Update latest from master

build/Defaults/Desktop/app.config

@@ -65,6 +65,10 @@
         <assemblyIdentity name="System.Diagnostics.StackTrace" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
         <bindingRedirect oldVersion="0.0.0.0-4.0.3.0" newVersion="4.0.3.0"/>
       </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Xml.XmlDocument" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
+        <bindingRedirect oldVersion="0.0.0.0-4.0.2.0" newVersion="4.0.2.0"/>
+      </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="System.Xml.XPath.XDocument" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
         <bindingRedirect oldVersion="0.0.0.0-4.0.2.0" newVersion="4.0.2.0"/>

build/Defaults/Portable/app.config

@@ -65,6 +65,10 @@
         <assemblyIdentity name="System.Diagnostics.StackTrace" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
         <bindingRedirect oldVersion="0.0.0.0-4.0.3.0" newVersion="4.0.3.0"/>
       </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Xml.XmlDocument" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
+        <bindingRedirect oldVersion="0.0.0.0-4.0.2.0" newVersion="4.0.2.0"/>
+      </dependentAssembly>
       <dependentAssembly>
         <assemblyIdentity name="System.Xml.XPath.XDocument" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
         <bindingRedirect oldVersion="0.0.0.0-4.0.2.0" newVersion="4.0.2.0"/>

src/Compilers/CSharp/Test/Semantic/Semantics/DeconstructionTests.cs

@@ -2729,5 +2729,57 @@ public void Deconstruct(out dynamic x, out dynamic y)
                 Diagnostic(ErrorCode.WRN_UnreferencedVar, "y4").WithArguments("y4").WithLocation(9, 25)
                 );
         }
+
+        [Fact]
+        public void DeclarationInsideNameof()
+        {
+            string source = @"
+class Program
+{
+    static void Main()
+    {
+        string s = nameof((int x1, var x2) = (1, 2)).ToString();
+        string s1 = x1, s2 = x2;
+    }
+}
+";
+            var comp = CreateCompilationWithMscorlib(source, references: s_valueTupleRefs);
+            comp.VerifyDiagnostics(
+                // (6,28): error CS8185: A declaration is not allowed in this context.
+                //         string s = nameof((int x1, var x2) = (1, 2)).ToString();
+                Diagnostic(ErrorCode.ERR_DeclarationExpressionNotPermitted, "int x1").WithLocation(6, 28),
+                // (6,27): error CS8081: Expression does not have a name.
+                //         string s = nameof((int x1, var x2) = (1, 2)).ToString();
+                Diagnostic(ErrorCode.ERR_ExpressionHasNoName, "(int x1, var x2) = (1, 2)").WithLocation(6, 27),
+                // (7,21): error CS0029: Cannot implicitly convert type 'int' to 'string'
+                //         string s1 = x1, s2 = x2;
+                Diagnostic(ErrorCode.ERR_NoImplicitConv, "x1").WithArguments("int", "string").WithLocation(7, 21),
+                // (7,30): error CS0029: Cannot implicitly convert type 'int' to 'string'
+                //         string s1 = x1, s2 = x2;
+                Diagnostic(ErrorCode.ERR_NoImplicitConv, "x2").WithArguments("int", "string").WithLocation(7, 30),
+                // (7,21): error CS0165: Use of unassigned local variable 'x1'
+                //         string s1 = x1, s2 = x2;
+                Diagnostic(ErrorCode.ERR_UseDefViolation, "x1").WithArguments("x1").WithLocation(7, 21),
+                // (7,30): error CS0165: Use of unassigned local variable 'x2'
+                //         string s1 = x1, s2 = x2;
+                Diagnostic(ErrorCode.ERR_UseDefViolation, "x2").WithArguments("x2").WithLocation(7, 30)
+                );
+
+            var tree = comp.SyntaxTrees.First();
+            var model = comp.GetSemanticModel(tree);
+            var designations = tree.GetCompilationUnitRoot().DescendantNodes().OfType<SingleVariableDesignationSyntax>().ToArray();
+            Assert.Equal(2, designations.Count());
+            var refs = tree.GetCompilationUnitRoot().DescendantNodes().OfType<IdentifierNameSyntax>();
+
+            var x1 = model.GetDeclaredSymbol(designations[0]);
+            Assert.Equal("x1", x1.Name);
+            Assert.Equal("System.Int32", ((LocalSymbol)x1).Type.ToTestDisplayString());
+            Assert.Same(x1, model.GetSymbolInfo(refs.Where(r => r.Identifier.ValueText == "x1").Single()).Symbol);
+
+            var x2 = model.GetDeclaredSymbol(designations[1]);
+            Assert.Equal("x2", x2.Name);
+            Assert.Equal("System.Int32", ((LocalSymbol)x2).Type.ToTestDisplayString());
+            Assert.Same(x2, model.GetSymbolInfo(refs.Where(r => r.Identifier.ValueText == "x2").Single()).Symbol);
+        }
     }
 }

