Enable nullable annotations in hosting of Scripting

src/core/Microsoft.Scripting/Hosting/CompiledCode.cs

@@ -2,13 +2,16 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 #if FEATURE_REMOTING
 using System.Runtime.Remoting;
 #else
 using MarshalByRefObject = System.Object;
 #endif
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 
 using Microsoft.Scripting.Utils;
@@ -19,7 +22,7 @@ namespace Microsoft.Scripting.Hosting {
     /// Hosting API counterpart for <see cref="ScriptCode"/>.
     /// </summary>
     public sealed class CompiledCode : MarshalByRefObject {
-        private ScriptScope _defaultScope;
+        private ScriptScope? _defaultScope;
 
         internal ScriptCode ScriptCode { get; }
 
@@ -44,73 +47,75 @@ public ScriptScope DefaultScope {
                 if (_defaultScope is null) {
                     Interlocked.CompareExchange(ref _defaultScope, new ScriptScope(Engine, ScriptCode.CreateScope()), null);
                 }
-                return _defaultScope; 
+                return _defaultScope;
             }
         }
 
         /// <summary>
         /// Executes code in a default scope.
         /// </summary>
-        public dynamic Execute() {
+        public dynamic? Execute() {
             return ScriptCode.Run(DefaultScope.Scope);
         }
 
         /// <summary>
         /// Execute code within a given scope and returns the result.
         /// </summary>
-        public dynamic Execute(ScriptScope scope) {
+        public dynamic? Execute(ScriptScope scope) {
             ContractUtils.RequiresNotNull(scope, nameof(scope));
             return ScriptCode.Run(scope.Scope);
         }
 
         /// <summary>
         /// Executes code in in a default scope and converts to a given type.
         /// </summary>
+        [return: MaybeNull]
         public T Execute<T>() {
-            return Engine.Operations.ConvertTo<T>((object)Execute());
+            return Engine.Operations.ConvertTo<T>((object?)Execute());
         }
 
         /// <summary>
         /// Execute code within a given scope and converts result to a given type.
         /// </summary>
+        [return: MaybeNull]
         public T Execute<T>(ScriptScope scope) {
-            return Engine.Operations.ConvertTo<T>((object)Execute(scope));
+            return Engine.Operations.ConvertTo<T>((object?)Execute(scope));
         }
 
 
 #if FEATURE_REMOTING
         /// <summary>
         /// Executes the code in an empty scope.
-        /// Returns an ObjectHandle wrapping the resulting value of running the code.  
+        /// Returns an ObjectHandle wrapping the resulting value of running the code.
         /// </summary>
         public ObjectHandle ExecuteAndWrap() {
-            return new ObjectHandle((object)Execute());
+            return new ObjectHandle((object?)Execute());
         }
 
         /// <summary>
         /// Executes the code in the specified scope.
-        /// Returns an ObjectHandle wrapping the resulting value of running the code.  
+        /// Returns an ObjectHandle wrapping the resulting value of running the code.
         /// </summary>
         public ObjectHandle ExecuteAndWrap(ScriptScope scope) {
-            return new ObjectHandle((object)Execute(scope));
+            return new ObjectHandle((object?)Execute(scope));
         }
 
         /// <summary>
         /// Executes the code in an empty scope.
-        /// Returns an ObjectHandle wrapping the resulting value of running the code.  
-        /// 
+        /// Returns an ObjectHandle wrapping the resulting value of running the code.
+        ///
         /// If an exception is thrown the exception is caught and an ObjectHandle to
         /// the exception is provided.
         /// </summary>
         /// <remarks>
-        /// Use this API to handle non-serializable exceptions (exceptions might not be serializable due to security restrictions) 
+        /// Use this API to handle non-serializable exceptions (exceptions might not be serializable due to security restrictions)
         /// or if an exception serialization loses information.
         /// </remarks>
-        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes")]
-        public ObjectHandle ExecuteAndWrap(out ObjectHandle exception) {
+        [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes")]
+        public ObjectHandle? ExecuteAndWrap(out ObjectHandle? exception) {
             exception = null;
             try {
-                return new ObjectHandle((object)Execute());
+                return new ObjectHandle((object?)Execute());
             } catch (Exception e) {
                 exception = new ObjectHandle(e);
                 return null;
@@ -119,28 +124,27 @@ public ObjectHandle ExecuteAndWrap(out ObjectHandle exception) {
 
