Merge pull request #5588 from Microsoft/reexport-default-export

Reexport default export

src/compiler/checker.ts

@@ -486,9 +486,19 @@ namespace ts {
                         if (location.kind === SyntaxKind.SourceFile ||
                             (location.kind === SyntaxKind.ModuleDeclaration && (<ModuleDeclaration>location).name.kind === SyntaxKind.StringLiteral)) {
 
-                            // It's an external module. Because of module/namespace merging, a module's exports are in scope,
-                            // yet we never want to treat an export specifier as putting a member in scope. Therefore,
-                            // if the name we find is purely an export specifier, it is not actually considered in scope.
+                            // It's an external module. First see if the module has an export default and if the local
+                            // name of that export default matches.
+                            if (result = moduleExports["default"]) {
+                                const localSymbol = getLocalSymbolForExportDefault(result);
+                                if (localSymbol && (result.flags & meaning) && localSymbol.name === name) {
+                                    break loop;
+                                }
+                                result = undefined;
+                            }
+
+                            // Because of module/namespace merging, a module's exports are in scope,
+                            // yet we never want to treat an export specifier as putting a member in scope. 
+                            // Therefore, if the name we find is purely an export specifier, it is not actually considered in scope.
                             // Two things to note about this:
                             //     1. We have to check this without calling getSymbol. The problem with calling getSymbol
                             //        on an export specifier is that it might find the export specifier itself, and try to
@@ -502,13 +512,6 @@ namespace ts {
                                 getDeclarationOfKind(moduleExports[name], SyntaxKind.ExportSpecifier)) {
                                 break;
                             }
-
-                            result = moduleExports["default"];
-                            const localSymbol = getLocalSymbolForExportDefault(result);
-                            if (result && localSymbol && (result.flags & meaning) && localSymbol.name === name) {
-                                break loop;
-                            }
-                            result = undefined;
                         }
 
                         if (result = getSymbol(moduleExports, name, meaning & SymbolFlags.ModuleMember)) {

tests/baselines/reference/reExportDefaultExport.js

@@ -0,0 +1,27 @@
+//// [tests/cases/conformance/es6/modules/reExportDefaultExport.ts] ////
+
+//// [m1.ts]
+
+export default function f() {
+}
+export {f};
+
+
+//// [m2.ts]
+import foo from "./m1";
+import {f} from "./m1";
+
+f();
+foo();
+
+//// [m1.js]
+function f() {
+}
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = f;
+exports.f = f;
+//// [m2.js]
+var m1_1 = require("./m1");
+var m1_2 = require("./m1");
+m1_2.f();
+m1_1.default();

tests/baselines/reference/reExportDefaultExport.symbols

@@ -0,0 +1,22 @@
+=== tests/cases/conformance/es6/modules/m1.ts ===
+
+export default function f() {
+>f : Symbol(f, Decl(m1.ts, 0, 0))
+}
+export {f};
+>f : Symbol(f, Decl(m1.ts, 3, 8))
+
+
+=== tests/cases/conformance/es6/modules/m2.ts ===
+import foo from "./m1";
+>foo : Symbol(foo, Decl(m2.ts, 0, 6))
+
+import {f} from "./m1";
+>f : Symbol(f, Decl(m2.ts, 1, 8))
+
+f();
+>f : Symbol(f, Decl(m2.ts, 1, 8))
+
+foo();
+>foo : Symbol(foo, Decl(m2.ts, 0, 6))
+

tests/baselines/reference/reExportDefaultExport.types

@@ -0,0 +1,24 @@
+=== tests/cases/conformance/es6/modules/m1.ts ===
+
+export default function f() {
+>f : () => void
+}
+export {f};
+>f : () => void
+
+
+=== tests/cases/conformance/es6/modules/m2.ts ===
+import foo from "./m1";
+>foo : () => void
+
+import {f} from "./m1";
+>f : () => void
+
+f();
+>f() : void
+>f : () => void
+
+foo();
+>foo() : void
+>foo : () => void
+

tests/cases/conformance/es6/modules/reExportDefaultExport.ts

@@ -0,0 +1,15 @@
+// @module: commonjs
+// @target: ES5
+
+// @filename: m1.ts
+export default function f() {
+}
+export {f};
+
+
+// @filename: m2.ts
+import foo from "./m1";
+import {f} from "./m1";
+
+f();
+foo();