From 1fc4b1c86777f486d5778f6ad8442cbd958d4579 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Mon, 24 Jun 2019 18:09:01 -0400
Subject: [PATCH] add Error to known globals, declare catch block parameter.
 fixes #3064

---
 src/compiler/compile/utils/scope.ts                 |  7 +++++++
 src/compiler/utils/names.ts                         |  1 +
 .../catch-declares-error-variable/input.svelte      | 13 +++++++++++++
 .../catch-declares-error-variable/warnings.json     |  1 +
 4 files changed, 22 insertions(+)
 create mode 100644 test/validator/samples/catch-declares-error-variable/input.svelte
 create mode 100644 test/validator/samples/catch-declares-error-variable/warnings.json

diff --git a/src/compiler/compile/utils/scope.ts b/src/compiler/compile/utils/scope.ts
index 75e44f0adf..0255ac9419 100644
--- a/src/compiler/compile/utils/scope.ts
+++ b/src/compiler/compile/utils/scope.ts
@@ -40,6 +40,13 @@ export function create_scopes(expression: Node) {
 				map.set(node, scope);
 			} else if (/(Class|Variable)Declaration/.test(node.type)) {
 				scope.add_declaration(node);
+			} else if (node.type === 'CatchClause') {
+				scope = new Scope(scope, true);
+				map.set(node, scope);
+
+				extract_names(node.param).forEach(name => {
+					scope.declarations.set(name, node.param);
+				});
 			} else if (node.type === 'Identifier' && is_reference(node as ESTreeNode, parent as ESTreeNode)) {
 				if (!scope.has(node.name) && !globals.has(node.name)) {
 					globals.set(node.name, node);
diff --git a/src/compiler/utils/names.ts b/src/compiler/utils/names.ts
index f1413548aa..9805c92b91 100644
--- a/src/compiler/utils/names.ts
+++ b/src/compiler/utils/names.ts
@@ -13,6 +13,7 @@ export const globals = new Set([
 	'document',
 	'encodeURI',
 	'encodeURIComponent',
+	'Error',
 	'Infinity',
 	'Intl',
 	'isFinite',
diff --git a/test/validator/samples/catch-declares-error-variable/input.svelte b/test/validator/samples/catch-declares-error-variable/input.svelte
new file mode 100644
index 0000000000..b44e854cf5
--- /dev/null
+++ b/test/validator/samples/catch-declares-error-variable/input.svelte
@@ -0,0 +1,13 @@
+<script>
+	let value = null;
+</script>
+
+<button on:click={event => {
+	try {
+		throw new Error('foo');
+	} catch (error) {
+		value = error;
+	}
+}}>Click to create error</button>
+
+{String(value)}
diff --git a/test/validator/samples/catch-declares-error-variable/warnings.json b/test/validator/samples/catch-declares-error-variable/warnings.json
new file mode 100644
index 0000000000..0637a088a0
--- /dev/null
+++ b/test/validator/samples/catch-declares-error-variable/warnings.json
@@ -0,0 +1 @@
+[]
\ No newline at end of file