src/Compilers/CSharp/Test/Semantic/Semantics/PatternMatchingTests_Scope.cs

@@ -11765,5 +11765,43 @@ static bool Dummy(params object[] data)
             var z2Ref = GetReferences(tree, "z2").Single();
             Assert.Equal("System.Boolean", compilation.GetSemanticModel(tree).GetTypeInfo(z2Ref).Type.ToTestDisplayString());
         }
+
+        [Fact]
+        public void DeclarationInsideNameof()
+        {
+            string source = @"
+class Program
+{
+    static void Main(int i)
+    {
+        string s = nameof(M(i is var x1, x1)).ToString();
+        string s1 = x1;
+    }
+    static void M(bool b, int i) {}
+}
+";
+            var comp = CreateCompilationWithMscorlib(source);
+            comp.VerifyDiagnostics(
+                // (6,27): error CS8081: Expression does not have a name.
+                //         string s = nameof(M(i is var x1, x1)).ToString();
+                Diagnostic(ErrorCode.ERR_ExpressionHasNoName, "M(i is var x1, x1)").WithLocation(6, 27),
+                // (7,21): error CS0029: Cannot implicitly convert type 'int' to 'string'
+                //         string s1 = x1;
+                Diagnostic(ErrorCode.ERR_NoImplicitConv, "x1").WithArguments("int", "string").WithLocation(7, 21),
+                // (7,21): error CS0165: Use of unassigned local variable 'x1'
+                //         string s1 = x1;
+                Diagnostic(ErrorCode.ERR_UseDefViolation, "x1").WithArguments("x1").WithLocation(7, 21)
+                );
+
+            var tree = comp.SyntaxTrees.First();
+            var model = comp.GetSemanticModel(tree);
+            var designation = GetPatternDeclarations(tree).Single();
+            var refs = GetReferences(tree, "x1").ToArray();
+
+            VerifyModelForDeclarationPattern(model, designation, refs);
+
+            var x1 = (LocalSymbol)model.GetDeclaredSymbol(designation);
+            Assert.Equal("System.Int32", x1.Type.ToTestDisplayString());
+        }
     }
 }

src/EditorFeatures/Core/Implementation/IntelliSense/QuickInfo/Providers/AbstractSemanticQuickInfoProvider.cs

@@ -8,6 +8,7 @@
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.DocumentationComments;
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
+using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.LanguageServices;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Shared.Utilities;
@@ -75,7 +76,7 @@ internal abstract partial class AbstractSemanticQuickInfoProvider : AbstractQuic
             foreach (var link in linkedDocumentIds)
             {
                 var linkedDocument = document.Project.Solution.GetDocument(link);
-                var linkedToken = await FindTokenInLinkedDocument(token, linkedDocument, cancellationToken).ConfigureAwait(false);
+                var linkedToken = await FindTokenInLinkedDocument(token, document, linkedDocument, cancellationToken).ConfigureAwait(false);
 
                 if (linkedToken != default(SyntaxToken))
                 {
@@ -116,7 +117,7 @@ internal abstract partial class AbstractSemanticQuickInfoProvider : AbstractQuic
             return await CreateContentAsync(document.Project.Solution.Workspace, token, bestBinding.Item2, bestBinding.Item3, supportedPlatforms, cancellationToken).ConfigureAwait(false);
         }
 
