From 4d99099d1ab69183325a85bb5c4b45867a43b15b Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Thu, 31 Jan 2019 11:01:16 -0800
Subject: [PATCH 1/8] Ensure that marshalArgs pulls wildcard info value from
 __data It currently pulls the value from `changedProps` rather than __data,
 meaning it could provide stale data for re-entrant changes.

---
 lib/mixins/property-effects.js     | 48 ++++++++++++++----------------
 test/unit/path-effects-elements.js | 36 ++++++++++++++++++++++
 test/unit/path-effects.html        | 11 +++++++
 3 files changed, 69 insertions(+), 26 deletions(-)

diff --git a/lib/mixins/property-effects.js b/lib/mixins/property-effects.js
index 4961eec486..eeff962645 100644
--- a/lib/mixins/property-effects.js
+++ b/lib/mixins/property-effects.js
@@ -2140,37 +2140,33 @@ export const PropertyEffects = dedupingMixin(superClass => {
      */
     _marshalArgs(args, path, props) {
       const data = this.__data;
-      let values = [];
+      const values = [];
       for (let i=0, l=args.length; i<l; i++) {
-        let arg = args[i];
-        let name = arg.name;
-        let v;
-        if (arg.literal) {
-          v = arg.value;
-        } else {
-          if (arg.structured) {
-            v = get(data, name);
-            // when data is not stored e.g. `splices`
-            if (v === undefined) {
-              v = props[name];
+        let {name, structured, wildcard, value, literal} = args[i];
+        let argPath = name;
+        if (!literal) {
+          if (structured) {
+            // If the triggered path matches the wildcard, use that path
+            if (wildcard && (path === name || isDescendant(name, path))) {
+              argPath = path;
+            }
+            value = get(data, argPath);
+            // when data is not stored e.g. `splices`, get the changed value
+            if (value === undefined) {
+              value = props[argPath];
             }
           } else {
-            v = data[name];
+            value = data[name];
+          }
+          if (wildcard) {
+            value = {
+              path: argPath,
+              value,
+              base: argPath === path ? get(data, name) : value
+            };
           }
         }
-        if (arg.wildcard) {
-          // Only send the actual path changed info if the change that
-          // caused the observer to run matched the wildcard
-          let baseChanged = (name.indexOf(path + '.') === 0);
-          let matches = (path.indexOf(name) === 0 && !baseChanged);
-          values[i] = {
-            path: matches ? path : name,
-            value: matches ? props[path] : v,
-            base: v
-          };
-        } else {
-          values[i] = v;
-        }
+        values[i] = value;
       }
       return values;
     }
diff --git a/test/unit/path-effects-elements.js b/test/unit/path-effects-elements.js
index 2a80f07b3a..f0d18cc66b 100644
--- a/test/unit/path-effects-elements.js
+++ b/test/unit/path-effects-elements.js
@@ -245,6 +245,42 @@ Polymer({
     this.objChanged = sinon.spy();
   }
 });
+
+Polymer({
+
+  is: 'x-reentry-wildcard',
+
+  properties: {
+    array: {
+      type: Array,
+      computed: 'computeArray(trigger, size)'
+    },
+    size: {
+      type: Number
+    },
+    trigger: {
+      type: Boolean,
+      observer: 'triggerChanged',
+      value: true
+    }
+  },
+  
+  observers: ['arrayChanged(array.*)'],
+
+  created() {
+    this.arrayChanged = sinon.spy();
+  },
+  
+  computeArray(trigger, size) {
+    return new Array(size || 0);
+  },
+  
+  triggerChanged() {
+    this.size = 1;
+  }
+  
+});
+
 Polymer({
   is: 'x-path-client',
   observers: ['objChanged(obj.*)'],
diff --git a/test/unit/path-effects.html b/test/unit/path-effects.html
index b597469d72..6d378760f1 100644
--- a/test/unit/path-effects.html
+++ b/test/unit/path-effects.html
@@ -1099,6 +1099,17 @@
     assert.equal(host.objChanged.secondCall.args[0].value, 1);
   });
 
+  test('reentry after wildcard observer queued', function() {
+    let el = document.createElement('x-reentry-wildcard');
+    document.body.appendChild(el);
+    assert.equal(el.arrayChanged.callCount, 2);
+    assert.equal(el.arrayChanged.firstCall.args[0].base.length, 1);
+    assert.equal(el.arrayChanged.firstCall.args[0].value.length, 1);
+    assert.equal(el.arrayChanged.secondCall.args[0].base.length, 1);
+    assert.equal(el.arrayChanged.secondCall.args[0].value.length, 1);
+    document.body.removeChild(el);
+  });
+
   test('element without notify effects still notifies paths (1.x guarantee)', function() {
     let host = document.createElement('x-path-host');
     let listener = sinon.spy();

From c78f679989384ae4bd89440aa801ff36552d4592 Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Thu, 31 Jan 2019 16:14:33 -0800
Subject: [PATCH 2/8] Refactor to make code more readable, add tests, remove
 dead code.

---
 lib/mixins/property-effects.js     |  37 +++++-----
 test/unit/path-effects-elements.js |   8 ++-
 test/unit/path-effects.html        | 106 +++++++++++++++++++++++++++++
 3 files changed, 131 insertions(+), 20 deletions(-)

diff --git a/lib/mixins/property-effects.js b/lib/mixins/property-effects.js
index eeff962645..030c7951c5 100644
--- a/lib/mixins/property-effects.js
+++ b/lib/mixins/property-effects.js
@@ -964,6 +964,19 @@ function parseArg(rawArg) {
   return a;
 }
 
+function getArgValue(data, props, structured, path) {
+  if (structured) {
+    let value = get(data, path);
+    // when data is not stored e.g. `splices`, get the changed value
+    if (value === undefined) {
+      value = props[path];
+    }
+    return value;
+  } else {
+    return data[path];
+  }
+}
+
 // data api
 
