Provider: Migrate provider to null-safety

[mehmetf]

This is a tracker issue for migrating package:provider to null-safety. More details coming soon.

[mehmetf]

We first need to migrate package:nested which is a dependency of provider.

[mehmetf]

@rrousselGit FYI null-safety is still in beta. Why are we migrating some packages now? package:provider is a critical package to Flutter ecosystem. As such, it is being used in other critical packages/apps that we would like to migrate.

We have several options w.r.t. to this migration before null-safety hits stable in Dart:

• Keep separate a separate null-safety branch and keep it in sync with master. This is useful if you want to be able to develop/submit fixes to non-null-safe version of the code and publish it on pub. However, it is quite an overhead.

• Declare master to be null-safe and change pubspec accordingly. The downside for this is that you have effectively frozen your normal releases until null-safety hits stable. If users want to use the null-safe version, they would need to upgrade their Flutter/Dart version to something that supports null-safety. This is what we recommend. It gives you a clean null-safe master repo to work on.

• Don't do anything. We can fork this package within Google and migrate it. We can then send you a PR that sits there unmerged until you feel like merging it. This is also not the best option since the PR will atrophy.

[rrousselGit]

Hello!

I'm fine with either of these solutions.
Honestly, I would do the migration myself. But I am in the middle of a burnout at the moment.

Hopefully I will be able to resume working after a little bit of time

[vishna]

Take care! Added a PR for nested https://github.com/rrousselGit/nested/pull/10

[mit-mit]

It looks like all deps of provider have migrated now:

• collection: 1.15.0-nullsafety.5
• nested: 0.0.5-nullsafety.1

[mehmetf]

Yes, we have a draft PR that aims to migrate provider but migrating the tests are challenging as they heavily use mockito.

[rrousselGit]

I will fully migrate provider by the end of the week.

[mehmetf]

Thanks Remi. Take care of yourself first. As I mentioned, it is not a big deal if we cannot push all the _right_ changes in the first cut. Just making it null-safe compatible would suffice to unblock further migration up the chain.

[rrousselGit]

In case some people missed it:

A null-safety version is available on pub: 5.0.0-nullsafety.1

[mehmetf]

Remi, do you intend to merge this to master so that any subsequent changes to code is null-safe?

[rrousselGit]

Not for now

Since NNBD isn't available on stable as far as I know, that would prevent updates for people using the stable channel

[mehmetf]

OK. Originally, stopping the updates to stable is what I have recommended in https://github.com/rrousselGit/provider/issues/573#issuecomment-730070224.

So, instead, you prefer accepting more PRs in master, rebasing and fixing the null-safety PR and merging when nnbd hits stable, right?

That's fine by me as well. We need to move to null-safe version in Google but I can stop updating it for now and resume when you merge null-safety PR to master.

[rrousselGit]

Provider is unlikely to have a lot of changes in the short term

I just think keeping NNBD in a separate branch for now is the best bet, as I have no idea when would be the stable release of non-nullable types.

Since I'm working on a tab in Flutter's devtool to inspect the state of providers at the moment, it would be a shame if stable users couldn't benefit from it until NNBD is released officially

[mehmetf]

Looking forward to it. Thanks!