Switch 'use auto prop' to use NRT and make us more null safe.

src/Analyzers/CSharp/Analyzers/UseAutoProperty/CSharpUseAutoPropertyAnalyzer.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
@@ -47,18 +49,18 @@ protected override bool CanExplicitInterfaceImplementationsBeFixed()
             MemberDeclarationSyntax member,
             List<AnalysisResult> analysisResults)
         {
-            if (member.IsKind(SyntaxKind.NamespaceDeclaration, out NamespaceDeclarationSyntax namespaceDeclaration))
+            if (member.IsKind(SyntaxKind.NamespaceDeclaration, out NamespaceDeclarationSyntax? namespaceDeclaration))
             {
                 AnalyzeMembers(context, namespaceDeclaration.Members, analysisResults);
             }
-            else if (member.IsKind(SyntaxKind.ClassDeclaration, out TypeDeclarationSyntax typeDeclaration) ||
+            else if (member.IsKind(SyntaxKind.ClassDeclaration, out TypeDeclarationSyntax? typeDeclaration) ||
                 member.IsKind(SyntaxKind.StructDeclaration, out typeDeclaration) ||
                 member.IsKind(SyntaxKindEx.RecordDeclaration, out typeDeclaration))
             {
                 // If we have a class or struct, recurse inwards.
                 AnalyzeMembers(context, typeDeclaration.Members, analysisResults);
             }
-            else if (member.IsKind(SyntaxKind.PropertyDeclaration, out PropertyDeclarationSyntax propertyDeclaration))
+            else if (member.IsKind(SyntaxKind.PropertyDeclaration, out PropertyDeclarationSyntax? propertyDeclaration))
             {
                 AnalyzeProperty(context, propertyDeclaration, analysisResults);
             }
@@ -68,7 +70,7 @@ protected override bool CanExplicitInterfaceImplementationsBeFixed()
             List<AnalysisResult> analysisResults, HashSet<IFieldSymbol> ineligibleFields,
             Compilation compilation, CancellationToken cancellationToken)
         {
-            var groups = analysisResults.Select(r => (typeDeclaration: (TypeDeclarationSyntax)r.PropertyDeclaration.Parent, r.SemanticModel))
+            var groups = analysisResults.Select(r => (typeDeclaration: (TypeDeclarationSyntax)r.PropertyDeclaration.Parent!, r.SemanticModel))
                                         .Distinct()
                                         .GroupBy(n => n.typeDeclaration.SyntaxTree);
 
@@ -94,7 +96,7 @@ protected override bool CanExplicitInterfaceImplementationsBeFixed()
             }
         }
 
-        protected override ExpressionSyntax GetFieldInitializer(
+        protected override ExpressionSyntax? GetFieldInitializer(
             VariableDeclaratorSyntax variable, CancellationToken cancellationToken)
         {
             return variable.Initializer?.Value;
@@ -111,7 +113,7 @@ protected override bool CanExplicitInterfaceImplementationsBeFixed()
                 AddIneligibleField(symbol);
             }
 
-            void AddIneligibleField(ISymbol symbol)
+            void AddIneligibleField(ISymbol? symbol)
             {
                 if (symbol is IFieldSymbol field)
                 {
@@ -122,7 +124,7 @@ void AddIneligibleField(ISymbol symbol)
 
         private static bool CheckExpressionSyntactically(ExpressionSyntax expression)
         {
-            if (expression.IsKind(SyntaxKind.SimpleMemberAccessExpression, out MemberAccessExpressionSyntax memberAccessExpression))
+            if (expression.IsKind(SyntaxKind.SimpleMemberAccessExpression, out MemberAccessExpressionSyntax? memberAccessExpression))
             {
                 return memberAccessExpression.Expression.Kind() == SyntaxKind.ThisExpression &&
                     memberAccessExpression.Name.Kind() == SyntaxKind.IdentifierName;
@@ -135,7 +137,7 @@ private static bool CheckExpressionSyntactically(ExpressionSyntax expression)
             return false;
         }
 