 /**
@@ -982,8 +995,6 @@ function notifySplices(inst, array, path, splices) {
   let splicesPath = path + '.splices';
   inst.notifyPath(splicesPath, { indexSplices: splices });
   inst.notifyPath(path + '.length', array.length);
-  // Null here to allow potentially large splice records to be GC'ed.
-  inst.__data[splicesPath] = {indexSplices: null};
 }
 
 /**
@@ -2143,26 +2154,14 @@ export const PropertyEffects = dedupingMixin(superClass => {
       const values = [];
       for (let i=0, l=args.length; i<l; i++) {
         let {name, structured, wildcard, value, literal} = args[i];
-        let argPath = name;
         if (!literal) {
-          if (structured) {
-            // If the triggered path matches the wildcard, use that path
-            if (wildcard && (path === name || isDescendant(name, path))) {
-              argPath = path;
-            }
-            value = get(data, argPath);
-            // when data is not stored e.g. `splices`, get the changed value
-            if (value === undefined) {
-              value = props[argPath];
-            }
-          } else {
-            value = data[name];
-          }
+          value = getArgValue(data, props, structured, name);
           if (wildcard) {
+            const matches = isDescendant(name, path);
             value = {
-              path: argPath,
-              value,
-              base: argPath === path ? get(data, name) : value
+              path: matches ? path : name,
+              value: matches ? getArgValue(data, props, structured, path) : value,
+              base: value
             };
           }
         }
diff --git a/test/unit/path-effects-elements.js b/test/unit/path-effects-elements.js
index f0d18cc66b..4deac1bc44 100644
--- a/test/unit/path-effects-elements.js
+++ b/test/unit/path-effects-elements.js
@@ -162,6 +162,9 @@ Polymer({
     'aChanged(a.*)',
     'xChanged(x.*)',
     'yChanged(y.*)',
+    'abChanged(a.b.*)',
+    'abcChanged(a.b.c.*)',
+    'abcxChanged(a.b.c.*, x)'
   ],
 
   created: function() {
@@ -190,6 +193,9 @@ Polymer({
       this.$.forward.resetObservers();
       this.$.pe.resetObservers();
     }
+    this.abChanged = sinon.spy();
+    this.abcChanged = sinon.spy();
+    this.abcxChanged = sinon.spy();
   },
 
   computeFromPaths: function(a, b, c) {
@@ -309,4 +315,4 @@ Polymer({
   created: function() {
     this.objChanged = sinon.spy();
   }
-});
+});
\ No newline at end of file
diff --git a/test/unit/path-effects.html b/test/unit/path-effects.html
index 6d378760f1..0347dc1a11 100644
--- a/test/unit/path-effects.html
+++ b/test/unit/path-effects.html
@@ -341,6 +341,112 @@
     assert.equal(el.$.compose.$.basic1.othervalue, 98);
   });
 
+  suite('ancestors and descendants', function() {
+
+    test('change base', function() {
+      let c = {}, b = {c}, a = {b};
+      el.a = a;
+      assert.equal(el.aChanged.callCount, 1);
+      assert.deepEqual(el.aChanged.firstCall.args[0], {path: 'a', base: a, value: a});
+      assert.equal(el.abChanged.callCount, 1);
+      assert.deepEqual(el.abChanged.firstCall.args[0], {path: 'a.b', base: b, value: b});
+      assert.equal(el.abcChanged.callCount, 1);
+      assert.deepEqual(el.abcChanged.firstCall.args[0], {path: 'a.b.c', base: c, value: c});
+      assert.equal(el.abcxChanged.callCount, 1);
+      assert.deepEqual(el.abcxChanged.firstCall.args[0], {path: 'a.b.c', base: c, value: c});
+    });
+
+    test('change subpath level 1', function() {
+      let c = {}, b = {c}, a = {b};
+      el.a = a;
+      el.resetObservers();
+      c = {},
+      b = {c};
+      el.set('a.b', b);
+      assert.equal(el.aChanged.callCount, 1);
+      assert.deepEqual(el.aChanged.firstCall.args[0], {path: 'a.b', base: a, value: b});
+      assert.equal(el.abChanged.callCount, 1);
+      assert.deepEqual(el.abChanged.firstCall.args[0], {path: 'a.b', base: b, value: b});
+      assert.equal(el.abcChanged.callCount, 1);
+      assert.deepEqual(el.abcChanged.firstCall.args[0], {path: 'a.b.c', base: c, value: c});
+      assert.equal(el.abcxChanged.callCount, 1);
+      assert.deepEqual(el.abcxChanged.firstCall.args[0], {path: 'a.b.c', base: c, value: c});
+    });
+
+    test('change subpath level 2', function() {
+      let c = {}, b = {c}, a = {b};
+      el.a = a;
+      el.resetObservers();
+      c = {},
+      el.set('a.b.c', c);
+      assert.equal(el.aChanged.callCount, 1);
+      assert.deepEqual(el.aChanged.firstCall.args[0], {path: 'a.b.c', base: a, value: c});
+      assert.equal(el.abChanged.callCount, 1);
+      assert.deepEqual(el.abChanged.firstCall.args[0], {path: 'a.b.c', base: b, value: c});
+      assert.equal(el.abcChanged.callCount, 1);
+      assert.deepEqual(el.abcChanged.firstCall.args[0], {path: 'a.b.c', base: c, value: c});
+      assert.equal(el.abcxChanged.callCount, 1);
+      assert.deepEqual(el.abcxChanged.firstCall.args[0], {path: 'a.b.c', base: c, value: c});
+    });
+
+    test('change subpath of base only', function() {
+      let c = {}, b = {c}, a = {b};
+      el.a = a;
+      el.resetObservers();
+      let d = {};
+      el.set('a.d', d);
+      assert.equal(el.aChanged.callCount, 1);
+      assert.deepEqual(el.aChanged.firstCall.args[0], {path: 'a.d', base: a, value: d});
+      assert.equal(el.abChanged.callCount, 0);
+      assert.equal(el.abcChanged.callCount, 0);
+      assert.equal(el.abcxChanged.callCount, 0);
+    });
+
+    test('change subpath of level 1 only', function() {
+      let c = {}, b = {c}, a = {b};
+      el.a = a;
+      el.resetObservers();
+      let e = {};
+      el.set('a.b.e', e);
+      assert.equal(el.aChanged.callCount, 1);
+      assert.deepEqual(el.aChanged.firstCall.args[0], {path: 'a.b.e', base: a, value: e});
+      assert.equal(el.abChanged.callCount, 1);
+      assert.deepEqual(el.abChanged.firstCall.args[0], {path: 'a.b.e', base: b, value: e});
+      assert.equal(el.abcChanged.callCount, 0);
+      assert.equal(el.abcxChanged.callCount, 0);
+    });
+    
+    test('change subpath of level 2', function() {
+      let c = {}, b = {c}, a = {b};
+      el.a = a;
+      el.resetObservers();
+      let f = {};
+      el.set('a.b.c.f', f);
+      assert.equal(el.aChanged.callCount, 1);
+      assert.deepEqual(el.aChanged.firstCall.args[0], {path: 'a.b.c.f', base: a, value: f});
+      assert.equal(el.abChanged.callCount, 1);
+      assert.deepEqual(el.abChanged.firstCall.args[0], {path: 'a.b.c.f', base: b, value: f});
+      assert.equal(el.abcChanged.callCount, 1);
+      assert.deepEqual(el.abcChanged.firstCall.args[0], {path: 'a.b.c.f', base: c, value: f});
+      assert.equal(el.abcxChanged.callCount, 1);
+      assert.deepEqual(el.abcxChanged.firstCall.args[0], {path: 'a.b.c.f', base: c, value: f});
+    });
+    
+    test('change non-wildcard argument', function() {
+      let c = {}, b = {c}, a = {b};
+      el.a = a;
+      el.resetObservers();
+      let x = el.x = {};
+      assert.equal(el.aChanged.callCount, 0);
+      assert.equal(el.abChanged.callCount, 0);
+      assert.equal(el.abcChanged.callCount, 0);
+      assert.equal(el.abcxChanged.callCount, 1);
+      assert.deepEqual(el.abcxChanged.firstCall.args[0], {path: 'a.b.c', base: c, value: c});
+      assert.equal(el.abcxChanged.firstCall.args[1], x);
+    });
+    
+  });
+
 });
 
