allow props to expect a two-way binding type

src/compiler/compile-props.js

@@ -77,6 +77,15 @@ module.exports = function compileProps (el, propOptions) {
  )
  }
  }
+ if (
+ process.env.NODE_ENV !== 'production' &&
+ options.twoWay &&
+ prop.mode !== propBindingModes.TWO_WAY
+ ) {
+ _.warn(
+ 'Prop "' + name + '" expects a two-way binding type.'
+ )
+ }
  }
  } else if (options && options.required) {
  process.env.NODE_ENV !== 'production' && _.warn(

test/unit/specs/compiler/compile_spec.js

@@ -177,7 +177,11 @@ if (_.inBrowser) {
  }
  }
  },
- 'withDataPrefix'
+ 'withDataPrefix',
+ {
+ name: 'forceTwoWay',
+ twoWay: true
+ }
  ].map(function (p) {
  return typeof p === 'string' ? { name: p } : p
  })
@@ -193,9 +197,10 @@ if (_.inBrowser) {
  el.setAttribute('boolean-literal', '{{true}}')
  el.setAttribute('boolean', '')
  el.setAttribute('data-with-data-prefix', '1')
+ el.setAttribute('force-two-way', '{{a}}')
  compiler.compileAndLinkProps(vm, el, props)
  // should skip literals and one-time bindings
- expect(vm._bindDir.calls.count()).toBe(4)
+ expect(vm._bindDir.calls.count()).toBe(5)
  // data-some-attr
  var args = vm._bindDir.calls.argsFor(0)
  expect(args[0]).toBe('prop')
@@ -228,6 +233,8 @@ if (_.inBrowser) {
  expect(args[2].parentPath).toBe('this._applyFilters(a,null,[{"name":"filter"}],false)')
  expect(args[2].mode).toBe(bindingModes.ONE_WAY)
  expect(args[3]).toBe(def)
+ // warn when expecting two-way binding but not getting it
+ expect(hasWarned(_, 'expects a two-way binding type')).toBe(true)
  // literal and one time should've been set on the _data
  // and numbers should be casted
  expect(Object.keys(vm._data).length).toBe(10)