-        private async Task<SyntaxToken> FindTokenInLinkedDocument(SyntaxToken token, Document linkedDocument, CancellationToken cancellationToken)
+        private async Task<SyntaxToken> FindTokenInLinkedDocument(SyntaxToken token, Document originalDocument, Document linkedDocument, CancellationToken cancellationToken)
         {
             if (!linkedDocument.SupportsSyntaxTree)
             {
@@ -125,13 +126,24 @@ private async Task<SyntaxToken> FindTokenInLinkedDocument(SyntaxToken token, Doc
 
             var root = await linkedDocument.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
 
-            // Don't search trivia because we want to ignore inactive regions
-            var linkedToken = root.FindToken(token.SpanStart);
+            try
+            {
+                // Don't search trivia because we want to ignore inactive regions
+                var linkedToken = root.FindToken(token.SpanStart);
 
-            // The new and old tokens should have the same span?
-            if (token.Span == linkedToken.Span)
+                // The new and old tokens should have the same span?
+                if (token.Span == linkedToken.Span)
+                {
+                    return linkedToken;
+                }
+            }
+            catch (Exception e)
             {
-                return linkedToken;
+                // We are seeing linked files with different spans cause FindToken to crash.
+                // Capturing more information for https://devdiv.visualstudio.com/DevDiv/_workitems?id=209299
+                var originalText = await originalDocument.GetTextAsync().ConfigureAwait(false);
+                var linkedText = await linkedDocument.GetTextAsync().ConfigureAwait(false);
+                FatalError.Report(e);
             }
 
             return default(SyntaxToken);

src/EditorFeatures/TestUtilities/Remote/InProcRemostHostClient.cs

@@ -16,7 +16,7 @@
 
 namespace Roslyn.Test.Utilities.Remote
 {
-    internal class InProcRemoteHostClient : RemoteHostClient
+    internal sealed class InProcRemoteHostClient : RemoteHostClient
     {
         private readonly InProcRemoteServices _inprocServices;
         private readonly JsonRpc _rpc;
@@ -47,10 +47,12 @@ public static async Task<RemoteHostClient> CreateAsync(Workspace workspace, bool
         {
             _inprocServices = inprocServices;
 
-            _rpc = JsonRpc.Attach(stream, target: this);
+            _rpc = new JsonRpc(stream, stream, target: this);
 
             // handle disconnected situation
             _rpc.Disconnected += OnRpcDisconnected;
+
+            _rpc.StartListening();
         }
 
         public AssetStorage AssetStorage => _inprocServices.AssetStorage;

src/Setup/Templates/CSharp/Diagnostic/Analyzer/DiagnosticAnalyzer.vstemplate

@@ -39,7 +39,7 @@
       <package id="System.Collections.Immutable" version="1.1.36" skipAssemblyReferences="false" />
       <package id="System.Reflection.Metadata" version="1.0.21" skipAssemblyReferences="false" />
       <package id="Microsoft.Composition" version="1.0.27" skipAssemblyReferences="false" />
-      <package id="NuGet.CommandLine" />
+      <package id="NuGet.CommandLine" version="2.8.5" />
     </packages>
   </WizardData>
 </VSTemplate>

src/Setup/Templates/VisualBasic/Diagnostic/Analyzer/DiagnosticAnalyzer.vstemplate

@@ -41,7 +41,7 @@
       <package id="System.Collections.Immutable" version="1.1.36" skipAssemblyReferences="false" />
       <package id="System.Reflection.Metadata" version="1.0.21" skipAssemblyReferences="false" />
       <package id="Microsoft.Composition" version="1.0.27" skipAssemblyReferences="false" />
-      <package id="NuGet.CommandLine" />
+      <package id="NuGet.CommandLine" version="2.8.5" />
     </packages>
   </WizardData>
 </VSTemplate>
\ No newline at end of file

src/VisualStudio/Core/Next/Remote/JsonRpcClient.cs

@@ -25,7 +25,8 @@ internal class JsonRpcClient : IDisposable
             var target = useThisAsCallback ? this : callbackTarget;
             _cancellationToken = cancellationToken;
 
