warn special case for v-repeat $value sync

Author: yyx990803

src/directives/repeat.js

@@ -384,6 +384,16 @@ module.exports = {
       (type === 'string' || type === 'number')
     ) {
       vm.$watch(alias || '$value', function (val) {
+        if (dir.filters) {
+          _.warn(
+            'You seem to be mutating the $value reference of ' +
+            'a v-repeat instance (likely through v-model) ' +
+            'and filtering the v-repeat at the same time. ' +
+            'This will not work properly with an Array of ' +
+            'primitive values. Please use an Array of ' +
+            'Objects instead.'
+          )
+        }
         dir._withLock(function () {
           if (dir.converted) {
             dir.rawValue[vm.$key] = val

src/util/debug.js

@@ -36,7 +36,7 @@ function enableDebug () {
       /* istanbul ignore if */
       if (config.debug) {
         /* jshint debug: true */
-        console.warn((e || new Error()).stack)
+        console.warn((e || new Error('Warning Stack Trace')).stack)
       }
     }
   }

test/unit/specs/directives/repeat_spec.js

@@ -623,27 +623,45 @@ if (_.inBrowser) {
       }, 100)
     })
 
-    it('sync $value changes back to original array/object', function (done) {
+    it('sync $value/alias changes back to original array/object', function (done) {
       var vm = new Vue({
         el: el,
         template:
           '<div v-repeat="items">{{$value}}</div>' +
-          '<div v-repeat="obj">{{$value}}</div>',
+          '<div v-repeat="obj">{{$value}}</div>' +
+          '<div v-repeat="val:vals">{{val}}</div>',
         data: {
           items: ['a', 'b'],
-          obj: { foo: 'a', bar: 'b' }
+          obj: { foo: 'a', bar: 'b' },
+          vals: [1, 2]
         }
       })
       vm._children[0].$value = 'c'
       var key = vm._children[2].$key
       vm._children[2].$value = 'd'
+      vm._children[4].val = 3
       _.nextTick(function () {
         expect(vm.items[0]).toBe('c')
         expect(vm.obj[key]).toBe('d')
+        expect(vm.vals[0]).toBe(3)
         done()
       })
     })
 
+    it('warn $value sync with filters', function () {
+      var vm = new Vue({
+        el: el,
+        template: '<div v-repeat="items | orderBy \'$value\'"></div>',
+        data: {
+          items: ['a', 'b']
+        }
+      })
+      vm._children[0].$value = 'c'
+      _.nextTick(function () {
+        expect(hasWarned(_, 'use an Array of Objects instead')).toBe(true)
+      })
+    })
+
     it('nested track by', function (done) {
       assertTrackBy('<div v-repeat="list" track-by="id">{{msg}}<div v-repeat="list" track-by="id">{{msg}}</div></div>', function () {
         assertTrackBy('<div v-repeat="list" track-by="id">{{msg}}<div v-repeat="list" track-by="id">{{msg}}</div></div>', done)