diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 228b1067bb01a..01fc97314c263 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11061,7 +11061,7 @@ namespace ts {
let someHaveQuestionToken = false;
let allHaveQuestionToken = true;
let hasOverloads = false;
- let bodyDeclaration: FunctionLikeDeclaration;
+ let implementationDeclaration: FunctionLikeDeclaration; // should be the first declaration with a body
let lastSeenNonAmbientDeclaration: FunctionLikeDeclaration;
let previousDeclaration: FunctionLikeDeclaration;
@@ -11143,12 +11143,17 @@ namespace ts {
someHaveQuestionToken = someHaveQuestionToken || hasQuestionToken(node);
allHaveQuestionToken = allHaveQuestionToken && hasQuestionToken(node);
- if (nodeIsPresent(node.body) && bodyDeclaration) {
+ if (nodeIsPresent(node.body) && implementationDeclaration) {
if (isConstructor) {
multipleConstructorImplementation = true;
}
else {
duplicateFunctionDeclaration = true;
+
+ // We expect both implementations to agree in defaultness for later on.
+ if ((node.flags & NodeFlags.Default) !== (implementationDeclaration.flags & NodeFlags.Default)) {
+ Debug.fail("Expected first and current implementations of and current to agree in export default flag.");
+ }
}
}
else if (!isExportSymbolInsideModule && previousDeclaration && previousDeclaration.parent === node.parent && previousDeclaration.end !== node.pos) {
@@ -11156,8 +11161,8 @@ namespace ts {
}
if (nodeIsPresent(node.body)) {
- if (!bodyDeclaration) {
- bodyDeclaration = node;
+ if (!implementationDeclaration) {
+ implementationDeclaration = node;
}
}
else {
@@ -11173,15 +11178,19 @@ namespace ts {
}
if (multipleConstructorImplementation) {
- forEach(declarations, declaration => {
+ for (let declaration of declarations) {
error(declaration, Diagnostics.Multiple_constructor_implementations_are_not_allowed);
- });
+ }
}
if (duplicateFunctionDeclaration) {
- forEach(declarations, declaration => {
- error(declaration.name, Diagnostics.Duplicate_function_implementation);
- });
+ let message = implementationDeclaration.flags & NodeFlags.Default && areAllFunctionDeclarationsWhereSomeNamesDiffer(declarations) ?
+ Diagnostics.A_module_cannot_have_multiple_default_exports :
+ Diagnostics.Duplicate_function_implementation;
+
+ for (let declaration of declarations) {
+ error(declaration.name || declaration, message);
+ }
}
// Abstract methods can't have an implementation -- in particular, they don't need one.
@@ -11191,12 +11200,12 @@ namespace ts {
}
if (hasOverloads) {
- checkFlagAgreementBetweenOverloads(declarations, bodyDeclaration, flagsToCheck, someNodeFlags, allNodeFlags);
- checkQuestionTokenAgreementBetweenOverloads(declarations, bodyDeclaration, someHaveQuestionToken, allHaveQuestionToken);
+ checkFlagAgreementBetweenOverloads(declarations, implementationDeclaration, flagsToCheck, someNodeFlags, allNodeFlags);
+ checkQuestionTokenAgreementBetweenOverloads(declarations, implementationDeclaration, someHaveQuestionToken, allHaveQuestionToken);
- if (bodyDeclaration) {
+ if (implementationDeclaration) {
let signatures = getSignaturesOfSymbol(symbol);
- let bodySignature = getSignatureFromDeclaration(bodyDeclaration);
+ let bodySignature = getSignatureFromDeclaration(implementationDeclaration);
// If the implementation signature has string literals, we will have reported an error in
// checkSpecializedSignatureDeclaration
if (!bodySignature.hasStringLiterals) {
@@ -11225,6 +11234,56 @@ namespace ts {
}
}
+ /**
+ * Determines if all declarations in the given list are function declarations, and that
+ * all the declarations have the same name. This is useful for how we report errors.
+ *
+ * For instance, if a user has
+ *
+ * export default function foo() { }
+ * export default function bar() { }
+ *
+ * We want to tell the user that there are multiple default exports. However, if a user has
+ *
+ * export default function foo() { }
+ * export default function foo() { }
+ *
+ * It is probably more accurate to say that there are duplicate function implementations.
+ *
+ * @param declarations
+ */
+ function areAllFunctionDeclarationsWhereSomeNamesDiffer(declarations: Declaration[]) {
+ let numDeclarations = declarations.length;
+ Debug.assert(numDeclarations > 0, "Expected at least one declaration.");
+
+ let firstDeclaration = declarations[0];
+ if (firstDeclaration.kind !== SyntaxKind.FunctionDeclaration) {
+ return false;
+ }
+
+ let firstName = (firstDeclaration as FunctionDeclaration).name;
+ for (let i = 1; i < numDeclarations; i++) {
+ let currentDeclaration = declarations[i];
+ if (currentDeclaration.kind !== SyntaxKind.FunctionDeclaration) {
+ return false;
+ }
+
+ let currentName = (currentDeclaration as FunctionDeclaration).name;
+ if (currentName) {
+ if (!firstName || currentName.text !== firstName.text) {
+ // Either 'firstName' must be undefined or the text must differ.
+ return true;
+ }
+ }
+ else if (firstName) {
+ // 'currentName' is not defined but 'firstName' is.
