fix: add slotFlags for implicit default slots

Author: KaelWD

packages/babel-plugin-jsx/src/transform-vue-jsx.ts

@@ -512,7 +512,11 @@ const transformJSXElement = (
     ) {
       VNodeChild = t.objectExpression([
         t.objectProperty(t.identifier('default'), child),
-      ]);
+        optimize && t.objectProperty(
+          t.identifier('_'),
+          t.numericLiteral(slotFlag),
+        ) as any,
+      ].filter(Boolean));
     } else if (t.isObjectExpression(child)) {
       VNodeChild = t.objectExpression(
         [
@@ -526,9 +530,13 @@ const transformJSXElement = (
         ? t.objectExpression([
             t.objectProperty(
               t.identifier('default'),
-              t.arrowFunctionExpression([], t.arrayExpression([child]))
+              t.arrowFunctionExpression([], child),
             ),
-          ])
+            optimize && t.objectProperty(
+              t.identifier('_'),
+              t.numericLiteral(slotFlag),
+            ) as any,
+        ].filter(Boolean))
         : t.arrayExpression([child]);
     }
   }

packages/babel-plugin-jsx/test/__snapshots__/snapshot.test.ts.snap

@@ -164,7 +164,8 @@ _createVNode(_resolveComponent("A"), null, {
 exports[`passing object slots via JSX children single expression, function expression > single expression, function expression 1`] = `
 "import { resolveComponent as _resolveComponent, createVNode as _createVNode } from "vue";
 _createVNode(_resolveComponent("A"), null, {
-  default: () => "foo"
+  default: () => "foo",
+  _: 1
 });"
 `;