-        protected override ExpressionSyntax GetGetterExpression(IMethodSymbol getMethod, CancellationToken cancellationToken)
+        protected override ExpressionSyntax? GetGetterExpression(IMethodSymbol getMethod, CancellationToken cancellationToken)
         {
             // Getter has to be of the form:
             // 1. Getter can be defined as accessor or expression bodied lambda
@@ -154,7 +156,7 @@ protected override ExpressionSyntax GetGetterExpression(IMethodSymbol getMethod,
             return CheckExpressionSyntactically(expr) ? expr : null;
         }
 
-        private static ExpressionSyntax GetGetterExpressionFromSymbol(IMethodSymbol getMethod, CancellationToken cancellationToken)
+        private static ExpressionSyntax? GetGetterExpressionFromSymbol(IMethodSymbol getMethod, CancellationToken cancellationToken)
         {
             var declaration = getMethod.DeclaringSyntaxReferences[0].GetSyntax(cancellationToken);
             switch (declaration)
@@ -169,7 +171,7 @@ private static ExpressionSyntax GetGetterExpressionFromSymbol(IMethodSymbol getM
             }
         }
 
-        private static T GetSingleStatementFromAccessor<T>(AccessorDeclarationSyntax accessorDeclaration) where T : StatementSyntax
+        private static T? GetSingleStatementFromAccessor<T>(AccessorDeclarationSyntax? accessorDeclaration) where T : StatementSyntax
         {
             var statements = accessorDeclaration?.Body?.Statements;
             if (statements?.Count == 1)
@@ -181,7 +183,7 @@ private static ExpressionSyntax GetGetterExpressionFromSymbol(IMethodSymbol getM
             return null;
         }
 
-        protected override ExpressionSyntax GetSetterExpression(
+        protected override ExpressionSyntax? GetSetterExpression(
             IMethodSymbol setMethod, SemanticModel semanticModel, CancellationToken cancellationToken)
         {
             // Setter has to be of the form:
@@ -205,7 +207,7 @@ private static ExpressionSyntax GetGetterExpressionFromSymbol(IMethodSymbol getM
             return null;
         }
 
-        private static ExpressionSyntax GetExpressionFromSetter(AccessorDeclarationSyntax setAccessor)
+        private static ExpressionSyntax? GetExpressionFromSetter(AccessorDeclarationSyntax? setAccessor)
             => setAccessor?.ExpressionBody?.Expression ??
                GetSingleStatementFromAccessor<ExpressionStatementSyntax>(setAccessor)?.Expression;
 

src/Analyzers/Core/Analyzers/UseAutoProperty/AbstractUseAutoPropertyAnalyzer.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Threading;
@@ -13,7 +15,10 @@
 namespace Microsoft.CodeAnalysis.UseAutoProperty
 {
     internal abstract class AbstractUseAutoPropertyAnalyzer<
-        TPropertyDeclaration, TFieldDeclaration, TVariableDeclarator, TExpression> : AbstractBuiltInCodeStyleDiagnosticAnalyzer
+        TPropertyDeclaration,
+        TFieldDeclaration,
+        TVariableDeclarator,
+        TExpression> : AbstractBuiltInCodeStyleDiagnosticAnalyzer
         where TPropertyDeclaration : SyntaxNode
         where TFieldDeclaration : SyntaxNode
         where TVariableDeclarator : SyntaxNode
@@ -34,9 +39,9 @@ protected AbstractUseAutoPropertyAnalyzer()
         protected abstract bool SupportsReadOnlyProperties(Compilation compilation);
         protected abstract bool SupportsPropertyInitializer(Compilation compilation);
         protected abstract bool CanExplicitInterfaceImplementationsBeFixed();
-        protected abstract TExpression GetFieldInitializer(TVariableDeclarator variable, CancellationToken cancellationToken);
-        protected abstract TExpression GetGetterExpression(IMethodSymbol getMethod, CancellationToken cancellationToken);
-        protected abstract TExpression GetSetterExpression(IMethodSymbol setMethod, SemanticModel semanticModel, CancellationToken cancellationToken);
+        protected abstract TExpression? GetFieldInitializer(TVariableDeclarator variable, CancellationToken cancellationToken);
+        protected abstract TExpression? GetGetterExpression(IMethodSymbol getMethod, CancellationToken cancellationToken);
+        protected abstract TExpression? GetSetterExpression(IMethodSymbol setMethod, SemanticModel semanticModel, CancellationToken cancellationToken);
         protected abstract SyntaxNode GetNodeToFade(TFieldDeclaration fieldDeclaration, TVariableDeclarator variableDeclarator);
 