-            _rpc = JsonRpc.Attach(stream, target);
+            _rpc = new JsonRpc(stream, stream, target);
+
             _rpc.Disconnected += OnDisconnected;
         }
 
@@ -84,6 +85,13 @@ public void Dispose()
             _rpc.Dispose();
         }
 
+        protected void StartListening()
+        {
+            // due to this issue - https://github.com/dotnet/roslyn/issues/16900#issuecomment-277378950
+            // _rpc need to be explicitly started
+            _rpc.StartListening();
+        }
+
         protected virtual void OnDisposed()
         {
             // do nothing

src/VisualStudio/Core/Next/Remote/JsonRpcSession.cs

@@ -114,6 +114,8 @@ public ServiceJsonRpcClient(Stream stream, object callbackTarget, CancellationTo
             {
                 // this one doesn't need cancellation token since it has nothing to cancel
                 _callbackTarget = callbackTarget;
+
+                StartListening();
             }
         }
 
@@ -137,6 +139,8 @@ public SnapshotJsonRpcClient(JsonRpcSession owner, Stream stream, CancellationTo
             {
                 _owner = owner;
                 _source = new CancellationTokenSource();
+
+                StartListening();
             }
 
             private PinnedRemotableDataScope PinnedScope => _owner.PinnedScope;

src/VisualStudio/Core/Next/Remote/ServiceHubRemoteHostClient.cs

@@ -18,7 +18,7 @@ namespace Microsoft.VisualStudio.LanguageServices.Remote
     using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
     using Workspace = Microsoft.CodeAnalysis.Workspace;
 
-    internal partial class ServiceHubRemoteHostClient : RemoteHostClient
+    internal sealed partial class ServiceHubRemoteHostClient : RemoteHostClient
     {
         private readonly HubClient _hubClient;
         private readonly JsonRpc _rpc;
@@ -81,10 +81,12 @@ private static async Task RegisterWorkspaceHostAsync(Workspace workspace, Remote
             _hubClient = hubClient;
             _hostGroup = hostGroup;
 
-            _rpc = JsonRpc.Attach(stream, target: this);
+            _rpc = new JsonRpc(stream, stream, target: this);
 
             // handle disconnected situation
             _rpc.Disconnected += OnRpcDisconnected;
+
+            _rpc.StartListening();
         }
 
         protected override async Task<Session> CreateServiceSessionAsync(string serviceName, PinnedRemotableDataScope snapshot, object callbackTarget, CancellationToken cancellationToken)

src/Workspaces/Core/Portable/Rename/ConflictEngine/ConflictResolver.cs

@@ -8,6 +8,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.ErrorReporting;
 using Microsoft.CodeAnalysis.FindSymbols;
 using Microsoft.CodeAnalysis.LanguageServices;
 using Microsoft.CodeAnalysis.Options;
@@ -177,64 +178,76 @@ private static bool IsRenameValid(ConflictResolution conflictResolution, ISymbol
             IDictionary<Location, Location> reverseMappedLocations,
             CancellationToken cancellationToken)
         {
-            if (renamedSymbol.ContainingSymbol.IsKind(SymbolKind.NamedType))
+            try
             {
-                var otherThingsNamedTheSame = renamedSymbol.ContainingType.GetMembers(renamedSymbol.Name)
-                                                       .Where(s => !s.Equals(renamedSymbol) &&
-                                                                   string.Equals(s.MetadataName, renamedSymbol.MetadataName, StringComparison.Ordinal) &&
-                                                                   (s.Kind != SymbolKind.Method || renamedSymbol.Kind != SymbolKind.Method));
-
-                AddConflictingSymbolLocations(otherThingsNamedTheSame, conflictResolution, reverseMappedLocations);
-            }
-
-
-            if (renamedSymbol.IsKind(SymbolKind.Namespace) && renamedSymbol.ContainingSymbol.IsKind(SymbolKind.Namespace))
-            {
-                var otherThingsNamedTheSame = ((INamespaceSymbol)renamedSymbol.ContainingSymbol).GetMembers(renamedSymbol.Name)
-                                                        .Where(s => !s.Equals(renamedSymbol) &&
-                                                                    !s.IsKind(SymbolKind.Namespace) &&
-                                                                    string.Equals(s.MetadataName, renamedSymbol.MetadataName, StringComparison.Ordinal));
+                if (renamedSymbol.ContainingSymbol.IsKind(SymbolKind.NamedType))
+                {
+                    var otherThingsNamedTheSame = renamedSymbol.ContainingType.GetMembers(renamedSymbol.Name)
+                                                           .Where(s => !s.Equals(renamedSymbol) &&
+                                                                       string.Equals(s.MetadataName, renamedSymbol.MetadataName, StringComparison.Ordinal) &&
+                                                                       (s.Kind != SymbolKind.Method || renamedSymbol.Kind != SymbolKind.Method));
 
