// x < 0 >>> false
private static void AnalyzeLessThanExpression(SyntaxNodeAnalysisContext context)
{
var lessThanExpression = (BinaryExpressionSyntax)context.Node;
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo(lessThanExpression);
if (!info.Success)
{
return;
}
if (!IsAlwaysEqualToTrueOrFalse(lessThanExpression, info.Left, info.Right, context.SemanticModel, context.CancellationToken))
{
return;
}
ReportExpressionAlwaysEqualToTrueOrFalse(context, "false");
}
// x > 0 (x > 0) true/false
// 0 > x (x < 0) false
public static void GreaterThanExpression(SyntaxNodeAnalysisContext context)
{
var greaterThanExpression = (BinaryExpressionSyntax)context.Node;
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo(greaterThanExpression);
if (!info.Success)
{
return;
}
if (!IsFixable(greaterThanExpression, info.Right, info.Left, context.SemanticModel, context.CancellationToken))
{
return;
}
ReportDiagnostic(context, "false");
}
// x <= 0 (x <= 0) true/false
// 0 <= x (x >= 0) true
public static void AnalyzeLessThanOrEqualExpression(SyntaxNodeAnalysisContext context)
{
var lessThanOrEqualExpression = (BinaryExpressionSyntax)context.Node;
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo(lessThanOrEqualExpression);
if (!info.Success)
{
return;
}
if (!IsFixable(lessThanOrEqualExpression, info.Right, info.Left, context.SemanticModel, context.CancellationToken))
{
return;
}
ReportDiagnostic(context, "true");
}
private static void AnalyzeSimpleAssignment(SyntaxNodeAnalysisContext context)
{
var assignmentExpression = (AssignmentExpressionSyntax)context.Node;
SimpleAssignmentExpressionInfo assignmentInfo = SyntaxInfo.SimpleAssignmentExpressionInfo(assignmentExpression);
if (!assignmentInfo.Success)
{
return;
}
if (assignmentExpression.IsParentKind(SyntaxKind.ObjectInitializerExpression))
{
return;
}
ExpressionSyntax right = assignmentInfo.Right;
if (!CanBeReplacedWithCompoundAssignment(right.Kind()))
{
return;
}
BinaryExpressionInfo binaryInfo = SyntaxInfo.BinaryExpressionInfo((BinaryExpressionSyntax)right);
if (!binaryInfo.Success)
{
return;
}
if (!CSharpFactory.AreEquivalent(assignmentInfo.Left, binaryInfo.Left))
{
return;
}
var binaryExpression = (BinaryExpressionSyntax)right;
context.ReportDiagnostic(DiagnosticDescriptors.UseCompoundAssignment, assignmentExpression, GetCompoundAssignmentOperatorText(binaryExpression));
context.ReportNode(DiagnosticDescriptors.UseCompoundAssignmentFadeOut, binaryExpression.Left);
}
// x:
// byte
// ushort
// uint
// ulong
// Array.Length
// string.Length
// ICollection<T>.Count
// IReadOnlyCollection<T>.Count
// x >= 0 >>> true
// 0 >= x >>> 0 == x
private static void AnalyzeGreaterThanOrEqualExpression(SyntaxNodeAnalysisContext context)
{
var greaterThanOrEqualExpression = (BinaryExpressionSyntax)context.Node;
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo(greaterThanOrEqualExpression);
if (!info.Success)
{
return;
}
if (!context.IsAnalyzerSuppressed(DiagnosticDescriptors.ExpressionIsAlwaysEqualToTrueOrFalse) &&
IsAlwaysEqualToTrueOrFalse(greaterThanOrEqualExpression, info.Left, info.Right, context.SemanticModel, context.CancellationToken))
{
ReportExpressionAlwaysEqualToTrueOrFalse(context, "true");
}
else if (!context.IsAnalyzerSuppressed(DiagnosticDescriptors.UnnecessaryOperator) &&
IsUnnecessaryRelationalOperator(info.Right, info.Left, context.SemanticModel, context.CancellationToken))
{
ReportUnnecessaryRelationalOperator(context, info.OperatorToken);
}
}
// 0 <= x >>> true
// x <= 0 >>> x == 0
private static void AnalyzeLessThanOrEqualExpression(SyntaxNodeAnalysisContext context)
{
var lessThanOrEqualExpression = (BinaryExpressionSyntax)context.Node;
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo(lessThanOrEqualExpression);
if (!info.Success)
{
return;
}
if (DiagnosticRules.ExpressionIsAlwaysEqualToTrueOrFalse.IsEffective(context) &&
IsAlwaysEqualToTrueOrFalse(lessThanOrEqualExpression, info.Right, info.Left, context.SemanticModel, context.CancellationToken))
{
ReportExpressionAlwaysEqualToTrueOrFalse(context, "true");
}
else if (DiagnosticRules.UnnecessaryOperator.IsEffective(context) &&
IsUnnecessaryRelationalOperator(info.Left, info.Right, context.SemanticModel, context.CancellationToken))
{
ReportUnnecessaryRelationalOperator(context, info.OperatorToken);
}
}
private static void AnalyzeEqualsExpression(SyntaxNodeAnalysisContext context)
{
var equalsExpression = (BinaryExpressionSyntax)context.Node;
if (equalsExpression.ContainsDirectives)
{
return;
}
BinaryExpressionInfo equalsExpressionInfo = SyntaxInfo.BinaryExpressionInfo(equalsExpression);
if (!equalsExpressionInfo.Success)
{
return;
}
ExpressionSyntax left = equalsExpressionInfo.Left;
ExpressionSyntax right = equalsExpressionInfo.Right;
SemanticModel semanticModel = context.SemanticModel;
CancellationToken cancellationToken = context.CancellationToken;
if (CSharpUtility.IsEmptyStringExpression(left, semanticModel, cancellationToken))
{
