NRT much of the rename core.

src/Workspaces/Core/Portable/Rename/ConflictResolution.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.Immutable;
 using Microsoft.CodeAnalysis.Rename.ConflictEngine;
 using Microsoft.CodeAnalysis.Shared.Extensions;
@@ -12,7 +14,7 @@ namespace Microsoft.CodeAnalysis.Rename
 {
     internal readonly partial struct ConflictResolution
     {
-        public readonly string ErrorMessage;
+        public readonly string? ErrorMessage;
 
         private readonly Solution _newSolutionWithoutRenamedDocument;
         private readonly (DocumentId documentId, string newName) _renamedDocument;

src/Workspaces/Core/Portable/Rename/IRemoteRenamer.cs

@@ -2,7 +2,10 @@
 // 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.Immutable;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -10,6 +13,7 @@
 using Microsoft.CodeAnalysis.PooledObjects;
 using Microsoft.CodeAnalysis.Remote;
 using Microsoft.CodeAnalysis.Rename.ConflictEngine;
+using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
@@ -68,36 +72,35 @@ internal class SerializableSearchResult
     {
         // We use arrays so we can represent default immutable arrays.
 
-        public SerializableRenameLocation[] Locations;
-        public SerializableReferenceLocation[] ImplicitLocations;
-        public SerializableSymbolAndProjectId[] ReferencedSymbols;
+        public SerializableRenameLocation[]? Locations;
+        public SerializableReferenceLocation[]? ImplicitLocations;
+        public SerializableSymbolAndProjectId[]? ReferencedSymbols;
 
-        public static SerializableSearchResult Dehydrate(Solution solution, RenameLocations.SearchResult result, CancellationToken cancellationToken)
+        [return: NotNullIfNotNull("result")]
+        public static SerializableSearchResult? Dehydrate(Solution solution, RenameLocations.SearchResult? result, CancellationToken cancellationToken)
             => result == null ? null : new SerializableSearchResult
             {
-                Locations = result.Locations?.Select(loc => SerializableRenameLocation.Dehydrate(loc)).ToArray(),
+                Locations = result.Locations.Select(loc => SerializableRenameLocation.Dehydrate(loc)).ToArray(),
                 ImplicitLocations = result.ImplicitLocations.IsDefault ? null : result.ImplicitLocations.Select(loc => SerializableReferenceLocation.Dehydrate(loc, cancellationToken)).ToArray(),
                 ReferencedSymbols = result.ReferencedSymbols.IsDefault ? null : result.ReferencedSymbols.Select(s => SerializableSymbolAndProjectId.Dehydrate(solution, s, cancellationToken)).ToArray(),
             };
 
         public async Task<RenameLocations.SearchResult> RehydrateAsync(Solution solution, CancellationToken cancellationToken)
         {
-            ImmutableHashSet<RenameLocation> locations = null;
             ImmutableArray<ReferenceLocation> implicitLocations = default;
             ImmutableArray<ISymbol> referencedSymbols = default;
 
-            if (Locations != null)
-            {
-                using var _ = ArrayBuilder<RenameLocation>.GetInstance(Locations.Length, out var builder);
-                foreach (var loc in Locations)
-                    builder.Add(await loc.RehydrateAsync(solution, cancellationToken).ConfigureAwait(false));
+            Contract.ThrowIfNull(Locations);
 
-                locations = builder.ToImmutableHashSet();
-            }
+            using var _1 = ArrayBuilder<RenameLocation>.GetInstance(Locations.Length, out var locBuilder);
+            foreach (var loc in Locations)
+                locBuilder.Add(await loc.RehydrateAsync(solution, cancellationToken).ConfigureAwait(false));
+
+            var locations = locBuilder.ToImmutableHashSet();
 
             if (ImplicitLocations != null)
             {
-                using var _ = ArrayBuilder<ReferenceLocation>.GetInstance(ImplicitLocations.Length, out var builder);
+                using var _2 = ArrayBuilder<ReferenceLocation>.GetInstance(ImplicitLocations.Length, out var builder);
                 foreach (var loc in ImplicitLocations)
                     builder.Add(await loc.RehydrateAsync(solution, cancellationToken).ConfigureAwait(false));
 