-                AddConflictingSymbolLocations(otherThingsNamedTheSame, conflictResolution, reverseMappedLocations);
-            }
+                    AddConflictingSymbolLocations(otherThingsNamedTheSame, conflictResolution, reverseMappedLocations);
+                }
 
-            if (renamedSymbol.IsKind(SymbolKind.NamedType) && renamedSymbol.ContainingSymbol is INamespaceOrTypeSymbol)
-            {
-                var otherThingsNamedTheSame = ((INamespaceOrTypeSymbol)renamedSymbol.ContainingSymbol).GetMembers(renamedSymbol.Name)
-                                                        .Where(s => !s.Equals(renamedSymbol) &&
-                                                                    string.Equals(s.MetadataName, renamedSymbol.MetadataName, StringComparison.Ordinal));
 
-                var conflictingSymbolLocations = otherThingsNamedTheSame.Where(s => !s.IsKind(SymbolKind.Namespace));
-                if (otherThingsNamedTheSame.Any(s => s.IsKind(SymbolKind.Namespace)))
+                if (renamedSymbol.IsKind(SymbolKind.Namespace) && renamedSymbol.ContainingSymbol.IsKind(SymbolKind.Namespace))
                 {
-                    conflictingSymbolLocations = conflictingSymbolLocations.Concat(renamedSymbol);
+                    var otherThingsNamedTheSame = ((INamespaceSymbol)renamedSymbol.ContainingSymbol).GetMembers(renamedSymbol.Name)
+                                                            .Where(s => !s.Equals(renamedSymbol) &&
+                                                                        !s.IsKind(SymbolKind.Namespace) &&
+                                                                        string.Equals(s.MetadataName, renamedSymbol.MetadataName, StringComparison.Ordinal));
+
+                    AddConflictingSymbolLocations(otherThingsNamedTheSame, conflictResolution, reverseMappedLocations);
                 }
 
-                AddConflictingSymbolLocations(conflictingSymbolLocations, conflictResolution, reverseMappedLocations);
-            }
+                if (renamedSymbol.IsKind(SymbolKind.NamedType) && renamedSymbol.ContainingSymbol is INamespaceOrTypeSymbol)
+                {
+                    var otherThingsNamedTheSame = ((INamespaceOrTypeSymbol)renamedSymbol.ContainingSymbol).GetMembers(renamedSymbol.Name)
+                                                            .Where(s => !s.Equals(renamedSymbol) &&
+                                                                        string.Equals(s.MetadataName, renamedSymbol.MetadataName, StringComparison.Ordinal));
 
-            // Some types of symbols (namespaces, cref stuff, etc) might not have ContainingAssemblies
-            if (renamedSymbol.ContainingAssembly != null)
-            {
-                var project = conflictResolution.NewSolution.GetProject(renamedSymbol.ContainingAssembly, cancellationToken);
+                    var conflictingSymbolLocations = otherThingsNamedTheSame.Where(s => !s.IsKind(SymbolKind.Namespace));
+                    if (otherThingsNamedTheSame.Any(s => s.IsKind(SymbolKind.Namespace)))
+                    {
+                        conflictingSymbolLocations = conflictingSymbolLocations.Concat(renamedSymbol);
+                    }
 
