Add netcoreapp3.1 target for the features layer

src/Analyzers/Core/Analyzers/UseCoalesceExpression/AbstractUseCoalesceExpressionForNullableDiagnosticAnalyzer.cs

@@ -108,7 +108,7 @@ private void AnalyzeSyntax(SyntaxNodeAnalysisContext context)
             // actually looking at something Nullable (and not some type that uses a similar 
             // syntactic pattern).
             var semanticModel = context.SemanticModel;
-            var nullableType = semanticModel.Compilation.GetTypeByMetadataName(typeof(Nullable<>).FullName);
+            var nullableType = semanticModel.Compilation.GetTypeByMetadataName(typeof(Nullable<>).FullName!);
             if (nullableType == null)
             {
                 return;

src/Analyzers/Core/Analyzers/UseCollectionInitializer/AbstractUseCollectionInitializerDiagnosticAnalyzer.cs

@@ -49,7 +49,7 @@ protected override void InitializeWorker(AnalysisContext context)
 
         private void OnCompilationStart(CompilationStartAnalysisContext context)
         {
-            var ienumerableType = context.Compilation.GetTypeByMetadataName(typeof(IEnumerable).FullName);
+            var ienumerableType = context.Compilation.GetTypeByMetadataName(typeof(IEnumerable).FullName!);
             if (ienumerableType != null)
             {
                 var syntaxKinds = GetSyntaxFacts().SyntaxKinds;

src/Features/CSharp/Portable/CodeFixes/AddExplicitCast/InheritanceDistanceComparer.cs

@@ -30,7 +30,7 @@ namespace Microsoft.CodeAnalysis.CSharp.CodeFixes.AddExplicitCast
     /// 
     /// 'Derived1' is less specific than 'Derived2' compared to 'Base'
     /// </summary>
-    internal sealed class InheritanceDistanceComparer : IComparer<ITypeSymbol>
+    internal sealed class InheritanceDistanceComparer : IComparer<ITypeSymbol?>
     {
         private readonly ITypeSymbol _baseType;
         private readonly SemanticModel _semanticModel;
@@ -41,8 +41,13 @@ public InheritanceDistanceComparer(SemanticModel semanticModel, ITypeSymbol base
             _baseType = baseType;
         }
 
-        public int Compare(ITypeSymbol x, ITypeSymbol y)
+        public int Compare(ITypeSymbol? x, ITypeSymbol? y)
         {
+            if (x is null)
+                return y is null ? 0 : -1;
+            else if (y is null)
+                return 1;
+
             var xDist = GetInheritanceDistance(x);
             var yDist = GetInheritanceDistance(y);
             return xDist.CompareTo(yDist);

src/Features/CSharp/Portable/CodeFixes/Iterator/CSharpAddYieldCodeFixProvider.cs

@@ -117,10 +117,10 @@ public override ImmutableArray<string> FixableDiagnosticIds
 
         private bool IsCorrectTypeForYieldReturn(ITypeSymbol typeArgument, ITypeSymbol returnExpressionType, ITypeSymbol methodReturnType, SemanticModel model)
         {
-            var ienumerableSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerable).FullName);
-            var ienumeratorSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerator).FullName);
-            var ienumerableGenericSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerable<>).FullName);
-            var ienumeratorGenericSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerator<>).FullName);
+            var ienumerableSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerable).FullName!);
+            var ienumeratorSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerator).FullName!);
+            var ienumerableGenericSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerable<>).FullName!);
+            var ienumeratorGenericSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerator<>).FullName!);
 
             if (ienumerableGenericSymbol == null ||
                 ienumerableSymbol == null ||
@@ -190,8 +190,8 @@ private bool CanConvertTypes(ITypeSymbol typeArgument, ITypeSymbol returnExpress
 
         private bool IsCorrectTypeForYieldReturn(ITypeSymbol methodReturnType, SemanticModel model)
         {
-            var ienumerableSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerable).FullName);
-            var ienumeratorSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerator).FullName);
+            var ienumerableSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerable).FullName!);
+            var ienumeratorSymbol = model.Compilation.GetTypeByMetadataName(typeof(IEnumerator).FullName!);
 
             if (ienumerableSymbol == null ||
                     ienumeratorSymbol == null)

src/Features/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.Features.csproj

