Fix inability to remove 'Disabled' state from AccessibilityStates

Summary:
D8842691 split AccessibilityTraits into multiple RN properties.  However, the accessor code did not support REMOVING traits.
This results in buttons that were disabled (AccessibilityTraits & NotEnabled === true) never being enabled.

Fix the issue by making the split accessors properly mask in the bits, allowing you unset them without disturbing bits managed by the other accessor.

NOTE: setting AccessibilityTraits and AccessibilityRole or AccessibilityStates will still result in bugs.

Reviewed By: shergin

Differential Revision: D9661970

fbshipit-source-id: 77d70dd0754f2eaf8cbf895bfc13757c697a76d8

Author: Zack Gomez

Libraries/Components/View/ViewAccessibility.js

@@ -80,6 +80,7 @@ module.exports = {
     'radiobutton_checked',
     'radiobutton_unchecked',
   ],
+  // This must be kept in sync with the AccessibilityRolesMask in RCTViewManager.m
   AccessibilityRoles: [
     'none',
     'button',
@@ -93,5 +94,6 @@ module.exports = {
     'header',
     'summary',
   ],
+  // This must be kept in sync with the AccessibilityStatesMask in RCTViewManager.m
   AccessibilityStates: ['selected', 'disabled'],
 };

React/Views/RCTViewManager.m

@@ -151,12 +151,22 @@ - (RCTShadowView *)shadowView
 
 RCT_CUSTOM_VIEW_PROPERTY(accessibilityRole, UIAccessibilityTraits, RCTView)
 {
-    view.reactAccessibilityElement.accessibilityTraits |= json ? [RCTConvert UIAccessibilityTraits:json] : defaultView.accessibilityTraits;
+  // This mask must be kept in sync with the AccessibilityRoles enum defined in ViewAccessibility.js
+  const UIAccessibilityTraits AccessibilityRolesMask = UIAccessibilityTraitNone | UIAccessibilityTraitButton | UIAccessibilityTraitLink | UIAccessibilityTraitSearchField | UIAccessibilityTraitImage | UIAccessibilityTraitKeyboardKey | UIAccessibilityTraitStaticText | UIAccessibilityTraitAdjustable | UIAccessibilityTraitHeader | UIAccessibilityTraitSummaryElement;
+
+  UIAccessibilityTraits newTraits = json ? [RCTConvert UIAccessibilityTraits:json] : defaultView.accessibilityTraits;
+  UIAccessibilityTraits maskedTraits = newTraits & AccessibilityRolesMask;
+  view.reactAccessibilityElement.accessibilityTraits = (view.reactAccessibilityElement.accessibilityTraits & ~AccessibilityRolesMask) | maskedTraits;
 }
 
 RCT_CUSTOM_VIEW_PROPERTY(accessibilityStates, UIAccessibilityTraits, RCTView)
 {
-    view.reactAccessibilityElement.accessibilityTraits |= json ? [RCTConvert UIAccessibilityTraits:json] : defaultView.accessibilityTraits;
+  // This mask must be kept in sync with the AccessibilityStates enum defined in ViewAccessibility.js
+  const UIAccessibilityTraits AccessibilityStatesMask = UIAccessibilityTraitNotEnabled | UIAccessibilityTraitSelected;
+
+  UIAccessibilityTraits newTraits = json ? [RCTConvert UIAccessibilityTraits:json] : defaultView.accessibilityTraits;
+  UIAccessibilityTraits maskedTraits = newTraits & AccessibilityStatesMask;
+  view.reactAccessibilityElement.accessibilityTraits = (view.reactAccessibilityElement.accessibilityTraits & ~AccessibilityStatesMask) | maskedTraits;
 }
 
 RCT_CUSTOM_VIEW_PROPERTY(pointerEvents, RCTPointerEvents, RCTView)