if (CSharpUtility.IsStringExpression(right, semanticModel, cancellationToken) &&
!equalsExpression.IsInExpressionTree(semanticModel, cancellationToken))
{
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.UseStringLengthInsteadOfComparisonWithEmptyString, equalsExpression);
}
}
else if (CSharpUtility.IsEmptyStringExpression(right, semanticModel, cancellationToken) &&
CSharpUtility.IsStringExpression(left, semanticModel, cancellationToken) &&
!equalsExpression.IsInExpressionTree(semanticModel, cancellationToken))
{
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.UseStringLengthInsteadOfComparisonWithEmptyString, equalsExpression);
}
}
public static void AnalyzeLogicalOrExpression(SyntaxNodeAnalysisContext context)
{
SyntaxNode node = context.Node;
if (node.ContainsDiagnostics)
{
return;
}
if (node.SpanContainsDirectives())
{
return;
}
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo((BinaryExpressionSyntax)context.Node);
if (!info.Success)
{
return;
}
if (!info.Left.IsKind(SyntaxKind.LogicalAndExpression))
{
return;
}
if (!info.Right.IsKind(SyntaxKind.LogicalAndExpression))
{
return;
}
ExpressionPair expressions = GetExpressionPair((BinaryExpressionSyntax)info.Left);
if (!expressions.IsValid)
{
return;
}
ExpressionPair expressions2 = GetExpressionPair((BinaryExpressionSyntax)info.Right);
if (!expressions2.IsValid)
{
return;
}
if (expressions.Expression.Kind() != expressions2.NegatedExpression.Kind())
{
return;
}
if (expressions.NegatedExpression.Kind() != expressions2.Expression.Kind())
{
return;
}
if (!AreEquivalent(expressions.Expression, expressions2.NegatedExpression))
{
return;
}
if (!AreEquivalent(expressions.NegatedExpression, expressions2.Expression))
{
return;
}
context.ReportDiagnostic(DiagnosticDescriptors.UseExclusiveOrOperator, context.Node);
}
private static void AnalyzeBinaryExpression(SyntaxNodeAnalysisContext context)
{
var binaryExpression = (BinaryExpressionSyntax)context.Node;
BinaryExpressionInfo binaryExpressionInfo = SyntaxInfo.BinaryExpressionInfo(binaryExpression);
if (!binaryExpressionInfo.Success)
{
return;
}
if (binaryExpressionInfo.Right.Kind() != SyntaxKind.TrueLiteralExpression)
{
return;
}
ExpressionSyntax left = binaryExpressionInfo.Left;
if (left.Kind() != SyntaxKind.ConditionalAccessExpression)
{
return;
}
var conditionalAccess = (ConditionalAccessExpressionSyntax)left;
ExpressionSyntax whenNotNull = conditionalAccess.WhenNotNull;
if (whenNotNull.Kind() != SyntaxKind.InvocationExpression)
{
return;
}
var invocationExpression = (InvocationExpressionSyntax)whenNotNull;
if (invocationExpression.ArgumentList.Arguments.Count != 1)
{
return;
}
ExpressionSyntax expression = invocationExpression.Expression;
if (expression.Kind() != SyntaxKind.MemberBindingExpression)
{
return;
}
var memberBindingExpression = (MemberBindingExpressionSyntax)expression;
SimpleNameSyntax name = memberBindingExpression.Name;
if (name.Kind() != SyntaxKind.IdentifierName)
{
return;
}
var identifierName = (IdentifierNameSyntax)name;
if (!string.Equals(identifierName.Identifier.ValueText, "IsKind", StringComparison.Ordinal))
{
return;
}
ISymbol symbol = context.SemanticModel.GetSymbol(invocationExpression, context.CancellationToken);
if (symbol?.Kind != SymbolKind.Method)
{
return;
}
var methodSymbol = (IMethodSymbol)symbol;
if (methodSymbol.MethodKind != MethodKind.ReducedExtension)
{
return;
}
if (methodSymbol.ReturnType.SpecialType != SpecialType.System_Boolean)
{
return;
}
if (methodSymbol.ContainingType?.HasMetadataName(RoslynMetadataNames.Microsoft_CodeAnalysis_CSharpExtensions) != true)
{
return;
}
ImmutableArray <IParameterSymbol> parameters = methodSymbol
.ReducedFrom
.Parameters;
if (parameters.Length != 2)
{
return;
}
if (!parameters[0].Type.HasMetadataName(RoslynMetadataNames.Microsoft_CodeAnalysis_SyntaxNode))
{
return;
}
if (!parameters[1].Type.HasMetadataName(CSharpMetadataNames.Microsoft_CodeAnalysis_CSharp_SyntaxKind))
{
return;
}
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticDescriptors.UnnecessaryConditionalAccess, conditionalAccess.OperatorToken);
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticDescriptors.UnnecessaryConditionalAccessFadeOut, binaryExpression.Right);
}
private static void AnalyzeLogicalAndExpression(SyntaxNodeAnalysisContext context)
{
var logicalAnd = (BinaryExpressionSyntax)context.Node;
if (logicalAnd.SpanContainsDirectives())
{
return;
}
BinaryExpressionInfo logicalAndInfo = SyntaxInfo.BinaryExpressionInfo(logicalAnd);
if (!logicalAndInfo.Success)
{
return;
}
NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(
logicalAndInfo.Left,
context.SemanticModel,
NullCheckStyles.NotEqualsToNull | NullCheckStyles.HasValue,
cancellationToken: context.CancellationToken);
if (!nullCheck.Success)
{
return;
}
ExpressionSyntax right = logicalAndInfo.Right;
switch (right.Kind())
{
case SyntaxKind.LogicalNotExpression:
{
var logicalNot = (PrefixUnaryExpressionSyntax)right;
Analyze(nullCheck.Expression, logicalNot.Operand?.WalkDownParentheses(), null);
