Optional deprecation phase between `Runtime` and `End-of-Life`

[LiviaMedeiros]

Currently, the runtime deprecation warning phase is immediately followed by the complete removal of a deprecated feature.
In some cases, user code that relies on a deprecated feature continues to work after the End-of-Life phase but produces different results, which is usually worse than failing with explicit error.
To mitigate this, we could introduce an additional phase (namely 'throwing deprecation'). This phase would force users to update their code (or cap the max supported Node.js version) while still keeping End-of-Life with complete removal in next major release as the final goal.

[richardlau]

Do we need a whole need deprecation phase?

Runtime deprecations and End-of-Life are semver-major:

node/doc/contributing/collaborator-guide.md

Lines 490 to 492 in 038d829

	Runtime Deprecations and End-of-Life APIs (internal or public) are breaking
	changes (`semver-major`). The TSC can make exceptions, deciding that one of
	these deprecations is not a breaking change.

which means there should normally be one full release runtime deprecation (i.e. prints warning). A move to End-of-Life deprecation could be objected to at PR time, deferring to a future semver-major.

[targos]

Same question as Richard. I think we can introduce a thrown error at the End-of-Life stage (and eventually remove the throw later as a cleanup).

[LiviaMedeiros]

which means there should normally be one full release runtime deprecation (i.e. prints warning).

The problem here is that runtime deprecation might be ignored for a long time (unless --throw-deprecation becomes de-facto default for everyone), and at the first glance EoL will "fix" the warning. Introducing throwing for one extra major release would delay the actual EoL but potentially save someone from extra grey hair.

I think we can introduce a thrown error at the End-of-Life stage (and eventually remove the throw later as a cleanup).

Yep, this is essentially the same, End-of-Life as throwing phase and cleanup as the actual EoL. The only difference is the formal definition. Touching deprecation after reaching End-of-Life sounds awkward.
Were there any precedents when EoL's throw was removed in next major releases?

[github-actions]

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