@@ -4,7 +4,7 @@
   <PropertyGroup>
     <OutputType>Library</OutputType>
     <RootNamespace>Microsoft.CodeAnalysis.CSharp</RootNamespace>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netcoreapp3.1;netstandard2.0</TargetFrameworks>
     <ApplyNgenOptimization>partial</ApplyNgenOptimization>
 
     <!-- NuGet -->

src/Features/Core/Portable/CodeFixes/Configuration/ConfigurationUpdater.cs

@@ -274,7 +274,7 @@ private async Task<Solution> ConfigureAsync()
 
             // Otherwise, add analyzer config document to all applicable projects for the current project's solution.
             AnalyzerConfigDocument? analyzerConfigDocument = null;
-            var analyzerConfigDirectory = PathUtilities.GetDirectoryName(analyzerConfigPath);
+            var analyzerConfigDirectory = PathUtilities.GetDirectoryName(analyzerConfigPath) ?? throw ExceptionUtilities.Unreachable;
             var currentSolution = _project.Solution;
             foreach (var projectId in _project.Solution.ProjectIds)
             {

src/Features/Core/Portable/CodeRefactorings/CodeRefactoringService.cs

@@ -287,7 +287,7 @@ private ImmutableArray<CodeRefactoringProvider> CreateRefactorings(string langua
                                         attribute.Languages.Length == 0 ||
                                         attribute.Languages.Contains(language))
                                     {
-                                        builder.Add((CodeRefactoringProvider)Activator.CreateInstance(typeInfo.AsType()));
+                                        builder.Add((CodeRefactoringProvider)Activator.CreateInstance(typeInfo.AsType())!);
                                     }
                                 }
                             }

src/Features/Core/Portable/Completion/Providers/ImportCompletionProvider/AbstractImportCompletionCacheServiceFactory.cs

@@ -35,7 +35,7 @@ public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
             return new ImportCompletionCacheService(_peItemsCache, _projectItemsCache);
         }
 
-        private void OnCacheFlushRequested(object sender, EventArgs e)
+        private void OnCacheFlushRequested(object? sender, EventArgs e)
         {
             _peItemsCache.Clear();
             _projectItemsCache.Clear();

src/Features/Core/Portable/Completion/Providers/ImportCompletionProvider/AbstractTypeImportCompletionService.cs

@@ -215,6 +215,7 @@ static bool HasGlobalAlias(MetadataReference? metadataReference)
             bool forceCacheCreation,
             IDictionary<TKey, CacheEntry> cache,
             CancellationToken cancellationToken)
+            where TKey : notnull
         {
             var language = syntaxContext.SemanticModel.Language;
 

src/Features/Core/Portable/Diagnostics/AnalyzerHelper.cs

@@ -91,7 +91,7 @@ public static (string analyzerId, VersionStamp version) GetAnalyzerIdAndVersion(
         }
 
         public static string GetAnalyzerAssemblyName(this DiagnosticAnalyzer analyzer)
-            => analyzer.GetType().Assembly.GetName().Name;
+            => analyzer.GetType().Assembly.GetName().Name ?? throw ExceptionUtilities.Unreachable;
 
         public static OptionSet GetAnalyzerOptionSet(this AnalyzerOptions analyzerOptions, SyntaxTree syntaxTree, CancellationToken cancellationToken)
         {

src/Features/Core/Portable/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.StateSet.cs

@@ -6,6 +6,7 @@
 
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -125,10 +126,10 @@ public bool IsActiveFile(DocumentId documentId)
             public bool FromBuild(ProjectId projectId)
                 => _projectStates.TryGetValue(projectId, out var projectState) && projectState.FromBuild;
 
