Resolve aliases to preserve 'Cannot find name' errors for namespace imports

Author: jwbay

src/compiler/checker.ts

@@ -999,12 +999,19 @@ namespace ts {
             }
 
             const nameAsType = resolveName(errorLocation, name, strictlyTypeMeanings, nameNotFoundMessage, nameArg);
-            if (nameAsType) {
-                error(errorLocation, Diagnostics.Cannot_find_name_0_A_type_exists_with_this_name_but_no_value, name);
-                return true;
+            if (!nameAsType) {
+                return false;
             }
 
-            return false;
+            if (nameAsType.flags & SymbolFlags.Alias) {
+                const resolvedSymbol = resolveAlias(nameAsType);
+                if (resolvedSymbol.flags & SymbolFlags.NamespaceModule) {
+                    return false;
+                }
+            }
+
+            error(errorLocation, Diagnostics.Cannot_find_name_0_A_type_exists_with_this_name_but_no_value, name);
+            return true;
         }
 
         function checkResolvedBlockScopedVariable(result: Symbol, errorLocation: Node): void {

tests/baselines/reference/aliasOnMergedModuleInterface.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/compiler/aliasOnMergedModuleInterface_1.ts(5,16): error TS2691: Cannot find name 'foo'. A type exists with this name, but no value.
+tests/cases/compiler/aliasOnMergedModuleInterface_1.ts(5,16): error TS2304: Cannot find name 'foo'.
 
 
 ==== tests/cases/compiler/aliasOnMergedModuleInterface_1.ts (1 errors) ====
@@ -8,7 +8,7 @@ tests/cases/compiler/aliasOnMergedModuleInterface_1.ts(5,16): error TS2691: Cann
     z.bar("hello"); // This should be ok
     var x: foo.A = foo.bar("hello"); // foo.A should be ok but foo.bar should be error
                    ~~~
-!!! error TS2691: Cannot find name 'foo'. A type exists with this name, but no value.
+!!! error TS2304: Cannot find name 'foo'.
 
 ==== tests/cases/compiler/aliasOnMergedModuleInterface_0.ts (0 errors) ====
     declare module "foo"

tests/baselines/reference/typeUsedAsValueError2.errors.txt

@@ -0,0 +1,28 @@
+tests/cases/compiler/world.ts(4,1): error TS2691: Cannot find name 'HelloInterface'. A type exists with this name, but no value.
+tests/cases/compiler/world.ts(5,1): error TS2304: Cannot find name 'HelloNamespace'.
+
+
+==== tests/cases/compiler/world.ts (2 errors) ====
+    import HelloInterface = require("helloInterface");
+    import HelloNamespace = require("helloNamespace");
+    
+    HelloInterface.world;
+    ~~~~~~~~~~~~~~
+!!! error TS2691: Cannot find name 'HelloInterface'. A type exists with this name, but no value.
+    HelloNamespace.world;
+    ~~~~~~~~~~~~~~
+!!! error TS2304: Cannot find name 'HelloNamespace'.
+==== tests/cases/compiler/helloInterface.ts (0 errors) ====
+    interface HelloInterface {
+        world: any;
+    }
+    
+    export = HelloInterface;
+    
+==== tests/cases/compiler/helloNamespace.ts (0 errors) ====
+    namespace HelloNamespace {
+        export type world = any;
+    }
+    
+    export = HelloNamespace;
+    

tests/baselines/reference/typeUsedAsValueError2.js

@@ -0,0 +1,37 @@
+//// [tests/cases/compiler/typeUsedAsValueError2.ts] ////
+
+//// [helloInterface.ts]
+interface HelloInterface {
+    world: any;
+}
+
+export = HelloInterface;
+
+//// [helloNamespace.ts]
+namespace HelloNamespace {
+    export type world = any;
+}
+
+export = HelloNamespace;
+
+//// [world.ts]
+import HelloInterface = require("helloInterface");
+import HelloNamespace = require("helloNamespace");
+
+HelloInterface.world;
+HelloNamespace.world;
+
+//// [helloInterface.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+});
+//// [helloNamespace.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+});
+//// [world.js]
+define(["require", "exports"], function (require, exports) {
+    "use strict";
+    HelloInterface.world;
+    HelloNamespace.world;
+});

tests/cases/compiler/typeUsedAsValueError2.ts

@@ -0,0 +1,21 @@
+// @module: amd
+// @filename: helloInterface.ts
+interface HelloInterface {
+    world: any;
+}
+
+export = HelloInterface;
+
+// @filename: helloNamespace.ts
+namespace HelloNamespace {
+    export type world = any;
+}
+
+export = HelloNamespace;
+
+// @filename: world.ts
+import HelloInterface = require("helloInterface");
+import HelloNamespace = require("helloNamespace");
+
+HelloInterface.world;
+HelloNamespace.world;