Add Drupal core compatibility info to release & project pages
>>> [!note] Migrated issue
<!-- Drupal.org comment -->
<!-- Migrated from issue #3121281. -->
Reported by: [dww](https://www.drupal.org/user/46549)
>>>
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p>This has come in in passing in various places. Drupal core's Update manager now knows if a recommended release is compatible with your currently-installed version of Drupal core or not. See especially <span class="drupalorg-gitlab-issue-link project-issue-status-info project-issue-status-7"><a href="https://www.drupal.org/project/drupal/issues/3102724" title="Status: Closed (fixed)">#3102724: Improve usability of core compatibility ranges on available updates report</a></span>.</p>
<p>The d.o case is harder, since we don't know what the currently installed version of core is going to be for any random visitor. So we can't actually say "Compatible" vs. "Not compatible" nor can we filter/prune the ranges based on only showing future updates (which is what Update manager does). But we can do something.</p>
<h3 id="summary-proposed-resolution">Proposed resolution</h3>
<p>Add something about core compatibility on d.o release nodes.</p>
<p>At the bare minimum, we can print out the Composer semver library constraints that are present in the release history feeds, e.g.:</p>
<pre>Core compatibility: ^8.7.10<br>Core compatibility: ^8.8 || ^9<br>...</pre><p>Better yet, translated into human-speak:</p>
<pre>Compatible with Drupal core: 8.7.10 and up<br>Compatible with Drupal core: 8.8.0 and higher for 8*, or any version of Drupal 9<br>...</pre><p>
(approx)</p>
<p>@xjm mocked this up:<br>
<img src="https://www.drupal.org/files/issues/2020-03-30/Semantic_versioning_example___Drupal_org.png"></p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
<ol>
<li>Decide exactly what this should look like.</li>
<li>Implement.</li>
<li>Review/test.</li>
<li>Commit</li>
<li>Deploy.</li>
</ol>
<h3 id="summary-ui-changes">User interface changes</h3>
<p>TBD.</p>
<h3 id="summary-api-changes">API changes</h3>
<p>Probably none.</p>
<h3 id="summary-data-model-changes">Data model changes</h3>
<p>Probably none.</p>
<h3 id="summary-release-notes">Release notes snippet</h3>
<p>N/A</p>
> Related issue: [Issue #3102724](https://www.drupal.org/node/3102724)
> Related issue: [Issue #3096078](https://www.drupal.org/node/3096078)
issue