 suite('path effects', function() {

From 2480b259a97ebad1f73de1fafdfed1704ea6ff33 Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Thu, 31 Jan 2019 18:42:14 -0800
Subject: [PATCH 3/8] Upgrade webcomponentsjs

---
 package-lock.json | 92 ++++++++++++++++++++---------------------------
 package.json      |  2 +-
 2 files changed, 40 insertions(+), 54 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index 9da912d1cb..b468dee87f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1310,9 +1310,9 @@
       "integrity": "sha512-bx0TzeZ11VqYDGLuXfznen8+4u0hADk2dD5RNMFxWL9MM4c5NXCDCgNXgssb4i2zQOos/GGe4tl5AuE0LzJkLA=="
     },
     "@webcomponents/webcomponentsjs": {
-      "version": "2.2.2",
-      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.2.2.tgz",
-      "integrity": "sha512-t45WI6m/dD+gmMaQ/u0k1gCrSg5yESnfGaxfFPV1GST2RL/aEScoaotFsfjfP8DPcq2OH6leyHoWBT+pSuGsdQ==",
+      "version": "2.2.5",
+      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.2.5.tgz",
+      "integrity": "sha512-aLSQa2+NjGv+6hwjQ/mHhrav7qhRf1ZMsUNWNqP3ca9BK9YoDmjsrcFFr8TaZ+ucwm+JiNVEtoQinNpbn863pw==",
       "dev": true
     },
     "abbrev": {
@@ -9756,7 +9756,7 @@
         },
         "array-flatten": {
           "version": "1.1.1",
-          "resolved": "http://registry.npmjs.org/array-flatten/-/array-flatten-1.1.1.tgz",
+          "resolved": "https://registry.npmjs.org/array-flatten/-/array-flatten-1.1.1.tgz",
           "integrity": "sha1-ml9pkFGx5wczKPKgCJaLZOopVdI=",
           "dev": true
         },
@@ -10635,7 +10635,7 @@
             },
             "string_decoder": {
               "version": "0.10.31",
-              "resolved": "http://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
+              "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
               "integrity": "sha1-YuIDvEF2bGwoyfyEMB2rHFMQ+pQ=",
               "dev": true
             }
@@ -11119,7 +11119,7 @@
         },
         "concat-stream": {
           "version": "1.6.2",
-          "resolved": "http://registry.npmjs.org/concat-stream/-/concat-stream-1.6.2.tgz",
+          "resolved": "https://registry.npmjs.org/concat-stream/-/concat-stream-1.6.2.tgz",
           "integrity": "sha512-27HBghJxjiZtIk3Ycvn/4kbJk/1uZuJFfuPEns6LaEvpvG1f0hTea8lilrouyo9mVc2GWdcEZ8OLoGmSADlrCw==",
           "dev": true,
           "requires": {
@@ -11145,7 +11145,7 @@
         },
         "content-disposition": {
           "version": "0.5.2",
-          "resolved": "http://registry.npmjs.org/content-disposition/-/content-disposition-0.5.2.tgz",
+          "resolved": "https://registry.npmjs.org/content-disposition/-/content-disposition-0.5.2.tgz",
           "integrity": "sha1-DPaLud318r55YcOoUXjLhdunjLQ=",
           "dev": true
         },
@@ -11529,7 +11529,7 @@
             },
             "string_decoder": {
               "version": "0.10.31",
-              "resolved": "http://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
+              "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
               "integrity": "sha1-YuIDvEF2bGwoyfyEMB2rHFMQ+pQ=",
               "dev": true
             }
@@ -11895,7 +11895,7 @@
         },
         "expand-range": {
           "version": "1.8.2",
-          "resolved": "http://registry.npmjs.org/expand-range/-/expand-range-1.8.2.tgz",
+          "resolved": "https://registry.npmjs.org/expand-range/-/expand-range-1.8.2.tgz",
           "integrity": "sha1-opnv/TNf4nIeuujiV+x5ZE/IUzc=",
           "dev": true,
           "requires": {
@@ -12144,7 +12144,7 @@
                 },
                 "is-accessor-descriptor": {
                   "version": "0.1.6",
-                  "resolved": "http://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
+                  "resolved": "https://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
                   "integrity": "sha1-qeEss66Nh2cn7u84Q/igiXtcmNY=",
                   "dev": true,
                   "requires": {
@@ -12164,7 +12164,7 @@
                 },
                 "is-data-descriptor": {
                   "version": "0.1.4",
-                  "resolved": "http://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
+                  "resolved": "https://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
                   "integrity": "sha1-C17mSDiOLIYCgueT8YVv7D8wG1Y=",
                   "dev": true,
                   "requires": {
@@ -12683,15 +12683,13 @@
               "version": "1.0.0",
               "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
               "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
-              "dev": true,
-              "optional": true
+              "dev": true
             },
             "brace-expansion": {
               "version": "1.1.11",
               "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
               "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
               "dev": true,
-              "optional": true,
               "requires": {
                 "balanced-match": "^1.0.0",
                 "concat-map": "0.0.1"
@@ -12708,22 +12706,19 @@
               "version": "1.1.0",
               "resolved": "https://registry.npmjs.org/code-point-at/-/code-point-at-1.1.0.tgz",
               "integrity": "sha1-DQcLTQQ6W+ozovGkDi7bPZpMz3c=",
-              "dev": true,
-              "optional": true
+              "dev": true
             },
             "concat-map": {
               "version": "0.0.1",
               "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
               "integrity": "sha1-2Klr13/Wjfd5OnMDajug1UBdR3s=",
-              "dev": true,
-              "optional": true
+              "dev": true
             },
             "console-control-strings": {
               "version": "1.1.0",
               "resolved": "https://registry.npmjs.org/console-control-strings/-/console-control-strings-1.1.0.tgz",
               "integrity": "sha1-PXz0Rk22RG6mRL9LOVB/mFEAjo4=",