-            public bool TryGetActiveFileState(DocumentId documentId, out ActiveFileState state)
+            public bool TryGetActiveFileState(DocumentId documentId, [NotNullWhen(true)] out ActiveFileState? state)
                 => _activeFileStates.TryGetValue(documentId, out state);
 
-            public bool TryGetProjectState(ProjectId projectId, out ProjectState state)
+            public bool TryGetProjectState(ProjectId projectId, [NotNullWhen(true)] out ProjectState? state)
                 => _projectStates.TryGetValue(projectId, out state);
 
             public ActiveFileState GetOrCreateActiveFileState(DocumentId documentId)

src/Features/Core/Portable/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.cs

@@ -100,7 +100,7 @@ public bool NeedsReanalysisOnOptionChanged(object sender, OptionChangedEventArgs
 #pragma warning restore CS0618 // Type or member is obsolete
         }
 
-        private void OnProjectAnalyzerReferenceChanged(object sender, ProjectAnalyzerReferenceChangedEventArgs e)
+        private void OnProjectAnalyzerReferenceChanged(object? sender, ProjectAnalyzerReferenceChangedEventArgs e)
         {
             if (e.Removed.Length == 0)
             {

src/Features/Core/Portable/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer_GetDiagnosticsForSpan.cs

@@ -440,15 +440,27 @@ internal static bool AreEquivalent(Diagnostic[] diagnosticsA, Diagnostic[] diagn
             return set.SetEquals(diagnosticsB);
         }
 
-        private sealed class DiagnosticComparer : IEqualityComparer<Diagnostic>
+        private sealed class DiagnosticComparer : IEqualityComparer<Diagnostic?>
         {
             internal static readonly DiagnosticComparer Instance = new DiagnosticComparer();
 
-            public bool Equals(Diagnostic x, Diagnostic y)
-                => x.Id == y.Id && x.Location == y.Location;
+            public bool Equals(Diagnostic? x, Diagnostic? y)
+            {
+                if (x is null)
+                    return y is null;
+                else if (y is null)
+                    return false;
+
+                return x.Id == y.Id && x.Location == y.Location;
+            }
 
-            public int GetHashCode(Diagnostic obj)
-                => Hash.Combine(obj.Id.GetHashCode(), obj.Location.GetHashCode());
+            public int GetHashCode(Diagnostic? obj)
+            {
+                if (obj is null)
+                    return 0;
+
+                return Hash.Combine(obj.Id.GetHashCode(), obj.Location.GetHashCode());
+            }
         }
 #endif
     }

src/Features/Core/Portable/Diagnostics/HostDiagnosticAnalyzers.cs

@@ -322,7 +322,7 @@ public HostAnalyzerReferenceDiagnosticReporter(AbstractHostDiagnosticUpdateSourc
                 _primaryWorkspace = primaryWorkspace;
             }
 
-            public void OnAnalyzerLoadFailed(object sender, AnalyzerLoadFailureEventArgs e)
+            public void OnAnalyzerLoadFailed(object? sender, AnalyzerLoadFailureEventArgs e)
             {
                 if (!(sender is AnalyzerFileReference reference))
                 {

src/Features/Core/Portable/EditAndContinue/AbstractEditAndContinueAnalyzer.cs

@@ -2108,11 +2108,11 @@ private static int CompareLineChanges(LineChange x, LineChange y)
 
         #region Semantic Analysis
 
-        private sealed class AssemblyEqualityComparer : IEqualityComparer<IAssemblySymbol>
+        private sealed class AssemblyEqualityComparer : IEqualityComparer<IAssemblySymbol?>
         {
-            public static readonly IEqualityComparer<IAssemblySymbol> Instance = new AssemblyEqualityComparer();
+            public static readonly IEqualityComparer<IAssemblySymbol?> Instance = new AssemblyEqualityComparer();
 
-            public bool Equals(IAssemblySymbol x, IAssemblySymbol y)
+            public bool Equals(IAssemblySymbol? x, IAssemblySymbol? y)
             {
                 // Types defined in old source assembly need to be treated as equivalent to types in the new source assembly,
                 // provided that they only differ in their containing assemblies.
@@ -2123,11 +2123,11 @@ public bool Equals(IAssemblySymbol x, IAssemblySymbol y)
                 // a single PE symbol. Thus comparing assemblies by identity partitions them so that each partition
                 // contains assemblies that originated from the same Gen0 assembly.
 
