Make sure uninitialised exports turn up via .hasOwnProperty for non-ES formats

src/ast/nodes/VariableDeclaration.ts

@@ -1,5 +1,6 @@
 import MagicString from 'magic-string';
 import { BLANK } from '../../utils/blank';
+import { isReassignedExportsMember } from '../../utils/reassignedExportsMember';
 import {
 	findFirstOccurrenceOutsideComment,
 	findNonWhiteSpace,
@@ -19,15 +20,6 @@ import * as NodeType from './NodeType';
 import { IncludeChildren, NodeBase } from './shared/Node';
 import VariableDeclarator from './VariableDeclarator';
 
-function isReassignedExportsMember(
-	variable: Variable,
-	exportNamesByVariable: Map<Variable, string[]>
-): boolean {
-	return (
-		variable.renderBaseName !== null && exportNamesByVariable.has(variable) && variable.isReassigned
-	);
-}
-
 function areAllDeclarationsIncludedAndNotExported(
 	declarations: VariableDeclarator[],
 	exportNamesByVariable: Map<Variable, string[]>
@@ -149,7 +141,7 @@ export default class VariableDeclaration extends NodeBase {
 	private renderReplacedDeclarations(
 		code: MagicString,
 		options: RenderOptions,
-		{ start = this.start, end = this.end, isNoStatement }: NodeRenderOptions
+		{ isNoStatement }: NodeRenderOptions
 	): void {
 		const separatedNodes = getCommaSeparatedNodesWithBoundaries(
 			this.declarations,
@@ -168,15 +160,7 @@ export default class VariableDeclaration extends NodeBase {
 			nextSeparatorString;
 		const systemPatternExports: Variable[] = [];
 		for (const { node, start, separator, contentEnd, end } of separatedNodes) {
-			if (
-				!node.included ||
-				(node.id instanceof Identifier &&
-					isReassignedExportsMember(
-						(node.id as IdentifierWithVariable).variable,
-						options.exportNamesByVariable
-					) &&
-					node.init === null)
-			) {
+			if (!node.included) {
 				code.remove(start, end);
 				continue;
 			}
@@ -240,19 +224,15 @@ export default class VariableDeclaration extends NodeBase {
 			lastSeparatorPos = separator!;
 			separatorString = nextSeparatorString;
 		}
-		if (hasRenderedContent) {
-			this.renderDeclarationEnd(
-				code,
-				separatorString,
-				lastSeparatorPos,
-				actualContentEnd!,
-				renderedContentEnd,
-				systemPatternExports,
-				options,
-				isNoStatement
-			);
-		} else {
-			code.remove(start, end);
-		}
+		this.renderDeclarationEnd(
+			code,
+			separatorString,
+			lastSeparatorPos,
+			actualContentEnd!,
+			renderedContentEnd,
+			systemPatternExports,
+			options,
+			isNoStatement
+		);
 	}
 }

src/ast/nodes/VariableDeclarator.ts

@@ -1,5 +1,6 @@
 import MagicString from 'magic-string';
 import { BLANK } from '../../utils/blank';
+import { isReassignedExportsMember } from '../../utils/reassignedExportsMember';
 import {
 	findFirstOccurrenceOutsideComment,
 	findNonWhiteSpace,
@@ -8,6 +9,7 @@ import {
 import { HasEffectsContext, InclusionContext } from '../ExecutionContext';
 import { ObjectPath } from '../utils/PathTracker';
 import { UNDEFINED_EXPRESSION } from '../values';
+import Identifier from './Identifier';
 import * as NodeType from './NodeType';
 import { ExpressionNode, IncludeChildren, NodeBase } from './shared/Node';
 import { PatternNode } from './shared/Pattern';
@@ -53,6 +55,12 @@ export default class VariableDeclarator extends NodeBase {
 				options,
 				renderId ? BLANK : { renderedParentType: NodeType.ExpressionStatement }
 			);
+		} else if (
+			this.id instanceof Identifier &&
+			isReassignedExportsMember(this.id.variable!, options.exportNamesByVariable)
+		) {
+			const _ = options.compact ? '' : ' ';
+			code.appendLeft(this.end, `${_}=${_}void 0`);
 		}
 	}
 }

