From 566f1458f8ee135c5ba30a3b3080c256700764ec Mon Sep 17 00:00:00 2001
From: Conduitry <git@chor.date>
Date: Tue, 10 Dec 2019 09:24:05 -0500
Subject: [PATCH] fix bitmask overflow when using slotted components (#4077)

---
 src/compiler/compile/render_dom/Renderer.ts         | 6 +++++-
 test/runtime/samples/bitmask-overflow-3/_config.js  | 4 ++++
 test/runtime/samples/bitmask-overflow-3/main.svelte | 4 ++++
 3 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 test/runtime/samples/bitmask-overflow-3/_config.js
 create mode 100644 test/runtime/samples/bitmask-overflow-3/main.svelte

diff --git a/src/compiler/compile/render_dom/Renderer.ts b/src/compiler/compile/render_dom/Renderer.ts
index 29389ed3c3d8..035b47e74f7c 100644
--- a/src/compiler/compile/render_dom/Renderer.ts
+++ b/src/compiler/compile/render_dom/Renderer.ts
@@ -220,7 +220,11 @@ export default class Renderer {
 				const i = (value / 31) | 0;
 				const n = 1 << (value % 31);
 
-				if (!bitmask[i]) bitmask[i] = { n: 0, names: [] };
+				if (bitmask.length <= i) {
+					for (let j = bitmask.length; j <= i; j++) {
+						bitmask[j] = { n: 0, names: [] };
+					}
+				}
 
 				bitmask[i].n |= n;
 				bitmask[i].names.push(name);
diff --git a/test/runtime/samples/bitmask-overflow-3/_config.js b/test/runtime/samples/bitmask-overflow-3/_config.js
new file mode 100644
index 000000000000..13f18b386cb2
--- /dev/null
+++ b/test/runtime/samples/bitmask-overflow-3/_config.js
@@ -0,0 +1,4 @@
+export default {
+	solo: true,
+	error: `A is not defined`,
+};
\ No newline at end of file
diff --git a/test/runtime/samples/bitmask-overflow-3/main.svelte b/test/runtime/samples/bitmask-overflow-3/main.svelte
new file mode 100644
index 000000000000..aa2c56a14759
--- /dev/null
+++ b/test/runtime/samples/bitmask-overflow-3/main.svelte
@@ -0,0 +1,4 @@
+<script>
+	let x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15, x16, x17, x18, x19, x20, x21, x22, x23, x24, x25, x26, x27, x28, x29, x30, x31;
+</script>
+<A>foo</A>