@@ -106,7 +109,7 @@ public async Task<RenameLocations.SearchResult> RehydrateAsync(Solution solution
 
             if (ReferencedSymbols != null)
             {
-                using var _ = ArrayBuilder<ISymbol>.GetInstance(ReferencedSymbols.Length, out var builder);
+                using var _3 = ArrayBuilder<ISymbol>.GetInstance(ReferencedSymbols.Length, out var builder);
                 foreach (var symbol in ReferencedSymbols)
                     builder.AddIfNotNull(await symbol.TryRehydrateAsync(solution, cancellationToken).ConfigureAwait(false));
 
@@ -141,8 +144,8 @@ public static SerializableRenameLocation Dehydrate(RenameLocation location)
 
         public async Task<RenameLocation> RehydrateAsync(Solution solution, CancellationToken cancellation)
         {
-            var document = solution.GetDocument(DocumentId);
-            var tree = await document.GetSyntaxTreeAsync(cancellation).ConfigureAwait(false);
+            var document = solution.GetRequiredDocument(DocumentId);
+            var tree = await document.GetRequiredSyntaxTreeAsync(cancellation).ConfigureAwait(false);
 
             return new RenameLocation(
                 CodeAnalysis.Location.Create(tree, Location),
@@ -169,11 +172,14 @@ public SerializableRenameLocations Dehydrate(Solution solution, CancellationToke
                 CommentsResult = _commentsResult.IsDefault ? null : _commentsResult.Select(r => SerializableRenameLocation.Dehydrate(r)).ToArray(),
             };
 
-        internal static async Task<RenameLocations> RehydrateAsync(Solution solution, SerializableRenameLocations locations, CancellationToken cancellationToken)
+        internal static async Task<RenameLocations?> TryRehydrateAsync(Solution solution, SerializableRenameLocations locations, CancellationToken cancellationToken)
         {
             if (locations == null)
                 return null;
 
+            if (locations.Symbol == null)
+                return null;
+
             var symbol = await locations.Symbol.TryRehydrateAsync(solution, cancellationToken).ConfigureAwait(false);
             if (symbol == null)
                 return null;
@@ -209,11 +215,17 @@ internal static async Task<RenameLocations> RehydrateAsync(Solution solution, Se
                 commentsResult = builder.ToImmutable();
             }
 
+            var originalSymbolResult = locations.OriginalSymbolResult == null
+                ? null
+                : await locations.OriginalSymbolResult.RehydrateAsync(solution, cancellationToken).ConfigureAwait(false);
+
+            Contract.ThrowIfNull(locations.MergedResult);
+
             return new RenameLocations(
                 symbol,
                 solution,
                 locations.Options.Rehydrate(),
-                await locations.OriginalSymbolResult.RehydrateAsync(solution, cancellationToken).ConfigureAwait(false),
+                originalSymbolResult,
                 await locations.MergedResult.RehydrateAsync(solution, cancellationToken).ConfigureAwait(false),
                 overloadsResult,
                 stringsResult,
@@ -223,15 +235,15 @@ internal static async Task<RenameLocations> RehydrateAsync(Solution solution, Se
 
     internal class SerializableRenameLocations
     {
-        public SerializableSymbolAndProjectId Symbol;
+        public SerializableSymbolAndProjectId? Symbol;
         public SerializableRenameOptionSet Options;
-        public SerializableSearchResult OriginalSymbolResult;
-        public SerializableSearchResult MergedResult;
+        public SerializableSearchResult? OriginalSymbolResult;
+        public SerializableSearchResult? MergedResult;
 