         protected abstract void RegisterIneligibleFieldsAction(
@@ -213,7 +218,7 @@ private void AnalyzeSemanticModel(SemanticModelAnalysisContext context)
                 return;
             }
 
-            if (!(variableDeclarator?.Parent?.Parent is TFieldDeclaration fieldDeclaration))
+            if (!(variableDeclarator.Parent?.Parent is TFieldDeclaration fieldDeclaration))
             {
                 return;
             }
@@ -230,26 +235,27 @@ private void AnalyzeSemanticModel(SemanticModelAnalysisContext context)
             }
 
             // Looks like a viable property/field to convert into an auto property.
-            analysisResults.Add(new AnalysisResult(property, getterField, propertyDeclaration,
-                fieldDeclaration, variableDeclarator, semanticModel, property.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)));
+            analysisResults.Add(new AnalysisResult(
+                property, getterField, propertyDeclaration, fieldDeclaration, variableDeclarator, semanticModel,
+                property.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)));
         }
 
         protected virtual bool CanConvert(IPropertySymbol property)
             => true;
 
-        private IFieldSymbol GetSetterField(
+        private IFieldSymbol? GetSetterField(
             SemanticModel semanticModel, IMethodSymbol setMethod, CancellationToken cancellationToken)
         {
             return CheckFieldAccessExpression(semanticModel, GetSetterExpression(setMethod, semanticModel, cancellationToken));
         }
 
-        private IFieldSymbol GetGetterField(
+        private IFieldSymbol? GetGetterField(
             SemanticModel semanticModel, IMethodSymbol getMethod, CancellationToken cancellationToken)
         {
             return CheckFieldAccessExpression(semanticModel, GetGetterExpression(getMethod, cancellationToken));
         }
 
-        private static IFieldSymbol CheckFieldAccessExpression(SemanticModel semanticModel, TExpression expression)
+        private static IFieldSymbol? CheckFieldAccessExpression(SemanticModel semanticModel, TExpression? expression)
         {
             if (expression == null)
             {
@@ -310,7 +316,8 @@ private void Process(AnalysisResult result, SemanticModelAnalysisContext context
             // an auto property.  For each diagnostic store both location so we can easily retrieve
             // them when performing the code fix.
             var additionalLocations = ImmutableArray.Create(
-                propertyDeclaration.GetLocation(), variableDeclarator.GetLocation());
+                propertyDeclaration.GetLocation(),
+                variableDeclarator.GetLocation());
 
             var option = context.GetOption(CodeStyleOptions2.PreferAutoProperties, propertyDeclaration.Language);
             if (option.Notification.Severity == ReportDiagnostic.Suppress)

src/Features/CSharp/Portable/UseAutoProperty/CSharpUseAutoPropertyCodeFixProvider.cs

@@ -27,6 +27,9 @@ public CSharpUseAutoPropertyCodeFixProvider()
         {
         }
 
+        protected override PropertyDeclarationSyntax GetPropertyDeclaration(SyntaxNode node)
+            => (PropertyDeclarationSyntax)node;
+
         protected override SyntaxNode GetNodeToRemove(VariableDeclaratorSyntax declarator)
         {
             var fieldDeclaration = (FieldDeclarationSyntax)declarator.Parent.Parent;

src/Features/Core/Portable/UseAutoProperty/AbstractUseAutoPropertyCodeFixProvider.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
@@ -36,6 +38,7 @@ public sealed override ImmutableArray<string> FixableDiagnosticIds
 
         public sealed override FixAllProvider GetFixAllProvider() => WellKnownFixAllProviders.BatchFixer;
 
