diff --git a/.changeset/fresh-dots-destroy.md b/.changeset/fresh-dots-destroy.md
new file mode 100644
index 0000000000..867be39213
--- /dev/null
+++ b/.changeset/fresh-dots-destroy.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: add validation around disallowed sequence expressions to element attributes
diff --git a/packages/svelte/src/compiler/phases/2-analyze/validation.js b/packages/svelte/src/compiler/phases/2-analyze/validation.js
index ed840f5303..0c47d768ba 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/validation.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/validation.js
@@ -98,7 +98,12 @@ function validate_element(node, context) {
if (context.state.analysis.runes && is_expression) {
const expression = attribute.value[0].expression;
if (expression.type === 'SequenceExpression') {
- error(expression, 'invalid-sequence-expression');
+ let i = /** @type {number} */ (expression.start);
+ while (--i > 0) {
+ const char = context.state.analysis.source[i];
+ if (char === '(') break; // parenthesized sequence expressions are ok
+ if (char === '{') error(expression, 'invalid-sequence-expression');
+ }
}
}
diff --git a/packages/svelte/tests/compiler-errors/samples/attribute-sequence-expression-2/_config.js b/packages/svelte/tests/compiler-errors/samples/attribute-sequence-expression-2/_config.js
new file mode 100644
index 0000000000..5fc3e7b5fa
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/attribute-sequence-expression-2/_config.js
@@ -0,0 +1,10 @@
+import { test } from '../../test';
+
+export default test({
+ error: {
+ code: 'invalid-sequence-expression',
+ message:
+ 'Sequence expressions are not allowed as attribute/directive values in runes mode, unless wrapped in parentheses',
+ position: [124, 131]
+ }
+});
diff --git a/packages/svelte/tests/compiler-errors/samples/attribute-sequence-expression-2/main.svelte b/packages/svelte/tests/compiler-errors/samples/attribute-sequence-expression-2/main.svelte
new file mode 100644
index 0000000000..3e83430c25
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/attribute-sequence-expression-2/main.svelte
@@ -0,0 +1,9 @@
+
+
+
+
+
+
+