fix(slot): add a function to return the slot fallback content

src/compiler/codegen/index.js

@@ -546,7 +546,7 @@ export function genComment (comment: ASTText): string {
 function genSlot (el: ASTElement, state: CodegenState): string {
  const slotName = el.slotName || '"default"'
  const children = genChildren(el, state)
- let res = `_t(${slotName}${children ? `,${children}` : ''}`
+ let res = `_t(${slotName}${children ? `,function(){return ${children}}` : ''}`
  const attrs = el.attrs || el.dynamicAttrs
  ? genProps((el.attrs || []).concat(el.dynamicAttrs || []).map(attr => ({
  // slot props are camelized

src/core/instance/render-helpers/render-slot.js

@@ -7,7 +7,7 @@ import { extend, warn, isObject } from 'core/util/index'
  */
 export function renderSlot (
  name: string,
- fallback: ?Array<VNode>,
+ fallbackRender: ?() => Array<VNode>,
  props: ?Object,
  bindObject: ?Object
 ): ?Array<VNode> {
@@ -24,9 +24,9 @@ export function renderSlot (
  }
  props = extend(extend({}, bindObject), props)
  }
- nodes = scopedSlotFn(props) || fallback
+ nodes = scopedSlotFn(props) || (fallbackRender && fallbackRender())
  } else {
- nodes = this.$slots[name] || fallback
+ nodes = this.$slots[name] || (fallbackRender && fallbackRender())
  }
 
  const target = props && props.slot

test/unit/features/component/component-slot.spec.js

@@ -109,6 +109,26 @@ describe('Component slot', () => {
  expect(child.$el.children[1].textContent).toBe('slot b')
  })
 
+ it('fallback content should not be evaluated when the parent is providing it', () => {
+ const test = jasmine.createSpy('test')
+ const vm = new Vue({
+ template: '<test>slot default</test>',
+ components: {
+ test: {
+ template: '<div><slot>{{test()}}</slot></div>',
+ methods: {
+ test () {
+ test()
+ return 'test'
+ }
+ }
+ }
+ }
+ }).$mount()
+ expect(vm.$el.textContent).toBe('slot default')
+ expect(test).not.toHaveBeenCalled()
+ })
+
  it('selector matching multiple elements', () => {
  mount({
  childTemplate: '<div><slot name="t"></slot></div>',

test/unit/modules/compiler/codegen.spec.js

@@ -196,7 +196,7 @@ describe('codegen', () => {
  it('generate slot fallback content', () => {
  assertCodegen(
  '<div><slot><div>hi</div></slot></div>',
- `with(this){return _c('div',[_t("default",[_c('div',[_v("hi")])])],2)}`
+ `with(this){return _c('div',[_t("default",function(){return [_c('div',[_v("hi")])]})],2)}`
  )
  })