+        protected abstract TPropertyDeclaration GetPropertyDeclaration(SyntaxNode node);
         protected abstract SyntaxNode GetNodeToRemove(TVariableDeclarator declarator);
 
         protected abstract IEnumerable<AbstractFormattingRule> GetFormattingRules(Document document);
@@ -69,21 +72,21 @@ private async Task<Solution> ProcessResultAsync(CodeFixContext context, Diagnost
             var propertyLocation = locations[0];
             var declaratorLocation = locations[1];
 
-            var declarator = declaratorLocation.FindToken(cancellationToken).Parent.FirstAncestorOrSelf<TVariableDeclarator>();
-            var fieldDocument = context.Document.Project.GetDocument(declarator.SyntaxTree);
-            var fieldSemanticModel = await fieldDocument.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
+            var solution = context.Document.Project.Solution;
+            var declarator = (TVariableDeclarator)declaratorLocation.FindNode(cancellationToken);
+            var fieldDocument = solution.GetRequiredDocument(declarator.SyntaxTree);
+            var fieldSemanticModel = await fieldDocument.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
             var fieldSymbol = (IFieldSymbol)fieldSemanticModel.GetDeclaredSymbol(declarator, cancellationToken);
 
-            var property = propertyLocation.FindToken(cancellationToken).Parent.FirstAncestorOrSelf<TPropertyDeclaration>();
-            var propertyDocument = context.Document.Project.GetDocument(property.SyntaxTree);
-            var propertySemanticModel = await propertyDocument.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
+            var property = GetPropertyDeclaration(propertyLocation.FindNode(cancellationToken));
+            var propertyDocument = solution.GetRequiredDocument(property.SyntaxTree);
+            var propertySemanticModel = await propertyDocument.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
             var propertySymbol = (IPropertySymbol)propertySemanticModel.GetDeclaredSymbol(property, cancellationToken);
 
             Debug.Assert(fieldDocument.Project == propertyDocument.Project);
             var project = fieldDocument.Project;
-            var compilation = await project.GetCompilationAsync(cancellationToken).ConfigureAwait(false);
+            var compilation = await project.GetRequiredCompilationAsync(cancellationToken).ConfigureAwait(false);
 
-            var solution = context.Document.Project.Solution;
             var fieldLocations = await Renamer.FindRenameLocationsAsync(
                 solution, fieldSymbol, RenameOptionSet.From(solution), cancellationToken).ConfigureAwait(false);
 
@@ -127,7 +130,8 @@ private async Task<Solution> ProcessResultAsync(CodeFixContext context, Diagnost
             // same as the property we're trying to get the references pointing to.
 
             var filteredLocations = fieldLocations.Filter(
-                location => !location.IntersectsWith(declaratorLocation) &&
+                location => location.SourceTree != null &&
+                            !location.IntersectsWith(declaratorLocation) &&
                             CanEditDocument(solution, location.SourceTree, linkedFiles, canEdit));
 
             var resolution = await filteredLocations.ResolveConflictsAsync(
@@ -140,19 +144,18 @@ private async Task<Solution> ProcessResultAsync(CodeFixContext context, Diagnost
             solution = resolution.NewSolution;
 