break;
}
case SyntaxKind.EqualsExpression:
case SyntaxKind.LessThanExpression:
case SyntaxKind.LessThanOrEqualExpression:
case SyntaxKind.GreaterThanExpression:
case SyntaxKind.GreaterThanOrEqualExpression:
{
BinaryExpressionInfo binaryExpressionInfo = SyntaxInfo.BinaryExpressionInfo((BinaryExpressionSyntax)right);
if (!binaryExpressionInfo.Success)
{
break;
}
ExpressionSyntax left = binaryExpressionInfo.Left;
Analyze(nullCheck.Expression, left, binaryExpressionInfo.Right);
break;
}
case SyntaxKind.SimpleMemberAccessExpression:
{
AnalyzeSimpleMemberAccessExpression(nullCheck.Expression, (MemberAccessExpressionSyntax)right, null);
break;
}
}
void Analyze(ExpressionSyntax expression1, ExpressionSyntax expression2, ExpressionSyntax expression3)
{
if (expression2.IsKind(SyntaxKind.SimpleMemberAccessExpression))
{
AnalyzeSimpleMemberAccessExpression(expression1, (MemberAccessExpressionSyntax)expression2, expression3);
}
}
void AnalyzeSimpleMemberAccessExpression(ExpressionSyntax expression, MemberAccessExpressionSyntax memberAccessExpression, ExpressionSyntax expression3)
{
if (memberAccessExpression.Name is not IdentifierNameSyntax identifierName ||
!string.Equals(identifierName.Identifier.ValueText, "Value", StringComparison.Ordinal))
{
return;
}
if (!SyntaxUtility.IsPropertyOfNullableOfT(memberAccessExpression, "Value", context.SemanticModel, context.CancellationToken))
{
return;
}
if (!AreEquivalent(expression, memberAccessExpression.Expression))
{
return;
}
if (expression3 != null)
{
switch (expression3.Kind())
{
case SyntaxKind.NumericLiteralExpression:
case SyntaxKind.StringLiteralExpression:
case SyntaxKind.CharacterLiteralExpression:
case SyntaxKind.TrueLiteralExpression:
case SyntaxKind.FalseLiteralExpression:
{
break;
}
case SyntaxKind.NullLiteralExpression:
case SyntaxKind.DefaultLiteralExpression:
{
return;
}
default:
{
if (context.SemanticModel.GetTypeSymbol(expression3, context.CancellationToken).IsNullableType())
{
return;
}
break;
}
}
}
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.UnnecessaryNullCheck, logicalAnd);
}
}
private static void AnalyzeElementAccessExpression(SyntaxNodeAnalysisContext context)
{
var elementAccessExpression = (ElementAccessExpressionSyntax)context.Node;
ExpressionSyntax expression = elementAccessExpression
.ArgumentList
.Arguments
.SingleOrDefault(shouldThrow: false)?
.Expression
.WalkDownParentheses();
if (expression == null)
{
return;
}
if (!expression.IsKind(SyntaxKind.SubtractExpression))
{
return;
}
BinaryExpressionInfo subtractExpressionInfo = SyntaxInfo.BinaryExpressionInfo((BinaryExpressionSyntax)expression);
if (!subtractExpressionInfo.Right.IsNumericLiteralExpression("1"))
{
return;
}
if (!subtractExpressionInfo.Left.IsKind(SyntaxKind.SimpleMemberAccessExpression))
{
return;
}
var memberAccessExpression = (MemberAccessExpressionSyntax)subtractExpressionInfo.Left;
if (!(memberAccessExpression.Name is IdentifierNameSyntax identifierName))
{
return;
}
if (identifierName.Identifier.ValueText != "Count")
{
return;
}
if (!CSharpFactory.AreEquivalent(elementAccessExpression.Expression, memberAccessExpression.Expression))
{
return;
}
ISymbol symbol = context.SemanticModel.GetSymbol(elementAccessExpression, context.CancellationToken);
if (symbol?.Kind != SymbolKind.Property ||
symbol.IsStatic ||
symbol.DeclaredAccessibility != Accessibility.Public ||
!RoslynSymbolUtility.IsList(symbol.ContainingType.OriginalDefinition))
{
return;
}
context.ReportDiagnostic(DiagnosticDescriptors.CallLastInsteadOfUsingElementAccess, elementAccessExpression.ArgumentList);
}
public override async Task RegisterCodeFixesAsync(CodeFixContext context)
{
SyntaxNode root = await context.GetSyntaxRootAsync().ConfigureAwait(false);
if (!TryFindNode(root, context.Span, out ExpressionSyntax expression))
{
return;
}
foreach (Diagnostic diagnostic in context.Diagnostics)
{
switch (diagnostic.Id)
{
case CompilerDiagnosticIdentifiers.CannotImplicitlyConvertTypeExplicitConversionExists:
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
TypeInfo typeInfo = semanticModel.GetTypeInfo(expression, context.CancellationToken);
ITypeSymbol type = typeInfo.Type;
ITypeSymbol convertedType = typeInfo.ConvertedType;
if ((type is INamedTypeSymbol namedType) &&
namedType.IsNullableType())
{
if (convertedType?.SpecialType == SpecialType.System_Boolean ||
AddComparisonWithBooleanLiteralRefactoring.IsCondition(expression))
{
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.AddComparisonWithBooleanLiteral))
{
CodeAction codeAction = CodeAction.Create(
AddComparisonWithBooleanLiteralRefactoring.GetTitle(expression),
cancellationToken => AddComparisonWithBooleanLiteralRefactoring.RefactorAsync(context.Document, expression, cancellationToken),
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.AddComparisonWithBooleanLiteral));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
else if (SymbolEqualityComparer.Default.Equals(namedType.TypeArguments[0], convertedType))
{