-                // There also might be language specific rules we need to include
-                var languageRenameService = project.LanguageServices.GetService<IRenameRewriterLanguageService>();
-                var languageConflicts = await languageRenameService.ComputeDeclarationConflictsAsync(
-                    conflictResolution.ReplacementText,
-                    renamedSymbol,
-                    renameSymbol,
-                    referencedSymbols,
-                    conflictResolution.OldSolution,
-                    conflictResolution.NewSolution,
-                    reverseMappedLocations,
-                    cancellationToken).ConfigureAwait(false);
+                    AddConflictingSymbolLocations(conflictingSymbolLocations, conflictResolution, reverseMappedLocations);
+                }
 
-                foreach (var languageConflict in languageConflicts)
+                // Some types of symbols (namespaces, cref stuff, etc) might not have ContainingAssemblies
+                if (renamedSymbol.ContainingAssembly != null)
                 {
-                    conflictResolution.AddOrReplaceRelatedLocation(new RelatedLocation(languageConflict.SourceSpan, conflictResolution.OldSolution.GetDocument(languageConflict.SourceTree).Id, RelatedLocationType.UnresolvableConflict));
+                    var project = conflictResolution.NewSolution.GetProject(renamedSymbol.ContainingAssembly, cancellationToken);
+
+                    // There also might be language specific rules we need to include
+                    var languageRenameService = project.LanguageServices.GetService<IRenameRewriterLanguageService>();
+                    var languageConflicts = await languageRenameService.ComputeDeclarationConflictsAsync(
+                        conflictResolution.ReplacementText,
+                        renamedSymbol,
+                        renameSymbol,
+                        referencedSymbols,
+                        conflictResolution.OldSolution,
+                        conflictResolution.NewSolution,
+                        reverseMappedLocations,
+                        cancellationToken).ConfigureAwait(false);
+
+                    foreach (var languageConflict in languageConflicts)
+                    {
+                        conflictResolution.AddOrReplaceRelatedLocation(new RelatedLocation(languageConflict.SourceSpan, conflictResolution.OldSolution.GetDocument(languageConflict.SourceTree).Id, RelatedLocationType.UnresolvableConflict));
+                    }
                 }
             }
+            catch (Exception e) when (FatalError.ReportUnlessCanceled(e))
+            {
+                // A NullReferenceException is happening in this method, but the dumps do not
+                // contain information about this stack frame because this method is async and
+                // therefore the exception filter in IdentifyConflictsAsync is insufficient.
+                // See https://devdiv.visualstudio.com/DevDiv/_workitems?_a=edit&id=378642
+
+                throw ExceptionUtilities.Unreachable;
+            }
         }
 
         internal static void AddConflictingParametersOfProperties(

src/Workspaces/Core/Portable/Workspace/Workspace.cs

@@ -49,6 +49,27 @@ public abstract partial class Workspace : IDisposable
 
         private Action<string> _testMessageLogger;
 
