disregard effects in dead branches

src/ast/nodes/ConditionalExpression.js

@@ -4,13 +4,13 @@ import { UNKNOWN } from '../values.js';
 export default class ConditionalExpression extends Node {
 	initialise ( scope ) {
 		if ( this.module.bundle.treeshake ) {
-			const testValue = this.test.getValue();
+			this.testValue = this.test.getValue();
 
-			if ( testValue === UNKNOWN	 ) {
+			if ( this.testValue === UNKNOWN	 ) {
 				super.initialise( scope );
 			}
 
-			else if ( testValue ) {
+			else if ( this.testValue ) {
 				this.consequent.initialise( scope );
 				this.alternate = null;
 			} else if ( this.alternate ) {
@@ -47,13 +47,11 @@ export default class ConditionalExpression extends Node {
 		}
 
 		else {
-			const testValue = this.test.getValue();
-
-			if ( testValue === UNKNOWN ) {
+			if ( this.testValue === UNKNOWN ) {
 				super.render( code, es );
 			}
 
-			else if ( testValue ) {
+			else if ( this.testValue ) {
 				code.remove( this.start, this.consequent.start );
 				code.remove( this.consequent.end, this.end );
 			} else {

src/ast/nodes/IfStatement.js

@@ -3,26 +3,6 @@ import { UNKNOWN } from '../values.js';
 
 // TODO DRY this out
 export default class IfStatement extends Node {
-	bind ( scope ) {
-		if ( this.module.bundle.treeshake ) {
-			if ( this.testValue === UNKNOWN ) {
-				super.bind( scope );
-			}
-
-			else if ( this.testValue ) {
-				this.consequent.bind( scope );
-				this.alternate = null;
-			} else if ( this.alternate ) {
-				this.alternate.bind( scope );
-				this.consequent = null;
-			}
-		}
-
-		else {
-			super.bind( scope );
-		}
-	}
-
 	initialise ( scope ) {
 		this.testValue = this.test.getValue();
 
@@ -33,8 +13,10 @@ export default class IfStatement extends Node {
 
 			else if ( this.testValue ) {
 				this.consequent.initialise( scope );
-			} else if ( this.alternate ) {
-				this.alternate.initialise( scope );
+				this.alternate = null;
+			} else {
+				if ( this.alternate ) this.alternate.initialise( scope );
+				this.consequent = null;
 			}
 		}
 

test/form/side-effect-q/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'discards effects in conditional expressions with known test values'
+};

test/form/side-effect-q/_expected/amd.js

@@ -0,0 +1,5 @@
+define(function () { 'use strict';
+
+
+
+});

test/form/side-effect-q/_expected/cjs.js

@@ -0,0 +1,2 @@
+'use strict';
+

test/form/side-effect-q/_expected/iife.js

@@ -0,0 +1,6 @@
+(function () {
+	'use strict';
+
+
+
+}());

test/form/side-effect-q/_expected/umd.js

@@ -0,0 +1,9 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, (function () { 'use strict';
+
+
+
+})));

test/form/side-effect-q/main.js

@@ -0,0 +1,5 @@
+var x = true ? foo () : bar();
+
+function foo () {
+	return 'should be removed, because x is unused';
+}