-              "dev": true,
-              "optional": true
+              "dev": true
             },
             "core-util-is": {
               "version": "1.0.2",
@@ -12854,8 +12849,7 @@
               "version": "2.0.3",
               "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
               "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4=",
-              "dev": true,
-              "optional": true
+              "dev": true
             },
             "ini": {
               "version": "1.3.5",
@@ -12869,7 +12863,6 @@
               "resolved": "https://registry.npmjs.org/is-fullwidth-code-point/-/is-fullwidth-code-point-1.0.0.tgz",
               "integrity": "sha1-754xOG8DGn8NZDr4L95QxFfvAMs=",
               "dev": true,
-              "optional": true,
               "requires": {
                 "number-is-nan": "^1.0.0"
               }
@@ -12886,7 +12879,6 @@
               "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
               "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
               "dev": true,
-              "optional": true,
               "requires": {
                 "brace-expansion": "^1.1.7"
               }
@@ -12895,15 +12887,13 @@
               "version": "0.0.8",
               "resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.8.tgz",
               "integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0=",
-              "dev": true,
-              "optional": true
+              "dev": true
             },
             "minipass": {
               "version": "2.2.4",
               "resolved": "https://registry.npmjs.org/minipass/-/minipass-2.2.4.tgz",
               "integrity": "sha512-hzXIWWet/BzWhYs2b+u7dRHlruXhwdgvlTMDKC6Cb1U7ps6Ac6yQlR39xsbjWJE377YTCtKwIXIpJ5oP+j5y8g==",
               "dev": true,
-              "optional": true,
               "requires": {
                 "safe-buffer": "^5.1.1",
                 "yallist": "^3.0.0"
@@ -12924,7 +12914,6 @@
               "resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.1.tgz",
               "integrity": "sha1-MAV0OOrGz3+MR2fzhkjWaX11yQM=",
               "dev": true,
-              "optional": true,
               "requires": {
                 "minimist": "0.0.8"
               }
@@ -13013,8 +13002,7 @@
               "version": "1.0.1",
               "resolved": "https://registry.npmjs.org/number-is-nan/-/number-is-nan-1.0.1.tgz",
               "integrity": "sha1-CXtgK1NCKlIsGvuHkDGDNpQaAR0=",
-              "dev": true,
-              "optional": true
+              "dev": true
             },
             "object-assign": {
               "version": "4.1.1",
@@ -13028,7 +13016,6 @@
               "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
               "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
               "dev": true,
-              "optional": true,
               "requires": {
                 "wrappy": "1"
               }
@@ -13166,7 +13153,6 @@
               "resolved": "https://registry.npmjs.org/string-width/-/string-width-1.0.2.tgz",
               "integrity": "sha1-EYvfW4zcUaKn5w0hHgfisLmxB9M=",
               "dev": true,
-              "optional": true,
               "requires": {
                 "code-point-at": "^1.0.0",
                 "is-fullwidth-code-point": "^1.0.0",
@@ -13423,7 +13409,7 @@
             },
             "string_decoder": {
               "version": "0.10.31",
-              "resolved": "http://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
+              "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
               "integrity": "sha1-YuIDvEF2bGwoyfyEMB2rHFMQ+pQ=",
               "dev": true
             },
@@ -13456,7 +13442,7 @@
         },
         "global-modules": {
           "version": "0.2.3",
-          "resolved": "http://registry.npmjs.org/global-modules/-/global-modules-0.2.3.tgz",
+          "resolved": "https://registry.npmjs.org/global-modules/-/global-modules-0.2.3.tgz",
           "integrity": "sha1-6lo77ULG1s6ZWk+KEmm12uIjgo0=",
           "dev": true,
           "requires": {
@@ -13474,7 +13460,7 @@
         },
         "global-prefix": {
           "version": "0.1.5",
-          "resolved": "http://registry.npmjs.org/global-prefix/-/global-prefix-0.1.5.tgz",
+          "resolved": "https://registry.npmjs.org/global-prefix/-/global-prefix-0.1.5.tgz",
           "integrity": "sha1-jTvGuNo8qBEqFg2NSW/wRiv+948=",
           "dev": true,
           "requires": {
@@ -14009,7 +13995,7 @@
         },
         "is-accessor-descriptor": {
           "version": "0.1.6",
-          "resolved": "http://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
+          "resolved": "https://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
           "integrity": "sha1-qeEss66Nh2cn7u84Q/igiXtcmNY=",
           "dev": true,
           "requires": {
@@ -14057,7 +14043,7 @@
         },
         "is-data-descriptor": {
           "version": "0.1.4",
-          "resolved": "http://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
+          "resolved": "https://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
           "integrity": "sha1-C17mSDiOLIYCgueT8YVv7D8wG1Y=",
           "dev": true,
           "requires": {
@@ -15046,7 +15032,7 @@
         },
         "multimatch": {
           "version": "2.1.0",
-          "resolved": "http://registry.npmjs.org/multimatch/-/multimatch-2.1.0.tgz",
+          "resolved": "https://registry.npmjs.org/multimatch/-/multimatch-2.1.0.tgz",
           "integrity": "sha1-nHkGoi+0wCkZ4vX3UWG0zb1LKis=",
           "dev": true,
           "requires": {
@@ -15058,7 +15044,7 @@
         },
         "multipipe": {
           "version": "1.0.2",
-          "resolved": "http://registry.npmjs.org/multipipe/-/multipipe-1.0.2.tgz",
+          "resolved": "https://registry.npmjs.org/multipipe/-/multipipe-1.0.2.tgz",
           "integrity": "sha1-zBPv2DPJzamfIk+GhGG44aP9k50=",
           "dev": true,