             // Now find the field and property again post rename.
-            fieldDocument = solution.GetDocument(fieldDocument.Id);
-            propertyDocument = solution.GetDocument(propertyDocument.Id);
+            fieldDocument = solution.GetRequiredDocument(fieldDocument.Id);
+            propertyDocument = solution.GetRequiredDocument(propertyDocument.Id);
             Debug.Assert(fieldDocument.Project == propertyDocument.Project);
 
             compilation = await fieldDocument.Project.GetCompilationAsync(cancellationToken).ConfigureAwait(false);
 
             fieldSymbol = (IFieldSymbol)fieldSymbol.GetSymbolKey(cancellationToken).Resolve(compilation, cancellationToken: cancellationToken).Symbol;
             propertySymbol = (IPropertySymbol)propertySymbol.GetSymbolKey(cancellationToken).Resolve(compilation, cancellationToken: cancellationToken).Symbol;
-            Debug.Assert(fieldSymbol != null && propertySymbol != null);
+            Contract.ThrowIfTrue(fieldSymbol == null || propertySymbol == null);
 
             declarator = (TVariableDeclarator)await fieldSymbol.DeclaringSyntaxReferences[0].GetSyntaxAsync(cancellationToken).ConfigureAwait(false);
-            var temp = await propertySymbol.DeclaringSyntaxReferences[0].GetSyntaxAsync(cancellationToken).ConfigureAwait(false);
-            property = temp.FirstAncestorOrSelf<TPropertyDeclaration>();
+            property = GetPropertyDeclaration(await propertySymbol.DeclaringSyntaxReferences[0].GetSyntaxAsync(cancellationToken).ConfigureAwait(false));
 
             var nodeToRemove = GetNodeToRemove(declarator);
 
@@ -187,7 +190,7 @@ private async Task<Solution> ProcessResultAsync(CodeFixContext context, Diagnost
             // because there's nothing to actually separate it from.
             if (fieldDocument == propertyDocument)
             {
-                var syntaxFacts = fieldDocument.GetLanguageService<ISyntaxFactsService>();
+                var syntaxFacts = fieldDocument.GetRequiredLanguageService<ISyntaxFactsService>();
                 if (WillRemoveFirstFieldInTypeDirectlyAboveProperty(syntaxFacts, property, nodeToRemove) &&
                     syntaxFacts.GetLeadingBlankLines(nodeToRemove).Length == 0)
                 {
@@ -213,10 +216,11 @@ private async Task<Solution> ProcessResultAsync(CodeFixContext context, Diagnost
             else
             {
                 // In different files.  Just update both files.
-                var fieldTreeRoot = await fieldDocument.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
-                var propertyTreeRoot = await propertyDocument.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
+                var fieldTreeRoot = await fieldDocument.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
+                var propertyTreeRoot = await propertyDocument.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
 
                 var newFieldTreeRoot = fieldTreeRoot.RemoveNode(nodeToRemove, syntaxRemoveOptions);
+                Contract.ThrowIfNull(newFieldTreeRoot);
                 var newPropertyTreeRoot = propertyTreeRoot.ReplaceNode(property, updatedProperty);
 
                 newFieldTreeRoot = await FormatAsync(newFieldTreeRoot, fieldDocument, cancellationToken).ConfigureAwait(false);
@@ -311,7 +315,7 @@ private async Task<SyntaxNode> FormatAsync(SyntaxNode newRoot, Document document
                 return false;
             }
 
-            var syntaxFacts = solution.GetDocument(location.DocumentId).GetLanguageService<ISyntaxFactsService>();
+            var syntaxFacts = solution.GetRequiredDocument(location.DocumentId).GetRequiredLanguageService<ISyntaxFactsService>();
             var node = location.Location.FindToken(cancellationToken).Parent;
 
             while (node != null && !syntaxFacts.IsAnonymousOrLocalFunction(node))

src/Features/VisualBasic/Portable/UseAutoProperty/VisualBasicUseAutoPropertyCodeFixProvider.vb

@@ -21,6 +21,14 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UseAutoProperty
         Public Sub New()
         End Sub
 
+        Protected Overrides Function GetPropertyDeclaration(node As SyntaxNode) As PropertyBlockSyntax
+            If TypeOf node Is PropertyStatementSyntax Then
+                node = node.Parent
+            End If
+
+            Return DirectCast(node, PropertyBlockSyntax)
+        End Function
+
         Protected Overrides Function GetNodeToRemove(identifier As ModifiedIdentifierSyntax) As SyntaxNode
             Return Utilities.GetNodeToRemove(identifier)
         End Function