fix sibling combinators with spread attributes (#5467)

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 * Add `EventSource` to known globals ([#5463](https://github.com/sveltejs/svelte/issues/5463))
+* Fix compiler exception with `~`/`+` combinators and `{...spread}` attributes ([#5465](https://github.com/sveltejs/svelte/issues/5465))
 
 ## 3.28.0
 

src/compiler/compile/css/Selector.ts

@@ -406,7 +406,7 @@ function get_possible_element_siblings(node: INode, adjacent_only: boolean): Map
 	let prev: INode = node;
 	while (prev = prev.prev) {
 		if (prev.type === 'Element') {
-			if (!prev.attributes.find(attr => attr.name.toLowerCase() === 'slot')) {
+			if (!prev.attributes.find(attr => attr.type === 'Attribute' && attr.name.toLowerCase() === 'slot')) {
 				result.set(prev, NodeExist.Definitely);
 			}
 

test/css/samples/siblings-combinator-with-spread/_config.js

@@ -0,0 +1,3 @@
+export default {
+	warnings: []
+};

test/css/samples/siblings-combinator-with-spread/expected.css

@@ -0,0 +1 @@
+input.svelte-xyz:focus+div.svelte-xyz{color:red}input.svelte-xyz:focus~div.svelte-xyz{color:red}

test/css/samples/siblings-combinator-with-spread/expected.html

@@ -0,0 +1,2 @@
+<input placeholder="Text" class="svelte-xyz">
+<div class="svelte-xyz">Should be red, when input is focused</div>

test/css/samples/siblings-combinator-with-spread/input.svelte

@@ -0,0 +1,11 @@
+<script>
+	const test = { placeholder: 'Text' };
+</script>
+
+<style>
+	input:focus + div { color: red; }
+	input:focus ~ div { color: red; }
+</style>
+
+<input {...test}>
+<div>Should be red, when input is focused</div>