I will leave it to Ben to expand on the timeline. As for !10479 the decision to merge this in 9.14 has been made on 15th of July. Since 9.14 is going to be an LTS release, ultimately the choice was between: * A increased workload for many backports over the next years by pushing it to 9.16.    Accompanied by a further delay of resolving bugs related to polymorphic specialisation. * The risk of introducing bugs through landing it now and a potential delay of 9.16 While bugs are always a risk, pushing it to 9.16 is unlikely to meaningfully reduce the number of bugs landing this will incur. In the end those bugs will need to be fixed, be that in 9.14.2 or 9.16.2. It's not uncommon to identify *some* bugs in patches on master. However with !10479 there has been more testing than usual on the MR pre-merge. Including not just head.hackage but also other packages. Reducing the risk associated with this somewhat. With 9.14 having a planned lifetime of potentially three years, backporting through this change would add up to a fairly high cost over time. Which is the main argument for landing this patch in 9.14. This was discussed in the GHC call and ultimately we came to the conclusion that given the resources available, and the state and nature of the patch landing it for 9.14 is the preferable option. Since then not much has changed. While pushing the MR back to 9.16 *now* would be possible, it's unclear this would change the release date meaningfully. After all there are other unresolved blockers for the first alpha for 9.14. It's also worth pointing out that most of the delays on 9.14 had to do with toolchain issues and were not related to this patch being included at all. Should !10479 become the sole blocker for a number of days, or should a large number of issues be discovered that can be traced back to it during the alpha it would make sense to reevaluate this decision. We have never ruled out this option completely. However today I still believe going forward with !10479 being included in 9.14 is in the best interest of the GHC project. Especially because it will reduce the cost of maintaining the LTS branch going forward. Cheers Andreas On 12/08/2025 13:27, Matthew Pickering wrote:

Hi,

Thanks for the update Ben. Can you clarify the timeline now?

It seems that there is a plan to merge !10479 into the 9.14 branch.

https://gitlab.haskell.org/ghc/ghc/-/merge_requests/10479

!10479 appears to be a very significant patch which touches many sensitive areas of the compiler. I believe regressions will be reported due to this patch.

It also will be merged two months after the merge deadline for the branch and the release schedule seems to have already slipped significantly.

Therefore, I believe it would be prudent to delay merging this one until the 9.16 release so that regressions can be discovered and fixed before it is released to users.

Cheers,

Matt

On Tue, Aug 12, 2025 at 12:25 PM Andreas Klebinger via ghc-devs wrote:

...

I'm merely forwarding this from ghc-releases for those not following there:

Hi all,

A brief update on the GHC 9.14 release status. As noted last time, the release process has been held up by a few significant bodies of on-going work:

- the upgrade of the Windows toolchain which has revealed a number of linking issues,

- enabling support for LLVM 20 (#26267), along with the resolution of a few correctness issues which were uncovered in the process (#26109)

- the resolution to #23109, a rather invasive correctness fix which we want to ensure is adequately tested prior to the release,

At this point we have resolved, or are close to resolving, all of these issues. We expect that #23109 will land today, with the resolution to #26109 hopefully landing shortly thereafter.

One wrinkle here is a late request for a boot library bump (#26268) which has had a number of knock-on effects. We are still trying to land this in `master`; we tentatively plan to backport but given how the state of the release process we will not delay the release if things do not go smoothly.

Once the above has happened we will backport to `ghc-9.14` and begin preparation of the first alpha release. This may happen as soon as Thursday.

Cheers,

- Ben

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