+        /// <summary>
+        /// <see cref="OnProjectRemoved"/> takes the <see cref="_serializationLock"/>, but can also
+        /// cause Shared Project IVsHierarchys to notify us that their context hierarchy has
+        /// changed while we are still holding the lock. In response to this, we try to set the new
+        /// active context document for open files, which also tries to take the lock, and we 
+        /// deadlock.
+        /// 
+        /// For.NET Framework Projects that reference Shared Projects, two things prevent deadlocks
+        /// when projects unload. During solution close, any Shared Projects are disconnected
+        /// before the projects start to unload, so no IVsHierarchy events are fired. During a
+        /// single project unload, we receive notification of the context hierarchy change before
+        /// the project is unloaded, avoiding any IVsHierarchy events if we tell the shared
+        /// hierarchy to set its context hierarchy to what it already is.
+        /// 
+        /// Neither of these behaviors are safe to rely on with .NET Standard (CPS) projects, so we
+        /// have to prevent the deadlock ourselves. We do this by remembering if we're already in 
+        /// the serialization lock due to project unload, and then not take the lock to update 
+        /// document contexts if so (but continuing to lock if it's not during a project unload).
+        /// </summary>
+        private ThreadLocal<bool> _isProjectUnloading = new ThreadLocal<bool>(() => false);
+
         /// <summary>
         /// Constructs a new workspace instance.
         /// </summary>
@@ -415,15 +436,24 @@ protected internal virtual void OnProjectRemoved(ProjectId projectId)
         {
             using (_serializationLock.DisposableWait())
             {
-                CheckProjectIsInCurrentSolution(projectId);
-                this.CheckProjectCanBeRemoved(projectId);
+                _isProjectUnloading.Value = true;
 
-                var oldSolution = this.CurrentSolution;
+                try
+                {
+                    CheckProjectIsInCurrentSolution(projectId);
+                    this.CheckProjectCanBeRemoved(projectId);
+
+                    var oldSolution = this.CurrentSolution;
 
-                this.ClearProjectData(projectId);
-                var newSolution = this.SetCurrentSolution(oldSolution.RemoveProject(projectId));
+                    this.ClearProjectData(projectId);
+                    var newSolution = this.SetCurrentSolution(oldSolution.RemoveProject(projectId));
 
-                this.RaiseWorkspaceChangedEventAsync(WorkspaceChangeKind.ProjectRemoved, oldSolution, newSolution, projectId);
+                    this.RaiseWorkspaceChangedEventAsync(WorkspaceChangeKind.ProjectRemoved, oldSolution, newSolution, projectId);
+                }
+                finally
+                {
+                    _isProjectUnloading.Value = false;
+                }
             }
         }
 

src/Workspaces/Core/Portable/Workspace/Workspace_Editor.cs

@@ -335,7 +335,14 @@ protected void OnDocumentContextUpdated(DocumentId documentId)
 
             if (container != null)
             {
-                OnDocumentContextUpdated(documentId, container);
+                if (_isProjectUnloading.Value)
+                {
+                    OnDocumentContextUpdated_NoSerializationLock(documentId, container);
+                }
+                else
+                {
+                    OnDocumentContextUpdated(documentId, container);
+                }
             }
         }
 
@@ -346,17 +353,22 @@ internal void OnDocumentContextUpdated(DocumentId documentId, SourceTextContaine
         {
             using (_serializationLock.DisposableWait())
             {
-                DocumentId oldActiveContextDocumentId;
+                OnDocumentContextUpdated_NoSerializationLock(documentId, container);
+            }
+        }
 
-                using (_stateLock.DisposableWait())
-                {
-                    oldActiveContextDocumentId = _bufferToDocumentInCurrentContextMap[container];
-                    _bufferToDocumentInCurrentContextMap[container] = documentId;
-                }
+        internal void OnDocumentContextUpdated_NoSerializationLock(DocumentId documentId, SourceTextContainer container)
+        {
+            DocumentId oldActiveContextDocumentId;
 
-                // fire and forget
-                this.RaiseDocumentActiveContextChangedEventAsync(container, oldActiveContextDocumentId: oldActiveContextDocumentId, newActiveContextDocumentId: documentId);
+            using (_stateLock.DisposableWait())
+            {
+                oldActiveContextDocumentId = _bufferToDocumentInCurrentContextMap[container];
+                _bufferToDocumentInCurrentContextMap[container] = documentId;
             }
+
+            // fire and forget
+            this.RaiseDocumentActiveContextChangedEventAsync(container, oldActiveContextDocumentId: oldActiveContextDocumentId, newActiveContextDocumentId: documentId);
         }
 
         protected void CheckDocumentIsClosed(DocumentId documentId)

