1 files changed, 134 insertions, 0 deletions
diff --git a/src/ILLink.CodeFix/DAMCodeFixProvider.cs b/src/ILLink.CodeFix/DAMCodeFixProvider.cs
new file mode 100644
index 000000000..60de66cea
--- /dev/null
+++ b/src/ILLink.CodeFix/DAMCodeFixProvider.cs
@@ -0,0 +1,134 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Collections.Immutable;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using ILLink.CodeFixProvider;
+using ILLink.RoslynAnalyzer;
+using ILLink.Shared;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Editing;
+using Microsoft.CodeAnalysis.Simplification;
+
+namespace ILLink.CodeFix
+{
+	public class DAMCodeFixProvider : Microsoft.CodeAnalysis.CodeFixes.CodeFixProvider
+	{
+		public static ImmutableArray<DiagnosticDescriptor> GetSupportedDiagnostics ()
+		{
+			var diagDescriptorsArrayBuilder = ImmutableArray.CreateBuilder<DiagnosticDescriptor> ();
+			diagDescriptorsArrayBuilder.Add (DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.DynamicallyAccessedMembersMismatchParameterTargetsThisParameter));
+			diagDescriptorsArrayBuilder.Add (DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.DynamicallyAccessedMembersMismatchFieldTargetsThisParameter));
+			return diagDescriptorsArrayBuilder.ToImmutable ();
+		}
+
+		public static ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => GetSupportedDiagnostics ();
+
+		public sealed override ImmutableArray<string> FixableDiagnosticIds => SupportedDiagnostics.Select (dd => dd.Id).ToImmutableArray ();
+
+		private protected static LocalizableString CodeFixTitle => new LocalizableResourceString (nameof (Resources.DynamicallyAccessedMembersCodeFixTitle), Resources.ResourceManager, typeof (Resources));
+
+		private protected static string FullyQualifiedAttributeName => DynamicallyAccessedMembersAnalyzer.FullyQualifiedDynamicallyAccessedMembersAttribute;
+
+		protected static SyntaxNode[] GetAttributeArguments (ISymbol targetSymbol, SyntaxGenerator syntaxGenerator, Diagnostic diagnostic)
+		{
+			object id = Enum.Parse (typeof (DiagnosticId), diagnostic.Id.Substring (2));
+			switch (id) {
+			case DiagnosticId.DynamicallyAccessedMembersMismatchParameterTargetsThisParameter:
+				return new[] { syntaxGenerator.AttributeArgument (syntaxGenerator.TypedConstantExpression (targetSymbol.GetAttributes ().First (attr => attr.AttributeClass?.ToDisplayString () == DynamicallyAccessedMembersAnalyzer.FullyQualifiedDynamicallyAccessedMembersAttribute).ConstructorArguments[0])) };
+			case DiagnosticId.DynamicallyAccessedMembersMismatchFieldTargetsThisParameter:
+				return new[] { syntaxGenerator.AttributeArgument (syntaxGenerator.TypedConstantExpression (targetSymbol.GetAttributes ().First (attr => attr.AttributeClass?.ToDisplayString () == DynamicallyAccessedMembersAnalyzer.FullyQualifiedDynamicallyAccessedMembersAttribute).ConstructorArguments[0])) };
+			default:
+				return Array.Empty<SyntaxNode> ();
+			}
+		}
+
+		public sealed override FixAllProvider GetFixAllProvider ()
+		{
+			// See https://github.com/dotnet/roslyn/blob/master/docs/analyzers/FixAllProvider.md for more information on Fix All Providers
+			return WellKnownFixAllProviders.BatchFixer;
+		}
+
+		public override async Task RegisterCodeFixesAsync (CodeFixContext context)
+		{
+			var document = context.Document;
+			if (await document.GetSyntaxRootAsync (context.CancellationToken).ConfigureAwait (false) is not { } root)
+				return;
+			var diagnostic = context.Diagnostics.First ();
+			SyntaxNode diagnosticNode = root.FindNode (diagnostic.Location.SourceSpan, getInnermostNodeForTie: true);
+			if (await document.GetSemanticModelAsync (context.CancellationToken).ConfigureAwait (false) is not { } model)
+				return;
+			// Note: We get the target symbol from the diagnostic location. 
+			// This works when the diagnostic location is a method call, because the target symbol will be the called method with annotations, but won't work in general for other kinds of diagnostics.
+			if (model.GetSymbolInfo (diagnosticNode).Symbol is not { } targetSymbol)
+				return;
+			if (model.Compilation.GetTypeByMetadataName (FullyQualifiedAttributeName) is not { } attributeSymbol)
+				return;
+
+			if (diagnosticNode is not InvocationExpressionSyntax invocationExpression)
+				return;
+
+			var arguments = invocationExpression.ArgumentList.Arguments;
+
+			if (arguments.Count > 1)
+				return;
+
+			if (arguments.Count == 1) {
+				if (arguments[0].Expression is not LiteralExpressionSyntax literalSyntax
+					|| literalSyntax.Kind () is not SyntaxKind.StringLiteralExpression) {
+					return;
+				}
+			}
+
+			// N.B. May be null for FieldDeclaration, since field declarations can declare multiple variables
+			var attributableSymbol = (invocationExpression.Expression is MemberAccessExpressionSyntax simpleMember
+					&& simpleMember.Expression is IdentifierNameSyntax name) ? model.GetSymbolInfo (name).Symbol : null;
+
+
+			if (attributableSymbol is null)
+				return;
+
+			var attributableNodeList = attributableSymbol.DeclaringSyntaxReferences;
+
+			if (attributableNodeList.Length != 1)
+				return;
+
+			var attributableNode = attributableNodeList[0].GetSyntax ();
+
+			if (attributableNode is null) return;
+
+			var attributeArguments = GetAttributeArguments (targetSymbol, SyntaxGenerator.GetGenerator (document), diagnostic);
+			var codeFixTitle = CodeFixTitle.ToString ();
+
+			context.RegisterCodeFix (CodeAction.Create (
+				title: codeFixTitle,
+				createChangedDocument: ct => AddAttributeAsync (
+					document, attributableNode, attributeArguments, attributeSymbol, ct),
+				equivalenceKey: codeFixTitle), diagnostic);
+		}
+
+		private static async Task<Document> AddAttributeAsync (
+			Document document,
+			SyntaxNode targetNode,
+			SyntaxNode[] attributeArguments,
+			ITypeSymbol attributeSymbol,
+			CancellationToken cancellationToken)
+		{
+			var editor = await DocumentEditor.CreateAsync (document, cancellationToken).ConfigureAwait (false);
+			var generator = editor.Generator;
+			var attribute = generator.Attribute (
+				generator.TypeExpression (attributeSymbol), attributeArguments)
+				.WithAdditionalAnnotations (Simplifier.Annotation, Simplifier.AddImportsAnnotation);
+
+			editor.AddAttribute (targetNode, attribute);
+			return editor.GetChangedDocument ();
+		}
+	}
+}