Hi, Derrick Stolee wrote: > On 7/13/2020 4:18 PM, Junio C Hamano wrote: >> The "fail and warn" approach introduced in the previous step may be >> with smaller impact to the codebase, but >> >> - it requires the end-user to read, understand and execute the >> manual upgrade >> >> - it encourages to follow the same procedure blindly, making the >> protection even less useful >> >> Let's instead keep failing hard without teaching how to bypass the >> repository protection, but allow upgrading even when only the >> worktreeconfig extension exists in an old repository, which is >> likely to be set by a broke version of Git that did not update the >> repository version when setting the extension. > > This is a more subtle way to handle the case. In fact, it > silently makes extensions.worktreeConfig work as it did in 2.27, > which means users will not have any troubles after upgrading. I'd like to propose a different endgame: Instead of looking at `extensions.*` settings one by one to see how various implementations handled them with repositoryFormatVersion=0, what if we treat repositoryFormatVersion=0 as a synonym of version=1? That is: 1. in new repositories, set repositoryFormatVersion = 1, since (1) Git versions in the wild should all already know how to handle it and (2) as we've learned, other Git implementations need to understand some of extensions.* anyway 2. whenever setting any extensions.*, automatically upgrade to repositoryFormatVersion = 1 3. when in an existing repository with extensions.* set and repositoryFormatVersion = 0, act as though repositoryFormatVersion = 1 4. document this new behavior with repositoryFormatVersion = 0 in Documentation/technical/repository-version.txt This way, the result is simpler than where we started. Unfortunately, we are not even that consistent about what to do with extensions.* settings when repositoryFormatVersion = 0 today. So we'll have to exercise some care and analyze them one by one to make sure this is safe (and if it isn't, at *that* point we'd come up with a more complex variant on (2) and (3) above). It's too late to go that far for 2.28. It would be tempting to try a simple revert of 14c7fa269e4 (check_repository_format_gently(): refuse extensions for old repositories, 2020-06-05) to get back to tried and true behavior but that does not do enough --- it still produces an error when trying to upgrade repository format when any extensions are set. So how about such a revert plus Junio's patch plus the analogous change to Junio's patch for extensions.preciousObjects extensions.partialClone ? Thanks, Jonathan