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.UseCoalesceExpression))
{
CodeAction codeAction = CodeAction.Create(
"Use coalesce expression",
cancellationToken =>
{
ExpressionSyntax defaultValue = convertedType.GetDefaultValueSyntax(context.Document.GetDefaultSyntaxOptions());
ExpressionSyntax newNode = CoalesceExpression(expression.WithoutTrivia(), defaultValue)
.WithTriviaFrom(expression)
.Parenthesize()
.WithFormatterAnnotation();
return(context.Document.ReplaceNodeAsync(expression, newNode, cancellationToken));
},
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.UseCoalesceExpression));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ChangeMemberTypeAccordingToReturnExpression) &&
expression.IsParentKind(SyntaxKind.ReturnStatement, SyntaxKind.YieldReturnStatement))
{
ChangeMemberTypeRefactoring.ComputeCodeFix(context, diagnostic, expression, semanticModel);
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.AddCastExpression))
{
CodeFixRegistrator.AddCastExpression(context, diagnostic, expression, convertedType, semanticModel);
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ChangeTypeAccordingToInitializer))
{
ChangeTypeAccordingToInitializerRefactoring.ComputeCodeFix(context, diagnostic, expression, semanticModel);
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.CreateSingletonArray) &&
type?.IsErrorType() == false &&
!SymbolEqualityComparer.Default.Equals(type, convertedType) &&
(convertedType is IArrayTypeSymbol arrayType) &&
semanticModel.IsImplicitConversion(expression, arrayType.ElementType))
{
CodeAction codeAction = CodeAction.Create(
"Create singleton array",
cancellationToken => CreateSingletonArrayRefactoring.RefactorAsync(context.Document, expression, arrayType.ElementType, semanticModel, cancellationToken),
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.CreateSingletonArray));
context.RegisterCodeFix(codeAction, diagnostic);
}
break;
}
case CompilerDiagnosticIdentifiers.ConstantValueCannotBeConverted:
{
if (!Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.UseUncheckedExpression))
{
break;
}
CodeAction codeAction = CodeAction.Create(
"Use 'unchecked'",
cancellationToken =>
{
CheckedExpressionSyntax newNode = CSharpFactory.UncheckedExpression(expression.WithoutTrivia());
newNode = newNode.WithTriviaFrom(expression);
return(context.Document.ReplaceNodeAsync(expression, newNode, cancellationToken));
},
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case CompilerDiagnosticIdentifiers.ExpressionBeingAssignedMustBeConstant:
{
SyntaxNode parent = expression.Parent;
if (parent?.IsKind(SyntaxKind.EqualsValueClause) != true)
{
break;
}
parent = parent.Parent;
if (parent?.IsKind(SyntaxKind.VariableDeclarator) != true)
{
break;
}
parent = parent.Parent;
if (!(parent is VariableDeclarationSyntax variableDeclaration))
{
break;
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.RemoveConstModifier) &&
variableDeclaration.Parent is LocalDeclarationStatementSyntax localDeclarationStatement)
{
SyntaxTokenList modifiers = localDeclarationStatement.Modifiers;
if (!modifiers.Contains(SyntaxKind.ConstKeyword))
{
break;
}
ModifiersCodeFixRegistrator.RemoveModifier(context, diagnostic, localDeclarationStatement, SyntaxKind.ConstKeyword);
}
else if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ReplaceConstantWithField) &&
variableDeclaration.Variables.Count == 1 &&
(variableDeclaration.Parent is FieldDeclarationSyntax fieldDeclaration) &&
fieldDeclaration.Modifiers.Contains(SyntaxKind.ConstKeyword))
{
CodeAction codeAction = CodeAction.Create(
ReplaceConstantWithFieldRefactoring.Title,
cancellationToken => ReplaceConstantWithFieldRefactoring.RefactorAsync(context.Document, fieldDeclaration, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
break;
}
case CompilerDiagnosticIdentifiers.CannotConvertNullToTypeBecauseItIsNonNullableValueType:
case CompilerDiagnosticIdentifiers.CannotConvertNullToTypeParameterBecauseItCouldBeNonNullableValueType:
{
if (!Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ReplaceNullLiteralExpressionWithDefaultValue))
{
break;
}
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
CodeFixRegistrator.ReplaceNullWithDefaultValue(context, diagnostic, expression, semanticModel);
break;
}
case CompilerDiagnosticIdentifiers.ResultOfExpressionIsAlwaysConstantSinceValueIsNeverEqualToNull:
{
if (!Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.RemoveConditionThatIsAlwaysEqualToTrueOrFalse))
{
break;
}
NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(expression, allowedStyles: NullCheckStyles.ComparisonToNull);
if (!nullCheck.Success)
{
break;
}
CodeAction codeAction = CodeAction.Create(
"Remove condition",
cancellationToken =>
{
cancellationToken.ThrowIfCancellationRequested();
SyntaxNode newRoot = RemoveCondition(root, expression, nullCheck.Style == NullCheckStyles.NotEqualsToNull);
cancellationToken.ThrowIfCancellationRequested();
return(Task.FromResult(context.Document.WithSyntaxRoot(newRoot)));
},