         /// <summary>
         /// Executes the expression in the specified scope and return a result.
-        /// Returns an ObjectHandle wrapping the resulting value of running the code.  
-        /// 
+        /// Returns an ObjectHandle wrapping the resulting value of running the code.
+        ///
         /// If an exception is thrown the exception is caught and an ObjectHandle to
         /// the exception is provided.
         /// </summary>
         /// <remarks>
-        /// Use this API to handle non-serializable exceptions (exceptions might not be serializable due to security restrictions) 
+        /// Use this API to handle non-serializable exceptions (exceptions might not be serializable due to security restrictions)
         /// or if an exception serialization loses information.
         /// </remarks>
-        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes")]
-        public ObjectHandle ExecuteAndWrap(ScriptScope scope, out ObjectHandle exception) {
+        [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes")]
+        public ObjectHandle? ExecuteAndWrap(ScriptScope scope, out ObjectHandle? exception) {
             exception = null;
             try{
-                return new ObjectHandle((object)Execute(scope));
+                return new ObjectHandle((object?)Execute(scope));
             } catch (Exception e) {
                 exception = new ObjectHandle(e);
                 return null;
             }
         }
 
-        // TODO: Figure out what is the right lifetime
-        public override object InitializeLifetimeService() {
+        public override object? InitializeLifetimeService() {
             return null;
         }
 #endif

src/core/Microsoft.Scripting/Hosting/Configuration/LanguageElementCollection.cs

@@ -2,10 +2,10 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
-#if FEATURE_CONFIGURATION
-
 #nullable enable
 
+#if FEATURE_CONFIGURATION
+
 using System.Configuration;
 
 namespace Microsoft.Scripting.Hosting.Configuration {

src/core/Microsoft.Scripting/Hosting/Configuration/OptionElementCollection.cs

@@ -2,10 +2,10 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
-#if FEATURE_CONFIGURATION
-
 #nullable enable
 
+#if FEATURE_CONFIGURATION
+
 using System.Configuration;
 
 namespace Microsoft.Scripting.Hosting.Configuration {

src/core/Microsoft.Scripting/Hosting/Configuration/Section.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 #if FEATURE_CONFIGURATION
 
 using System;
@@ -83,7 +85,7 @@ public IEnumerable<OptionElement> GetOptions() {
             }
         }
 
-        private static Section LoadFromFile(Stream configFileStream) {
+        private static Section? LoadFromFile(Stream configFileStream) {
             var result = new Section();
             using (var reader = XmlReader.Create(configFileStream)) {
                 if (reader.ReadToDescendant("configuration") && reader.ReadToDescendant(SectionName)) {
@@ -95,7 +97,7 @@ private static Section LoadFromFile(Stream configFileStream) {
             return result;
         }
 
-        internal static void LoadRuntimeSetup(ScriptRuntimeSetup setup, Stream configFileStream) {
+        internal static void LoadRuntimeSetup(ScriptRuntimeSetup setup, Stream? configFileStream) {
             var config = configFileStream is not null
                 ? LoadFromFile(configFileStream)
                 : System.Configuration.ConfigurationManager.GetSection(SectionName) as Section;
@@ -112,10 +114,10 @@ internal static void LoadRuntimeSetup(ScriptRuntimeSetup setup, Stream configFil
             }
 
             foreach (var languageConfig in config.GetLanguages()) {
-                var provider = languageConfig.Type;
-                var names = languageConfig.GetNamesArray();
-                var extensions = languageConfig.GetExtensionsArray();
-                var displayName = languageConfig.DisplayName ?? ((names.Length > 0) ? names[0] : languageConfig.Type);
+                string provider = languageConfig.Type ?? "<unknown>";
+                string[] names = languageConfig.GetNamesArray();
+                string[] extensions = languageConfig.GetExtensionsArray();
+                string displayName = languageConfig.DisplayName ?? ((names.Length > 0) ? names[0] : provider);
 