           "requires": {
@@ -15495,7 +15481,7 @@
         },
         "pako": {
           "version": "0.2.9",
-          "resolved": "http://registry.npmjs.org/pako/-/pako-0.2.9.tgz",
+          "resolved": "https://registry.npmjs.org/pako/-/pako-0.2.9.tgz",
           "integrity": "sha1-8/dSL073gjSNqBYbrZ7P1Rv4OnU=",
           "dev": true
         },
@@ -16079,7 +16065,7 @@
         },
         "pretty-bytes": {
           "version": "4.0.2",
-          "resolved": "http://registry.npmjs.org/pretty-bytes/-/pretty-bytes-4.0.2.tgz",
+          "resolved": "https://registry.npmjs.org/pretty-bytes/-/pretty-bytes-4.0.2.tgz",
           "integrity": "sha1-sr+C5zUNZcbDOqlaqlpPYyf2HNk=",
           "dev": true
         },
@@ -16378,7 +16364,7 @@
                 },
                 "is-accessor-descriptor": {
                   "version": "0.1.6",
-                  "resolved": "http://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
+                  "resolved": "https://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
                   "integrity": "sha1-qeEss66Nh2cn7u84Q/igiXtcmNY=",
                   "dev": true,
                   "requires": {
@@ -16398,7 +16384,7 @@
                 },
                 "is-data-descriptor": {
                   "version": "0.1.4",
-                  "resolved": "http://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
+                  "resolved": "https://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
                   "integrity": "sha1-C17mSDiOLIYCgueT8YVv7D8wG1Y=",
                   "dev": true,
                   "requires": {
@@ -16792,7 +16778,7 @@
         },
         "resolve-dir": {
           "version": "0.1.1",
-          "resolved": "http://registry.npmjs.org/resolve-dir/-/resolve-dir-0.1.1.tgz",
+          "resolved": "https://registry.npmjs.org/resolve-dir/-/resolve-dir-0.1.1.tgz",
           "integrity": "sha1-shklmlYC+sXFxJatiUpujMQwJh4=",
           "dev": true,
           "requires": {
@@ -17555,7 +17541,7 @@
         },
         "string-width": {
           "version": "1.0.2",
-          "resolved": "http://registry.npmjs.org/string-width/-/string-width-1.0.2.tgz",
+          "resolved": "https://registry.npmjs.org/string-width/-/string-width-1.0.2.tgz",
           "integrity": "sha1-EYvfW4zcUaKn5w0hHgfisLmxB9M=",
           "dev": true,
           "requires": {
@@ -17566,7 +17552,7 @@
         },
         "string_decoder": {
           "version": "1.1.1",
-          "resolved": "http://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
+          "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
           "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
           "dev": true,
           "requires": {
@@ -17624,7 +17610,7 @@
         },
         "supports-color": {
           "version": "2.0.0",
-          "resolved": "http://registry.npmjs.org/supports-color/-/supports-color-2.0.0.tgz",
+          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-2.0.0.tgz",
           "integrity": "sha1-U10EXOa2Nj+kARcIRimZXp3zJMc=",
           "dev": true
         },
@@ -17767,7 +17753,7 @@
         },
         "temp": {
           "version": "0.8.3",
-          "resolved": "http://registry.npmjs.org/temp/-/temp-0.8.3.tgz",
+          "resolved": "https://registry.npmjs.org/temp/-/temp-0.8.3.tgz",
           "integrity": "sha1-4Ma8TSa5AxJEEOT+2BEDAU38H1k=",
           "dev": true,
           "requires": {
@@ -18116,7 +18102,7 @@
         },
         "underscore": {
           "version": "1.6.0",
-          "resolved": "http://registry.npmjs.org/underscore/-/underscore-1.6.0.tgz",
+          "resolved": "https://registry.npmjs.org/underscore/-/underscore-1.6.0.tgz",
           "integrity": "sha1-izixDKze9jM3uLJOT/htRa6lKag=",
           "dev": true
         },
@@ -18302,7 +18288,7 @@
           "dependencies": {
             "ansi-align": {
               "version": "1.1.0",
-              "resolved": "http://registry.npmjs.org/ansi-align/-/ansi-align-1.1.0.tgz",
+              "resolved": "https://registry.npmjs.org/ansi-align/-/ansi-align-1.1.0.tgz",
               "integrity": "sha1-LwwWWIKXOa3V67FeawxuNCPwFro=",
               "dev": true,
               "requires": {
@@ -18930,7 +18916,7 @@
                 },
                 "is-accessor-descriptor": {
                   "version": "0.1.6",
-                  "resolved": "http://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
+                  "resolved": "https://registry.npmjs.org/is-accessor-descriptor/-/is-accessor-descriptor-0.1.6.tgz",
                   "integrity": "sha1-qeEss66Nh2cn7u84Q/igiXtcmNY=",
                   "dev": true,
                   "requires": {
@@ -18950,7 +18936,7 @@
                 },
                 "is-data-descriptor": {
                   "version": "0.1.4",
-                  "resolved": "http://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
+                  "resolved": "https://registry.npmjs.org/is-data-descriptor/-/is-data-descriptor-0.1.4.tgz",
                   "integrity": "sha1-C17mSDiOLIYCgueT8YVv7D8wG1Y=",
                   "dev": true,
                   "requires": {
@@ -21021,7 +21007,7 @@
     },
     "stream-combiner": {
       "version": "0.2.2",
-      "resolved": "https://registry.npmjs.org/stream-combiner/-/stream-combiner-0.2.2.tgz",
+      "resolved": "http://registry.npmjs.org/stream-combiner/-/stream-combiner-0.2.2.tgz",
       "integrity": "sha1-rsjLrBd7Vrb0+kec7YwZEs7lKFg=",
       "dev": true,
       "requires": {
diff --git a/package.json b/package.json
index 26c688e629..860067b899 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
     "@polymer/gen-typescript-declarations": "^1.5.1",
     "@polymer/iron-component-page": "^3.0.0-pre.12",
     "@polymer/test-fixture": "^3.0.0-pre.12",
-    "@webcomponents/webcomponentsjs": "^2.2.2",
+    "@webcomponents/webcomponentsjs": "^2.2.5",
     "babel-eslint": "^7.2.3",
     "babel-preset-minify": "^0.2.0",
     "del": "^3.0.0",