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case CompilerDiagnosticIdentifiers.OnlyAssignmentCallIncrementDecrementAndNewObjectExpressionsCanBeUsedAsStatement:
{
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.RemoveParentheses) &&
expression is ParenthesizedExpressionSyntax parenthesizedExpression &&
parenthesizedExpression?.IsMissing == false)
{
CodeAction codeAction = CodeActionFactory.RemoveParentheses(context.Document, parenthesizedExpression, equivalenceKey: GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
if (expression.Parent is ArrowExpressionClauseSyntax arrowExpresssionClause)
{
if (!Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ChangeMemberTypeAccordingToReturnExpression))
{
break;
}
ChangeMemberTypeRefactoring.ComputeCodeFix(context, diagnostic, expression, semanticModel);
}
else if (expression.Parent is ExpressionStatementSyntax expressionStatement)
{
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.AddArgumentList) &&
expression.IsKind(
SyntaxKind.IdentifierName,
SyntaxKind.SimpleMemberAccessExpression))
{
SyntaxNode invocationExpression = InvocationExpression(expression);
if (semanticModel.GetSpeculativeMethodSymbol(expression.SpanStart, invocationExpression) != null)
{
CodeAction codeAction = CodeAction.Create(
"Add argument list",
cancellationToken => context.Document.ReplaceNodeAsync(expression, invocationExpression, cancellationToken),
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.AddArgumentList));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ReplaceComparisonWithAssignment) &&
expression.IsKind(SyntaxKind.EqualsExpression))
{
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo(expression);
if (!info.Success)
{
break;
}
ITypeSymbol leftTypeSymbol = semanticModel.GetTypeSymbol(info.Left, context.CancellationToken);
if (leftTypeSymbol?.IsErrorType() != false)
{
break;
}
if (!semanticModel.IsImplicitConversion(info.Right, leftTypeSymbol))
{
break;
}
CodeAction codeAction = CodeAction.Create(
"Replace comparison with assignment",
cancellationToken =>
{
AssignmentExpressionSyntax simpleAssignment = SimpleAssignmentExpression(info.Left, info.Right).WithTriviaFrom(expression);
return(context.Document.ReplaceNodeAsync(expression, simpleAssignment, cancellationToken));
},
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.ReplaceComparisonWithAssignment));
context.RegisterCodeFix(codeAction, diagnostic);
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ReplaceConditionalExpressionWithIfElse) &&
(expression is ConditionalExpressionSyntax conditionalExpression) &&
conditionalExpression.Condition != null)
{
ExpressionSyntax whenTrue = conditionalExpression.WhenTrue;
ExpressionSyntax whenFalse = conditionalExpression.WhenFalse;
if (whenTrue != null &&
whenFalse != null &&
semanticModel.GetTypeSymbol(whenTrue, context.CancellationToken)?.SpecialType == SpecialType.System_Void &&
semanticModel.GetTypeSymbol(whenFalse, context.CancellationToken)?.SpecialType == SpecialType.System_Void)
{
CodeAction codeAction = CodeAction.Create(
"Replace ?: with if-else",
cancellationToken =>
{
IfStatementSyntax newNode = IfStatement(
conditionalExpression.Condition.WalkDownParentheses(),
Block(ExpressionStatement(whenTrue)),
ElseClause(Block(ExpressionStatement(whenFalse))));
newNode = newNode
.WithTriviaFrom(expressionStatement)
.WithFormatterAnnotation();
return(context.Document.ReplaceNodeAsync(expressionStatement, newNode, cancellationToken));
},
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.ReplaceConditionalExpressionWithIfElse));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
if (semanticModel.GetSymbol(expression, context.CancellationToken)?.IsErrorType() != false)
{
break;
}
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(expression, context.CancellationToken);
if (typeSymbol?.IsErrorType() != false)
{
break;
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.IntroduceLocalVariable) &&
!expressionStatement.IsEmbedded())
{
bool addAwait = typeSymbol.OriginalDefinition.EqualsOrInheritsFromTaskOfT() &&
semanticModel.GetEnclosingSymbol(expressionStatement.SpanStart, context.CancellationToken).IsAsyncMethod();
CodeAction codeAction = CodeAction.Create(
IntroduceLocalVariableRefactoring.GetTitle(expression),
cancellationToken => IntroduceLocalVariableRefactoring.RefactorAsync(context.Document, expressionStatement, typeSymbol, addAwait, semanticModel, cancellationToken),
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.IntroduceLocalVariable));
context.RegisterCodeFix(codeAction, diagnostic);
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.IntroduceField))
{
CodeAction codeAction = CodeAction.Create(
$"Introduce field for '{expression}'",
cancellationToken => IntroduceFieldRefactoring.RefactorAsync(context.Document, expressionStatement, typeSymbol, semanticModel, cancellationToken),
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.IntroduceField));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
