Currently it's not clear whether Url::fromUserInput expect a URL relative to the Drupal root, or relative to the host.
In 99% of the cases this is the same, but when installing Drupal in a subdirectory this is not the same.
If Drupal is installed in example.com/subdirectory one might understand that it's possible to pass the url relative to the host to Url::fromUserInput (/subdirectory/whatever-route). This however should never happen, as it results in incorrectly parsed Url strings. (subdirectory/subdirectory/whatever-route)
The fact that this is not documented, and the fact that the testbot in some cases doesn't actually fail, leads to problems: see the related issues.
As said, there is no way of stripping out the subdirectory within current API. This is because the 'fromUserInput' can come from various sources which might or might not include the subdirectory. When that subdirectory is, say, 'admin', and the drupal relative url is also 'admin', there is no way to know what to strip away.
Proposed solution is to at least make sure that this is properly documented and that there is a clear pattern/helper of how to strip away the subdirectory if necessary.
Url::fromUserInput.
Postponed: needs info
10.1 ✨
Primarily changes documentation, not code. For Drupal core issues, select the Documentation component instead of using this tag. In general, component selection is preferred over tag selection.
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
This issue is being reviewed by the kind folks in Slack, #needs-review-queue-initiative. We are working to keep the size of Needs Review queue [2700+ issues] to around 400 (1 month or less), following Review a patch or merge request → as a guide.
@catch are you saying a follow up needs to be opened for #12 could you elaborate some?