Views' cache tag-based caching only sets cache tags for related entities based on Views relationships, should also do so for entity reference fields

Updated: Comment #0

Problem/Motivation

#1712456: How to leverage cache tags in Views introduced cache tags for Views. And there was rejoicing :)

Unfortunately, I found a few pesky problems :( (While investigating #2183017: Views doesn't bubble up rendered entities' cache tags.)

Steps to reproduce

1. Install Drupal 8 in the Standard profile.
2. Edit the front page view (at admin/structure/views/view/frontpage) and enable tag-based caching.
3. Create one node (with a title, a taxonomy term or two and something in the body field), that is visible on the front page.
4. Visit the front page. Now you will have some data in your cache_views_results DB table.

The "results" cache entry

Cache ID: frontpage:page_1:results:<something like e7266527aeec0343c0f02bc762f6e9f7ddc3708b36fe774c7f5fc0a0ed708a3e>

Cache tags: view:frontpage node_view:1 node:1 node_view_article:1

As you can see, the cache tags for the taxonomy terms and the author user are missing.

The "output" cache entry

Cache ID: frontpage:page_1:output:<something like ebd8521f12c0efa33b507a11561c55f882ab8be5c9c0fdb2d28cc0f0685e12de>

Cache tags: view:frontpage node_view:1 node:1 node_view_article:1

The same remarks as for the "results" cache entry apply… with one added caveat: in this case, the cache tag for the text format used in the body field should also appear!
In other words, the cache tags in this case should be a superset of the cache tags generated for the rendered entities and their fields… which in fact makes this problem almost exactly #2183017: Views doesn't bubble up rendered entities' cache tags, but not quite.

Proposed resolution

TBD

Remaining tasks

TBD

User interface changes

None.

API changes

TBD