From a28cddd41b8e51096c2f54d85dff9539d33ad93b Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Mon, 19 Aug 2019 11:41:34 -0400
Subject: [PATCH] allow slots to have missing props in SSR - fixes #3322

---
 src/compiler/compile/render_ssr/handlers/Slot.ts       |  2 +-
 .../samples/component-slot-let-missing-prop/Bar.svelte |  5 +++++
 .../samples/component-slot-let-missing-prop/Foo.svelte |  1 +
 .../samples/component-slot-let-missing-prop/_config.js |  5 +++++
 .../component-slot-let-missing-prop/main.svelte        | 10 ++++++++++
 5 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 test/runtime/samples/component-slot-let-missing-prop/Bar.svelte
 create mode 100644 test/runtime/samples/component-slot-let-missing-prop/Foo.svelte
 create mode 100644 test/runtime/samples/component-slot-let-missing-prop/_config.js
 create mode 100644 test/runtime/samples/component-slot-let-missing-prop/main.svelte

diff --git a/src/compiler/compile/render_ssr/handlers/Slot.ts b/src/compiler/compile/render_ssr/handlers/Slot.ts
index 087519979b..ef0699ee80 100644
--- a/src/compiler/compile/render_ssr/handlers/Slot.ts
+++ b/src/compiler/compile/render_ssr/handlers/Slot.ts
@@ -8,7 +8,7 @@ export default function(node: Slot, renderer: Renderer, options: RenderOptions)
 
 	const slot_data = get_slot_data(node.values, true);
 
-	const arg = slot_data.length > 0 ? `{ ${slot_data.join(', ')} }` : '';
+	const arg = slot_data.length > 0 ? `{ ${slot_data.join(', ')} }` : '{}';
 
 	renderer.append(`\${$$slots${prop} ? $$slots${prop}(${arg}) : \``);
 
diff --git a/test/runtime/samples/component-slot-let-missing-prop/Bar.svelte b/test/runtime/samples/component-slot-let-missing-prop/Bar.svelte
new file mode 100644
index 0000000000..d3707c7d8b
--- /dev/null
+++ b/test/runtime/samples/component-slot-let-missing-prop/Bar.svelte
@@ -0,0 +1,5 @@
+<script>
+	export let thing;
+</script>
+
+<p>{thing}</p>
\ No newline at end of file
diff --git a/test/runtime/samples/component-slot-let-missing-prop/Foo.svelte b/test/runtime/samples/component-slot-let-missing-prop/Foo.svelte
new file mode 100644
index 0000000000..49aeb95a1d
--- /dev/null
+++ b/test/runtime/samples/component-slot-let-missing-prop/Foo.svelte
@@ -0,0 +1 @@
+<slot></slot>
\ No newline at end of file
diff --git a/test/runtime/samples/component-slot-let-missing-prop/_config.js b/test/runtime/samples/component-slot-let-missing-prop/_config.js
new file mode 100644
index 0000000000..b3bf13b01b
--- /dev/null
+++ b/test/runtime/samples/component-slot-let-missing-prop/_config.js
@@ -0,0 +1,5 @@
+export default {
+	html: `
+		<p>undefined</p>
+	`
+};
diff --git a/test/runtime/samples/component-slot-let-missing-prop/main.svelte b/test/runtime/samples/component-slot-let-missing-prop/main.svelte
new file mode 100644
index 0000000000..3ac3ba5363
--- /dev/null
+++ b/test/runtime/samples/component-slot-let-missing-prop/main.svelte
@@ -0,0 +1,10 @@
+<script>
+	import Foo from './Foo.svelte';
+	import Bar from './Bar.svelte';
+
+	const things = { '1': 'one' };
+</script>
+
+<Foo let:id>
+	<Bar thing={things[id]}/>
+</Foo>
\ No newline at end of file