Disable legacy lifecycle methods linting in scope of no-deprecated rule for now

[sergei-startsev]

As per Dan's request, legacy lifecycle methods have been "excluded" from no-deprecated rule for now since the methods aren't formally deprecated yet.

UPDATED: The original PR has been broken down into 2 parts, the current includes changes related to no-deprecated rule. The 2nd PR is #2075.

Summary

• Legacy lifecycle methods linting has been disabled in no-deprecated rule until it's decided which release deprecates them. React version 16.999.0 has been set for componentWillMount, componentWillUpdate, componentWillReceiveProps lifecycle methods to disable lint errors for now.
• rename-unsafe-lifecycles codemod details have been added to no-deprecated rule.
• no-unsafe rule has been adjusted to handle all unsafe life-cycle methods including their aliases. Developers who want to avoid using of legacy lifecycle methods can enable it today.
• Instructions on updating components have been adjusted in no-unsafe rule to be consistent with React runtime warnings.
• Documentation pages have been updated.
• Corresponding unit tests have been updated/added.

@gaearon, @ljharb could you take a look?

[ljharb]

Just to confirm: this PR will not cause any new errors to be issued, it will only reduce errors for those with a version set low enough?

[ljharb]

this description should remain, since it's still valid given the proper version settings.

[sergei-startsev]

Fixed

[ljharb]

these are a semver-patch.

[sergei-startsev]

It has to be semver-MINOR, otherwise it doesn't suppress deprecation warnings for the existing React versions (16.3.0 - 16.6.3) where these component lifecycle methods aren't deprecated yet.

[ljharb]

why? a minor is for adding new options - this isn't adding a new feature, it's just removing warnings for 16.3-16.6 users. Can you explain more?

[sergei-startsev]

I might have misunderstood your first comment. What semver did you mean? React or eslint-plugin-react? I agree that current PR can be considered as a patch of eslint-plugin-react.

[ljharb]

I'm talking about this repo :-)

[sergei-startsev]

@ljharb PR doesn't cause any new errors for react/recommended preset, it disables linting of legacy lifecycle methods until it's decided which release deprecates them.

To allow developers to prevent using of unsafe methods in ^16.3.0 React versions, no-unsafe rule has been adjusted. The rule isn't in the recommended list.

[ljharb]

Not being in the recommended list isn't solely the issue - if no-unsafe is going to be creating new errors for any existing consumer of it, it's potentially a breaking change.

[sergei-startsev]

I find it unlikely that no-unsafe rule is used without no-deprecated or code contains both legacy lifecycle methods and their aliases, however it can be theoretically. I could propose to split the PR to two:

• the 1st includes disabling no-deprecated warnings (no breaking changes);
• the 2nd PR will contain adjustments for no-unsafe (potential breaking changes)

Thoughts?

[ljharb]

Certainly separating it out to get the non-breaking parts in sooner is a great idea. It'd be great, however, if we could find a way to avoid the breaking changes on no-unsafe as well.

[sergei-startsev]

@ljharb There're no breaking changes in updated PR now.