fix #58736

src/vs/editor/contrib/snippet/snippetParser.ts

@@ -158,7 +158,13 @@ export abstract class Marker {
 		const newChildren = parent.children.slice(0);
 		newChildren.splice(idx, 1, ...others);
 		parent._children = newChildren;
-		others.forEach(node => node.parent = parent);
+
+		(function _fixParent(children: Marker[], parent: Marker) {
+			for (const child of children) {
+				child.parent = parent;
+				_fixParent(child.children, child);
+			}
+		})(others, parent);
 	}
 
 	get children(): Marker[] {

src/vs/editor/contrib/snippet/test/snippetParser.test.ts

@@ -723,4 +723,30 @@ suite('SnippetParser', () => {
 	test('snippets variable not resolved in JSON proposal #52931', function () {
 		assertTextAndMarker('FOO${1:/bin/bash}', 'FOO/bin/bash', Text, Placeholder);
 	});
+
+	test('Mirroring sequence of nested placeholders not selected properly on backjumping #58736', function () {
+		let snippet = new SnippetParser().parse('${3:nest1 ${1:nest2 ${2:nest3}}} $3');
+		assert.equal(snippet.children.length, 3);
+		assert.ok(snippet.children[0] instanceof Placeholder);
+		assert.ok(snippet.children[1] instanceof Text);
+		assert.ok(snippet.children[2] instanceof Placeholder);
+
+		function assertParent(marker: Marker) {
+			marker.children.forEach(assertParent);
+			if (!(marker instanceof Placeholder)) {
+				return;
+			}
+			let found = false;
+			let m: Marker = marker;
+			while (m && !found) {
+				if (m.parent === snippet) {
+					found = true;
+				}
+				m = m.parent;
+			}
+			assert.ok(found);
+		}
+		let [, , clone] = snippet.children;
+		assertParent(clone);
+	});
 });