prevent infinite set loops

compiler/generate/index.js

@@ -254,9 +254,13 @@ export default function generate ( parsed, source, options ) {
 	}
 
 	setStatements.push( deindent`
+		if ( setting ) return;
+
+		setting = true;
 		dispatchObservers( observers.immediate, newState, oldState );
 		if ( mainFragment ) mainFragment.update( state );
 		dispatchObservers( observers.deferred, newState, oldState );
+		setting = false;
 	` );
 
 	const topLevelStatements = [];
@@ -325,6 +329,8 @@ export default function generate ( parsed, source, options ) {
 				return state[ key ];
 			};
 
+			let setting = false;
+
 			this.set = function set ( newState ) {
 				${setStatements.join( '\n\n' )}
 			};

test/compiler/set-prevents-loop/Foo.html

@@ -0,0 +1 @@
+<div></div>

test/compiler/set-prevents-loop/_config.js

@@ -0,0 +1 @@
+export default {};

test/compiler/set-prevents-loop/main.html

@@ -0,0 +1,20 @@
+{{#if visible}}
+	<Foo bind:answer/>
+{{else}}
+	<Foo bind:answer/>
+{{/if}}
+
+<script>
+	import Foo from './Foo.html';
+
+	export default {
+		data: () => ({
+			visible: true,
+			answer: 42
+		}),
+
+		components: {
+			Foo
+		}
+	};
+</script>