From 98304fb60143fd26bd1679be04ed7c0648c2a489 Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Mon, 4 Feb 2019 12:01:09 -0800
Subject: [PATCH 4/8] Updates based on review.

---
 lib/mixins/property-effects.js     |  27 +++---
 test/unit/path-effects-elements.js | 132 ++++++++++++++++++++++++++---
 test/unit/path-effects.html        |  56 ++++++++++--
 3 files changed, 183 insertions(+), 32 deletions(-)

diff --git a/lib/mixins/property-effects.js b/lib/mixins/property-effects.js
index 030c7951c5..d78f42f657 100644
--- a/lib/mixins/property-effects.js
+++ b/lib/mixins/property-effects.js
@@ -964,17 +964,13 @@ function parseArg(rawArg) {
   return a;
 }
 
-function getArgValue(data, props, structured, path) {
-  if (structured) {
-    let value = get(data, path);
-    // when data is not stored e.g. `splices`, get the changed value
-    if (value === undefined) {
-      value = props[path];
-    }
-    return value;
-  } else {
-    return data[path];
+function getArgValue(data, props, path) {
+  let value = get(data, path);
+  // when data is not stored e.g. `splices`, get the changed value
+  if (value === undefined) {
+    value = props[path];
   }
+  return value;
 }
 
 // data api
@@ -992,8 +988,7 @@ function getArgValue(data, props, structured, path) {
  * @private
  */
 function notifySplices(inst, array, path, splices) {
-  let splicesPath = path + '.splices';
-  inst.notifyPath(splicesPath, { indexSplices: splices });
+  inst.notifyPath(path + '.splices', { indexSplices: splices });
   inst.notifyPath(path + '.length', array.length);
 }
 
@@ -2155,14 +2150,16 @@ export const PropertyEffects = dedupingMixin(superClass => {
       for (let i=0, l=args.length; i<l; i++) {
         let {name, structured, wildcard, value, literal} = args[i];
         if (!literal) {
-          value = getArgValue(data, props, structured, name);
           if (wildcard) {
             const matches = isDescendant(name, path);
+            const pathValue = getArgValue(data, props, matches ? path : name);
             value = {
               path: matches ? path : name,
-              value: matches ? getArgValue(data, props, structured, path) : value,
-              base: value
+              value: pathValue,
+              base: matches ? get(data, name) : pathValue
             };
+          } else {
+            value = structured ? getArgValue(data, props, name) : data[name];
           }
         }
         values[i] = value;
diff --git a/test/unit/path-effects-elements.js b/test/unit/path-effects-elements.js
index 4deac1bc44..7c153e4e75 100644
--- a/test/unit/path-effects-elements.js
+++ b/test/unit/path-effects-elements.js
@@ -254,15 +254,50 @@ Polymer({
 
 Polymer({
 
-  is: 'x-reentry-wildcard',
+  is: 'x-reentry-true',
 
   properties: {
-    array: {
-      type: Array,
-      computed: 'computeArray(trigger, size)'
+    prop: {
+      type: Boolean,
+      computed: 'computeProp(trigger, value)'
+    },
+    value: {
+      type: Boolean
+    },
+    trigger: {
+      type: Boolean,
+      observer: 'triggerChanged',
+      value: true
+    }
+  },
+  
+  observers: ['propChanged(prop.*)'],
+
+  created() {
+    this.propChanged = sinon.spy();
+  },
+  
+  computeProp(trigger, value) {
+    return Boolean(value);
+  },
+  
+  triggerChanged() {
+    this.value = true;
+  }
+  
+});
+
+Polymer({
+
+  is: 'x-reentry-undefined',
+
+  properties: {
+    prop: {
+      type: Boolean,
+      computed: 'computeProp(trigger, value)'
     },
-    size: {
-      type: Number
+    value: {
+      type: Boolean
     },
     trigger: {
       type: Boolean,
@@ -271,18 +306,93 @@ Polymer({
     }
   },
   
