Problem/Motivation
As stated in the parent issue #3050389: Remove dependency to Classy from core themes, Classy will be moved to contrib before Drupal 9 and we have to remove dependencies on Classy from all core themes.
This process included documenting template usage in this spreadsheet:Core Theme's use of Classy. This documenting made it apparent that there are 24 templates in Classy that are identical to the same-named templates in Stable. This makes it possible to simply remove these files so they are no longer a Classy dependency for any core theme. (as opposed to copying individual versions of every Classy-inherted template to every core theme, a step that will be necessary for most templates.
Running diff -srq classy/ stable/ | grep identical shows that these templates are identical:
Files classy/templates/content-edit/file-upload-help.html.twig and stable/templates/content-edit/file-upload-help.html.twig are identical
Files classy/templates/content-edit/file-widget-multiple.html.twig and stable/templates/content-edit/file-widget-multiple.html.twig are identical
Files classy/templates/field/image-style.html.twig and stable/templates/field/image-style.html.twig are identical
Files classy/templates/form/checkboxes.html.twig and stable/templates/form/checkboxes.html.twig are identical
Files classy/templates/form/confirm-form.html.twig and stable/templates/form/confirm-form.html.twig are identical
Files classy/templates/form/container.html.twig and stable/templates/form/container.html.twig are identical
Files classy/templates/form/dropbutton-wrapper.html.twig and stable/templates/form/dropbutton-wrapper.html.twig are identical
Files classy/templates/form/form-element-label.html.twig and stable/templates/form/form-element-label.html.twig are identical
Files classy/templates/form/form.html.twig and stable/templates/form/form.html.twig are identical
Files classy/templates/form/input.html.twig and stable/templates/form/input.html.twig are identical
Files classy/templates/navigation/links.html.twig and stable/templates/navigation/links.html.twig are identical
Files classy/templates/navigation/menu-local-action.html.twig and stable/templates/navigation/menu-local-action.html.twig are identical
Files classy/templates/navigation/pager.html.twig and stable/templates/navigation/pager.html.twig are identical
Files classy/templates/navigation/vertical-tabs.html.twig and stable/templates/navigation/vertical-tabs.html.twig are identical
Files classy/templates/views/views-view-grid.html.twig and stable/templates/views/views-view-grid.html.twig are identical
Files classy/templates/views/views-view-list.html.twig and stable/templates/views/views-view-list.html.twig are identical
Files classy/templates/views/views-view-mapping-test.html.twig and stable/templates/views/views-view-mapping-test.html.twig are identical
Files classy/templates/views/views-view-opml.html.twig and stable/templates/views/views-view-opml.html.twig are identical
Files classy/templates/views/views-view-row-opml.html.twig and stable/templates/views/views-view-row-opml.html.twig are identical
Files classy/templates/views/views-view-rss.html.twig and stable/templates/views/views-view-rss.html.twig are identical
Files classy/templates/views/views-view-unformatted.html.twig and stable/templates/views/views-view-unformatted.html.twig are identical
There are 3 additional templates that should be added to this list as they should be identical.classy/templates/field/image-formatter.html.twig: the only difference a line in Classy's DocBlock that should have been removed in #2350837: Convert most usages of EntityInterface::getSystemPath() to use routes.classy/templates/form/select.html.twig: the only difference are annotation changes that should have been applied to Stable in #2546248: Use consistent style to mention HTML tags in code comments, but were only applied to Classy.classy/templates/form/field-multiple-value-form.html.twig: the version in stable had a line of whitespace following the DocBlock that was not present in Classy's
Proposed resolution
Address the differences in the 3 almost-identical templates listed in Problem/Motivation
Remove the templates from Classy
Add a test that confirms these templates were truly identical.
Remaining tasks
Implement, review.
User interface changes
n/a
API changes
n/a
Data model changes
n/a
Release notes snippet
n/a