Discuss WF checks and type aliases

[nikomatsakis]

Summary

We should discuss our plans around well-formedness requirements for type aliases. This has been a long-standing point, and with the edition coming up, we may want to make some changes here.

Background reading

You don't necessarily have to read all these, but before the meeting I at least would try to prepare some information to present based on these sources:

• Perform WF-check on types with no type parameters rust#69741 -- proposes to add checks only for non-generic cases
• finish up type alias PRs rust#55222 -- "finish up type alias PRs", contains notes from the last push we made on this point
• Reject bounds in type aliases with edition 2024 rust#49441 -- proposal to reject type alias PRs

About this issue

This issue corresponds to a lang-team design meeting proposal. It corresponds
to a possible topic of discussion that may be scheduled for deeper discussion
during one of our design meetings.

[nikomatsakis]

Tentatively scheduled for July 1st.

EDIT: Unscheduled for now, because we have 2 other upcoming meetings.

[nikomatsakis]

Scheduled for July 22.

[nikomatsakis]

Rescheduled to July 29.