Move around the SDK directory dependency

It's no longer needed on the ICompilerServerHost implementation.  It is
just threaded through the compiler server creation like the other
directory parameters.

src/Compilers/Server/PortableServer/CoreClrCompilerServerHost.cs

@@ -41,11 +41,6 @@ public async Task<IClientConnection> CreateListenTask(CancellationToken cancella
             return new TcpClientConnection(tcpClient);
         }
 
-        public string GetSdkDirectory()
-        {
-            return null;
-        }
-
         public void Log(string message)
         {
             // BTODO: Do we need this anymore? 

src/Compilers/Server/PortableServer/Program.cs

@@ -14,7 +14,7 @@ public static void Main(string[] args)
             var endPoint = new IPEndPoint(ipAddress, port: 12000);
             var clientDirectory = AppContext.BaseDirectory;
             var compilerHost = new CoreClrCompilerServerHost(endPoint);
-            var compilerRequestHandler = new CompilerRequestHandler(compilerHost, clientDirectory);
+            var compilerRequestHandler = new CompilerRequestHandler(compilerHost, clientDirectory, sdkDirectory: null);
             var serverDispatcher = new ServerDispatcher(compilerHost, compilerRequestHandler, new EmptyDiagnosticListener());
             serverDispatcher.ListenAndDispatchConnections(keepAlive: null, cancellationToken: CancellationToken.None);
         }

src/Compilers/Server/ServerShared/CompilerRequestHandler.cs

@@ -42,10 +42,16 @@ internal sealed class CompilerRequestHandler : IRequestHandler
         /// </summary>
         private readonly string _clientDirectory;
 
-        internal CompilerRequestHandler(ICompilerServerHost compilerServerHost, string clientDirectory)
+        /// <summary>
+        /// Directory holding mscorlib.  It will be null when run under CoreCLR, 
+        /// </summary>
+        private readonly string _sdkDirectory;
+
+        internal CompilerRequestHandler(ICompilerServerHost compilerServerHost, string clientDirectory, string sdkDirectory)
         {
             _compilerServerHost = compilerServerHost;
             _clientDirectory = clientDirectory;
+            _sdkDirectory = sdkDirectory;
         }
 
         /// <summary>
@@ -106,7 +112,7 @@ private CommonCompiler CreateCSharpCompiler(RunRequest request)
                 request.Arguments,
                 _clientDirectory,
                 request.CurrentDirectory,
-                _compilerServerHost.GetSdkDirectory(),
+                _sdkDirectory,
                 request.LibDirectory,
                 _compilerServerHost.AnalyzerAssemblyLoader);
         }
@@ -118,7 +124,7 @@ private CommonCompiler CreateBasicCompiler(RunRequest request)
                 request.Arguments,
                 _clientDirectory,
                 request.CurrentDirectory,
-                _compilerServerHost.GetSdkDirectory(),
+                _sdkDirectory,
                 request.LibDirectory,
                 _compilerServerHost.AnalyzerAssemblyLoader);
         }

src/Compilers/Server/ServerShared/ICompilerServerHost.cs

@@ -16,7 +16,6 @@ internal interface ICompilerServerHost
         Func<string, MetadataReferenceProperties, PortableExecutableReference> AssemblyReferenceProvider { get; }
         Task<IClientConnection> CreateListenTask(CancellationToken cancellationToken);
 
-        string GetSdkDirectory();
         bool CheckAnalyzers(string baseDirectory, ImmutableArray<CommandLineAnalyzerReference> analyzers);
         void Log(string message);
     }

src/Compilers/Server/VBCSCompiler/DesktopCompilerServerHost.cs

@@ -42,11 +42,6 @@ public bool CheckAnalyzers(string baseDirectory, ImmutableArray<CommandLineAnaly
             return AnalyzerConsistencyChecker.Check(baseDirectory, analyzers, s_analyzerLoader);
         }
 
-        public string GetSdkDirectory()
-        {
-            return RuntimeEnvironment.GetRuntimeDirectory();
-        }
-
         public void Log(string message)
         {
             CompilerServerLogger.Log(message);

src/Compilers/Server/VBCSCompiler/VBCSCompiler.cs

@@ -13,6 +13,7 @@
 using System.Threading.Tasks;
 using System.Globalization;
 using Microsoft.CodeAnalysis.CommandLine;
+using System.Runtime.InteropServices;
 
 namespace Microsoft.CodeAnalysis.CompilerServer
 {
@@ -100,10 +101,11 @@ private static int Run(TimeSpan? keepAliveTimeout, string compilerExeDirectory,
             CompilerServerLogger.Log("Keep alive timeout is: {0} milliseconds.", keepAliveTimeout?.TotalMilliseconds ?? 0);
             FatalError.Handler = FailFast.OnFatalException;
 
+            var sdkDirectory = RuntimeEnvironment.GetRuntimeDirectory();
             var compilerServerHost = new DesktopCompilerServerHost(pipeName);
             var dispatcher = new ServerDispatcher(
                 compilerServerHost,
-                new CompilerRequestHandler(compilerServerHost, compilerExeDirectory), 
+                new CompilerRequestHandler(compilerServerHost, compilerExeDirectory, sdkDirectory), 
                 new EmptyDiagnosticListener());
 
             dispatcher.ListenAndDispatchConnections(keepAliveTimeout);

src/Compilers/Server/VBCSCompilerTests/CompilerServerApiTest.cs

@@ -10,6 +10,7 @@
 using Moq;
 using Roslyn.Test.Utilities;
 using Xunit;
+using System.Runtime.InteropServices;
 
 namespace Microsoft.CodeAnalysis.CompilerServer.UnitTests
 {
@@ -316,7 +317,7 @@ public async Task KeepAliveAfterMultipleConnection()
             {
                 var dispatcher = new ServerDispatcher(
                     CreateNopCompilerServerHost().Object,
-                    new CompilerRequestHandler(CreateNopCompilerServerHost().Object, Temp.CreateDirectory().Path), 
+                    new CompilerRequestHandler(CreateNopCompilerServerHost().Object, Temp.CreateDirectory().Path, RuntimeEnvironment.GetRuntimeDirectory()), 
                     listener);
                 dispatcher.ListenAndDispatchConnections(keepAlive);
             });
@@ -345,7 +346,7 @@ public async Task KeepAliveAfterSimultaneousConnection()
             {
                 var dispatcher = new ServerDispatcher(
                     CreateNopCompilerServerHost().Object,
-                    new CompilerRequestHandler(CreateNopCompilerServerHost().Object, Temp.CreateDirectory().Path), 
+                    new CompilerRequestHandler(CreateNopCompilerServerHost().Object, Temp.CreateDirectory().Path, RuntimeEnvironment.GetRuntimeDirectory()), 
                     listener);
                 dispatcher.ListenAndDispatchConnections(keepAlive);
             });