         // We use arrays so we can represent default immutable arrays.
-        public SerializableSearchResult[] OverloadsResult;
-        public SerializableRenameLocation[] StringsResult;
-        public SerializableRenameLocation[] CommentsResult;
+        public SerializableSearchResult[]? OverloadsResult;
+        public SerializableRenameLocation[]? StringsResult;
+        public SerializableRenameLocation[]? CommentsResult;
     }
 
     internal class SerializableComplexifiedSpan
@@ -257,7 +269,7 @@ internal class SerializableRelatedLocation
         public TextSpan ConflictCheckSpan;
         public RelatedLocationType Type;
         public bool IsReference;
-        public DocumentId DocumentId;
+        public DocumentId? DocumentId;
         public TextSpan ComplexifiedTargetSpan;
 
         public RelatedLocation Rehydrate()
@@ -276,7 +288,7 @@ public static SerializableRelatedLocation Dehydrate(RelatedLocation location)
 
     internal class SerializableConflictResolution
     {
-        public string ErrorMessage;
+        public string? ErrorMessage;
 
         public bool ReplacementTextValid;
 
@@ -286,12 +298,12 @@ internal class SerializableConflictResolution
         //
         // We also flatten dictionaries into key/value tuples because jsonrpc only supports dictionaries with string keys.
 
-        public DocumentId[] DocumentIds;
-        public SerializableRelatedLocation[] RelatedLocations;
-        public (DocumentId, TextChange[])[] DocumentTextChanges;
-        public (DocumentId, ImmutableArray<(TextSpan oldSpan, TextSpan newSpan)>)[] DocumentToModifiedSpansMap;
-        public (DocumentId, ImmutableArray<SerializableComplexifiedSpan>)[] DocumentToComplexifiedSpansMap;
-        public (DocumentId, ImmutableArray<SerializableRelatedLocation>)[] DocumentToRelatedLocationsMap;
+        public DocumentId[]? DocumentIds;
+        public SerializableRelatedLocation[]? RelatedLocations;
+        public (DocumentId, TextChange[])[]? DocumentTextChanges;
+        public (DocumentId, ImmutableArray<(TextSpan oldSpan, TextSpan newSpan)>)[]? DocumentToModifiedSpansMap;
+        public (DocumentId, ImmutableArray<SerializableComplexifiedSpan>)[]? DocumentToComplexifiedSpansMap;
+        public (DocumentId, ImmutableArray<SerializableRelatedLocation>)[]? DocumentToRelatedLocationsMap;
 
         public async Task<ConflictResolution> RehydrateAsync(Solution oldSolution, CancellationToken cancellationToken)
         {

src/Workspaces/Core/Portable/Rename/IRenameRewriterLanguageService.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;

src/Workspaces/Core/Portable/Rename/RenameLocation.ReferenceProcessing.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.Diagnostics;
@@ -31,14 +33,12 @@ internal static class ReferenceProcessing
             /// Given a symbol in a document, returns the "right" symbol that should be renamed in
             /// the case the name binds to things like aliases _and_ the underlying type at once.
             /// </summary>
-            public static async Task<ISymbol> GetRenamableSymbolAsync(
+            public static async Task<ISymbol?> TryGetRenamableSymbolAsync(
                 Document document, int position, CancellationToken cancellationToken)
             {
                 var symbol = await SymbolFinder.FindSymbolAtPositionAsync(document, position, cancellationToken: cancellationToken).ConfigureAwait(false);
                 if (symbol == null)
-                {
                     return null;
-                }
 
                 var definitionSymbol = await FindDefinitionSymbolAsync(symbol, document.Project.Solution, cancellationToken).ConfigureAwait(false);
                 Contract.ThrowIfNull(definitionSymbol);
@@ -115,7 +115,7 @@ internal static class ReferenceProcessing
                 }
 