break;
}
case CompilerDiagnosticIdentifiers.CannotImplicitlyConvertType:
{
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ReplaceYieldReturnWithForEach) &&
expression.IsParentKind(SyntaxKind.YieldReturnStatement))
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ReplaceYieldReturnWithForEachRefactoring.ComputeCodeFix(context, diagnostic, expression, semanticModel);
break;
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ChangeMemberTypeAccordingToReturnExpression) &&
expression.IsParentKind(SyntaxKind.ReturnStatement, SyntaxKind.YieldReturnStatement, SyntaxKind.ArrowExpressionClause))
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ChangeMemberTypeRefactoring.ComputeCodeFix(context, diagnostic, expression, semanticModel);
break;
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ChangeTypeAccordingToInitializer))
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
CodeFixRegistrationResult result = ChangeTypeAccordingToInitializerRefactoring.ComputeCodeFix(context, diagnostic, expression, semanticModel);
if (!result.Success)
{
RemoveAssignmentOfVoidExpression(context, diagnostic, expression, semanticModel);
}
break;
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.ReplaceStringLiteralWithCharacterLiteral) &&
expression?.Kind() == SyntaxKind.StringLiteralExpression)
{
var literalExpression = (LiteralExpressionSyntax)expression;
if (literalExpression.Token.ValueText.Length == 1)
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
if (semanticModel.GetTypeInfo(expression, context.CancellationToken).ConvertedType?.SpecialType == SpecialType.System_Char)
{
CodeAction codeAction = CodeAction.Create(
"Replace string literal with character literal",
cancellationToken => ReplaceStringLiteralWithCharacterLiteralRefactoring.RefactorAsync(context.Document, literalExpression, cancellationToken),
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.ReplaceStringLiteralWithCharacterLiteral));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
}
if (Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.UseYieldReturnInsteadOfReturn) &&
expression.IsParentKind(SyntaxKind.ReturnStatement))
{
var returnStatement = (ReturnStatementSyntax)expression.Parent;
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ISymbol containingSymbol = semanticModel.GetEnclosingSymbol(returnStatement.SpanStart, context.CancellationToken);
if (containingSymbol?.Kind == SymbolKind.Method &&
((IMethodSymbol)containingSymbol).ReturnType.OriginalDefinition.IsIEnumerableOrIEnumerableOfT())
{
CodeAction codeAction = CodeAction.Create(
"Use yield return instead of return",
cancellationToken => UseYieldReturnInsteadOfReturnRefactoring.RefactorAsync(context.Document, returnStatement, SyntaxKind.YieldReturnStatement, semanticModel, cancellationToken),
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.UseYieldReturnInsteadOfReturn));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
break;
}
case CompilerDiagnosticIdentifiers.LeftHandSideOfAssignmentMustBeVariablePropertyOrIndexer:
{
if (!Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.RemoveConstModifier))
{
return;
}
if (!expression.IsKind(SyntaxKind.IdentifierName))
{
return;
}
if (!expression.IsParentKind(SyntaxKind.SimpleAssignmentExpression))
{
return;
}
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
SymbolInfo symbolInfo = semanticModel.GetSymbolInfo(expression, context.CancellationToken);
if (symbolInfo.CandidateReason != CandidateReason.NotAVariable)
{
return;
}
if (!(symbolInfo.CandidateSymbols.SingleOrDefault(shouldThrow: false) is ILocalSymbol localSymbol))
{
return;
}
if (!localSymbol.IsConst)
{
return;
}
SyntaxNode node = localSymbol.GetSyntaxOrDefault(context.CancellationToken);
if (!node.IsKind(SyntaxKind.VariableDeclarator))
{
return;
}
node = node.Parent;
if (!node.IsKind(SyntaxKind.VariableDeclaration))
{
return;
}
node = node.Parent;
if (!(node is LocalDeclarationStatementSyntax localDeclaration))
{
return;
}
SyntaxToken constModifier = localDeclaration.Modifiers.Find(SyntaxKind.ConstKeyword);
if (!constModifier.IsKind(SyntaxKind.ConstKeyword))
{
return;
}
ModifiersCodeFixRegistrator.RemoveModifier(context, diagnostic, localDeclaration, constModifier);
break;
}
case CompilerDiagnosticIdentifiers.ReadOnlyFieldCannotBeAssignedTo:
{
if (!Settings.IsEnabled(diagnostic.Id, CodeFixIdentifiers.MakeFieldWritable))
{
break;
}
SimpleAssignmentExpressionInfo simpleAssignment = SyntaxInfo.SimpleAssignmentExpressionInfo(expression.Parent);
if (!simpleAssignment.Success)
{
return;
}
if (simpleAssignment.Left != expression)
{
return;
}
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
SymbolInfo symbolInfo = semanticModel.GetSymbolInfo(expression, context.CancellationToken);
if (symbolInfo.CandidateReason != CandidateReason.NotAVariable)
{
return;
}
if (!(symbolInfo.CandidateSymbols.SingleOrDefault(shouldThrow: false) is IFieldSymbol fieldSymbol))
{
return;
}
if (fieldSymbol.DeclaredAccessibility != Accessibility.Private)
