From c2f6ea3321e46e077083f5048754e0d0d02c62b5 Mon Sep 17 00:00:00 2001
From: Tan Li Hau <lhtan93@gmail.com>
Date: Sat, 20 Feb 2021 09:33:27 +0800
Subject: [PATCH] no warning on contextual-store if declaring it as a parameter
 / variable

---
 src/compiler/compile/Component.ts             | 16 ++++++------
 .../store-shadow-scope-declaration/_config.js |  1 +
 .../main.svelte                               | 25 +++++++++++++++++++
 3 files changed, 35 insertions(+), 7 deletions(-)
 create mode 100644 test/runtime/samples/store-shadow-scope-declaration/_config.js
 create mode 100644 test/runtime/samples/store-shadow-scope-declaration/main.svelte

diff --git a/src/compiler/compile/Component.ts b/src/compiler/compile/Component.ts
index 8aab2b4898..64e658c049 100644
--- a/src/compiler/compile/Component.ts
+++ b/src/compiler/compile/Component.ts
@@ -751,7 +751,7 @@ export default class Component {
 					return this.skip();
 				}
 
-				component.warn_on_undefined_store_value_references(node, parent, scope);
+				component.warn_on_undefined_store_value_references(node, parent, prop, scope);
 			},
 
 			leave(node: Node) {
@@ -843,7 +843,7 @@ export default class Component {
 		});
 	}
 
-	warn_on_undefined_store_value_references(node, parent, scope: Scope) {
+	warn_on_undefined_store_value_references(node: Node, parent: Node, prop: string, scope: Scope) {
 		if (
 			node.type === 'LabeledStatement' &&
 			node.label.name === '$' &&
@@ -855,7 +855,7 @@ export default class Component {
 			});
 		}
 
-		if (is_reference(node as Node, parent as Node)) {
+		if (is_reference(node, parent)) {
 			const object = get_object(node);
 			const { name } = object;
 
@@ -865,10 +865,12 @@ export default class Component {
 				}
 
 				if (name[1] !== '$' && scope.has(name.slice(1)) && scope.find_owner(name.slice(1)) !== this.instance_scope) {
-					this.error(node, {
-						code: 'contextual-store',
-						message: 'Stores must be declared at the top level of the component (this may change in a future version of Svelte)'
-					});
+					if (!((/Function/.test(parent.type) && prop === 'params') || (parent.type === 'VariableDeclarator' && prop === 'id'))) {
+						this.error(node as any, {
+							code: 'contextual-store',
+							message: 'Stores must be declared at the top level of the component (this may change in a future version of Svelte)'
+						});
+					}
 				}
 			}
 		}
diff --git a/test/runtime/samples/store-shadow-scope-declaration/_config.js b/test/runtime/samples/store-shadow-scope-declaration/_config.js
new file mode 100644
index 0000000000..ff8b4c5632
--- /dev/null
+++ b/test/runtime/samples/store-shadow-scope-declaration/_config.js
@@ -0,0 +1 @@
+export default {};
diff --git a/test/runtime/samples/store-shadow-scope-declaration/main.svelte b/test/runtime/samples/store-shadow-scope-declaration/main.svelte
new file mode 100644
index 0000000000..fa76d33df8
--- /dev/null
+++ b/test/runtime/samples/store-shadow-scope-declaration/main.svelte
@@ -0,0 +1,25 @@
+<script>
+	function test(store) {
+		// allow declaring $store as parameter
+		// it's not referring to the store value of the 
+		// `store` variable in the upper scope
+		return derived(store, $store => {
+
+		});
+	}
+
+	function test2(store) {
+		// allow declaring the `$store` variable
+		// it is not referring to the store value of the `store` variable
+		let $store;
+	}
+</script>
+
+<div
+	on:test={(store) => {
+		derived(store, $store => {});
+	}}
+	on:test2={(store) => {
+		let $store;
+	}}
+/>