                 // Honor the latest-wins behavior of the <languages> tag for options that were already included in the setup object;
                 // Keep the options though.

src/core/Microsoft.Scripting/Hosting/DocumentationOperations.cs

@@ -56,8 +56,8 @@ public ICollection<OverloadDoc> GetOverloads(ObjectHandle value) {
         }
 
         // TODO: Figure out what is the right lifetime
-        public override object InitializeLifetimeService() {
-            return base.InitializeLifetimeService();
+        public override object? InitializeLifetimeService() {
+            return null;
         }
 #endif
  }

src/core/Microsoft.Scripting/Hosting/ErrorListener.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 using System;
 
 #if FEATURE_REMOTING
@@ -27,8 +29,7 @@ internal void ReportError(ScriptSource source, string message, in SourceSpan spa
         public abstract void ErrorReported(ScriptSource source, string message, SourceSpan span, int errorCode, Severity severity);
 
 #if FEATURE_REMOTING
-        // TODO: Figure out what is the right lifetime
-        public override object InitializeLifetimeService() {
+        public override object? InitializeLifetimeService() {
             return null;
         }
 #endif

src/core/Microsoft.Scripting/Hosting/ErrorListenerProxy.cs

@@ -2,10 +2,12 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 namespace Microsoft.Scripting.Hosting {
 
     /// <summary>
-    /// Bridges ErrorSink and ErrorListener. 
+    /// Bridges ErrorSink and ErrorListener.
     /// Errors reported by language compilers to ErrorSink are forwarded to the ErrorListener provided by the host.
     /// </summary>
     /// <remarks>
@@ -18,10 +20,10 @@ namespace Microsoft.Scripting.Hosting {
     /// within the context of compilation unit.
     /// </remarks>
     internal sealed class ErrorListenerProxySink : ErrorSink {
-        private readonly ErrorListener _listener;
+        private readonly ErrorListener? _listener;
         private readonly ScriptSource _source;
 
-        public ErrorListenerProxySink(ScriptSource source, ErrorListener listener) {
+        public ErrorListenerProxySink(ScriptSource source, ErrorListener? listener) {
             _listener = listener;
             _source = source;
         }

src/core/Microsoft.Scripting/Hosting/ErrorSinkProxyListener.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 namespace Microsoft.Scripting.Hosting {
     /// <summary>
     /// Bridges ErrorListener and ErrorSink. It provides the reverse functionality as ErrorSinkProxyListener
@@ -14,11 +16,11 @@ public ErrorSinkProxyListener(ErrorSink errorSink) {
         }
 
         public override void ErrorReported(ScriptSource source, string message, SourceSpan span, int errorCode, Severity severity) {
-            // Note that we cannot use "source.SourceUnit" since "source" may be a proxy object, and we will not be able to marshall 
+            // Note that we cannot use "source.SourceUnit" since "source" may be a proxy object, and we will not be able to marshall
             // "source.SourceUnit" to the current AppDomain
 
-            string code = null;
-            string line = null;
+            string? code = null;
+            string? line = null;
             try {
                 code = source.GetCode();
                 line = source.GetCodeLine(span.Start.Line);

src/core/Microsoft.Scripting/Hosting/ExceptionOperations.cs

@@ -74,8 +74,8 @@ public IList<DynamicStackFrame> GetStackFrames(ObjectHandle exception) {
             return _context.GetStackFrames(exceptionObj!);
         }
 
-        public override object InitializeLifetimeService() {
-            return base.InitializeLifetimeService();
+        public override object? InitializeLifetimeService() {
+            return null;
         }
 #endif
     }