Re: Plan for the 5.9 branch

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Wed, Feb 19, 2020 at 2:32 AM Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx> wrote:
>
> Now, suppose we add a new feature in March, then in April make
> a release off master that ships that feature, and then in May we find
> a bug in that feature.  Are we allowed to break compatibility with the
> the April version of the feature in order to fix the bug?

If it's a bug such that the feature does not function usably in some
circumstances, or causes a crash, compatibility isn't an issue.

If it's a behavioral difference where the feature does something
usable/useful but inconsistent with the intended behavior, then the
compatibility question arises.  The longer the feature has been "in
the wild" the more likely we are to need to keep compatibility.  For
two months I wouldn't be especially concerned; two years and it
becomes serious.

I can't think of a better approach than to poll a few user channels
(zsh-users, /r/zsh, whatever) to get a feel for how many people are
depending on the anomalous behavior and whether the repair would be
preferable.  Other considerations are how easy it is to make a
run-time decision about which behavior is present (testing a version
number is not an "easy" test in this situation).