This statement makes me wonder if people already know the effort that is put into the extension scanner and the documentation that has to be written for every change.
Let me shorty describe how I would deal with an extension upgrade for version 9 and why I don't really get these concerns.
Given you have a version 8 installation with some extensions, you
- Uninstall all extensions
- Upgrade the core
- Enter the install tool and start the extension scanner which covers (at this very moment) about 60-70% of all deprecations that we have in master.
I assume you browse the messages and study the documentation to understand what has changed and why. Then you adjust your code according to the documents. After that the chances are high you have very few or no parts in your code base that rely on deprecated code. However, you might have an inspection (PHPStorm) in place that scans for deprecated stuff and there are a few things left.
Q: Why aren't these things covered by the extension scanner in the first place?
A: It's very likely that it could not be covered by a simple rule and therefore is a change you can hardly describe in one sentence.
Given that statement is true in most cases, a oneliner, hardly describing the change, will not help you at all. I'd even say, that if you are willing to solve a problem, that couldn't be covered by the extension scanner, on your own (without or with hardly any documentation), you are doing something wrong.
I truly believe that all of us will even become better develoers by reading the documentation, even if you are not struck by a change. Because, in most cases, changes happen as code is improved. Especially when things become deprecated.
Sorry, but I really hope everyone did. Why should we even write documentation in the first place if developers first try to solve problems on their own instead of getting all the necessary information from the one who is responsible for the change and therefore the work the developer is dealing with?
I assume providing a link might be difficult as the link is not known at the time of writing the patchset, but we have the issue number. Like many others said, we could add that to the deprecation message and you'll easily find the docs, if you are not using the extension scanner or the scanner didn't help.