From ef676b4081a670d51d61ee8ef29009389e1915bc Mon Sep 17 00:00:00 2001
From: Rich-Harris <richard.a.harris@gmail.com>
Date: Thu, 8 Sep 2016 09:12:57 -0400
Subject: [PATCH] disregard effects in dead branches

---
 src/ast/nodes/ConditionalExpression.js    | 12 +++++------
 src/ast/nodes/IfStatement.js              | 26 ++++-------------------
 test/form/side-effect-q/_config.js        |  3 +++
 test/form/side-effect-q/_expected/amd.js  |  5 +++++
 test/form/side-effect-q/_expected/cjs.js  |  2 ++
 test/form/side-effect-q/_expected/es.js   |  0
 test/form/side-effect-q/_expected/iife.js |  6 ++++++
 test/form/side-effect-q/_expected/umd.js  |  9 ++++++++
 test/form/side-effect-q/main.js           |  5 +++++
 9 files changed, 39 insertions(+), 29 deletions(-)
 create mode 100644 test/form/side-effect-q/_config.js
 create mode 100644 test/form/side-effect-q/_expected/amd.js
 create mode 100644 test/form/side-effect-q/_expected/cjs.js
 create mode 100644 test/form/side-effect-q/_expected/es.js
 create mode 100644 test/form/side-effect-q/_expected/iife.js
 create mode 100644 test/form/side-effect-q/_expected/umd.js
 create mode 100644 test/form/side-effect-q/main.js

diff --git a/src/ast/nodes/ConditionalExpression.js b/src/ast/nodes/ConditionalExpression.js
index 6a6c803..c5e336d 100644
--- a/src/ast/nodes/ConditionalExpression.js
+++ b/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 {
diff --git a/src/ast/nodes/IfStatement.js b/src/ast/nodes/IfStatement.js
index baccbd5..1a5c184 100644
--- a/src/ast/nodes/IfStatement.js
+++ b/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;
 			}
 		}
 
diff --git a/test/form/side-effect-q/_config.js b/test/form/side-effect-q/_config.js
new file mode 100644
index 0000000..944a58a
--- /dev/null
+++ b/test/form/side-effect-q/_config.js
@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'discards effects in conditional expressions with known test values'
+};
diff --git a/test/form/side-effect-q/_expected/amd.js b/test/form/side-effect-q/_expected/amd.js
new file mode 100644
index 0000000..ec759b1
--- /dev/null
+++ b/test/form/side-effect-q/_expected/amd.js
@@ -0,0 +1,5 @@
+define(function () { 'use strict';
+
+
+
+});
\ No newline at end of file
diff --git a/test/form/side-effect-q/_expected/cjs.js b/test/form/side-effect-q/_expected/cjs.js
new file mode 100644
index 0000000..eb109ab
--- /dev/null
+++ b/test/form/side-effect-q/_expected/cjs.js
@@ -0,0 +1,2 @@
+'use strict';
+
diff --git a/test/form/side-effect-q/_expected/es.js b/test/form/side-effect-q/_expected/es.js
new file mode 100644
index 0000000..e69de29
diff --git a/test/form/side-effect-q/_expected/iife.js b/test/form/side-effect-q/_expected/iife.js
new file mode 100644
index 0000000..f3d1016
--- /dev/null
+++ b/test/form/side-effect-q/_expected/iife.js
@@ -0,0 +1,6 @@
+(function () {
+	'use strict';
+
+
+
+}());
\ No newline at end of file
diff --git a/test/form/side-effect-q/_expected/umd.js b/test/form/side-effect-q/_expected/umd.js
new file mode 100644
index 0000000..d561e69
--- /dev/null
+++ b/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';
+
+
+
+})));
\ No newline at end of file
diff --git a/test/form/side-effect-q/main.js b/test/form/side-effect-q/main.js
new file mode 100644
index 0000000..2272edb
--- /dev/null
+++ b/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';
+}