Report error for await in static script variable initializer

src/Compilers/CSharp/Portable/Binder/Binder_Await.cs

@@ -125,7 +125,14 @@ private bool ReportBadAwaitWithoutAsync(CSharpSyntaxNode node, DiagnosticBag dia
                     case SymbolKind.Field:
                         if (containingMemberOrLambda.ContainingType.IsScriptClass)
                         {
-                            return false;
+                            if (((FieldSymbol)containingMemberOrLambda).IsStatic)
+                            {
+                                info = new CSDiagnosticInfo(ErrorCode.ERR_BadAwaitInStaticVariableInitializer);
+                            }
+                            else
+                            {
+                                return false;
+                            }
                         }
                         break;
                     case SymbolKind.Method:

src/Compilers/CSharp/Portable/CSharpResources.Designer.cs

@@ -1051,6 +1051,15 @@ internal class CSharpResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to The &apos;await&apos; operator cannot be used in a static script variable initializer..
+        /// </summary>
+        internal static string ERR_BadAwaitInStaticVariableInitializer {
+            get {
+                return ResourceManager.GetString("ERR_BadAwaitInStaticVariableInitializer", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to The &apos;await&apos; operator can only be used when contained within a method or lambda expression marked with the &apos;async&apos; modifier.
         /// </summary>

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -3530,6 +3530,9 @@ Give the compiler some way to differentiate the methods. For example, you can gi
   <data name="ERR_BadAwaitInLock" xml:space="preserve">
     <value>Cannot await in the body of a lock statement</value>
   </data>
+  <data name="ERR_BadAwaitInStaticVariableInitializer" xml:space="preserve">
+    <value>The 'await' operator cannot be used in a static script variable initializer.</value>
+  </data>
   <data name="ERR_AwaitInUnsafeContext" xml:space="preserve">
     <value>Cannot await in an unsafe context</value>
   </data>

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

@@ -1315,5 +1315,6 @@ internal enum ErrorCode
         ERR_LoadDirectiveOnlyAllowedInScripts = 8097,
         ERR_PPLoadFollowsToken = 8098,
         ERR_SourceFileReferencesNotSupported = 8099,
+        ERR_BadAwaitInStaticVariableInitializer = 8100,
     }
 }

src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncTests.cs

@@ -3672,20 +3672,38 @@ public void AwaitInInteractiveDeclaration()
 
         /// <summary>
         /// await should be disallowed in static field initializer
-        /// since the static initialization of the class should
-        /// complete before other members are used.
+        /// since the static initialization of the class must be
+        /// handled synchronously in the .cctor.
         /// </summary>
-        [Fact(Skip = "Not handled")]
-        public void AwaitInStaticInitializer()
+        [WorkItem(5787)]
+        [Fact]
+        public void AwaitInScriptStaticInitializer()
+        {
+            var source =
+@"static int x = 1 +
+    await System.Threading.Tasks.Task.FromResult(1);
+int y = x +
+    await System.Threading.Tasks.Task.FromResult(2);";
+            var compilation = CreateCompilationWithMscorlib45(source, parseOptions: TestOptions.Script, options: TestOptions.DebugExe);
+            compilation.VerifyDiagnostics(
+                // (2,5): error CS8100: The 'await' operator cannot be used in a static script variable initializer.
+                //     await System.Threading.Tasks.Task.FromResult(1);
+                Diagnostic(ErrorCode.ERR_BadAwaitInStaticVariableInitializer, "await System.Threading.Tasks.Task.FromResult(1)").WithLocation(2, 5));
+        }
+
+        [WorkItem(5787)]
+        [Fact]
+        public void AwaitInInteractiveStaticInitializer()
         {
             var references = new[] { MscorlibRef_v4_0_30316_17626, SystemCoreRef };
             var source =
-@"static int x = await System.Threading.Tasks.Task.FromResult(1);";
+@"static int x = await System.Threading.Tasks.Task.FromResult(1);
+int y = await System.Threading.Tasks.Task.FromResult(2);";
             var compilation = CSharpCompilation.CreateSubmission("s0.dll", SyntaxFactory.ParseSyntaxTree(source, options: TestOptions.Interactive), references);
             compilation.VerifyDiagnostics(
-                // (1,16): error CS1992: The 'await' operator can only be used when contained within a method or lambda expression marked with the 'async' modifier
+                // (1,16): error CS8100: The 'await' operator cannot be used in a static script variable initializer.
                 // static int x = await System.Threading.Tasks.Task.FromResult(1);
-                Diagnostic(ErrorCode.ERR_BadAwaitWithoutAsync, "await System.Threading.Tasks.Task.FromResult(1)").WithLocation(1, 16));
+                Diagnostic(ErrorCode.ERR_BadAwaitInStaticVariableInitializer, "await System.Threading.Tasks.Task.FromResult(1)").WithLocation(1, 16));
         }
 
         [Fact, WorkItem(4839, "https://github.com/dotnet/roslyn/issues/4839")]