                 // in case this is e.g. an overridden property accessor, we'll treat the property itself as the definition symbol
-                var property = await GetPropertyFromAccessorOrAnOverrideAsync(bestSymbol, solution, cancellationToken).ConfigureAwait(false);
+                var property = await TryGetPropertyFromAccessorOrAnOverrideAsync(bestSymbol, solution, cancellationToken).ConfigureAwait(false);
 
                 return property ?? bestSymbol;
             }
@@ -214,7 +214,7 @@ static bool IsConstructorForType(ISymbol possibleConstructor, ISymbol possibleTy
                 }
             }
 
-            internal static async Task<ISymbol> GetPropertyFromAccessorOrAnOverrideAsync(
+            internal static async Task<ISymbol?> TryGetPropertyFromAccessorOrAnOverrideAsync(
                 ISymbol symbol, Solution solution, CancellationToken cancellationToken)
             {
                 if (symbol.IsPropertyAccessor())
@@ -229,7 +229,7 @@ static bool IsConstructorForType(ISymbol possibleConstructor, ISymbol possibleTy
 
                     if (originalSourceSymbol != null)
                     {
-                        return await GetPropertyFromAccessorOrAnOverrideAsync(originalSourceSymbol, solution, cancellationToken).ConfigureAwait(false);
+                        return await TryGetPropertyFromAccessorOrAnOverrideAsync(originalSourceSymbol, solution, cancellationToken).ConfigureAwait(false);
                     }
                 }
 
@@ -241,7 +241,7 @@ static bool IsConstructorForType(ISymbol possibleConstructor, ISymbol possibleTy
 
                     foreach (var methodImplementor in methodImplementors)
                     {
-                        var propertyAccessorOrAnOverride = await GetPropertyFromAccessorOrAnOverrideAsync(methodImplementor, solution, cancellationToken).ConfigureAwait(false);
+                        var propertyAccessorOrAnOverride = await TryGetPropertyFromAccessorOrAnOverrideAsync(methodImplementor, solution, cancellationToken).ConfigureAwait(false);
                         if (propertyAccessorOrAnOverride != null)
                         {
                             return propertyAccessorOrAnOverride;
@@ -255,7 +255,7 @@ static bool IsConstructorForType(ISymbol possibleConstructor, ISymbol possibleTy
             private static async Task<bool> IsPropertyAccessorOrAnOverrideAsync(
                 ISymbol symbol, Solution solution, CancellationToken cancellationToken)
             {
-                var result = await GetPropertyFromAccessorOrAnOverrideAsync(
+                var result = await TryGetPropertyFromAccessorOrAnOverrideAsync(
                     symbol, solution, cancellationToken).ConfigureAwait(false);
                 return result != null;
             }
@@ -300,7 +300,8 @@ private static string TrimNameToAfterLastDot(string name)
                 if (originalSymbol.Kind == SymbolKind.Alias)
                 {
                     var location = originalSymbol.Locations.Single();
-                    results.Add(new RenameLocation(location, solution.GetDocument(location.SourceTree).Id));
+                    Contract.ThrowIfNull(location.SourceTree);
+                    results.Add(new RenameLocation(location, solution.GetRequiredDocument(location.SourceTree).Id));
                     return results.ToImmutableAndFree();
                 }
 
@@ -309,9 +310,10 @@ private static string TrimNameToAfterLastDot(string name)
                 {
                     if (location.IsInSource)
                     {
+                        Contract.ThrowIfNull(location.SourceTree);
                         results.Add(new RenameLocation(
                             location,
-                            solution.GetDocument(location.SourceTree).Id,
+                            solution.GetRequiredDocument(location.SourceTree).Id,
                             isRenamableAccessor: isRenamableAccessor));
                     }
                 }
@@ -320,7 +322,10 @@ private static string TrimNameToAfterLastDot(string name)
                 // destructors declarations that match the name
                 if (referencedSymbol.Kind == SymbolKind.NamedType && referencedSymbol.Locations.All(l => l.IsInSource))
                 {
-                    var syntaxFacts = solution.GetDocument(referencedSymbol.Locations[0].SourceTree).GetLanguageService<ISyntaxFactsService>();
+                    var firstLocation = referencedSymbol.Locations[0];
+                    Contract.ThrowIfNull(firstLocation.SourceTree);
+                    var syntaxFacts = solution.GetRequiredDocument(firstLocation.SourceTree)
+                                              .GetRequiredLanguageService<ISyntaxFactsService>();
 
