prevent infinite loop

src/compiler/compile/Component.ts

@@ -27,7 +27,7 @@ import Slot from './nodes/Slot';
 import { Node, ImportDeclaration, Identifier, Program, ExpressionStatement, AssignmentExpression, Literal } from 'estree';
 import add_to_set from './utils/add_to_set';
 import check_graph_for_cycles from './utils/check_graph_for_cycles';
-import { print, x } from 'code-red';
+import { print, x, b } from 'code-red';
 
 interface ComponentOptions {
 	namespace?: string;
@@ -722,6 +722,8 @@ export default class Component {
 			toRemove.unshift([parent, prop, index]);
 		};
 
+		const toInsert = new Map();
+
 		walk(content, {
 			enter(node, parent, prop, index) {
 				if (map.has(node)) {
@@ -747,12 +749,37 @@ export default class Component {
 				}
 
 				component.warn_on_undefined_store_value_references(node, parent, scope);
+
+				if (component.compile_options.dev) {
+					const to_insert_for_loop_protect = component.loop_protect(node, prop, index);
+					if (to_insert_for_loop_protect) {
+						if (!Array.isArray(parent[prop])) {
+							parent[prop] = {
+								type: 'BlockStatement',
+								body: [to_insert_for_loop_protect.node, node],
+							};
+						} else {
+							// can't insert directly, will screw up the index in the for-loop of estree-walker
+							if (!toInsert.has(parent)) {
+								toInsert.set(parent, []);
+							}
+							toInsert.get(parent).push(to_insert_for_loop_protect);
+						}
+					}
+				}
 			},
 
 			leave(node) {
 				if (map.has(node)) {
 					scope = scope.parent;
 				}
+				if (toInsert.has(node)) {
+					const nodes_to_insert = toInsert.get(node);
+					for (const { index, prop, node: node_to_insert } of nodes_to_insert.reverse()) {
+						node[prop].splice(index, 0, node_to_insert);
+					}
+					toInsert.delete(node);
+				}
 			},
 		});
 
@@ -836,6 +863,35 @@ export default class Component {
 		}
 	}
 
+	loop_protect(node, prop, index) {
+		if (node.type === 'WhileStatement' ||
+			node.type === 'ForStatement' ||
+			node.type === 'DoWhileStatement') {
+			const id = this.get_unique_name('LP');
+			this.add_var({
+				name: id.name,
+				internal: true,
+			});
+
+			const before = b`const ${id} = Date.now();`;
+			const inside = b`
+			if (Date.now() - ${id} > 100) {
+				throw new Error('Infinite loop detected');
+			}
+			`;
+			// wrap expression statement with BlockStatement
+			if (node.body.type !== 'BlockStatement') {
+				node.body = {
+					type: 'BlockStatement',
+					body: [node.body],
+				};
+			}
+			node.body.body.push(inside[0]);
+			return { index, prop, node: before[0] };
+		}
+		return null;
+	}
+
 	invalidate(name, value?) {
 		const variable = this.var_lookup.get(name);
 

test/js/samples/loop_protect/_config.js

@@ -0,0 +1,5 @@
+export default {
+	options: {
+		dev: true
+	}
+};

test/js/samples/loop_protect/expected.js

@@ -0,0 +1,126 @@
+/* generated by Svelte vX.Y.Z */
+import {
+	SvelteComponentDev,
+	dispatch_dev,
+	init,
+	noop,
+	safe_not_equal
+} from "svelte/internal";
+
+const file = undefined;
+
+function create_fragment(ctx) {
+	const block = {
+		c: noop,
+		l: function claim(nodes) {
+			throw new Error("options.hydrate only works if the component was compiled with the `hydratable: true` option");
+		},
+		m: noop,
+		p: noop,
+		i: noop,
+		o: noop,
+		d: noop
+	};
+
+	dispatch_dev("SvelteRegisterBlock", {
+		block,
+		id: create_fragment.name,
+		type: "component",
+		source: "",
+		ctx
+	});
+
+	return block;
+}
+
+function instance($$self) {
+	const LP = Date.now();
+
+	while (true) {
+		foo();
+
+		if (Date.now() - LP > 100) {
+			throw new Error("Infinite loop detected");
+		}
+	}
+
+	const LP_1 = Date.now();
+
+	for (; ; ) {
+		foo();
+
+		if (Date.now() - LP_1 > 100) {
+			throw new Error("Infinite loop detected");
+		}
+	}
+
+	const LP_2 = Date.now();
+
+	while (true) {
+		foo();
+
+		if (Date.now() - LP_2 > 100) {
+			throw new Error("Infinite loop detected");
+		}
+	}
+
+	const LP_4 = Date.now();
+
+	do {
+		foo();
+
+		if (Date.now() - LP_4 > 100) {
+			throw new Error("Infinite loop detected");
+		}
+	} while (true);
+
+	$$self.$capture_state = () => {
+		return {};
+	};
+
+	$$self.$inject_state = $$props => {
+
+	};
+
+	$: {
+		const LP_3 = Date.now();
+
+		while (true) {
+			foo();
+
+			if (Date.now() - LP_3 > 100) {
+				throw new Error("Infinite loop detected");
+			}
+		}
+	}
+
+	$: {
+		const LP_5 = Date.now();
+
+		do {
+			foo();
+
+			if (Date.now() - LP_5 > 100) {
+				throw new Error("Infinite loop detected");
+			}
+		} while (true);
+	}
+
+	return {};
+}
+
+class Component extends SvelteComponentDev {
+	constructor(options) {
+		super(options);
+		init(this, options, instance, create_fragment, safe_not_equal, {});
+
+		dispatch_dev("SvelteRegisterComponent", {
+			component: this,
+			tagName: "Component",
+			options,
+			id: create_fragment.name
+		});
+	}
+}
+
+export default Component;

test/js/samples/loop_protect/input.svelte

@@ -0,0 +1,12 @@
+<script>
+  while(true) {
+    foo();
+  }
+  for(;;) {
+    foo();
+  }
+  while(true) foo();
+  $: while(true) foo();
+  do foo(); while(true);
+  $: do foo(); while(true);
+</script>

test/runtime/samples/loop-protect/_config.js

@@ -0,0 +1,6 @@
+export default {
+	error: 'Infinite loop detected',
+	compileOptions: {
+		dev: true,
+	}
+};

test/runtime/samples/loop-protect/main.svelte

@@ -0,0 +1,5 @@
+<script>
+  while(true) {
+    // do nothing
+  }
+</script>