src/utils/reassignedExportsMember.ts

@@ -0,0 +1,10 @@
+import Variable from '../ast/variables/Variable';
+
+export function isReassignedExportsMember(
+	variable: Variable,
+	exportNamesByVariable: Map<Variable, string[]>
+): boolean {
+	return (
+		variable.renderBaseName !== null && exportNamesByVariable.has(variable) && variable.isReassigned
+	);
+}

test/form/samples/assignment-to-exports/_expected/amd.js

@@ -5,6 +5,7 @@ define(['exports'], function (exports) { 'use strict';
 
 	// Reassigned uninitialised export
 	exports.bar1 = 1;
+	exports.bar1 = void 0;
 
 	// Reassigned initialised export
 	exports.baz1 = 1;
@@ -14,7 +15,7 @@ define(['exports'], function (exports) { 'use strict';
 	var kept1, foo2, kept2;
 
 	// Reassigned uninitialised export
-	var kept1, kept2;
+	var kept1; exports.bar2 = void 0; var kept2;
 	exports.bar2 = 1;
 
 	// Reassigned initialised export

test/form/samples/assignment-to-exports/_expected/cjs.js

@@ -7,6 +7,7 @@ var foo1;
 
 // Reassigned uninitialised export
 exports.bar1 = 1;
+exports.bar1 = void 0;
 
 // Reassigned initialised export
 exports.baz1 = 1;
@@ -16,7 +17,7 @@ exports.baz1 = 2;
 var kept1, foo2, kept2;
 
 // Reassigned uninitialised export
-var kept1, kept2;
+var kept1; exports.bar2 = void 0; var kept2;
 exports.bar2 = 1;
 
 // Reassigned initialised export

test/form/samples/assignment-to-exports/_expected/es.js

@@ -3,7 +3,7 @@ var foo1;
 
 // Reassigned uninitialised export
 bar1 = 1;
-var bar1; // this will be removed for non ES6 bundles
+var bar1;
 
 // Reassigned initialised export
 var baz1 = 1;

test/form/samples/assignment-to-exports/_expected/iife.js

@@ -6,6 +6,7 @@ var bundle = (function (exports) {
 
 	// Reassigned uninitialised export
 	exports.bar1 = 1;
+	exports.bar1 = void 0;
 
 	// Reassigned initialised export
 	exports.baz1 = 1;
@@ -15,7 +16,7 @@ var bundle = (function (exports) {
 	var kept1, foo2, kept2;
 
 	// Reassigned uninitialised export
-	var kept1, kept2;
+	var kept1; exports.bar2 = void 0; var kept2;
 	exports.bar2 = 1;
 
 	// Reassigned initialised export

test/form/samples/assignment-to-exports/_expected/system.js

@@ -15,7 +15,7 @@ System.register('bundle', [], function (exports) {
 
 			// Reassigned uninitialised export
 			bar1 = exports('bar1', 1);
-			var bar1; // this will be removed for non ES6 bundles
+			var bar1;
 
 			// Reassigned initialised export
 			var baz1 = exports('baz1', 1);

test/form/samples/assignment-to-exports/_expected/umd.js

@@ -9,6 +9,7 @@
 
 	// Reassigned uninitialised export
 	exports.bar1 = 1;
+	exports.bar1 = void 0;
 
 	// Reassigned initialised export
 	exports.baz1 = 1;
@@ -18,7 +19,7 @@
 	var kept1, foo2, kept2;
 
 	// Reassigned uninitialised export
-	var kept1, kept2;
+	var kept1; exports.bar2 = void 0; var kept2;
 	exports.bar2 = 1;
 
 	// Reassigned initialised export

test/form/samples/assignment-to-exports/main.js

@@ -3,7 +3,7 @@ export var foo1;
 
 // Reassigned uninitialised export
 bar1 = 1;
-export var bar1; // this will be removed for non ES6 bundles
+export var bar1;
 
 // Reassigned initialised export
 export var baz1 = 1;

test/form/samples/render-named-export-declarations/_expected/amd.js

@@ -1,9 +1,9 @@
 define(['exports'], function (exports) { 'use strict';
 