                     var namedType = (INamedTypeSymbol)referencedSymbol;
                     foreach (var method in namedType.GetMembers().OfType<IMethodSymbol>())
@@ -337,7 +342,8 @@ private static string TrimNameToAfterLastDot(string name)
                                     if (!syntaxFacts.IsReservedOrContextualKeyword(token) &&
                                         token.ValueText == referencedSymbol.Name)
                                     {
-                                        results.Add(new RenameLocation(location, solution.GetDocument(location.SourceTree).Id));
+                                        Contract.ThrowIfNull(location.SourceTree);
+                                        results.Add(new RenameLocation(location, solution.GetRequiredDocument(location.SourceTree).Id));
                                     }
                                 }
                             }
@@ -376,7 +382,8 @@ internal static async Task<IEnumerable<RenameLocation>> GetRenamableReferenceLoc
                         // We also need to add the location of the alias
                         // itself
                         var aliasLocation = location.Alias.Locations.Single();
-                        results.Add(new RenameLocation(aliasLocation, solution.GetDocument(aliasLocation.SourceTree).Id));
+                        Contract.ThrowIfNull(aliasLocation.SourceTree);
+                        results.Add(new RenameLocation(aliasLocation, solution.GetRequiredDocument(aliasLocation.SourceTree).Id));
                     }
                 }
                 else
@@ -394,7 +401,8 @@ internal static async Task<IEnumerable<RenameLocation>> GetRenamableReferenceLoc
 
                             // We also need to add the location of the alias itself
                             var aliasLocation = location.Alias.Locations.Single();
-                            results.Add(new RenameLocation(aliasLocation, solution.GetDocument(aliasLocation.SourceTree).Id));
+                            Contract.ThrowIfNull(aliasLocation.SourceTree);
+                            results.Add(new RenameLocation(aliasLocation, solution.GetRequiredDocument(aliasLocation.SourceTree).Id));
                         }
                     }
                     else
@@ -459,7 +467,7 @@ internal static async Task<IEnumerable<RenameLocation>> GetRenamableReferenceLoc
                 Document document, string renameText, ISyntaxFactsService syntaxFactsService,
                 ArrayBuilder<RenameLocation> renameLocations, CancellationToken cancellationToken)
             {
-                var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
+                var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
                 var renameTextLength = renameText.Length;
 
                 var renameStringsAndPositions = root
@@ -477,7 +485,7 @@ internal static async Task<IEnumerable<RenameLocation>> GetRenamableReferenceLoc
             private static async Task AddLocationsToRenameInCommentsAsync(
                 Document document, string renameText, ArrayBuilder<RenameLocation> renameLocations, CancellationToken cancellationToken)
             {
-                var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
+                var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
                 var renameTextLength = renameText.Length;
 
                 var renameStringsAndPositions = root
@@ -508,8 +516,11 @@ internal static async Task<IEnumerable<RenameLocation>> GetRenamableReferenceLoc
 
                     var matches = regex.Matches(renameString);
 
