fix double var declaration bug (#716)

src/ast/nodes/VariableDeclarator.js

@@ -11,12 +11,14 @@ class DeclaratorProxy {
 		this.isReassigned = false;
 		this.exportName = null;
 
+		this.duplicates = [];
 		this.possibleValues = new Set( init ? [ init ] : null );
 	}
 
 	activate () {
 		this.activated = true;
 		this.declarator.activate();
+		this.duplicates.forEach( dupe => dupe.activate() );
 	}
 
 	addReference () {

src/ast/scopes/Scope.js

@@ -1,3 +1,5 @@
+import getLocation from '../../utils/getLocation.js';
+import error from '../../utils/error.js';
 import { blank, keys } from '../../utils/object.js';
 import { UNKNOWN } from '../values.js';
 
@@ -49,7 +51,14 @@ export default class Scope {
 		if ( isVar && this.isBlockScope ) {
 			this.parent.addDeclaration( name, declaration, isVar, isParam );
 		} else {
-			this.declarations[ name ] = isParam ? new Parameter( name ) : declaration;
+			const existingDeclaration = this.declarations[ name ];
+
+			if ( existingDeclaration && existingDeclaration.duplicates ) {
+				// TODO warn/throw on duplicates?
+				existingDeclaration.duplicates.push( declaration );
+			} else {
+				this.declarations[ name ] = isParam ? new Parameter( name ) : declaration;
+			}
 		}
 	}
 

test/form/duplicated-var-declarations/_config.js

@@ -1,4 +1,3 @@
 module.exports = {
-	skip: true,
 	description: 'does not remove duplicated var declarations (#716)'
 };

test/form/duplicated-var-declarations/_expected/amd.js

@@ -0,0 +1,17 @@
+define(function () { 'use strict';
+
+	var a = 1;
+	var b = 2;
+
+	assert.equal( a, 1 );
+	assert.equal( b, 2 );
+
+	var a = 3;
+	var b = 4;
+	var c = 5;
+
+	assert.equal( a, 3 );
+	assert.equal( b, 4 );
+	assert.equal( c, 5 );
+
+});

test/form/duplicated-var-declarations/_expected/cjs.js

@@ -0,0 +1,15 @@
+'use strict';
+
+var a = 1;
+var b = 2;
+
+assert.equal( a, 1 );
+assert.equal( b, 2 );
+
+var a = 3;
+var b = 4;
+var c = 5;
+
+assert.equal( a, 3 );
+assert.equal( b, 4 );
+assert.equal( c, 5 );

test/form/duplicated-var-declarations/_expected/es.js

@@ -0,0 +1,13 @@
+var a = 1;
+var b = 2;
+
+assert.equal( a, 1 );
+assert.equal( b, 2 );
+
+var a = 3;
+var b = 4;
+var c = 5;
+
+assert.equal( a, 3 );
+assert.equal( b, 4 );
+assert.equal( c, 5 );

test/form/duplicated-var-declarations/_expected/iife.js

@@ -0,0 +1,18 @@
+(function () {
+	'use strict';
+
+	var a = 1;
+	var b = 2;
+
+	assert.equal( a, 1 );
+	assert.equal( b, 2 );
+
+	var a = 3;
+	var b = 4;
+	var c = 5;
+
+	assert.equal( a, 3 );
+	assert.equal( b, 4 );
+	assert.equal( c, 5 );
+
+}());

test/form/duplicated-var-declarations/_expected/umd.js

@@ -0,0 +1,21 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, (function () { 'use strict';
+
+	var a = 1;
+	var b = 2;
+
+	assert.equal( a, 1 );
+	assert.equal( b, 2 );
+
+	var a = 3;
+	var b = 4;
+	var c = 5;
+
+	assert.equal( a, 3 );
+	assert.equal( b, 4 );
+	assert.equal( c, 5 );
+
+})));