feat(types): drop TypeScript < 4.1

[ephys]

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• [no, the opposite actually] Have you added new tests to prevent regressions?
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Follow-up to sequelize/meetings#6 (comment)
This PR drops support for TypeScript < 4.1 and documents our TS support policy.

This release should cause a SemVer MINOR bump.

[WikiRik]

Small suggestion for additional clarity

[WikiRik]

Also, do we really want this in v6?

[ephys]

This in v6 would allow us to merge #13909 in v6 which would provide an easier migration path to the model changes I'd like to make in v7 (simplying model definition to class User extends Model<User> {}).

But I am also of two minds about it

[fzn0x]

I think it will be backward incompatible for some users right? how about adding it to v7 instead?

[ephys]

It will be incompatible for users that haven't updated TypeScript since Nov. 19 2020 yes. Which is why I'm of two minds.

On one hand, adding this to v6 would allow us to land #13909 in v6 which would be a great improvement for TS users & make migration to v7 easier. And 4.1 is more than one year old.
I also believe we should not make our TS changes SemVer major (hence the documentation update to reflect our policy).

On the other hand, tsc will report an error for users that are still on < 4.1.

But honestly, I have typings errors all the time after upgrades. Even Sequelize adding proper types for Model#toJSON completely broke the typings in my projects because my override had a different signature, so we (and others) are already causing typing breaking changes all the time in minor versions, or even patch. It's just too difficult to avoid. TypeScript itself doesn't follow SemVer (sequelize/meetings#6 (comment))

Honestly my only problem with this change is that we didn't document it earlier. But I think given it's been more than a year since 4.1, it's fine. Users that haven't updated TS since then are not going to update Sequelize either.

[WikiRik]

Yeah, it's more about that we have a policy now relatively close to a new major release. But I agree that with the changes we made to the typings many people that have updated to the latest version of sequelize also have a relatively new version of TS as well.

If migrating to v7 is made easier with this change I think it's fine if we do this in v6

[fzn0x]

If this makes our work easier for migrate typings, approve!

[ephys]

It won't make our job easier but it will allow users to massively reduce the boilerplate they need to write for TS support in v6

Current way: https://github.com/sequelize/sequelize/blob/main/docs/manual/other-topics/typescript.md#usage
Possible new way if we merge this in v6: https://github.com/sequelize/sequelize/blob/120e2447dc166d256f030dbc07928776b24aa649/docs/manual/other-topics/typescript.md#usage

Which would also make migration easier as that second way is what I'd like to make the default in v7

[ephys]

I'll merge this because there is consensus that we should support >= 4.1 in v7 ; but we can still debate whether we land it in v6 or not :)

Edit: If I understand correctly we first need to mark tests TS Typings (3.9) & TS Typings (4.0) as not required in the repository settings, which requires @sdepold?

[sdepold]

Power to the people!

it now requires either of @sdepold @ephys @WikiRik :)

[ephys]

Thanks @sdepold :')

[WikiRik]

I'll merge this because there is consensus that we should support >= 4.1 in v7 ; but we can still debate whether we land it in v6 or not :)

Seeing the difference in usage I think it's good to include this in v6 as well. Seeing that we have updated various typings in the recent releases of v6 already it should be fine.

Edit: If I understand correctly we first need to mark tests TS Typings (3.9) & TS Typings (4.0) as not required in the repository settings, which requires sdepold?

I updated the required checks so it requires 4.1 - 4.5 already for the main branch

[sdepold]

What's the benefit of having this in v6?

[WikiRik]

It won't make our job easier but it will allow users to massively reduce the boilerplate they need to write for TS support in v6

Current way: https://github.com/sequelize/sequelize/blob/main/docs/manual/other-topics/typescript.md#usage Possible new way if we merge this in v6: https://github.com/sequelize/sequelize/blob/120e2447dc166d256f030dbc07928776b24aa649/docs/manual/other-topics/typescript.md#usage

Which would also make migration easier as that second way is what I'd like to make the default in v7

@sdepold this is the benefit of having it in v6

EDIT: so not this PR specifically, but it allows us to merge other PRs to v6 as well which will accomplish at least the example quoted

[fzn0x]

It won't make our job easier but it will allow users to massively reduce the boilerplate they need to write for TS support in v6

Current way: https://github.com/sequelize/sequelize/blob/main/docs/manual/other-topics/typescript.md#usage Possible new way if we merge this in v6: https://github.com/sequelize/sequelize/blob/120e2447dc166d256f030dbc07928776b24aa649/docs/manual/other-topics/typescript.md#usage

Which would also make migration easier as that second way is what I'd like to make the default in v7

Cool!

[sdepold]

Ah sorry. My Mumbo jumbo brain somehow thought that this thread is about the utils conversion.

I think we should change the docs part in the commit message to something else. Maybe Feature for the lack of a better idea since docs is likely to result in a patch version

[ephys]

feat works for me. None of the others would cause a minor bump and we're not tagging it as BREAKING CHANGE

[github-actions]

🎉 This PR is included in version 7.0.0-alpha.6 🎉

The release is available on:

• npm package (@release-v7 dist-tag)
• GitHub release

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