hoist source level class declarations, fix error message

Author: vladima

src/compiler/checker.ts

@@ -10623,7 +10623,7 @@ module ts {
                 }
                 else if (compilerOptions.module === ModuleKind.System) {
                     // system modules does not support export assignment
-                    grammarErrorOnNode(node, Diagnostics.Export_assignment_is_not_supported_with_module_flag_is_system);
+                    grammarErrorOnNode(node, Diagnostics.Export_assignment_is_not_supported_when_module_flag_is_system);
                 }
             }
         }

src/compiler/diagnosticInformationMap.generated.ts

@@ -169,7 +169,7 @@ module ts {
         Ambient_const_enums_are_not_allowed_when_the_separateCompilation_flag_is_provided: { code: 1209, category: DiagnosticCategory.Error, key: "Ambient const enums are not allowed when the '--separateCompilation' flag is provided." },
         Invalid_use_of_0_Class_definitions_are_automatically_in_strict_mode: { code: 1210, category: DiagnosticCategory.Error, key: "Invalid use of '{0}'. Class definitions are automatically in strict mode." },
         A_class_declaration_without_the_default_modifier_must_have_a_name: { code: 1211, category: DiagnosticCategory.Error, key: "A class declaration without the 'default' modifier must have a name" },
-        Export_assignment_is_not_supported_with_module_flag_is_system: { code: 1212, category: DiagnosticCategory.Error, key: "Export assignment is not supported with '--module' flag is 'system'." },
+        Export_assignment_is_not_supported_when_module_flag_is_system: { code: 1212, category: DiagnosticCategory.Error, key: "Export assignment is not supported when '--module' flag is 'system'." },
         Duplicate_identifier_0: { code: 2300, category: DiagnosticCategory.Error, key: "Duplicate identifier '{0}'." },
         Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor: { code: 2301, category: DiagnosticCategory.Error, key: "Initializer of instance member variable '{0}' cannot reference identifier '{1}' declared in the constructor." },
         Static_members_cannot_reference_class_type_parameters: { code: 2302, category: DiagnosticCategory.Error, key: "Static members cannot reference class type parameters." },

src/compiler/diagnosticMessages.json

@@ -667,7 +667,7 @@
         "category": "Error",
         "code": 1211
     },
-    "Export assignment is not supported with '--module' flag is 'system'.": {
+    "Export assignment is not supported when '--module' flag is 'system'.": {
         "category": "Error",
         "code": 1212
     },

src/compiler/emitter.ts

@@ -3818,7 +3818,9 @@ var __param = this.__param || function(index, decorator) { return function (targ
 
             function emitClassLikeDeclarationBelowES6(node: ClassLikeDeclaration) {
                 if (node.kind === SyntaxKind.ClassDeclaration) {
-                    write("var ");
+                    if (!currentFileIsEmittedAsSystemModule() || !isSourceFileLevelDeclaration(node)) {
+                        write("var ");
+                    }
                     emitDeclarationName(node);
                     write(" = ");
                 }
@@ -4827,20 +4829,25 @@ var __param = this.__param || function(index, decorator) { return function (targ
             }
 
             function hoistTopLevelVariableAndFunctionDeclarations(node: SourceFile): void {
-                let hoistedLocals: Identifier[];
+                let hoistedVars: (Identifier | ClassDeclaration)[];
                 let hoistedFunctionDeclarations: FunctionDeclaration[];
 
                 visit(node);
 
-                if (hoistedLocals) {
+                if (hoistedVars) {
                     writeLine();
                     write("var ");
-                    for (let i = 0; i < hoistedLocals.length; ++i) {
-                        let local = hoistedLocals[i];
+                    for (let i = 0; i < hoistedVars.length; ++i) {
+                        let local = hoistedVars[i];
                         if (i !== 0) {
                             write(", ");
                         }
-                        emit(local);
+                        if (local.kind === SyntaxKind.ClassDeclaration) {
+                            emitDeclarationName(<ClassDeclaration>local);
+                        }
+                        else {
+                            emit(local);
+                        }
                     }
                     write(";")
                 }
@@ -4858,11 +4865,17 @@ var __param = this.__param || function(index, decorator) { return function (targ
                         return;
                     }
 
+                    if (node.kind === SyntaxKind.ClassDeclaration) {
+                        // TODO: rename block scoped classes
+                        (hoistedVars || (hoistedVars = [])).push(<ClassDeclaration>node);
+                        return;
+                    }
+
                     if (node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement) {
                         let name = (<VariableDeclaration | BindingElement>node).name;
                         if (name.kind === SyntaxKind.Identifier) {
                             renameNonTopLevelLetAndConst(name);
-                            (hoistedLocals || (hoistedLocals = [])).push(<Identifier>name);
+                            (hoistedVars || (hoistedVars = [])).push(<Identifier>name);
                         }
                         else {
                             forEachChild(name, visit);