Add configuration option to allow unreachable! in test functions

[AMS21]

changelog: [unreachable]: Add configuration option to allow usage in test functions

Summary Notes

• Feature-freeze by samueltardieu

Managed by @rustbot—see help for details

[rustbot]

r? @dswij

rustbot has assigned @dswij.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[samueltardieu]

Seems that you are trying to add a new configuration option!

We are currently in a feature freeze, so we are delaying all lint-adding PRs to September 18 and #15086.

Thanks a lot for your contribution, and sorry for the inconvenience.

@rustbot note Feature-freeze
@rustbot blocked
@rustbot label +A-lint