{
return;
}
if (!(fieldSymbol.GetSyntax().Parent.Parent is FieldDeclarationSyntax fieldDeclaration))
{
return;
}
TypeDeclarationSyntax containingTypeDeclaration = fieldDeclaration.FirstAncestor <TypeDeclarationSyntax>();
if (!expression.Ancestors().Any(f => f == containingTypeDeclaration))
{
return;
}
ModifiersCodeFixRegistrator.RemoveModifier(
context,
diagnostic,
fieldDeclaration,
SyntaxKind.ReadOnlyKeyword,
title: $"Make '{fieldSymbol.Name}' writable");
break;
}
}
}
}
public static void Analyze(SyntaxNodeAnalysisContext context, SimpleMemberInvocationExpressionInfo invocationInfo)
{
INamedTypeSymbol stringBuilderSymbol = context.GetTypeByMetadataName(MetadataNames.System_Text_StringBuilder);
if (stringBuilderSymbol == null)
{
return;
}
InvocationExpressionSyntax invocationExpression = invocationInfo.InvocationExpression;
IMethodSymbol methodSymbol = context.SemanticModel.GetMethodSymbol(invocationExpression, context.CancellationToken);
if (methodSymbol == null)
{
return;
}
if (methodSymbol.IsExtensionMethod)
{
return;
}
if (methodSymbol.ContainingType?.Equals(stringBuilderSymbol) != true)
{
return;
}
ImmutableArray <IParameterSymbol> parameters = methodSymbol.Parameters;
int parameterCount = parameters.Length;
if (parameterCount == 0)
{
if (methodSymbol.IsName("AppendLine"))
{
SimpleMemberInvocationExpressionInfo invocationInfo2 = SyntaxInfo.SimpleMemberInvocationExpressionInfo(invocationInfo.Expression);
if (invocationInfo2.Success &&
invocationInfo2.NameText == "Append" &&
invocationInfo2.Arguments.Count == 1)
{
IMethodSymbol methodInfo2 = context.SemanticModel.GetMethodSymbol(invocationInfo2.InvocationExpression, context.CancellationToken);
if (methodInfo2?.IsStatic == false &&
methodInfo2.ContainingType?.Equals(stringBuilderSymbol) == true &&
methodInfo2.HasSingleParameter(SpecialType.System_String))
{
context.ReportDiagnostic(DiagnosticDescriptors.OptimizeStringBuilderAppendCall, invocationInfo.Name, methodSymbol.Name);
}
}
}
}
else if (parameterCount == 1)
{
if (methodSymbol.IsName("Append", "AppendLine"))
{
ArgumentSyntax argument = invocationInfo.Arguments.SingleOrDefault(shouldThrow: false);
if (argument != null)
{
ExpressionSyntax expression = argument.Expression;
SyntaxKind expressionKind = expression.Kind();
switch (expressionKind)
{
case SyntaxKind.InterpolatedStringExpression:
{
context.ReportDiagnostic(DiagnosticDescriptors.OptimizeStringBuilderAppendCall, argument, methodSymbol.Name);
return;
}
case SyntaxKind.AddExpression:
{
BinaryExpressionInfo binaryExpressionInfo = SyntaxInfo.BinaryExpressionInfo((BinaryExpressionSyntax)expression);
if (binaryExpressionInfo.Success &&
binaryExpressionInfo.IsStringConcatenation(context.SemanticModel, context.CancellationToken))
{
context.ReportDiagnostic(DiagnosticDescriptors.OptimizeStringBuilderAppendCall, argument, methodSymbol.Name);
return;
}
break;
}
default:
{
if (expressionKind == SyntaxKind.InvocationExpression &&
IsFixable((InvocationExpressionSyntax)expression, context.SemanticModel, context.CancellationToken))
{
context.ReportDiagnostic(DiagnosticDescriptors.OptimizeStringBuilderAppendCall, argument, methodSymbol.Name);
return;
}
if (methodSymbol.IsName("Append") &&
parameterCount == 1 &&
parameters[0].Type.IsObject() &&
context.SemanticModel.GetTypeSymbol(argument.Expression, context.CancellationToken).IsValueType)
{
context.ReportDiagnostic(DiagnosticDescriptors.AvoidBoxingOfValueType, argument);
return;
}
break;
}
}
}
}
}
else if (parameterCount == 2)
{
if (methodSymbol.IsName("Insert") &&
parameters[0].Type.SpecialType == SpecialType.System_Int32 &&
parameters[1].Type.SpecialType == SpecialType.System_Object)
{
SeparatedSyntaxList <ArgumentSyntax> arguments = invocationInfo.Arguments;
if (arguments.Count == 2 &&
context.SemanticModel
.GetTypeSymbol(arguments[1].Expression, context.CancellationToken)
.IsValueType)
{
context.ReportDiagnostic(DiagnosticDescriptors.AvoidBoxingOfValueType, arguments[1]);
}
}
}
}
private static void AnalyzeSimpleAssignment(SyntaxNodeAnalysisContext context)
{
var assignmentExpression = (AssignmentExpressionSyntax)context.Node;
SimpleAssignmentExpressionInfo assignmentInfo = SyntaxInfo.SimpleAssignmentExpressionInfo(assignmentExpression);
if (!assignmentInfo.Success)
{
return;
}
if (assignmentExpression.IsParentKind(SyntaxKind.ObjectInitializerExpression))
{
return;
}
ExpressionSyntax right = assignmentInfo.Right;
if (!CanBeReplacedWithCompoundAssignment(right.Kind()))
{
return;
}
BinaryExpressionInfo binaryInfo = SyntaxInfo.BinaryExpressionInfo((BinaryExpressionSyntax)right);
if (!binaryInfo.Success)
{
return;
}
if (!CSharpFactory.AreEquivalent(assignmentInfo.Left, binaryInfo.Left))
{
return;
}
var binaryExpression = (BinaryExpressionSyntax)right;
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticDescriptors.UseCompoundAssignment, assignmentExpression, GetCompoundAssignmentOperatorText(binaryExpression));