+ return true;
+ }
+ }
+
+ return false;
+ }
+
function checkExportsOnMergedDeclarations(node: Node): void {
if (!produceDiagnostics) {
return;
diff --git a/tests/baselines/reference/multipleDefaultExports02.errors.txt b/tests/baselines/reference/multipleDefaultExports02.errors.txt
index 235f8f7c3e374..d6b9009b60381 100644
--- a/tests/baselines/reference/multipleDefaultExports02.errors.txt
+++ b/tests/baselines/reference/multipleDefaultExports02.errors.txt
@@ -1,18 +1,18 @@
-tests/cases/conformance/es6/modules/m1.ts(2,25): error TS2393: Duplicate function implementation.
-tests/cases/conformance/es6/modules/m1.ts(6,25): error TS2393: Duplicate function implementation.
+tests/cases/conformance/es6/modules/m1.ts(2,25): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/es6/modules/m1.ts(6,25): error TS2528: A module cannot have multiple default exports.
==== tests/cases/conformance/es6/modules/m1.ts (2 errors) ====
export default function foo() {
~~~
-!!! error TS2393: Duplicate function implementation.
+!!! error TS2528: A module cannot have multiple default exports.
}
export default function bar() {
~~~
-!!! error TS2393: Duplicate function implementation.
+!!! error TS2528: A module cannot have multiple default exports.
}
diff --git a/tests/baselines/reference/multipleDefaultExports05.errors.txt b/tests/baselines/reference/multipleDefaultExports05.errors.txt
new file mode 100644
index 0000000000000..5edcfc914c77d
--- /dev/null
+++ b/tests/baselines/reference/multipleDefaultExports05.errors.txt
@@ -0,0 +1,62 @@
+tests/cases/conformance/es6/modules/m1.ts(2,1): error TS2393: Duplicate function implementation.
+tests/cases/conformance/es6/modules/m1.ts(6,1): error TS2393: Duplicate function implementation.
+tests/cases/conformance/es6/modules/m2.ts(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/es6/modules/m2.ts(5,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/es6/modules/m3.ts(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/es6/modules/m3.ts(5,22): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/es6/modules/m4.ts(1,25): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/es6/modules/m4.ts(5,1): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/conformance/es6/modules/m1.ts (2 errors) ====
+
+ export default function () {
+ ~~~~~~
+!!! error TS2393: Duplicate function implementation.
+
+ }
+
+ export default function () {
+ ~~~~~~
+!!! error TS2393: Duplicate function implementation.
+
+ }
+
+==== tests/cases/conformance/es6/modules/m2.ts (2 errors) ====
+ export default function () {
+ ~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+
+ }
+
+ export default class {
+ ~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+
+ }
+
+==== tests/cases/conformance/es6/modules/m3.ts (2 errors) ====
+ export default function () {
+ ~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+
+ }
+
+ export default class C {
+ ~
+!!! error TS2528: A module cannot have multiple default exports.
+
+ }
+
+==== tests/cases/conformance/es6/modules/m4.ts (2 errors) ====
+ export default function f() {
+ ~
+!!! error TS2528: A module cannot have multiple default exports.
+
+ }
+
+ export default class {
+ ~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+
+ }
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleDefaultExports05.js b/tests/baselines/reference/multipleDefaultExports05.js
new file mode 100644
index 0000000000000..67458900bf9d2
--- /dev/null
+++ b/tests/baselines/reference/multipleDefaultExports05.js
@@ -0,0 +1,84 @@
+//// [tests/cases/conformance/es6/modules/multipleDefaultExports05.ts] ////
+
+//// [m1.ts]
+
+export default function () {
+
+}
+
+export default function () {
+
+}
+
+//// [m2.ts]
+export default function () {
+
+}
+
+export default class {
+
+}
+
+//// [m3.ts]
+export default function () {
+
+}
+
+export default class C {
+
+}
+
+//// [m4.ts]
+export default function f() {
+
+}
+
+export default class {
+
+}
+
+//// [m1.js]
+function default_1() {
+}
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = default_1;
+function default_2() {
+}
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = default_2;
+//// [m2.js]
+function default_1() {
+}
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = default_1;
+var default_2 = (function () {
+ function default_2() {
+ }
+ return default_2;
+})();
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = default_2;
+//// [m3.js]
+function default_1() {
+}
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = default_1;
+var C = (function () {
+ function C() {
+ }
+ return C;
+})();
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = C;
+//// [m4.js]
+function f() {
+}
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = f;
+var default_1 = (function () {
+ function default_1() {
+ }
+ return default_1;
+})();
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = default_1;
diff --git a/tests/cases/conformance/es6/modules/multipleDefaultExports05.ts b/tests/cases/conformance/es6/modules/multipleDefaultExports05.ts
new file mode 100644
index 0000000000000..e90b175d779bc
--- /dev/null
+++ b/tests/cases/conformance/es6/modules/multipleDefaultExports05.ts
@@ -0,0 +1,38 @@
+// @module: commonjs
+// @target: ES5
+
+// @filename: m1.ts
+export default function () {
+
+}
+
+export default function () {
+
+}
+
+// @filename: m2.ts
+export default function () {
+
+}
+
+export default class {
+
+}
+
+// @filename: m3.ts
+export default function () {
+
+}
+
+export default class C {
+
+}
+
+// @filename: m4.ts
+export default function f() {
+
+}
+
+export default class {
+
+}
\ No newline at end of file