Ember Data FEATURES aren't merged with Ember FEATURES

[alexander-alvarez]

There a feature in ds-check-should-serialize-relationships which has been true since ember-data 2.12 https://github.com/emberjs/data/blob/v2.12.0/config/features.json#L7

My interpretation of https://guides.emberjs.com/v2.16.0/configuring-ember/feature-flags/#toc_flagging-details leads me to believe that I should be able to use said feature in a non-beta (and non-canary) release of Ember.

I haven't gotten this to work

alexander-alvarez/ds-features-not-enabled@d89e7f3 reproduces it on ember: 2.15.x and ember-data: 2.15.x

My diagnosis

This check https://github.com/emberjs/data/blob/master/addon/serializers/json-api.js#L582 fails

When I dump Ember.FEATURES I get

{
  "ember-libraries-isregistered":false,
  "ember-improved-instrumentation":false,
  "ember-metal-weakmap":false,
  "ember-glimmer-allow-backtracking-rerender":false,
  "ember-routing-router-service":true,
  "ember-engines-mount-params":true,
  "ember-module-unification":false,
  "glimmer-custom-component-manager":false,
  "mandatory-setter":true,
  "ember-glimmer-detect-backtracking-rerender":true
}

which are the features enabled in https://github.com/emberjs/ember.js/blob/v2.15.1/features.json

Should it not also contain the features in ember-data's features.json?

[runspired]

@rwjblue we removed all of our feature flags, but we should still get this fixed before we add any new ones.

[runspired]

Feature flag infra was later improved to not require merging with Ember's.