Merge pull request #400 from rollup/gh-397

Side-effect detection in cyclical function calls

src/Declaration.js

@@ -43,14 +43,20 @@ export default class Declaration {
 
 	run ( strongDependencies ) {
 		if ( this.tested ) return this.hasSideEffects;
-		this.tested = true;
+
 
 		if ( !this.functionNode ) {
 			this.hasSideEffects = true; // err on the side of caution. TODO handle unambiguous `var x; x = y => z` cases
 		} else {
+			if ( this.running ) return true; // short-circuit infinite loop
+			this.running = true;
+
 			this.hasSideEffects = run( this.functionNode.body, this.functionNode._scope, this.statement, strongDependencies, false );
+
+			this.running = false;
 		}
 
+		this.tested = true;
 		return this.hasSideEffects;
 	}
 

src/Module.js

@@ -570,7 +570,7 @@ export default class Module {
 		let marked = false;
 
 		this.statements.forEach( statement => {
-			marked = marked || statement.run( this.strongDependencies, safe );
+			marked = statement.run( this.strongDependencies, safe ) || marked;
 		});
 
 		return marked;

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

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'detects side-effects with cyclical dependencies'
+};

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

@@ -0,0 +1,21 @@
+define(function () { 'use strict';
+
+	function odd ( n ) {
+		return n !== 0 && even( n - 1 );
+	}
+
+	var counter = 0;
+
+	// This should be in the output
+	var foo = odd( 12 );
+
+	function even ( n ) {
+		alert( counter++ )
+		return n === 0 || odd( n - 1 );
+	}
+
+	console.log( even( 5 ) );
+
+	console.log( counter );
+
+});

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

@@ -0,0 +1,19 @@
+'use strict';
+
+function odd ( n ) {
+	return n !== 0 && even( n - 1 );
+}
+
+var counter = 0;
+
+// This should be in the output
+var foo = odd( 12 );
+
+function even ( n ) {
+	alert( counter++ )
+	return n === 0 || odd( n - 1 );
+}
+
+console.log( even( 5 ) );
+
+console.log( counter );

test/form/side-effect-m/_expected/es6.js

@@ -0,0 +1,17 @@
+function odd ( n ) {
+	return n !== 0 && even( n - 1 );
+}
+
+var counter = 0;
+
+// This should be in the output
+var foo = odd( 12 );
+
+function even ( n ) {
+	alert( counter++ )
+	return n === 0 || odd( n - 1 );
+}
+
+console.log( even( 5 ) );
+
+console.log( counter );

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

@@ -0,0 +1,21 @@
+(function () { 'use strict';
+
+	function odd ( n ) {
+		return n !== 0 && even( n - 1 );
+	}
+
+	var counter = 0;
+
+	// This should be in the output
+	var foo = odd( 12 );
+
+	function even ( n ) {
+		alert( counter++ )
+		return n === 0 || odd( n - 1 );
+	}
+
+	console.log( even( 5 ) );
+
+	console.log( counter );
+
+})();

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

@@ -0,0 +1,25 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	(factory());
+}(this, function () { 'use strict';
+
+	function odd ( n ) {
+		return n !== 0 && even( n - 1 );
+	}
+
+	var counter = 0;
+
+	// This should be in the output
+	var foo = odd( 12 );
+
+	function even ( n ) {
+		alert( counter++ )
+		return n === 0 || odd( n - 1 );
+	}
+
+	console.log( even( 5 ) );
+
+	console.log( counter );
+
+}));

test/form/side-effect-m/even.js

@@ -0,0 +1,11 @@
+import { odd } from './odd.js'
+
+export var counter = 0;
+
+// This should be in the output
+export var foo = odd( 12 );
+
+export function even ( n ) {
+	alert( counter++ )
+	return n === 0 || odd( n - 1 );
+}

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

@@ -0,0 +1,5 @@
+import { counter, even } from './even.js';
+
+console.log( even( 5 ) );
+
+console.log( counter );

test/form/side-effect-m/odd.js

@@ -0,0 +1,5 @@
+import { even } from './even.js';
+
+export function odd ( n ) {
+	return n !== 0 && even( n - 1 );
+}