Add null check when querying for exports from a module

src/compiler/checker.ts

@@ -929,7 +929,7 @@ module ts {
             // The ES6 spec permits export * declarations in a module to circularly reference the module itself. For example,
             // module 'a' can 'export * from "b"' and 'b' can 'export * from "a"' without error.
             function visit(symbol: Symbol) {
-                if (symbol.flags & SymbolFlags.HasExports && !contains(visitedSymbols, symbol)) {
+                if (symbol && symbol.flags & SymbolFlags.HasExports && !contains(visitedSymbols, symbol)) {
                     visitedSymbols.push(symbol);
                     if (symbol !== moduleSymbol) {
                         if (!result) {

tests/baselines/reference/exportDeclarationInInternalModule.errors.txt

@@ -0,0 +1,24 @@
+tests/cases/compiler/exportDeclarationInInternalModule.ts(14,19): error TS1141: String literal expected.
+
+
+==== tests/cases/compiler/exportDeclarationInInternalModule.ts (1 errors) ====
+    
+    class Bbb {
+    }
+    
+    class Aaa extends Bbb { }
+    
+    module Aaa {
+        export class SomeType { }
+    }
+    
+    module Bbb {
+        export class SomeType { }
+    
+        export * from Aaa;      // this line causes the nullref
+                      ~~~
+!!! error TS1141: String literal expected.
+    }
+    
+    var a: Bbb.SomeType;
+    

tests/baselines/reference/exportDeclarationInInternalModule.js

@@ -0,0 +1,76 @@
+//// [exportDeclarationInInternalModule.ts]
+
+class Bbb {
+}
+
+class Aaa extends Bbb { }
+
+module Aaa {
+    export class SomeType { }
+}
+
+module Bbb {
+    export class SomeType { }
+
+    export * from Aaa;      // this line causes the nullref
+}
+
+var a: Bbb.SomeType;
+
+
+//// [exportDeclarationInInternalModule.js]
+var __extends = this.__extends || function (d, b) {
+    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
+    function __() { this.constructor = d; }
+    __.prototype = b.prototype;
+    d.prototype = new __();
+};
+var Bbb = (function () {
+    function Bbb() {
+    }
+    return Bbb;
+})();
+var Aaa = (function (_super) {
+    __extends(Aaa, _super);
+    function Aaa() {
+        _super.apply(this, arguments);
+    }
+    return Aaa;
+})(Bbb);
+var Aaa;
+(function (Aaa) {
+    var SomeType = (function () {
+        function SomeType() {
+        }
+        return SomeType;
+    })();
+    Aaa.SomeType = SomeType;
+})(Aaa || (Aaa = {}));
+var Bbb;
+(function (Bbb) {
+    var SomeType = (function () {
+        function SomeType() {
+        }
+        return SomeType;
+    })();
+    Bbb.SomeType = SomeType;
+    __export(require()); // this line causes the nullref
+})(Bbb || (Bbb = {}));
+var a;
+
+
+//// [exportDeclarationInInternalModule.d.ts]
+declare class Bbb {
+}
+declare class Aaa extends Bbb {
+}
+declare module Aaa {
+    class SomeType {
+    }
+}
+declare module Bbb {
+    class SomeType {
+    }
+    export * from Aaa;
+}
+declare var a: Bbb.SomeType;

tests/baselines/reference/exportStarFromEmptyModule.errors.txt

@@ -0,0 +1,30 @@
+tests/cases/compiler/exportStarFromEmptyModule_module3.ts(1,15): error TS2306: File 'tests/cases/compiler/exportStarFromEmptyModule_module2.ts' is not an external module.
+tests/cases/compiler/exportStarFromEmptyModule_module4.ts(4,5): error TS2339: Property 'r' does not exist on type 'typeof A'.
+
+
+==== tests/cases/compiler/exportStarFromEmptyModule_module1.ts (0 errors) ====
+    
