public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
{
if (!Settings.IsAnyCodeFixEnabled(
CodeFixIdentifiers.UseYieldReturnInsteadOfReturn,
CodeFixIdentifiers.RemoveReturnKeyword,
CodeFixIdentifiers.RemoveReturnExpression))
{
return;
}
SyntaxNode root = await context.GetSyntaxRootAsync().ConfigureAwait(false);
ReturnStatementSyntax returnStatement = root
.FindNode(context.Span, getInnermostNodeForTie: true)?
.FirstAncestorOrSelf <ReturnStatementSyntax>();
Debug.Assert(returnStatement != null, $"{nameof(returnStatement)} is null");
if (returnStatement == null)
{
return;
}
foreach (Diagnostic diagnostic in context.Diagnostics)
{
switch (diagnostic.Id)
{
case CompilerDiagnosticIdentifiers.CannotReturnValueFromIterator:
{
if (!Settings.IsCodeFixEnabled(CodeFixIdentifiers.UseYieldReturnInsteadOfReturn))
{
break;
}
ExpressionSyntax expression = returnStatement.Expression;
if (expression != null)
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ISymbol containingSymbol = semanticModel.GetEnclosingSymbol(returnStatement.SpanStart, context.CancellationToken);
if (containingSymbol?.IsKind(SymbolKind.Method) == true)
{
var methodSymbol = (IMethodSymbol)containingSymbol;
ITypeSymbol returnType = methodSymbol.ReturnType;
var replacementKind = SyntaxKind.None;
if (returnType.SpecialType == SpecialType.System_Collections_IEnumerable)
{
if (semanticModel
.GetTypeSymbol(expression, context.CancellationToken)
.IsIEnumerableOrConstructedFromIEnumerableOfT())
{
replacementKind = SyntaxKind.ForEachStatement;
}
else
{
replacementKind = SyntaxKind.YieldReturnStatement;
}
}
else if (returnType.IsNamedType())
{
var namedTypeSymbol = (INamedTypeSymbol)returnType;
if (namedTypeSymbol.IsConstructedFromIEnumerableOfT())
{
if (semanticModel.IsImplicitConversion(expression, namedTypeSymbol.TypeArguments[0]))
{
replacementKind = SyntaxKind.YieldReturnStatement;
}
else
{
replacementKind = SyntaxKind.ForEachStatement;
}
}
}
if (replacementKind == SyntaxKind.YieldReturnStatement ||
(replacementKind == SyntaxKind.ForEachStatement && !returnStatement.SpanContainsDirectives()))
{
CodeAction codeAction = CodeAction.Create(
"Use yield return instead of return",
cancellationToken => UseYieldReturnInsteadOfReturnRefactoring.RefactorAsync(context.Document, returnStatement, replacementKind, semanticModel, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
}
break;
}
case CompilerDiagnosticIdentifiers.SinceMethodReturnsVoidReturnKeywordMustNotBeFollowedByObjectExpression:
case CompilerDiagnosticIdentifiers.SinceMethodIsAsyncMethodThatReturnsTaskReturnKeywordMustNotBeFollowedByObjectExpression:
{
if (Settings.IsCodeFixEnabled(CodeFixIdentifiers.RemoveReturnExpression))
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ISymbol symbol = semanticModel.GetEnclosingSymbol(returnStatement.SpanStart, context.CancellationToken);
if (symbol?.IsMethod() == true)
{
var methodSymbol = (IMethodSymbol)symbol;
if (methodSymbol.ReturnsVoid ||
methodSymbol.ReturnType.Equals(semanticModel.GetTypeByMetadataName(MetadataNames.System_Threading_Tasks_Task)))
{
CodeAction codeAction = CodeAction.Create(
"Remove return expression",
cancellationToken =>
{
ReturnStatementSyntax newNode = returnStatement
.WithExpression(null)
.WithFormatterAnnotation();
return(context.Document.ReplaceNodeAsync(returnStatement, newNode, cancellationToken));
},
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.RemoveReturnExpression));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
}
if (Settings.IsCodeFixEnabled(CodeFixIdentifiers.RemoveReturnKeyword))
{
ExpressionSyntax expression = returnStatement.Expression;
if (expression.IsKind(
SyntaxKind.InvocationExpression,
SyntaxKind.ObjectCreationExpression,
SyntaxKind.PreDecrementExpression,
SyntaxKind.PreIncrementExpression,
SyntaxKind.PostDecrementExpression,
SyntaxKind.PostIncrementExpression) ||
expression is AssignmentExpressionSyntax)
{
CodeAction codeAction = CodeAction.Create(
"Remove 'return'",
cancellationToken =>
{
SyntaxTriviaList leadingTrivia = returnStatement
.GetLeadingTrivia()
.AddRange(returnStatement.ReturnKeyword.TrailingTrivia.EmptyIfWhitespace())
.AddRange(expression.GetLeadingTrivia().EmptyIfWhitespace());
ExpressionStatementSyntax newNode = SyntaxFactory.ExpressionStatement(
expression.WithLeadingTrivia(leadingTrivia),
returnStatement.SemicolonToken);
return(context.Document.ReplaceNodeAsync(returnStatement, newNode, cancellationToken));
},
GetEquivalenceKey(diagnostic, CodeFixIdentifiers.RemoveReturnKeyword));
context.RegisterCodeFix(codeAction, diagnostic);
}
}
break;
}
}
}
}
