Merge pull request #16704 from charlespierce/namespace_export_default

Diagnostics for default class / function export in namespace

Author: DanielRosenwasser

src/compiler/checker.ts

@@ -23666,7 +23666,14 @@ namespace ts {
                         }
                         flags |= ModifierFlags.Export;
                         break;
+                    case SyntaxKind.DefaultKeyword:
+                        const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent;
+                        if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) {
+                            return grammarErrorOnNode(modifier, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module);
+                        }
 
+                        flags |= ModifierFlags.Default;
+                        break;
                     case SyntaxKind.DeclareKeyword:
                         if (flags & ModifierFlags.Ambient) {
                             return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "declare");

src/compiler/transformers/ts.ts

@@ -3158,7 +3158,7 @@ namespace ts {
                 getExternalModuleOrNamespaceExportName(currentNamespaceContainerName, node, /*allowComments*/ false, /*allowSourceMaps*/ true),
                 getLocalName(node)
             );
-            setSourceMapRange(expression, createRange(node.name.pos, node.end));
+            setSourceMapRange(expression, createRange(node.name ? node.name.pos : node.pos, node.end));
 
             const statement = createStatement(expression);
             setSourceMapRange(statement, createRange(-1, node.end));

tests/baselines/reference/exportDefaultClassInNamespace.errors.txt

@@ -0,0 +1,17 @@
+tests/cases/compiler/exportDefaultClassInNamespace.ts(2,12): error TS1319: A default export can only be used in an ECMAScript-style module.
+tests/cases/compiler/exportDefaultClassInNamespace.ts(6,12): error TS1319: A default export can only be used in an ECMAScript-style module.
+
+
+==== tests/cases/compiler/exportDefaultClassInNamespace.ts (2 errors) ====
+    namespace ns_class {
+        export default class {}
+               ~~~~~~~
+!!! error TS1319: A default export can only be used in an ECMAScript-style module.
+    }
+    
+    namespace ns_abstract_class {
+        export default abstract class {}
+               ~~~~~~~
+!!! error TS1319: A default export can only be used in an ECMAScript-style module.
+    }
+    

tests/baselines/reference/exportDefaultClassInNamespace.js

@@ -0,0 +1,29 @@
+//// [exportDefaultClassInNamespace.ts]
+namespace ns_class {
+    export default class {}
+}
+
+namespace ns_abstract_class {
+    export default abstract class {}
+}
+
+
+//// [exportDefaultClassInNamespace.js]
+var ns_class;
+(function (ns_class) {
+    var default_1 = (function () {
+        function default_1() {
+        }
+        return default_1;
+    }());
+    ns_class.default_1 = default_1;
+})(ns_class || (ns_class = {}));
+var ns_abstract_class;
+(function (ns_abstract_class) {
+    var default_2 = (function () {
+        function default_2() {
+        }
+        return default_2;
+    }());
+    ns_abstract_class.default_2 = default_2;
+})(ns_abstract_class || (ns_abstract_class = {}));

tests/baselines/reference/exportDefaultClassInNamespace.symbols

@@ -0,0 +1,13 @@
+=== tests/cases/compiler/exportDefaultClassInNamespace.ts ===
+namespace ns_class {
+>ns_class : Symbol(ns_class, Decl(exportDefaultClassInNamespace.ts, 0, 0))
+
+    export default class {}
+}
+
+namespace ns_abstract_class {
+>ns_abstract_class : Symbol(ns_abstract_class, Decl(exportDefaultClassInNamespace.ts, 2, 1))
+
+    export default abstract class {}
+}
+

tests/baselines/reference/exportDefaultClassInNamespace.types

@@ -0,0 +1,13 @@
+=== tests/cases/compiler/exportDefaultClassInNamespace.ts ===
+namespace ns_class {
+>ns_class : typeof ns_class
+
+    export default class {}
+}
+
+namespace ns_abstract_class {
+>ns_abstract_class : typeof ns_abstract_class
+
+    export default abstract class {}
+}
+

tests/baselines/reference/exportDefaultFunctionInNamespace.errors.txt

@@ -0,0 +1,17 @@
+tests/cases/compiler/exportDefaultFunctionInNamespace.ts(2,12): error TS1319: A default export can only be used in an ECMAScript-style module.
+tests/cases/compiler/exportDefaultFunctionInNamespace.ts(6,12): error TS1319: A default export can only be used in an ECMAScript-style module.
+
+
+==== tests/cases/compiler/exportDefaultFunctionInNamespace.ts (2 errors) ====
+    namespace ns_function {
+        export default function () {}
+               ~~~~~~~
+!!! error TS1319: A default export can only be used in an ECMAScript-style module.
+    }
+    
+    namespace ns_async_function {
+        export default async function () {}
+               ~~~~~~~
+!!! error TS1319: A default export can only be used in an ECMAScript-style module.
+    }
+    

tests/baselines/reference/exportDefaultFunctionInNamespace.js

@@ -0,0 +1,60 @@
+//// [exportDefaultFunctionInNamespace.ts]
+namespace ns_function {
+    export default function () {}
+}
+
+namespace ns_async_function {
+    export default async function () {}
+}
+
+
+//// [exportDefaultFunctionInNamespace.js]
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
+    return new (P || (P = Promise))(function (resolve, reject) {
+        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
+        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
+        function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
+    });
+};
+var __generator = (this && this.__generator) || function (thisArg, body) {
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
+    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    function verb(n) { return function (v) { return step([n, v]); }; }
+    function step(op) {
+        if (f) throw new TypeError("Generator is already executing.");
+        while (_) try {
+            if (f = 1, y && (t = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t;
+            if (y = 0, t) op = [0, t.value];
+            switch (op[0]) {
+                case 0: case 1: t = op; break;
+                case 4: _.label++; return { value: op[1], done: false };
+                case 5: _.label++; y = op[1]; op = [0]; continue;
+                case 7: op = _.ops.pop(); _.trys.pop(); continue;
+                default:
+                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
+                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
+                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
+                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
+                    if (t[2]) _.ops.pop();
+                    _.trys.pop(); continue;
+            }
+            op = body.call(thisArg, _);
+        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
+        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
+    }
+};
+var ns_function;
+(function (ns_function) {
+    default function () { }
+    ns_function.default_1 = default_1;
+})(ns_function || (ns_function = {}));
+var ns_async_function;
+(function (ns_async_function) {
+    default function () {
+        return __awaiter(this, void 0, void 0, function () { return __generator(this, function (_a) {
+            return [2 /*return*/];
+        }); });
+    }
+    ns_async_function.default_2 = default_2;
+})(ns_async_function || (ns_async_function = {}));

tests/baselines/reference/exportDefaultFunctionInNamespace.symbols

@@ -0,0 +1,13 @@
+=== tests/cases/compiler/exportDefaultFunctionInNamespace.ts ===
+namespace ns_function {
+>ns_function : Symbol(ns_function, Decl(exportDefaultFunctionInNamespace.ts, 0, 0))
+
+    export default function () {}
+}
+
+namespace ns_async_function {
+>ns_async_function : Symbol(ns_async_function, Decl(exportDefaultFunctionInNamespace.ts, 2, 1))
+
+    export default async function () {}
+}
+

tests/baselines/reference/exportDefaultFunctionInNamespace.types

@@ -0,0 +1,13 @@
+=== tests/cases/compiler/exportDefaultFunctionInNamespace.ts ===
+namespace ns_function {
+>ns_function : typeof ns_function
+
+    export default function () {}
+}
+
+namespace ns_async_function {
+>ns_async_function : typeof ns_async_function
+
+    export default async function () {}
+}
+