fix: ensure svg namespace for `<a>` elements is correct (#14756)

* fix: ensure svg namespace persists from parent of if blocks

* better fix

* better fix

* address feedback

.changeset/nine-buses-own.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure svg namespace for `<a>`  elements is correct

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

@@ -86,7 +86,23 @@ export function RegularElement(node, context) {
 		(attribute) => attribute.type === 'SpreadAttribute'
 	);
 
-	node.metadata.svg = is_svg(node.name);
+	const is_svg_element = () => {
+		if (is_svg(node.name)) {
+			return true;
+		}
+		if (node.name === 'a') {
+			for (let i = context.path.length - 1; i >= 0; i--) {
+				const ancestor = context.path[i];
+				if (ancestor.type === 'RegularElement') {
+					return ancestor.metadata.svg;
+				}
+			}
+		}
+
+		return false;
+	};
+
+	node.metadata.svg = is_svg_element();
 	node.metadata.mathml = is_mathml(node.name);
 
 	if (is_custom_element_node(node) && node.attributes.length > 0) {

packages/svelte/tests/runtime-runes/samples/svg-namespace-if-block-2/_config.js

@@ -0,0 +1,11 @@
+import { test, ok } from '../../test';
+
+export default test({
+	html: `<svg><a href="/docs"><text class="small" x="20" y="40"></text></a></svg>`,
+	test({ assert, target }) {
+		const a = target.querySelector('a');
+		ok(a);
+
+		assert.equal(a.namespaceURI, 'http://www.w3.org/2000/svg');
+	}
+});

packages/svelte/tests/runtime-runes/samples/svg-namespace-if-block-2/main.svelte

@@ -0,0 +1,7 @@
+<svg>
+	{#if true}
+		<a href="/docs">
+			<text x="20" y="40" class="small">{name}</text>
+		</a>
+	{/if}
+</svg>