From 7f85b929d8610d6f474e3d960776207a60c2577c Mon Sep 17 00:00:00 2001
From: David A Kondrad <david.a.kondrad@jci.com>
Date: Fri, 24 Jan 2020 16:58:56 -0500
Subject: [PATCH] internal: scheduler: fix usage of seen_callbacks

The set that was added to block infinite loops wasn't actually doing anything.
Lift the declaration outside of the function and clear it at the end.
---
 src/runtime/internal/scheduler.ts                          | 7 ++++---
 .../samples/lifecycle-onmount-infinite-loop/Child.svelte   | 2 +-
 .../samples/lifecycle-onmount-infinite-loop/main.svelte    | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/runtime/internal/scheduler.ts b/src/runtime/internal/scheduler.ts
index 04c1264ab1..1ce255b217 100644
--- a/src/runtime/internal/scheduler.ts
+++ b/src/runtime/internal/scheduler.ts
@@ -31,8 +31,8 @@ export function add_flush_callback(fn) {
 	flush_callbacks.push(fn);
 }
 
+const seen_callbacks = new Set();
 export function flush() {
-	const seen_callbacks = new Set();
 
 	do {
 		// first, call beforeUpdate functions
@@ -52,10 +52,10 @@ export function flush() {
 			const callback = render_callbacks[i];
 
 			if (!seen_callbacks.has(callback)) {
-				callback();
-
 				// ...so guard against infinite loops
 				seen_callbacks.add(callback);
+
+				callback();
 			}
 		}
 
@@ -67,6 +67,7 @@ export function flush() {
 	}
 
 	update_scheduled = false;
+	seen_callbacks.clear();
 }
 
 function update($$) {
diff --git a/test/runtime/samples/lifecycle-onmount-infinite-loop/Child.svelte b/test/runtime/samples/lifecycle-onmount-infinite-loop/Child.svelte
index c1a538c62a..1772cb6513 100644
--- a/test/runtime/samples/lifecycle-onmount-infinite-loop/Child.svelte
+++ b/test/runtime/samples/lifecycle-onmount-infinite-loop/Child.svelte
@@ -1 +1 @@
-Child
\ No newline at end of file
+Child
diff --git a/test/runtime/samples/lifecycle-onmount-infinite-loop/main.svelte b/test/runtime/samples/lifecycle-onmount-infinite-loop/main.svelte
index ba2da663d6..293e37d4f1 100644
--- a/test/runtime/samples/lifecycle-onmount-infinite-loop/main.svelte
+++ b/test/runtime/samples/lifecycle-onmount-infinite-loop/main.svelte
@@ -13,4 +13,4 @@
 	});
 </script>
 
-<div bind:this={root}></div>
\ No newline at end of file
+<div bind:this={root}></div>