result.No, Result.Unknown))
{
return(false);
}
if (node.Parent is StatementSyntax)
{
return(true);
}
if (node.Parent is ArgumentSyntax argument)
{
if (argument.Parent.Parent is InvocationExpressionSyntax invocation)
{
using (var returnWalker = ReturnValueWalker.Create(invocation, Search.Recursive, semanticModel, cancellationToken))
{
foreach (var returnValue in returnWalker.Item)
{
if (MustBeHandled(returnValue, semanticModel, cancellationToken))
{
return(true);
}
}
}
return(false);
}
if (argument.Parent.Parent is ObjectCreationExpressionSyntax)
{
if (TryGetAssignedFieldOrProperty(argument, semanticModel, cancellationToken, out ISymbol member, out IMethodSymbol ctor) &&
member != null)
{
var initializer = argument.FirstAncestorOrSelf <ConstructorInitializerSyntax>();
if (initializer != null)
{
if (semanticModel.GetDeclaredSymbolSafe(initializer.Parent, cancellationToken) is IMethodSymbol chainedCtor &&
chainedCtor.ContainingType != member.ContainingType)
{
if (Disposable.TryGetDisposeMethod(chainedCtor.ContainingType, Search.TopLevel, out IMethodSymbol disposeMethod))
{
return(!Disposable.IsMemberDisposed(member, disposeMethod, semanticModel, cancellationToken));
}
}
}
if (Disposable.IsMemberDisposed(member, ctor.ContainingType, semanticModel, cancellationToken)
.IsEither(Result.Yes, Result.Maybe))
{
return(false);
}
return(true);
}
return(ctor?.ContainingType != KnownSymbol.StreamReader &&
ctor?.ContainingType != KnownSymbol.CompositeDisposable);
}
}
return(false);
}
internal static bool TryGetReturnExpression(this BlockSyntax body, SemanticModel semanticModel, CancellationToken cancellationToken, out ExpressionSyntax returnValue)
{
return(ReturnValueWalker.TryGetSingle(body, semanticModel, cancellationToken, out returnValue));
}
private bool AddRecursiveValues(ExpressionSyntax assignedValue)
{
if (assignedValue == null ||
assignedValue.IsMissing ||
!this.checkedLocations.Add(assignedValue))
{
return(false);
}
if (assignedValue.Parent is ArgumentSyntax argument &&
argument.RefOrOutKeyword.IsKind(SyntaxKind.OutKeyword))
{
if (assignedValue.TryFirstAncestor(out InvocationExpressionSyntax invocation) &&
this.semanticModel.TryGetSymbol(invocation, this.cancellationToken, out var target) &&
target.TrySingleMethodDeclaration(this.cancellationToken, out var targetDeclaration))
{
if (targetDeclaration.TryFindParameter(argument, out var parameter) &&
this.semanticModel.TryGetSymbol(parameter, this.cancellationToken, out var parameterSymbol))
{
using (var assignedValues = AssignedValueWalker.Borrow(parameterSymbol, this.semanticModel, this.cancellationToken))
{
assignedValues.HandleInvoke(target, invocation.ArgumentList);
return(this.AddManyRecursively(assignedValues));
}
}
return(false);
}
this.values.Add(invocation);
return(true);
}
switch (assignedValue)
{
case ArrayCreationExpressionSyntax _:
case DefaultExpressionSyntax _:
case ElementAccessExpressionSyntax _:
case ImplicitArrayCreationExpressionSyntax _:
case InitializerExpressionSyntax _:
case LiteralExpressionSyntax _:
case ObjectCreationExpressionSyntax _:
case TypeOfExpressionSyntax _:
this.values.Add(assignedValue);
return(true);
case BinaryExpressionSyntax binaryExpression:
switch (binaryExpression.Kind())
{
case SyntaxKind.CoalesceExpression:
var left = this.AddRecursiveValues(binaryExpression.Left);
var right = this.AddRecursiveValues(binaryExpression.Right);
return(left || right);
case SyntaxKind.AsExpression:
return(this.AddRecursiveValues(binaryExpression.Left));
default:
return(false);
}
case CastExpressionSyntax cast:
return(this.AddRecursiveValues(cast.Expression));
case ConditionalExpressionSyntax conditional:
var whenTrue = this.AddRecursiveValues(conditional.WhenTrue);
var whenFalse = this.AddRecursiveValues(conditional.WhenFalse);
return(whenTrue || whenFalse);
case AwaitExpressionSyntax awaitExpression:
using (var walker = ReturnValueWalker.Borrow(awaitExpression, ReturnValueSearch.RecursiveInside, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(walker));
}
}
if (this.semanticModel.TryGetSymbol(assignedValue, this.cancellationToken, out ISymbol symbol))
{
switch (symbol)
{
case ILocalSymbol _:
using (var assignedValues = AssignedValueWalker.Borrow(assignedValue, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(assignedValues));
}
case IParameterSymbol _:
this.values.Add(assignedValue);
using (var assignedValues = AssignedValueWalker.Borrow(assignedValue, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(assignedValues));
}
case IFieldSymbol _:
this.values.Add(assignedValue);
return(true);
case IPropertySymbol _:
case IMethodSymbol _:
if (symbol.DeclaringSyntaxReferences.Length == 0)
{
this.values.Add(assignedValue);
return(true);
}
using (var returnValues = ReturnValueWalker.Borrow(assignedValue, ReturnValueSearch.RecursiveInside, this.semanticModel, this.cancellationToken))
{
return(this.AddManyRecursively(returnValues));
}
}
}
return(false);
}