-                return x.Identity.Equals(y.Identity);
+                return Equals(x?.Identity, y?.Identity);
             }
 
-            public int GetHashCode(IAssemblySymbol obj)
-                => obj.Identity.GetHashCode();
+            public int GetHashCode(IAssemblySymbol? obj)
+                => obj?.Identity.GetHashCode() ?? 0;
         }
 
         protected static readonly SymbolEquivalenceComparer s_assemblyEqualityComparer = new SymbolEquivalenceComparer(
@@ -2727,7 +2727,7 @@ private static bool HasBackingField(IEventSymbol @event)
                 return false;
             }
 
-            lazyLayoutAttribute ??= model.Compilation.GetTypeByMetadataName(typeof(StructLayoutAttribute).FullName);
+            lazyLayoutAttribute ??= model.Compilation.GetTypeByMetadataName(typeof(StructLayoutAttribute).FullName!);
             if (lazyLayoutAttribute == null)
             {
                 return false;
@@ -3397,6 +3397,7 @@ private static void MarkVariables(ref BitVector mask, ImmutableArray<ISymbol> va
         }
 
         private static void BuildIndex<TKey>(Dictionary<TKey, int> index, ImmutableArray<TKey> array)
+            where TKey : notnull
         {
             for (var i = 0; i < array.Length; i++)
             {

src/Features/Core/Portable/EditAndContinue/DebuggingSession.cs

@@ -248,7 +248,7 @@ public async Task<(Guid Mvid, Diagnostic? Error)> GetProjectModuleIdAsync(Projec
         {
             Debug.Assert(Thread.CurrentThread.GetApartmentState() == ApartmentState.MTA, "SymReader requires MTA");
 
-            EmitBaseline baseline;
+            EmitBaseline? baseline;
             lock (_projectEmitBaselinesGuard)
             {
                 if (_projectEmitBaselines.TryGetValue(projectId, out baseline))

src/Features/Core/Portable/ExtractMethod/MethodExtractor.Analyzer.cs

@@ -628,7 +628,7 @@ private bool WellKnownFrameworkValueType(Compilation compilation, ITypeSymbol ty
                     return false;
                 }
 
-                var cancellationTokenType = compilation.GetTypeByMetadataName(typeof(CancellationToken).FullName);
+                var cancellationTokenType = compilation.GetTypeByMetadataName(typeof(CancellationToken).FullName!);
                 if (cancellationTokenType != null && cancellationTokenType.Equals(type))
                 {
                     return true;

src/Features/Core/Portable/GenerateEqualsAndGetHashCodeFromMembers/GenerateEqualsAndGetHashCodeAction.cs

@@ -111,7 +111,7 @@ protected override async Task<Document> GetChangedDocumentAsync(CancellationToke
                     return null;
 
                 var semanticModel = await _document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
-                var equatableType = semanticModel.Compilation.GetTypeByMetadataName(typeof(IEquatable<>).FullName);
+                var equatableType = semanticModel.Compilation.GetTypeByMetadataName(typeof(IEquatable<>).FullName!);
                 if (equatableType == null)
                     return null;
 

src/Features/Core/Portable/ImplementInterface/AbstractImplementInterfaceService.DisposePatternCodeAction.cs