-  observers: ['arrayChanged(array.*)'],
+  observers: ['propChanged(prop.*)'],
 
   created() {
-    this.arrayChanged = sinon.spy();
+    this.propChanged = sinon.spy();
   },
   
-  computeArray(trigger, size) {
-    return new Array(size || 0);
+  computeProp(trigger, value) {
+    return value ? undefined : true;
   },
   
   triggerChanged() {
-    this.size = 1;
+    this.value = true;
+  }
+  
+});
+
+Polymer({
+
+  is: 'x-reentry-undefined-path',
+
+  properties: {
+    prop: {
+      type: Object
+    },
+    value: {
+      type: Boolean
+    },
+    trigger: {
+      type: Boolean,
+      value: true
+    }
+  },
+  
+  observers: [
+    'computeProp(trigger, value)',
+    'triggerChanged(trigger)',
+    'propChanged(prop.sub.*)'
+  ],
+
+  created() {
+    this.propChanged = sinon.spy(function() {
+      this.debug = true;
+    });
+  },
+  
+  computeProp(trigger, value) {
+    if (value) {
+      this.set('prop.sub', undefined);
+    } else {
+      this.prop = {sub: true};
+    }
+  },
+  
+  triggerChanged() {
+    this.value = true;
+  }
+  
+});
+
+Polymer({
+
+  is: 'x-reentry-splices',
+
+  properties: {
+    array: {
+      type: Array,
+      value() { return []; }
+    }
+  },
+  
+  observers: [
+    'changeArray(array.splices.*)',
+    'arrayChanged(array.splices.*)'
+  ],
+
+  created() {
+    this.arrayChanged = sinon.spy(function() {
+      this.debug = true;
+    });
+  },
+
+  changeArray() {
+    if (this.array.length === 0) {
+      this.push('array', 'one');
+    } else if (this.array.length === 1) {
+      this.push('array', 'two')
+    }
   }
   
 });
diff --git a/test/unit/path-effects.html b/test/unit/path-effects.html
index 0347dc1a11..57ae116f80 100644
--- a/test/unit/path-effects.html
+++ b/test/unit/path-effects.html
@@ -1206,13 +1206,57 @@
   });
 
   test('reentry after wildcard observer queued', function() {
-    let el = document.createElement('x-reentry-wildcard');
+    let el = document.createElement('x-reentry-true');
     document.body.appendChild(el);
-    assert.equal(el.arrayChanged.callCount, 2);
-    assert.equal(el.arrayChanged.firstCall.args[0].base.length, 1);
-    assert.equal(el.arrayChanged.firstCall.args[0].value.length, 1);
-    assert.equal(el.arrayChanged.secondCall.args[0].base.length, 1);
-    assert.equal(el.arrayChanged.secondCall.args[0].value.length, 1);
+    assert.equal(el.propChanged.callCount, 2);
+    assert.equal(el.propChanged.firstCall.args[0].base, true);
+    assert.equal(el.propChanged.firstCall.args[0].value, true);
+    assert.equal(el.propChanged.secondCall.args[0].base, true);
+    assert.equal(el.propChanged.secondCall.args[0].value, true);
+    document.body.removeChild(el);
+  });
+
+  // TODO(kschaaf): address code in `getArgValue` that looks in changedProps
+  // when `undefined` for splices, which breaks this test (latent issue)
+  test.skip('reentry after prop goes back to undefined', function() {
+    let el = document.createElement('x-reentry-undefined');
+    document.body.appendChild(el);
+    assert.equal(el.propChanged.callCount, 2);
+    assert.equal(el.propChanged.firstCall.args[0].base, undefined);
+    assert.equal(el.propChanged.firstCall.args[0].value, undefined);
+    assert.equal(el.propChanged.secondCall.args[0].base, undefined);
+    assert.equal(el.propChanged.secondCall.args[0].value, undefined);
+    document.body.removeChild(el);
+  });
+
+  // TODO(kschaaf): address code in `getArgValue` that looks in changedProps
+  // when `undefined` for splices, which breaks this test (latent issue)
+  test.skip('reentry after path goes back to undefined', function() {
+    let el = document.createElement('x-reentry-undefined-path');
+    document.body.appendChild(el);
+    assert.equal(el.propChanged.callCount, 2);
+    assert.equal(el.propChanged.firstCall.args[0].base, undefined);
+    assert.equal(el.propChanged.firstCall.args[0].value, undefined);
+    assert.equal(el.propChanged.secondCall.args[0].base, undefined);
+    assert.equal(el.propChanged.secondCall.args[0].value, undefined);
+    document.body.removeChild(el);
+  });
+
+  test('reentry from array splices', function() {
+    let el = document.createElement('x-reentry-splices');
+    document.body.appendChild(el);
+    assert.equal(el.arrayChanged.callCount, 3);
+    assert.deepEqual(el.arrayChanged.getCalls()[0].args[0].value, {
+      indexSplices: [{ 
+        index: 1, addedCount: 1, removed: [], object: el.array, type: 'splice'
+      }]
+    });
+    assert.deepEqual(el.arrayChanged.getCalls()[1].args[0].value, {
+      indexSplices: [{ 
+        index: 0, addedCount: 1, removed: [], object: el.array, type: 'splice'
+      }]
+    });
+    assert.deepEqual(el.arrayChanged.getCalls()[2].args[0].value, undefined);
     document.body.removeChild(el);
   });
 

From 09fa9854311365cf3aa971ac4f561c15ab26466f Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Mon, 4 Feb 2019 12:02:16 -0800
Subject: [PATCH 5/8] Upgrade wcjs