DiagnosticHelpers.ReportNode(context, DiagnosticDescriptors.UseCompoundAssignmentFadeOut, binaryExpression.Left);
bool CanBeReplacedWithCompoundAssignment(SyntaxKind kind)
{
switch (kind)
{
case SyntaxKind.AddExpression:
case SyntaxKind.SubtractExpression:
case SyntaxKind.MultiplyExpression:
case SyntaxKind.DivideExpression:
case SyntaxKind.ModuloExpression:
case SyntaxKind.BitwiseAndExpression:
case SyntaxKind.ExclusiveOrExpression:
case SyntaxKind.BitwiseOrExpression:
case SyntaxKind.LeftShiftExpression:
case SyntaxKind.RightShiftExpression:
return(true);
case SyntaxKind.CoalesceExpression:
return(((CSharpCompilation)context.Compilation).LanguageVersion >= LanguageVersion.CSharp8);
default:
return(false);
}
}
}
private static void AnalyzeSimpleMemberAccessExpression(SyntaxNodeAnalysisContext context)
{
var memberAccessExpression = (MemberAccessExpressionSyntax)context.Node;
SimpleNameSyntax name = memberAccessExpression.Name;
switch (name)
{
case IdentifierNameSyntax identifierName:
{
switch (identifierName.Identifier.ValueText)
{
case "Start":
{
ExpressionSyntax expression = memberAccessExpression.Expression;
if (!expression.IsKind(SyntaxKind.SimpleMemberAccessExpression))
{
break;
}
ISymbol symbol = context.SemanticModel.GetSymbol(memberAccessExpression, context.CancellationToken);
if (symbol == null)
{
break;
}
if (!symbol.ContainingType.HasMetadataName(RoslynMetadataNames.Microsoft_CodeAnalysis_Text_TextSpan))
{
break;
}
var memberAccess2 = (MemberAccessExpressionSyntax)expression;
SimpleNameSyntax name2 = memberAccess2.Name;
if (!(name2 is IdentifierNameSyntax identifierName2))
{
break;
}
if (!string.Equals(identifierName2.Identifier.ValueText, "Span", StringComparison.Ordinal))
{
break;
}
ISymbol symbol2 = context.SemanticModel.GetSymbol(expression, context.CancellationToken);
if (symbol2 == null)
{
break;
}
if (!symbol2.ContainingType.HasMetadataName(RoslynMetadataNames.Microsoft_CodeAnalysis_SyntaxNode))
{
break;
}
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.UsePropertySyntaxNodeSpanStart, memberAccessExpression);
break;
}
case "Count":
{
CallAnyInsteadOfUsingCount();
break;
}
}
break;
}
}
void CallAnyInsteadOfUsingCount()
{
SyntaxNode expression = memberAccessExpression.WalkUpParentheses();
SyntaxNode parent = expression.Parent;
if (!parent.IsKind(SyntaxKind.EqualsExpression, SyntaxKind.NotEqualsExpression, SyntaxKind.GreaterThanExpression))
{
return;
}
BinaryExpressionInfo binaryExpressionInfo = SyntaxInfo.BinaryExpressionInfo((BinaryExpressionSyntax)parent);
if (!binaryExpressionInfo.Success)
{
return;
}
ExpressionSyntax otherExpression = (expression == binaryExpressionInfo.Left)
? binaryExpressionInfo.Right
: binaryExpressionInfo.Left;
if (!otherExpression.IsKind(SyntaxKind.NumericLiteralExpression))
{
return;
}
var numericLiteralExpression = (LiteralExpressionSyntax)otherExpression;
if (numericLiteralExpression.Token.ValueText != "0")
{
return;
}
ISymbol symbol = context.SemanticModel.GetSymbol(memberAccessExpression, context.CancellationToken);
if (symbol?.Kind != SymbolKind.Property ||
symbol.IsStatic ||
symbol.DeclaredAccessibility != Accessibility.Public ||
!RoslynSymbolUtility.IsList(symbol.ContainingType.OriginalDefinition))
{
return;
}
TextSpan span = (memberAccessExpression == binaryExpressionInfo.Left)
? TextSpan.FromBounds(name.SpanStart, numericLiteralExpression.Span.End)
: TextSpan.FromBounds(numericLiteralExpression.SpanStart, name.Span.End);
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.CallAnyInsteadOfAccessingCount, Location.Create(memberAccessExpression.SyntaxTree, span));
}
}
public static void ComputeRefactoring(RefactoringContext context, BinaryExpressionSyntax binaryExpression)
{
BinaryExpressionInfo info = SyntaxInfo.BinaryExpressionInfo(binaryExpression);
if (!info.Success)
{
return;
}
if (CanRefactor())
{
context.RegisterRefactoring(
"Swap operands",
ct =>
{
BinaryExpressionSyntax newBinaryExpression = SyntaxRefactorings.SwapBinaryOperands(binaryExpression);
newBinaryExpression = newBinaryExpression.WithOperatorToken(newBinaryExpression.OperatorToken.WithNavigationAnnotation());
return(context.Document.ReplaceNodeAsync(binaryExpression, newBinaryExpression, ct));
},
RefactoringDescriptors.SwapBinaryOperands);
}
bool CanRefactor()
{
SyntaxKind kind = binaryExpression.Kind();
switch (kind)
{
case SyntaxKind.LogicalAndExpression:
case SyntaxKind.LogicalOrExpression:
case SyntaxKind.BitwiseAndExpression:
case SyntaxKind.BitwiseOrExpression:
case SyntaxKind.ExclusiveOrExpression:
case SyntaxKind.AddExpression:
case SyntaxKind.MultiplyExpression:
{
return(!info.Left.IsKind(kind));
}
case SyntaxKind.EqualsExpression:
case SyntaxKind.NotEqualsExpression:
{
return(!info.Right.IsKind(
SyntaxKind.NullLiteralExpression,
SyntaxKind.TrueLiteralExpression,
SyntaxKind.FalseLiteralExpression));
}
case SyntaxKind.GreaterThanExpression:
case SyntaxKind.GreaterThanOrEqualExpression:
case SyntaxKind.LessThanExpression:
case SyntaxKind.LessThanOrEqualExpression:
{
return(true);
}
}
return(false);
}
}
