refactor(factory): improve fallback multiple v-if

close #11856

Author: ksh-code

Diff for: src/core/vdom/helpers/normalize-scoped-slots.js

@@ -61,8 +61,7 @@ function normalizeScopedSlot(normalSlots, key, fn) {
       ? [res] // single vnode
       : normalizeChildren(res)
     return res && (
-      res.length === 0 ||
-      (res.length === 1 && res[0].isComment) // #9658
+      res.every(r => r.isComment) // #9658, #11856
     ) ? undefined
       : res
   }

Diff for: test/unit/features/component/component-scoped-slot.spec.js

@@ -1294,6 +1294,19 @@ describe('Component scoped slot', () => {
     expect(vm.$el.textContent).toMatch('fallback')
   })
 
+  //#11856
+  it('fallback for scoped slot with multiple v-if', () => {
+    const vm = new Vue({
+      template: `<test><template v-if="0 === 1">hi</template><template v-if="1 === 0">hi2</template></test>`,
+      components: {
+        Test: {
+          template: `<div><slot>fallback</slot></div>`
+        }
+      }
+    }).$mount()
+    expect(vm.$el.textContent).toEqual('fallback')
+  })
+
   // #9699
   // Component only has normal slots, but is passing down $scopedSlots directly
   // $scopedSlots should not be marked as stable in this case