fix: update error message to clarify usage with radio inputs

Author: yuki0418

.changeset/slow-nails-push.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: update `bind:checked` error message to clarify usage with radio inputs

documentation/docs/03-template-syntax/12-bind.md

@@ -95,7 +95,7 @@ Since 5.6.0, if an `<input>` has a `defaultValue` and is part of a form, it will
 
 ## `<input bind:checked>`
 
-Checkbox and radio inputs can be bound with `bind:checked`:
+Checkbox can be bound with `bind:checked`:
 
 ```svelte
 <label>
@@ -117,6 +117,8 @@ Since 5.6.0, if an `<input>` has a `defaultChecked` attribute and is part of a f
 </form>
 ```
 
+> [!NOTE] Use `group:bind` for radio inputs instead of `bind:checked`.
+
 ## `<input bind:indeterminate>`
 
 Checkboxes can be in an [indeterminate](https://developer.mozilla.org/en-US/docs/Web/API/HTMLInputElement/indeterminate) state, independently of whether they are checked or unchecked:

packages/svelte/src/compiler/phases/2-analyze/visitors/BindDirective.js

@@ -67,7 +67,11 @@ export function BindDirective(node, context) {
 					}
 				} else {
 					if (node.name === 'checked' && type?.value[0].data !== 'checkbox') {
-						e.bind_invalid_target(node, node.name, '<input type="checkbox">');
+						e.bind_invalid_target(
+							node,
+							node.name,
+							`<input type="checkbox"> - for <input type="radio">, use 'group' binding`
+						);
 					}
 
 					if (node.name === 'files' && type?.value[0].data !== 'file') {

packages/svelte/tests/validator/samples/binding-input-checked/errors.json

@@ -1,7 +1,7 @@
 [
 	{
 		"code": "bind_invalid_target",
-		"message": "`bind:checked` can only be used with <input type=\"checkbox\">",
+		"message": "`bind:checked` can only be used with <input type=\"checkbox\"> - for <input type=\"radio\">, use 'group' binding",
 		"start": {
 			"line": 5,
 			"column": 7