-	var aFoo;
+	var aFoo; exports.aBar = void 0;
 	exports.aBar = 2;
 
-	var bBar;
+	exports.bFoo = void 0; var bBar;
 	exports.bFoo = 2;
 
 	var cFoo; exports.cBar = 1;

test/form/samples/render-named-export-declarations/_expected/cjs.js

@@ -2,10 +2,10 @@
 
 Object.defineProperty(exports, '__esModule', { value: true });
 
-var aFoo;
+var aFoo; exports.aBar = void 0;
 exports.aBar = 2;
 
-var bBar;
+exports.bFoo = void 0; var bBar;
 exports.bFoo = 2;
 
 var cFoo; exports.cBar = 1;

test/form/samples/render-named-export-declarations/_expected/iife.js

@@ -1,10 +1,10 @@
 var bundle = (function (exports) {
 	'use strict';
 
-	var aFoo;
+	var aFoo; exports.aBar = void 0;
 	exports.aBar = 2;
 
-	var bBar;
+	exports.bFoo = void 0; var bBar;
 	exports.bFoo = 2;
 
 	var cFoo; exports.cBar = 1;

test/form/samples/render-named-export-declarations/_expected/umd.js

@@ -4,10 +4,10 @@
 	(global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.bundle = {}));
 }(this, (function (exports) { 'use strict';
 
-	var aFoo;
+	var aFoo; exports.aBar = void 0;
 	exports.aBar = 2;
 
-	var bBar;
+	exports.bFoo = void 0; var bBar;
 	exports.bFoo = 2;
 
 	var cFoo; exports.cBar = 1;

test/function/samples/create-undefined-export-property-compact/_config.js

@@ -0,0 +1,17 @@
+const assert = require('assert');
+
+module.exports = {
+	description: 'creates an export as an exports property even if is has no initializer',
+	options: { output: { compact: true } },
+	exports(exports) {
+		assert.strictEqual(exports.foo, undefined);
+		assert.strictEqual(exports.bar, undefined);
+		assert.strictEqual(exports.baz, undefined);
+		assert.ok(exports.hasOwnProperty('foo'));
+		assert.ok(exports.hasOwnProperty('bar'));
+		assert.ok(exports.hasOwnProperty('baz'));
+		exports.defineFooBar();
+		assert.strictEqual(exports.foo, 'defined');
+		assert.strictEqual(exports.bar, 'defined');
+	}
+};

test/function/samples/create-undefined-export-property-compact/main.js

@@ -0,0 +1,6 @@
+export let foo;
+export let bar, quux = 3, baz;
+export function defineFooBar() {
+	foo = 'defined';
+	bar = 'defined';
+}

test/function/samples/create-undefined-export-property/_config.js

@@ -0,0 +1,16 @@
+const assert = require('assert');
+
+module.exports = {
+	description: 'creates an export as an exports property even if is has no initializer',
+	exports(exports) {
+		assert.strictEqual(exports.foo, undefined);
+		assert.strictEqual(exports.bar, undefined);
+		assert.strictEqual(exports.baz, undefined);
+		assert.ok(exports.hasOwnProperty('foo'));
+		assert.ok(exports.hasOwnProperty('bar'));
+		assert.ok(exports.hasOwnProperty('baz'));
+		exports.defineFooBar();
+		assert.strictEqual(exports.foo, 'defined');
+		assert.strictEqual(exports.bar, 'defined');
+	}
+};

test/function/samples/create-undefined-export-property/main.js

@@ -0,0 +1,6 @@
+export let foo;
+export let bar, quux = 3, baz;
+export function defineFooBar() {
+	foo = 'defined';
+	bar = 'defined';
+}

test/function/samples/destructuring-loop/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'handles loops with destructuring declarations'
+};

test/function/samples/destructuring-loop/main.js

@@ -0,0 +1,11 @@
+let result;
+
+for (const [foo] of [['foo']]) {
+	result = foo;
+}
+assert.strictEqual(result, 'foo');
+
+for (const { bar } of [{ bar: 'bar' }]) {
+	result = bar;
+}
+assert.strictEqual(result, 'bar');