Improves tree-shaking by only considering program-level

assignments as a Bundle's dependent expressions.

src/ast/nodes/AssignmentExpression.js

@@ -1,6 +1,7 @@
 import Node from '../Node.js';
 import disallowIllegalReassignment from './shared/disallowIllegalReassignment.js';
 import isUsedByBundle from './shared/isUsedByBundle.js';
+import isProgramLevel from '../utils/isProgramLevel.js';
 import { NUMBER, STRING } from '../values.js';
 
 export default class AssignmentExpression extends Node {
@@ -36,7 +37,10 @@ export default class AssignmentExpression extends Node {
 	initialise ( scope ) {
 		this.scope = scope;
 
-		this.module.bundle.dependentExpressions.push( this );
+		if ( isProgramLevel( this ) ) {
+			this.module.bundle.dependentExpressions.push( this );
+		}
+
 		super.initialise( scope );
 	}
 

src/ast/nodes/CallExpression.js

@@ -1,6 +1,7 @@
 import getLocation from '../../utils/getLocation.js';
 import error from '../../utils/error.js';
 import Node from '../Node.js';
+import isProgramLevel from '../utils/isProgramLevel.js';
 import callHasEffects from './shared/callHasEffects.js';
 
 export default class CallExpression extends Node {
@@ -40,14 +41,3 @@ export default class CallExpression extends Node {
 		return this.hasEffects( this.findScope() );
 	}
 }
-
-function isProgramLevel ( node ) {
-	do {
-		if ( node.type === 'Program' ) {
-			return true;
-		}
-		node = node.parent;
-	} while ( node && !/Function/.test( node.type ) );
-
-	return false;
-}

src/ast/utils/isProgramLevel.js

@@ -0,0 +1,10 @@
+export default function isProgramLevel ( node ) {
+	do {
+		if ( node.type === 'Program' ) {
+			return true;
+		}
+		node = node.parent;
+	} while ( node && !/Function/.test( node.type ) );
+
+	return false;
+}

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

@@ -1,4 +1,3 @@
 module.exports = {
-	skip: true,
 	description: 'discards unused function expression assigned to a variable that calls itself and a global'
 };

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

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

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

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

test/form/side-effect-r/_expected/es.js

@@ -0,0 +1 @@
+

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

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

test/form/side-effect-r/_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-s/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'discards unused function expression assigned to a variable that calls itself and has side effects'
+};

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

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

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

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

test/form/side-effect-s/_expected/es.js

@@ -0,0 +1 @@
+

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

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

test/form/side-effect-s/_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-s/main.js

@@ -0,0 +1,7 @@
+var foo = function foo(param) {
+	if ( whatever ) {
+		foo(param);
+	} else {
+		param.foo = 1;
+	}
+};

test/form/skips-dead-branches-h/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'skips a dead branch (h)'
+};

test/form/skips-dead-branches-h/_expected/amd.js

@@ -0,0 +1,8 @@
+define(function () { 'use strict';
+
+	function baz() {
+		console.log("baz");
+	}
+	baz();
+
+});

test/form/skips-dead-branches-h/_expected/cjs.js

@@ -0,0 +1,6 @@
+'use strict';
+
+function baz() {
+	console.log("baz");
+}
+baz();

test/form/skips-dead-branches-h/_expected/es.js

@@ -0,0 +1,4 @@
+function baz() {
+	console.log("baz");
+}
+baz();

test/form/skips-dead-branches-h/_expected/iife.js

@@ -0,0 +1,9 @@
+(function () {
+	'use strict';
+
+	function baz() {
+		console.log("baz");
+	}
+	baz();
+
+}());

test/form/skips-dead-branches-h/_expected/umd.js

@@ -0,0 +1,12 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, (function () { 'use strict';
+
+	function baz() {
+		console.log("baz");
+	}
+	baz();
+
+})));

test/form/skips-dead-branches-h/main.js

@@ -0,0 +1,11 @@
+function bar(umm) {
+	umm = hmm();
+	console.log("bar");
+}
+function hmm() {
+	return true;
+}
+function baz() {
+	console.log("baz");
+}
+baz();

test/form/skips-dead-branches-i/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'skips a dead branch (h)'
+};

test/form/skips-dead-branches-i/_expected/amd.js

@@ -0,0 +1,8 @@
+define(function () { 'use strict';
+
+	function baz() {
+		console.log("baz");
+	}
+	baz();
+
+});

test/form/skips-dead-branches-i/_expected/cjs.js

@@ -0,0 +1,6 @@
+'use strict';
+
+function baz() {
+	console.log("baz");
+}
+baz();

test/form/skips-dead-branches-i/_expected/es.js

@@ -0,0 +1,4 @@
+function baz() {
+	console.log("baz");
+}
+baz();

test/form/skips-dead-branches-i/_expected/iife.js

@@ -0,0 +1,9 @@
+(function () {
+	'use strict';
+
+	function baz() {
+		console.log("baz");
+	}
+	baz();
+
+}());

test/form/skips-dead-branches-i/_expected/umd.js

@@ -0,0 +1,12 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, (function () { 'use strict';
+
+	function baz() {
+		console.log("baz");
+	}
+	baz();
+
+})));

test/form/skips-dead-branches-i/main.js

@@ -0,0 +1,12 @@
+function bar() {
+	var t;
+	t = hmm();
+	console.log("bar");
+}
+function hmm() {
+	return true;
+}
+function baz() {
+	console.log("baz");
+}
+baz();