[BUGFIX release] Ensure local state can shadow attrs.

packages/ember-htmlbars/lib/hooks/get-root.js

@@ -30,12 +30,12 @@ function getKey(scope, key) {
 
   var self = scope.self || scope.locals.view;
 
-  if (scope.attrs && key in scope.attrs) {
+  if (self) {
+    return self.getKey(key);
+  } else if (scope.attrs && key in scope.attrs) {
     // TODO: attrs
     // Ember.deprecate("You accessed the `" + key + "` attribute directly. Please use `attrs." + key + "` instead.");
     return scope.attrs[key];
-  } else if (self) {
-    return self.getKey(key);
   }
 }
 

packages/ember-htmlbars/lib/templates/legacy-each.hbs

@@ -1,5 +1,5 @@
-{{~#each view._arrangedContent -legacy-keyword=keyword as |item|~}}
-  {{~#if keyword}}
+{{~#each view._arrangedContent -legacy-keyword=view.keyword as |item|~}}
+  {{~#if view.keyword}}
     {{~#if attrs.itemViewClass~}}
       {{~#view attrs.itemViewClass _defaultTagName=view._itemTagName~}}
         {{~legacy-yield item~}}

packages/ember-htmlbars/tests/integration/attrs_lookup_test.js

@@ -0,0 +1,84 @@
+import Registry from 'container/registry';
+import compile from 'ember-template-compiler/system/compile';
+import ComponentLookup from 'ember-views/component_lookup';
+import Component from 'ember-views/views/component';
+import { runAppend, runDestroy } from 'ember-runtime/tests/utils';
+import EmberView from 'ember-views/views/view';
+
+var registry, container, view;
+
+QUnit.module('component - attrs lookup', {
+  setup() {
+    registry = new Registry();
+    container = registry.container();
+    registry.optionsForType('component', { singleton: false });
+    registry.optionsForType('view', { singleton: false });
+    registry.optionsForType('template', { instantiate: false });
+    registry.register('component-lookup:main', ComponentLookup);
+  },
+
+  teardown() {
+    runDestroy(container);
+    runDestroy(view);
+    registry = container = view = null;
+  }
+});
+
+QUnit.test('should be able to lookup attrs without `attrs.` - template access', function() {
+  registry.register('template:components/foo-bar', compile('{{first}}'));
+
+  view = EmberView.extend({
+    template: compile('{{foo-bar first="first attr"}}'),
+    container: container
+  }).create();
+
+  runAppend(view);
+
+  equal(view.$().text(), 'first attr');
+});
+
+QUnit.test('should be able to lookup attrs without `attrs.` - component access', function() {
+  var component;
+
+  registry.register('component:foo-bar', Component.extend({
+    init() {
+      this._super(...arguments);
+      component = this;
+    }
+  }));
+
+  view = EmberView.extend({
+    template: compile('{{foo-bar first="first attr"}}'),
+    container: container
+  }).create();
+
+  runAppend(view);
+
+  equal(component.get('first'), 'first attr');
+});
+
+QUnit.test('should be able to modify a provided attr into local state #11571 / #11559', function() {
+  var component;
+
+  registry.register('component:foo-bar', Component.extend({
+    init() {
+      this._super(...arguments);
+      component = this;
+    },
+
+    didReceiveAttrs() {
+      this.set('first', this.getAttr('first').toUpperCase());
+    }
+  }));
+  registry.register('template:components/foo-bar', compile('{{first}}'));
+
+  view = EmberView.extend({
+    template: compile('{{foo-bar first="first attr"}}'),
+    container: container
+  }).create();
+
+  runAppend(view);
+
+  equal(view.$().text(), 'FIRST ATTR', 'template lookup uses local state');
+  equal(component.get('first'), 'FIRST ATTR', 'component lookup uses local state');
+});