-                    foreach (Match match in matches)
+                    foreach (Match? match in matches)
                     {
+                        if (match == null)
+                            continue;
+
                         var start = renameStringPosition + match.Index;
                         Debug.Assert(renameText.Length == match.Length);
                         var matchTextSpan = new TextSpan(start, renameText.Length);

src/Workspaces/Core/Portable/Rename/RenameLocation.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 Microsoft.CodeAnalysis.FindSymbols;
 using Microsoft.CodeAnalysis.Text;
@@ -48,7 +50,7 @@ public RenameLocation(ReferenceLocation referenceLocation, DocumentId documentId
         public bool Equals(RenameLocation other)
             => Location == other.Location;
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is RenameLocation loc &&
                    Equals(loc);

src/Workspaces/Core/Portable/Rename/RenameLocations.SearchResult.cs

@@ -2,8 +2,11 @@
 // 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.Immutable;
 using Microsoft.CodeAnalysis.FindSymbols;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Rename
 {
@@ -20,6 +23,7 @@ public class SearchResult
                 ImmutableArray<ReferenceLocation> implicitLocations,
                 ImmutableArray<ISymbol> referencedSymbols)
             {
+                Contract.ThrowIfNull(locations);
                 this.Locations = locations;
                 this.ImplicitLocations = implicitLocations;
                 this.ReferencedSymbols = referencedSymbols;

src/Workspaces/Core/Portable/Rename/RenameLocations.cs

@@ -150,8 +150,10 @@ internal sealed partial class RenameLocations
 
                         if (result.HasValue)
                         {
-                            return await RenameLocations.RehydrateAsync(
+                            var rehydrated = await RenameLocations.TryRehydrateAsync(
                                 solution, result.Value, cancellationToken).ConfigureAwait(false);
+                            if (rehydrated != null)
+                                return rehydrated;
                         }
                     }
                 }

src/Workspaces/Core/Portable/Rename/Renamer.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;
@@ -35,7 +37,7 @@ public static partial class Renamer
                 RenameOptionSet.From(solution, optionSet),
                 nonConflictSymbols: null, cancellationToken).ConfigureAwait(false);
 
-            // This is a public entrypoint.  So if rename failed to resolve conflicts, we report that back to caller as
+            // This is a public entry-point.  So if rename failed to resolve conflicts, we report that back to caller as
             // an exception.
             if (resolution.ErrorMessage != null)
                 throw new ArgumentException(resolution.ErrorMessage);
@@ -66,8 +68,8 @@ public static partial class Renamer
         public static async Task<RenameDocumentActionSet> RenameDocumentAsync(
             Document document,
             string newDocumentName,
-            IReadOnlyList<string> newDocumentFolders = null,
-            OptionSet optionSet = null,
+            IReadOnlyList<string>? newDocumentFolders = null,
+            OptionSet? optionSet = null,
             CancellationToken cancellationToken = default)
         {
             if (document is null)
@@ -109,7 +111,7 @@ internal static Task<RenameLocations> FindRenameLocationsAsync(Solution solution
             ISymbol symbol,
             string newName,
             RenameOptionSet optionSet,
-            ImmutableHashSet<ISymbol> nonConflictSymbols,
+            ImmutableHashSet<ISymbol>? nonConflictSymbols,
             CancellationToken cancellationToken)
         {
             Contract.ThrowIfNull(solution);
@@ -130,7 +132,7 @@ internal static Task<RenameLocations> FindRenameLocationsAsync(Solution solution
                             WellKnownServiceHubServices.CodeAnalysisService,
                             nameof(IRemoteRenamer.RenameSymbolAsync),
                             solution,
-                            new object[]
+                            new object?[]
                             {
                                 SerializableSymbolAndProjectId.Create(symbol, project, cancellationToken),
                                 newName,
@@ -156,7 +158,7 @@ internal static Task<RenameLocations> FindRenameLocationsAsync(Solution solution
             ISymbol symbol,
             string newName,
             RenameOptionSet optionSet,
-            ImmutableHashSet<ISymbol> nonConflictSymbols,
+            ImmutableHashSet<ISymbol>? nonConflictSymbols,
             CancellationToken cancellationToken)
         {
             Contract.ThrowIfNull(solution);