+    export class A {
+        static r;
+    }
+    
+==== tests/cases/compiler/exportStarFromEmptyModule_module2.ts (0 errors) ====
+    // empty
+    
+==== tests/cases/compiler/exportStarFromEmptyModule_module3.ts (1 errors) ====
+    export * from "exportStarFromEmptyModule_module2";
+                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2306: File 'exportStarFromEmptyModule_module2.ts' is not an external module.
+    export * from "exportStarFromEmptyModule_module1";
+    
+    export class A {
+        static q;
+    }
+    
+==== tests/cases/compiler/exportStarFromEmptyModule_module4.ts (1 errors) ====
+    import * as X from "exportStarFromEmptyModule_module3";
+    var s: X.A;
+    X.A.q;
+    X.A.r; // Error
+        ~
+!!! error TS2339: Property 'r' does not exist on type 'typeof A'.

tests/baselines/reference/exportStarFromEmptyModule.js

@@ -0,0 +1,65 @@
+//// [tests/cases/compiler/exportStarFromEmptyModule.ts] ////
+
+//// [exportStarFromEmptyModule_module1.ts]
+
+export class A {
+    static r;
+}
+
+//// [exportStarFromEmptyModule_module2.ts]
+// empty
+
+//// [exportStarFromEmptyModule_module3.ts]
+export * from "exportStarFromEmptyModule_module2";
+export * from "exportStarFromEmptyModule_module1";
+
+export class A {
+    static q;
+}
+
+//// [exportStarFromEmptyModule_module4.ts]
+import * as X from "exportStarFromEmptyModule_module3";
+var s: X.A;
+X.A.q;
+X.A.r; // Error
+
+//// [exportStarFromEmptyModule_module1.js]
+var A = (function () {
+    function A() {
+    }
+    return A;
+})();
+exports.A = A;
+//// [exportStarFromEmptyModule_module2.js]
+// empty
+//// [exportStarFromEmptyModule_module3.js]
+function __export(m) {
+    for (var p in m) if (!exports.hasOwnProperty(p)) exports[p] = m[p];
+}
+__export(require("exportStarFromEmptyModule_module2"));
+__export(require("exportStarFromEmptyModule_module1"));
+var A = (function () {
+    function A() {
+    }
+    return A;
+})();
+exports.A = A;
+//// [exportStarFromEmptyModule_module4.js]
+var X = require("exportStarFromEmptyModule_module3");
+var s;
+X.A.q;
+X.A.r; // Error
+
+
+//// [exportStarFromEmptyModule_module1.d.ts]
+export declare class A {
+    static r: any;
+}
+//// [exportStarFromEmptyModule_module2.d.ts]
+//// [exportStarFromEmptyModule_module3.d.ts]
+export * from "exportStarFromEmptyModule_module2";
+export * from "exportStarFromEmptyModule_module1";
+export declare class A {
+    static q: any;
+}
+//// [exportStarFromEmptyModule_module4.d.ts]

tests/cases/compiler/exportDeclarationInInternalModule.ts

@@ -0,0 +1,20 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+class Bbb {
+}
+
+class Aaa extends Bbb { }
+
+module Aaa {
+    export class SomeType { }
+}
+
+module Bbb {
+    export class SomeType { }
+
+    export * from Aaa;      // this line causes the nullref
+}
+
+var a: Bbb.SomeType;

tests/cases/compiler/exportStarFromEmptyModule.ts

@@ -0,0 +1,25 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+// @filename: exportStarFromEmptyModule_module1.ts
+export class A {
+    static r;
+}
+
+// @filename:exportStarFromEmptyModule_module2.ts
+// empty
+
+// @filename: exportStarFromEmptyModule_module3.ts
+export * from "exportStarFromEmptyModule_module2";
+export * from "exportStarFromEmptyModule_module1";
+
+export class A {
+    static q;
+}
+
+// @filename: exportStarFromEmptyModule_module4.ts
+import * as X from "exportStarFromEmptyModule_module3";
+var s: X.A;
+X.A.q;
+X.A.r; // Error