From 2d0f6ccba896fe34141d6d4f59eef6fba580c5c2 Mon Sep 17 00:00:00 2001
From: Daniel Tabuenca <dtabuenca@solutionstream.com>
Date: Wed, 27 Nov 2013 22:01:22 -0800
Subject: [PATCH] fix($compile): ensure isolated local watches' lastValue is
 always in sync

When using two-way binding with isolate scope, under some circumstances
the lastValue variable captured in the parentValueWatch function can get
out of sync.

Specifically, if both the value in the origin scope as well as the value
in the isolate scope get independently updated to the same value within
one digest cycle, the lastValue is never updated. This potentially causes
the watch to make the wrong decision as to which side to update on subsequent
passes.

This fixes things by ensuring lastValue is always set to the last seen
value even if the watch's logic was short circuited because there was no
difference between the values in the original and isolate scopes.

Closes #5182
---
 src/ng/compile.js      |  6 +++---
 test/ng/compileSpec.js | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/ng/compile.js b/src/ng/compile.js
index 0963b8d5d2bf..fd8a8729d87a 100644
--- a/src/ng/compile.js
+++ b/src/ng/compile.js
@@ -1438,13 +1438,13 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
                     // we are out of sync and need to copy
                     if (parentValue !== lastValue) {
                       // parent changed and it has precedence
-                      lastValue = isolateScope[scopeName] = parentValue;
+                      isolateScope[scopeName] = parentValue;
                     } else {
                       // if the parent can be assigned then do so
-                      parentSet(scope, parentValue = lastValue = isolateScope[scopeName]);
+                      parentSet(scope, parentValue = isolateScope[scopeName]);
                     }
                   }
-                  return parentValue;
+                  return lastValue = parentValue;
                 });
                 break;
 
diff --git a/test/ng/compileSpec.js b/test/ng/compileSpec.js
index 6de96f651b2e..c017bfa67e8b 100755
--- a/test/ng/compileSpec.js
+++ b/test/ng/compileSpec.js
@@ -2386,6 +2386,24 @@ describe('$compile', function() {
         expect(componentScope.refAlias).toBe($rootScope.name);
       }));
 
+      it('should not break if local and origin both change to the same value', inject(function() {
+        $rootScope.name = 'aaa';
+
+        compile('<div><span my-component ref="name">');
+
+        //change both sides to the same item withing the same digest cycle
+        componentScope.ref = 'same';
+        $rootScope.name = 'same';
+        $rootScope.$apply();
+
+        //change origin back to it's previous value
+        $rootScope.name = 'aaa';
+        $rootScope.$apply();
+
+        expect($rootScope.name).toBe('aaa');
+        expect(componentScope.ref).toBe('aaa');
+      }));
+
       it('should complain on non assignable changes', inject(function() {
         compile('<div><span my-component ref="\'hello \' + name">');
         $rootScope.name = 'world';