src/Workspaces/Remote/ServiceHub/Services/CodeAnalysisService.cs

@@ -9,8 +9,9 @@ namespace Microsoft.CodeAnalysis.Remote
     internal partial class CodeAnalysisService : ServiceHubServiceBase
     {
         public CodeAnalysisService(Stream stream, IServiceProvider serviceProvider) :
-            base(stream, serviceProvider)
+            base(serviceProvider, stream)
         {
+            Rpc.StartListening();
         }
     }
 }

src/Workspaces/Remote/ServiceHub/Services/RemoteHostService.cs

@@ -39,9 +39,10 @@ static RemoteHostService()
         }
 
         public RemoteHostService(Stream stream, IServiceProvider serviceProvider) :
-            base(stream, serviceProvider)
+            base(serviceProvider, stream)
         {
             // this service provide a way for client to make sure remote host is alive
+            Rpc.StartListening();
         }
 
         public string Connect(string host)

src/Workspaces/Remote/ServiceHub/Services/RemoteSymbolSearchUpdateEngine.cs

@@ -13,10 +13,12 @@ internal partial class RemoteSymbolSearchUpdateEngine : ServiceHubServiceBase, I
         private readonly SymbolSearchUpdateEngine _updateEngine;
 
         public RemoteSymbolSearchUpdateEngine(Stream stream, IServiceProvider serviceProvider)
-            : base(stream, serviceProvider)
+            : base(serviceProvider, stream)
         {
             _updateEngine = new SymbolSearchUpdateEngine(
                 new LogService(this), updateCancellationToken: this.CancellationToken);
+
+            Rpc.StartListening();
         }
 
         public Task UpdateContinuouslyAsync(string sourceName, string localSettingsDirectory)

src/Workspaces/Remote/ServiceHub/Services/SnapshotService.cs

@@ -20,9 +20,11 @@ internal partial class SnapshotService : ServiceHubServiceBase
         private AssetSource _source;
 
         public SnapshotService(Stream stream, IServiceProvider serviceProvider) :
-            base(stream, serviceProvider)
+            base(serviceProvider, stream)
         {
             _gate = new object();
+
+            Rpc.StartListening();
         }
 
         public override void Initialize(int sessionId, byte[] solutionChecksum)

src/Workspaces/Remote/ServiceHub/Shared/ServiceHubServiceBase.cs

@@ -29,6 +29,7 @@ internal abstract class ServiceHubServiceBase : IDisposable
         private Checksum _solutionChecksumOpt;
         private RoslynServices _lazyRoslynServices;
 
+        [Obsolete("For backward compatibility. this will be removed once all callers moved to new ctor")]
         protected ServiceHubServiceBase(Stream stream, IServiceProvider serviceProvider)
         {
             _instanceId = Interlocked.Add(ref s_instanceId, 1);
@@ -46,6 +47,26 @@ protected ServiceHubServiceBase(Stream stream, IServiceProvider serviceProvider)
             Rpc.Disconnected += OnRpcDisconnected;
         }
 
+        protected ServiceHubServiceBase(IServiceProvider serviceProvider, Stream stream)
+        {
+            _instanceId = Interlocked.Add(ref s_instanceId, 1);
+
+            // in unit test, service provider will return asset storage, otherwise, use the default one
+            AssetStorage = (AssetStorage)serviceProvider.GetService(typeof(AssetStorage)) ?? AssetStorage.Default;
+
+            Logger = (TraceSource)serviceProvider.GetService(typeof(TraceSource));
+            Logger.TraceInformation($"{DebugInstanceString} Service instance created");
+
+            _cancellationTokenSource = new CancellationTokenSource();
+            CancellationToken = _cancellationTokenSource.Token;
+
+            // due to this issue - https://github.com/dotnet/roslyn/issues/16900#issuecomment-277378950
+            // all sub type must explicitly start JsonRpc once everything is
+            // setup
+            Rpc = new JsonRpc(stream, stream, this);
+            Rpc.Disconnected += OnRpcDisconnected;
+        }
+
         protected string DebugInstanceString => $"{GetType()} ({_instanceId})";
 
         protected RoslynServices RoslynServices