C#: Disallow field-like event initializers in structs. Fixes #343.

***NO_CI***
 (changeset 1387165)

Src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs

@@ -2648,28 +2648,13 @@ private static void CheckInterfaceMember(Symbol member, DiagnosticBag diagnostic
         private void CheckForStructBadInitializers(MembersAndInitializersBuilder builder, DiagnosticBag diagnostics)
         {
             Debug.Assert(TypeKind == TypeKind.Struct);
-            if (builder.InstanceInitializers.Count > 0)
-            {
-                var members = builder.NonTypeNonIndexerMembers;
 
-                foreach (var s in members)
+            foreach (var initializers in builder.InstanceInitializers)
+            {
+                foreach (FieldOrPropertyInitializer initializer in initializers)
                 {
-                    var p = s as SourcePropertySymbol;
-                    if (p != null && !p.IsStatic && p.IsAutoProperty
-                        && p.BackingField.HasInitializer)
-                    {
-                        // '{0}': cannot have instance field initializers in structs
-                        diagnostics.Add(ErrorCode.ERR_FieldInitializerInStruct, p.Locations[0], this);
-                    }
-                    else
-                    {
-                        var f = s as SourceMemberFieldSymbol;
-                        if (f != null && !f.IsStatic && f.HasInitializer)
-                        {
-                            // '{0}': cannot have instance field initializers in structs
-                            diagnostics.Add(ErrorCode.ERR_FieldInitializerInStruct, f.Locations[0], this);
-                        }
-                    }
+                    // '{0}': cannot have instance field initializers in structs
+                    diagnostics.Add(ErrorCode.ERR_FieldInitializerInStruct, (initializer.Field.AssociatedSymbol ?? initializer.Field).Locations[0], this);
                 }
             }
         }

Src/Compilers/CSharp/Test/Semantic/Semantics/StructsTests.cs

@@ -38,6 +38,52 @@ public struct A
     );
         }
 
+        [WorkItem(1075325, "DevDiv"), WorkItem(343, "CodePlex")]
+        [Fact()]
+        public void TestInitEventStruct()
+        {
+            var text = @"
+struct S {
+    event System.Action E = null;
+
+    void M()
+    {
+        E();
+    }
+}
+";
+            CreateCompilationWithMscorlib(text).VerifyDiagnostics(
+    // (3,25): error CS0573: 'S': cannot have instance property or field initializers in structs
+    //     event System.Action E = null;
+    Diagnostic(ErrorCode.ERR_FieldInitializerInStruct, "E").WithArguments("S").WithLocation(3, 25)
+                );
+        }
+
+        [WorkItem(1075325, "DevDiv"), WorkItem(343, "CodePlex")]
+        [Fact()]
+        public void TestStaticInitInStruct()
+        {
+            var text = @"
+struct S {
+    static event System.Action E = M;
+    static int F = 10;
+    static int P {get; set;} = 20;
+
+    static void M()
+    {
+    }
+
+    static void Main()
+    {
+        System.Console.WriteLine(""{0} {1} {2}"", S.F, S.P, S.E == null);
+    }
+}
+";
+            var comp = CreateCompilationWithMscorlib(text, options: TestOptions.DebugExe);
+
+            CompileAndVerify(comp, expectedOutput: "10 20 False").VerifyDiagnostics();
+        }
+
         // Test constructor forwarding works for structs
         [WorkItem(540896, "DevDiv")]
         [Fact]