@@ -292,7 +292,7 @@ public override string Title
                 statements.Add(g.ExpressionStatement(
                     g.InvocationExpression(
                         g.MemberAccessExpression(
-                            g.TypeExpression(compilation.GetTypeByMetadataName(typeof(GC).FullName)),
+                            g.TypeExpression(compilation.GetTypeByMetadataName(typeof(GC).FullName!)),
                             nameof(GC.SuppressFinalize)),
                         g.ThisExpression())));
 

src/Features/Core/Portable/Microsoft.CodeAnalysis.Features.csproj

@@ -4,7 +4,7 @@
   <PropertyGroup>
     <OutputType>Library</OutputType>
     <RootNamespace>Microsoft.CodeAnalysis</RootNamespace>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netcoreapp3.1;netstandard2.0</TargetFrameworks>
     <ApplyNgenOptimization>partial</ApplyNgenOptimization>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     

src/Features/Core/Portable/SimplifyInterpolation/Helpers.cs

@@ -77,7 +77,7 @@ private static IOperation Unwrap(IOperation expression)
             {
                 if (invocation.Arguments.Length == 1 &&
                     invocation.Arguments[0].Value is ILiteralOperation { ConstantValue: { HasValue: true, Value: string value } } literal &&
-                    invocation.SemanticModel.Compilation.GetTypeByMetadataName(typeof(System.IFormattable).FullName) is { } systemIFormattable &&
+                    invocation.SemanticModel.Compilation.GetTypeByMetadataName(typeof(System.IFormattable).FullName!) is { } systemIFormattable &&
                     invocation.Instance.Type.Implements(systemIFormattable))
                 {
                     unwrapped = invocation.Instance;

src/Features/Core/Portable/UseSystemHashCode/Analyzer.cs

@@ -41,7 +41,7 @@ public static bool TryGetAnalyzer(Compilation compilation, [NotNullWhen(true)] o
             // This may not find anything.  However, CanAnalyze checks for this. So
             // we represent the value as non-nullable for all future code.
             var objectGetHashCodeMethod = objectType?.GetMembers(nameof(GetHashCode)).FirstOrDefault() as IMethodSymbol;
-            var equalityComparerType = compilation.GetTypeByMetadataName(typeof(EqualityComparer<>).FullName);
+            var equalityComparerType = compilation.GetTypeByMetadataName(typeof(EqualityComparer<>).FullName!);
             var systemHashCodeType = compilation.GetTypeByMetadataName("System.HashCode");
 
             if (systemHashCodeType == null || objectGetHashCodeMethod == null)

src/Features/Core/Portable/ValidateFormatString/AbstractValidateFormatStringDiagnosticAnalyzer.cs

@@ -71,7 +71,7 @@ public override void Initialize(AnalysisContext context)
 
             context.RegisterCompilationStartAction(startContext =>
             {
-                var formatProviderType = startContext.Compilation.GetTypeByMetadataName(typeof(System.IFormatProvider).FullName);
+                var formatProviderType = startContext.Compilation.GetTypeByMetadataName(typeof(System.IFormatProvider).FullName!);
                 if (formatProviderType == null)
                 {
                     return;
@@ -343,8 +343,10 @@ private bool FormatCallWorksAtRuntime(string formatString, int numberOfPlacehold
             var formatStringWithEscapedBracketsChangedToSpaces = RemoveEscapedBrackets(formatString);
 
             var matches = s_extractPlaceholdersRegex.Matches(formatStringWithEscapedBracketsChangedToSpaces);
-            foreach (Match match in matches)
+            foreach (Match? match in matches)
             {
+                RoslynDebug.AssertNotNull(match);
+
                 var textInsideBrackets = match.Groups[1].Value;
 
                 if (!PlaceholderIndexIsValid(textInsideBrackets, numberOfPlaceholderArguments))

src/Features/VisualBasic/Portable/Microsoft.CodeAnalysis.VisualBasic.Features.vbproj

@@ -3,7 +3,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Library</OutputType>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netcoreapp3.1;netstandard2.0</TargetFrameworks>
     <RootNamespace></RootNamespace>
     <ApplyNgenOptimization>partial</ApplyNgenOptimization>