injecting query results (salsaification)

[oli-obk]

Meeting proposal info

• Title: Allow queries to insert the return value of other queries
• Type: technical

Summary

Allow queries that programmatically insert entries into the query cache for certain keys. This allows queries to return results for keys that they would otherwise not have logic for.

A preliminary implementation including a demo is included in rust-lang/rust#96840, but we'll want to present and discuss this scheme before merging it.

cc @cjgillot

About this issue

This issue corresponds to a meeting proposal for the compiler team
steering meeting. It corresponds to a possible topic of
discussion. You can read more about the steering meeting procedure
here.

Comment policy

These issues are meant to be used as an "announcements channel"
regarding the proposal, and not as a place to discuss the technical
details. Feel free to subscribe to updates. We'll post comments when
reviewing the proposal in meetings or making a scheduling decision.
In the meantime, if you have questions or ideas, ping the proposers
on Zulip (or elsewhere).

[pnkfelix]

We had the meeting

Document: https://hackmd.io/8dZwSvOKR-6TFMTEe8nKJA

Zulip: https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bsteering.5D.202022-11-04.20compiler-team.23562.20inj.2E.20query.20results/near/307977502