---
 package-lock.json | 6 +++---
 package.json      | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index b468dee87f..d3fd24d2f2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1310,9 +1310,9 @@
       "integrity": "sha512-bx0TzeZ11VqYDGLuXfznen8+4u0hADk2dD5RNMFxWL9MM4c5NXCDCgNXgssb4i2zQOos/GGe4tl5AuE0LzJkLA=="
     },
     "@webcomponents/webcomponentsjs": {
-      "version": "2.2.5",
-      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.2.5.tgz",
-      "integrity": "sha512-aLSQa2+NjGv+6hwjQ/mHhrav7qhRf1ZMsUNWNqP3ca9BK9YoDmjsrcFFr8TaZ+ucwm+JiNVEtoQinNpbn863pw==",
+      "version": "2.2.6",
+      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.2.6.tgz",
+      "integrity": "sha512-TbuyV7hHIq4jMlvQ8pF3C6QNEqFeBX4be9AND5DO8UCRRYcZBpjl1yH9IChbebeWr1QNcK5WlZC3voAlQCdisQ==",
       "dev": true
     },
     "abbrev": {
diff --git a/package.json b/package.json
index 860067b899..3fcebe360a 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
     "@polymer/gen-typescript-declarations": "^1.5.1",
     "@polymer/iron-component-page": "^3.0.0-pre.12",
     "@polymer/test-fixture": "^3.0.0-pre.12",
-    "@webcomponents/webcomponentsjs": "^2.2.5",
+    "@webcomponents/webcomponentsjs": "^2.2.6",
     "babel-eslint": "^7.2.3",
     "babel-preset-minify": "^0.2.0",
     "del": "^3.0.0",

From 0c85340b1282a7d81e574b7bc3eb9cff2948694f Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Mon, 4 Feb 2019 14:09:48 -0800
Subject: [PATCH 6/8] Fix lint errors.

---
 test/unit/path-effects-elements.js | 10 +++-------
 test/unit/path-effects.html        |  4 ++--
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/test/unit/path-effects-elements.js b/test/unit/path-effects-elements.js
index 7c153e4e75..c68de108b2 100644
--- a/test/unit/path-effects-elements.js
+++ b/test/unit/path-effects-elements.js
@@ -346,9 +346,7 @@ Polymer({
   ],
 
   created() {
-    this.propChanged = sinon.spy(function() {
-      this.debug = true;
-    });
+    this.propChanged = sinon.spy();
   },
   
   computeProp(trigger, value) {
@@ -382,16 +380,14 @@ Polymer({
   ],
 
   created() {
-    this.arrayChanged = sinon.spy(function() {
-      this.debug = true;
-    });
+    this.arrayChanged = sinon.spy();
   },
 
   changeArray() {
     if (this.array.length === 0) {
       this.push('array', 'one');
     } else if (this.array.length === 1) {
-      this.push('array', 'two')
+      this.push('array', 'two');
     }
   }
   
diff --git a/test/unit/path-effects.html b/test/unit/path-effects.html
index 57ae116f80..93b8401898 100644
--- a/test/unit/path-effects.html
+++ b/test/unit/path-effects.html
@@ -360,7 +360,7 @@
       let c = {}, b = {c}, a = {b};
       el.a = a;
       el.resetObservers();
-      c = {},
+      c = {};
       b = {c};
       el.set('a.b', b);
       assert.equal(el.aChanged.callCount, 1);
@@ -377,7 +377,7 @@
       let c = {}, b = {c}, a = {b};
       el.a = a;
       el.resetObservers();
-      c = {},
+      c = {};
       el.set('a.b.c', c);
       assert.equal(el.aChanged.callCount, 1);
       assert.deepEqual(el.aChanged.firstCall.args[0], {path: 'a.b.c', base: a, value: c});

From d3f27d0ad5349727c1cc9f22549f50b4c4fa21fe Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Mon, 4 Feb 2019 15:04:32 -0800
Subject: [PATCH 7/8] Add issue for TODO

---
 test/unit/path-effects.html | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/unit/path-effects.html b/test/unit/path-effects.html
index 93b8401898..feebb9c901 100644
--- a/test/unit/path-effects.html
+++ b/test/unit/path-effects.html
@@ -1218,6 +1218,7 @@
 
   // TODO(kschaaf): address code in `getArgValue` that looks in changedProps
   // when `undefined` for splices, which breaks this test (latent issue)
+  // https://github.com/Polymer/polymer/issues/5479
   test.skip('reentry after prop goes back to undefined', function() {
     let el = document.createElement('x-reentry-undefined');
     document.body.appendChild(el);
@@ -1231,6 +1232,7 @@
 
   // TODO(kschaaf): address code in `getArgValue` that looks in changedProps
   // when `undefined` for splices, which breaks this test (latent issue)
+  // https://github.com/Polymer/polymer/issues/5479
   test.skip('reentry after path goes back to undefined', function() {
     let el = document.createElement('x-reentry-undefined-path');
     document.body.appendChild(el);

From 67caf458ba189fbae170b20f99f1d0ea50bc3283 Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Mon, 4 Feb 2019 15:15:55 -0800
Subject: [PATCH 8/8] Add comment re: undefined issue

---
 lib/mixins/property-effects.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/mixins/property-effects.js b/lib/mixins/property-effects.js
index d78f42f657..a1808d6b2e 100644
--- a/lib/mixins/property-effects.js
+++ b/lib/mixins/property-effects.js
@@ -966,7 +966,11 @@ function parseArg(rawArg) {
 
 function getArgValue(data, props, path) {
   let value = get(data, path);
-  // when data is not stored e.g. `splices`, get the changed value
+  // when data is not stored e.g. `splices`, get the value from changedProps
+  // TODO(kschaaf): Note, this can cause a rare issue where the wildcard
+  // info.value could pull a stale value out of changedProps during a reentrant
+  // change that sets the value back to undefined.
+  // https://github.com/Polymer/polymer/issues/5479
   if (value === undefined) {
     value = props[path];
   }